Acta Neurochir (Wien) (2007) 149: 647–660 DOI 10.1007/s00701-007-1179-0 Printed in The Netherlands Review Article Treatment of vestibular schwannomas. Why, when and how? E. Myrseth1 , P.-H. Pedersen1 , P. Møller2, and M. Lund-Johansen1 1 2 Department of Neurosurgery, Institute of Surgical Science, Haukeland University Hospital, University of Bergen, Bergen, Norway Department of Otorhinolaryngology, Institute of Surgical Science, Haukeland University Hospital, University of Bergen, Bergen, Norway Received July 13, 2006; accepted February 8, 2007; published online June 11, 2007 # Springer-Verlag 2007 Summary Introduction Sporadic vestibular schwannoma (VS) causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. In many cases, the tumour size may remain unchanged for many years following diagnosis, which is typically made by MRI. In the majority of cases the tumour is small, leaving the clinician and patient with the options of either serial scanning or active treatment by gamma knife radiosurgery (GKR) or microneurosurgery. Despite the vast number of published treatment reports, comparative studies are few, and evidence is no better than class III (May, 2006). The predominant clinical endpoints of VS treatment include tumour control, facial nerve function and hearing preservation. Less focus has been put on symptom relief and health-related quality of life (QOL). It is uncertain if treating a small tumour leaves the patient with a better chance of obtaining relief from future hearing loss, vertigo or tinnitus than by observing it without treatment. Recent data indicate that QOL is reduced in untreated VS patients, and may differ between patients who have been operated and patients treated with GKR. In the present paper we review the natural course and complaints of untreated VS patients, and the treatment alternatives and results. Furthermore, we review the literature concerning quality of life in patients with VS. Finally, we present our experience with a management strategy applied to more than 300 cases since 2001. Vestibular schwannoma (VS) is a benign tumour arising from the Schwann cells in the vestibular component of the statoacoustic nerve. The clinical incidence rate is 10–15 per million=year [45, 76, 79, 129], but the widespread use of MRI may lead to detection of more tumours and an increase in incidence. Post-mortem dissections of temporal bones have shown the incidence of small tumours to be much higher (0, 9%) possibly due to selection bias [124, 130]. In an unselected autopsy material of 298 temporal bones, no tumours were found [21, 53]. The diagnosis of VS is usually made in adults with a mean age ranging from 46 to 58 years in various series [37, 74, 84, 110, 140]. VS is rarely found in teenagers, and in these cases the tumour is often associated with neurofibromatosis type 2 (NF-2). Surgical treatment of VS has been one of the most challenging procedures of neurosurgical practice for more than a century. In 1894 Charles Ballance was probably the first surgeon to remove a VS, and in the surgical report he described the difficulties of getting his index finger around the tumour to achieve removal. The patient was still alive twelve years later although with fifth and seventh nerve palsies. Concerned about the high morbidity and mortality of early VS surgery, Cushing advocated intracapsular tumour debulking. As standards of neurosurgery and anaesthesiology improved, the concept of total tumour removal was reintroduced by Dandy. Olivecrona and Keywords: Vestibular schwannoma; microsurgery; radiosurgery; quality of life. 648 subsequent neurosurgeons contributed to further neurosurgical development by addressing facial nerve preservation [36]. In the early 1960’s Bill House set a new standard by introducing the operating microscope as a valuable tool in VS surgery (for a review: see Ref. [72]). In the early seventies Lars Leksell introduced Gamma knife radiosurgery (GKR), and it was demonstrated that GKR produced VS growth arrest or even involution. Until December 2004, 28,306 VS patients had been treated worldwide with GKR in 181 out of 213 reporting centres (http:==www.elekta.com=). Obvious as it may sound, it is nevertheless important to remember that the treatment of any condition only can be justified if the results of the treatment are better than the natural course of the disease. There is a growing debate on how VS can be best treated as it has become clear that the tumour may remain unchanged in size for years following diagnosis. A careful follow-up by MRI, so-called ‘‘wait and scan’’, has therefore emerged as a safe way of management in VS patients with small and medium-sized tumours. Thus, newly diagnosed VS may be managed by three principally different approaches. The options are, ‘‘wait and scan’’, GKR or surgical resection, and the decision needs to be made whether active treatment is indicated and which method of intervention is appropriate. VS treatment has traditionally focused on tumour control and preservation of cranial nerve function. During recent years however, health related quality of life (HRQOL) has emerged as a new issue in caretaking of VS patients, addressing outcome factors other than traditionally used endpoints. This research has given information about the patient’s perception of the disease and treatment in relation to daily activities and overall well-being. In the present article we review relevant data which may serve as a premise for future debate about VS treatment. This includes the clinical features and HRQOL in VS patients managed by ‘‘wait and scan’’, GKR, or surgical resection. Finally, we discuss treatment algorithms for VS patients and present our own management strategy. E. Myrseth et al. [10, 75, 80, 101, 107, 125, 134]. In a recent metaanalysis of VS growth, Yoshimoto found 22 retrospective and 4 prospective studies including 1340 patients [144]. The proportion of tumours showing growth varied considerably, from 15 to 85% in the different reports (average 46%), and the mean growth rate was 1.2 mm=year during a mean observation period of 38 months (range 6–64). Prospective studies, utilising MRI serial imaging showed tumour growth rates lower than the retrospective reports. Previous tumour growth has been shown to represent a predictor for further growth and eventual treatment [10, 24]. Intracanalicular tumours seem to have lower growth rates than extracanalicular lesions [101, 134], and a younger age is associated with more rapid tumour growth [74]. No other reliable clinical or radiological predictors have been found [101, 116, 123, 134]; for instance, the clinical growth index, as measured by the length of history divided by the maximum tumour diameter, did not associate with growth. Using volume estimations Mohyuddin et al. found a doubling time of 1.65 years (range 20.9–46.3 months) in 50 VS patients [80]. Modern neuroimaging software programs allow onscreen volume estimation, which may improve future studies of tumour growth [21]. Cochlear nerve symptoms Unilateral hearing loss The most common symptom of VS is reduced hearing on the affected side (Table 1). When hearing is measured, it is necessary to quantify both pure tone audiometry and speech discrimination and the results obtained are frequently classified using the Gardner-Robertson scale [35]. On admission, about 95% of patients report unilateral hearing impairment. Audiometry shows that serviceable hearing (Gardner-Robertson grade A þ B or class A1 þ A2 according to the Nordstadt ClassificaTable 1. Symptoms at onset and on admission in 301 patients with vestibular schwannoma referred to the oto-neurosurgical group at Haukeland University Hospital 2001–2005 Natural history Tumour growth The growth pattern of VS is highly variable, ranging from spontaneous involution [66] to rapid growth [46]. The tumours usually grow slowly or remain unchanged for years or growth may progress in a stepwise pattern Reduced hearing Tinnitus Vertigo Unsteadiness % Presenting % On admission 60.1 32.7 23.4 11.9 92.3 69.5 42.5 38.9 There is an increase in frequency of symptoms during the interval between onset and admission. 649 Treatment of vestibular schwannomas Table 2. Hearing acuity on admission, both ears, according to the Gardner-Robertson grading scheme in 298 out of 301 patients with vestibular schwannoma Grade Tumour ear (%) Contralateral ear(%) A B C D 22.3 26.3 14.2 37.2 90.9 7.3 1.1 0.7 tion) is present in about 50% of patients at diagnosis (Table 2). According to large series, the mean duration of gradual hearing loss before diagnosis is about 4 years [74, 83]. Increased age associates significantly with hearing disability in untreated VS patients [74]. Typically, hearing loss develops gradually, but an acute onset is found in 12–22% of patients [74, 77, 93]. The possible aetiological factors in these patients include a conduction block of the cochlear nerve or vascular compression within the internal auditory canal (IAC) by a tumour arising laterally. VS is rarely the cause of sudden deafness, as shown in the study by Saunders and co-workers, who found only 13 cases of VS among 836 such patients [119]. Patients suffering from sudden hearing loss seek medical attention early, and have a shorter clinical history than patients in whom the hearing loss is gradual [77, 93]. Tinnitus Subjective tinnitus is a false perception of sound in the absence of an acoustic stimulus [62]. In a prevalence study, 2.6% of the responders reported severe tinnitus [4]. Tinnitus associates with age, and is more common in men than in women affecting approximately 11% of men between age 64 and 75 years [62]. Tinnitus may be present in a deaf ear, supporting the hypothesis of a central pathophysiological origin. It is the second most frequent symptom in VS patients, occurring in 63–75% [74, 83, 84] of patients (Table 1) and in one third of those affected the symptom is intermittent. Tinnitus may be inversely proportional with tumour size [74, 83], and is associated with depression [105]. The intensity of tinnitus may be quantified subjectively by self-reporting questionnaires, such as the Tinnitus Impairment Index or a visual analogue scale (VAS) index [8, 68, 105]. Vestibular nerve symptoms Vertigo Vestibular nerve symptoms are found in 40–60% of VS patients (Table 1) who may report a combination of vertigo, dizziness and unsteadiness [54, 55, 74]. Dizziness is a common complaint, over time affecting up to 20–30% of individuals in the general population [87]. The incidence of true vestibular vertigo is approximately 5% and is distinguished from other types of dizziness by a sensation of movement. It is a result of a mismatch between the vestibular, visual, and somato-sensory systems. Since the functional ranges of these systems overlap, it permits partial compensation of their individual deficiencies [16, 25]. Vertigo may be constant or intermittent, ‘‘nautical’’ (feeling like being on a ship), or rotatory. Vertigo is associated with a significant reduction in HRQOL [29, 83, 142]. Vertigo is difficult to quantify by objective means but self-reporting instruments such as an impairment index or a VAS scale may be used [96]. Unsteadiness About 40–50% of VS patients (Table 1), report unsteadiness at diagnosis [19, 83]. In the study by Matthies and Samii, balance testing with eyes closed had the highest rates of pathological findings in Class T1 (purely intrameatal) and T4 (compressing the brain stem) tumours. Vestibular nerve signs were most pronounced in Class T1, and cerebellar signs in Class T4 tumours [74]. Sway motion can be measured by monitoring path length and speed, or area of sway on a balance platform [91]. Usually, values increase when the subject is tested with eyes closed, and the ratio between results obtained when testing with open and closed eyes, the so called Romberg Index, may be calculated. A modern stabilometry platform, such as the Equi-Test+ system (Neurocom, Clackamas, OR, USA), enables the investigator to discriminate vestibular from other causes of unsteadiness. In addition, results are automatically compared with built-in age-adjusted reference data. The path lengths of VS patients are significantly longer than those of normal subjects [83] especially when tested with eyes closed [19]. Thus, the reduced vestibular function in VS patients seems to be partially compensated by vision. Other symptoms and clinical findings Preoperative headache was recalled by one third of operated VS patients in a large retrospective cohort study [109, 110], and by 18% in a Finnish study [55]. In our prospective material, 42 out of 301 patients (14%) complained of headache, in 17 patients this was reported as a ‘‘fullness’’ or pressure in the ear region ipsilateral to the tumour. Since headache is a very common symptom 650 E. Myrseth et al. Table 3. Other neurological findings in 301 patients with vestibular schwannoma Table 4. Tumour length along the pyramid in 301 patients with vestibular schwannoma Impaired sensation in face Impaired corneal reflex Reduced taste Pyramidal signs Tumour size (mm) 11.0% 5.9% 5.2% 2.1% and there are no studies comparing headache in VS patients and a control group, it is uncertain whether headache is associated with untreated VS. A small proportion of newly diagnosed patients have gait disturbances or ataxia caused by hydrocephalus or compression of the brainstem and cerebellum. In addition, cranial nerve deficits, usually facial numbness and occasionally diplopia and dysphagia may be found [74, 83], usually associated with large tumours (Table 3). Canalicular <10 11–20 21–30 >30 28.6% 16.3% 33.9% 12.9% 8.3% angle (CPA), whereas tumour volumes were statistically similar in patients with or without tinnitus or vertigo [83]. In conclusion, many patients with useful hearing may loose it during conservative management. The development of other complaints is less known. Treatment Symptom progression Knowledge about the onset and development of complaints in VS patients is important when providing advice on conservative management. In addition, this knowledge is necessary to evaluate how treatment compares with the natural course of the tumour. Studies indicate that between one third [141] and one half [123] of conservatively managed VS patients loose useful hearing over a period of three years. Thus patients managed conservatively are definitely at risk of developing hearing loss. Our current knowledge about further symptom development during ‘‘wait -and scan’’ is scarce, and cannot be predicted to the individual patient. However, progression from onset to diagnosis is recalled by patients in several studies [55, 74]. In the 301 patients referred to us during the years 2001–2005, the median duration of symptoms at diagnosis was 26 months (mean 51). The patients report an increase in frequency of symptoms during the time interval from onset to diagnosis (Table 1). In a recent study of 199 untreated patients examined from 2001 out 2004 we found that the average length of the history was similar in patients with a combination of complaints and in patients presenting with hearing loss alone [83]. It is reported that symptoms and tumour growth may progress independently [134]. Although hearing impairment may associate with tumour growth, it may not be an indicator of growth. Tinnitus is reported to associate with small tumours, and vestibular disturbance with intrameatal lesions as well as large tumours compressing the brain stem [74]. In our study, we found that unsteadiness associated with large tumour size (more than 20 mm) in the cerebellopontine Conservative management (‘‘wait and scan’’: watchful waiting) The concept of ‘‘wait and scan’’ is based on two principles. First, a high proportion of the tumours do not grow following diagnosis. Second, there is little evidence that treatment of a non-growing lesion is beneficial to the patient, but well documented that treatment, in particular surgery, may cause additional complaints. Therefore, in spite of increasing hearing loss in many patients, conservative treatment may be a reasonable option for patients with small to medium-sized tumours. For the ‘‘wait and scan’’ strategy to be successful, patient compliance needs to be high and the follow up program meticulous [116, 123]. This is illustrated in two elderly patients who were referred to us during last year. In both, the tumour had been known for several years, but the follow up had been incomplete and both developed gait difficulties due to brainstem compression from a growing tumour. Such instances may be classified as complications of the ‘‘wait and scan’’ approach. Any progression of symptoms, such as hearing loss, may be considered a failure of conservative treatment. We believe that prospective studies need to be carried out before patients can be advised on a statistical basis about the relative merits of conservative management or GKR in relation to hearing preservation. Failure, defined as conversion from ‘‘wait and scan’’ to active treatment, is reported in 15–50% of patients in various studies [24, 85, 123, 141]. The authors do not report in detail why failure occurred, but tumour growth, increasing symptoms and patients’ own preference were probably the main reasons. 651 Treatment of vestibular schwannomas Surgery VS surgery is technically challenging, and several studies report on a gradual learning curve [17, 27, 52, 78, 136]. The translabyrinthine (TL) and the suboccipital=retrosigmoid (SO=RS) approaches can be used for all tumour sizes, whereas the middle cranial fossa (MCF) approach is useful only for removal of intracanalicular=small tumours. Hearing preservation can be achieved only through the SO=RS and MCF approaches. In many centres, VS patients are operated by an multidisciplinary team consisting of neurosurgeons and neurootologists [23, 84, 128], and the approach is chosen based on criteria such as tumour size, tumour extension, preoperative hearing level, and the surgeon’s experience. Tumour control In a review of 38 studies including a total of 5005 operated patients and 1475 treated with GKR, Yamakami and co-workers found on average 96% total tumour removal after microsurgery. The tumour recurrence rate was 1.8%, which compared favourably with the recurrence rates following radiosurgery and tumour progression following conservative treatment [141]. Some authors recommend subtotal tumour resection with subsequent GKR if a total resection puts the facial nerve function at a high risk [50], a strategy which is also advocated by our group. Due to inadequate access to the lateral part of the internal auditory canal, the RS=SO approach is claimed to be associated with a higher rate of tumour recurrence than the TL approach [143], but this has not been confirmed by comparative studies. Facial nerve preservation Second only to tumour removal, facial nerve preservation is the main goal of VS surgery. There are several grading systems for the evaluation of facial nerve function, the most widely used being the House-Brackmann scale [44] which provides a useful assessment tool. The scale is subjective and inter-observer variation is documented [20, 103]. In addition, the study by Martin and co-workers demonstrates that patients score their own facial function as being a poorer grade than assessed by the surgeons [73]. The size of the tumour and the surgeon’s experience are the pre-operative predictors of facial nerve outcome [11, 84, 114, 128]. In modern surgical practice per-operative facial nerve EMG is mandatory for anatomical and physiological monitoring, and provides a reliable predictor of post-operative function [39, 49, 73, 86]. In our experience (using the Nim- response system by Medtronic Xomed, Jacksonville, FL, USA), we have found that a stimulus of 0.10–0.20 mA generating normal signals indicates a good prognostic sign for normal post-operative facial nerve function. If the signals disappear in the medial portion of the nerve permanent facial nerve palsy may be expected, even if signals in the intracanalicular nerve segment are normal. It has been claimed that because the facial nerve is detected earlier during surgery it is more easily saved by the TL than by the SO=RS approach [14, 133], but evidence for this is difficult to find in published literature, as the functional results of both methods are within the same range [3, 14, 23, 58, 84, 90, 115, 139, 143]. Patients with small tumours (including intrameatal) who undergo the MCF approach may have a less favourable facial nerve outcome than those operated by the SO=RS or TL approaches [117], because the facial nerve is located superior to the tumour which usually arises from the inferior vestibular nerve in the internal auditory canal. When drilling into the IAC from above, the surgeon’s view of the tumour is obstructed by the facial nerve, which then becomes vulnerable to manipulation during tumour resection. Facial nerve transection is reported to occur in 2.5– 7% [23, 26, 114, 115] of surgical procedures. Immediate intracranial nerve repair should be attempted in such situations using a free graft from the great auricular or the sural nerve. Even in patients in whom the seventh nerve is anatomically and physiologically intact at closure, paresis increasing to complete palsy may develop during the early post-operative period. Usually, nerve function improves gradually over the next few months. In patients with postoperative facial nerve palsy, careful attention to the eye is necessary to prevent infection and erosions of the cornea caused by the impairment of eyelid closure. A tarsorraphy or insertion of a gold weight or spring in the upper eyelid will assist to protect the eye in these patients. When facial nerve function does not recover, reconstructive surgery by hypoglossal-facial or cross-face facial nerve anastomosis (with nerve graft) are the alternative methods of treatment. Either method may establish facial nerve function equivalent to House-Brackmann grade 3 in 61–79% of the patients [26]. In long lasting facial nerve palsies reconstruction of facial symmetry is achieved through various face-lift cosmetic procedures. Hearing preservation Post-operative hearing preservation correlates strongly with tumour size. In 1986, Glasscock et al. stated that 652 E. Myrseth et al. preservation of hearing is unlikely when the tumour is larger than 20 mm [38]. Yates et al. obtained no hearing preservation in tumours 25 mm in the CPA, and Tonn et al. had no hearing better than Gardner-Robertson grade D in tumours larger than 30 mm in the CPA [128, 143]. However, Samii and Matthies report good post-operative hearing preservation for a proportion of larger tumours [113]. Sanna and co-workers preserved hearing of class A or B, i.e. functional hearing according to the AAO-HNS grading scheme, in one third of patients operated by the SO=RS approach (tumors <20 mm in the CPA) or the MCF approach (tumour extending <5 mm into the CPA). Reviewing published series where patients had been operated through the SO=RS and MCF approaches to preserve hearing, the authors pointed out that their own complication rates of the latter were higher than in patients operated by the TL approach. They concluded that attempts at hearing preservation should be measured against the added risk of complications during these procedures [117]. In comparison with historical data, the intraoperative monitoring of cranial motor nerves and continuous recording of brain stem auditory evoked potentials (BAEP) substantially improves the outcome of hearing function [113, 128]. Similarly, studies reporting on post-operative vertigo are few, and prospective studies with baseline registration of symptom severity by VAS or impairment index questionnaires seem to be lacking. Lynn et al. assessed post-operative dysequilibrium (imbalance, vertigo, and light-headedness) in 237 VS patients operated by the SO=RS approach [69]. In this series, 65% reported dysequilibrium between 3 months and 7 years after surgery although with a mild impact on QOL. In the questionnaire study by Wiegand et al. [138], 9% of patients reported post-operative dysequilibrium as a severe handicap and only 10% reported normal function. In the prospective part of Levo et al.’s study [60], the sway velocity increased after the operation, and had not returned to preoperative values one year after surgery indicating an increase of vestibular complaints. Multivariate analysis revealed that the TL approach, rehabilitation, low age and preserved facial nerve function predicted a good outcome for postural stability. Patients operated by the SO=RS approach and diagnosed with depression were at risk of developing postoperative gait difficulties. In conclusion, most of our knowledge about the effect of VS surgery on tinnitus and vertigo derives from retrospective studies. Prospective studies with careful baseline recordings may provide further insight into these problems. Post-operative tinnitus, vertigo and unsteadiness Postoperative headache Only a few retrospective studies address the impact of VS surgery on tinnitus. The study by Baguley et al. investigating pre-and post-operative tinnitus among 129 patients, indicates a favourable effect with TL tumour removal [5]. The authors found that patients with no tinnitus preoperatively were unlikely to develop it, and mild or moderate tinnitus did usually remain unchanged, or it became less intense whereas severe tinnitus improved in some patients. In a study addressing HRQOL and the severity of tinnitus in a cohort of 51 operated VS patients, post-operative tinnitus did not correlate with tumour size or age [28]. The authors concluded that post-operative tinnitus status was unpredictable, but, in contrast to the results reported by Baguley et al., there was a slight overall increase in patients reporting tinnitus after surgery. Similar to our results [83], the authors found that tinnitus did not interfere with HRQOL measured by the GBI questionnaire. Andersson and coworkers concluded that among 141 patients operated, tinnitus was usually mild, and the likelihood of an improvement or worsening after surgery was low [2] and similar results were found by others [11, 138]. In the study by Ryzenman and co-workers, 42% of operated patients reported headache which was usually mild. Women, especially of a younger age, were more affected than men. During the first year after surgery, the SO approach was associated with headache more than the MCA and TL approaches, but this difference disappeared later. Tumour size did not associate with postoperative headache [110]. In our experience, postoperative headache is not a major problem in VS patients. We do not specifically address postoperative headache in our postoperative survey, but ask if there are any complaints other than the cardinal symptoms. We routinely use craniotomy with replacement of a free bone flap. Some studies indicate that a standard craniectomy may be associated with significant postoperative headache, which may be reduced with minimal bone removal during craniectomy [42, 51, 56, 118]. Other complications and mortality Improvements of surgical technique and refinements in anaesthesiology have reduced the mortality from more 653 Treatment of vestibular schwannomas than 25% in the hands of the early neurosurgical pioneers to 0–2% in the most recent series. In most patients the cause of death is postoperative cardiopulmonary complications [14, 23, 26, 41, 84, 112, 128, 141]. Apart from hearing loss and facial nerve dysfunction, CSF leakage is the most frequent postoperative complication, occurring in 3–15% of cases [14, 26, 41, 59, 112, 128]. Usually the CSF leak resolves after temporary lumbar drainage, leaving only a small number requiring a secondary procedure. The frequency of postoperative meningitis is about 1–3% [14, 26, 112, 128]. Cranial nerve or brainstem dysfunction is an infrequent postoperative problem, but may be found in patients with large tumors [15, 41, 59, 112]. Gamma knife radiosurgery (GKR) Dose and tumour control The Gamma knife consists of 201 60Cobalt sources which are arranged in a hemisphere. Beams from the radioactive sources are directed through collimators and converge to a common target. By individual plugging of collimators or weighting the different 60Cobalt sources the radiosurgeon can shape a three-dimensional radiation field similar to the lesion. Ideally, a single dose of radiation sufficient to stop further growth may be administered to the lesion, while the dose delivered to adjacent structures is much lower and therefore tolerable. Usually, the dose to the tumour margin is the primary radiophysical parameter during dose planning. Although there is no consensus about the optimal dose, high rates of tumour control with preservation of normal structures can be achieved with a margin dose of 12 Gy. Maximum doses of 20–25 Gy to the tumour centre are effective, but there is a tendency nowadays to reduce the maximum doses [32, 131, 132]. In order to obtain a margin dose of 12 Gy and a maximum dose within accepted limits, the maximum tumour diameter should not exceed approximately 30 mm. However, a recent study shows beneficial effect of low-dose GKR in a series of larger tumours, up to 40 mm [47]. GKR has been used for more than three decades, and worldwide an increasing number of VS patients receive treatment by GKR instead of surgery. The aim of GKR is tumour control, defined as either reduced or unchanged tumour volume. The majority of centres report tumour control rates between 89 and 100%, but few report observation periods longer than five years. Therefore, late regrowth may alter these figures, although a recent long-term series showing a 10-year progression- free survival of 92% indicates that recurrences develop during the first three years [43]. The tumour growth rates before GKR (or surgery) are usually unknown in reported series. Consequently, a proportion of treated tumours might have remained unchanged without any treatment at all. Effect on symptoms Hearing preservation according to the GardnerRobertson scale (grade A–C) is reported in 50% to 89% of patients undergoing GKR [31, 82, 94, 102, 116]. In our own retrospective material, the frequency of hearing loss was higher [84]. This may be due to variation in radiation doses, but may as well be related to differences in tumour volume and configuration. For instance, reports indicate that the risk of facial nerve dysfunction may correspond to the length of the nerve irradiated, tumour diameter and the dose delivered to the brainstem [30, 34, 61]. In the literature covering GKR of VS, the main focus of interest has been on tumour control and hearing preservation. The effect on tinnitus and vertigo is largely unknown. More knowledge about this is of interest, as reports indicate that in particular vertigo causes considerable discomfort and leads to impairment of quality of life [83, 87, 96, 142]. Complications The risk of facial nerve dysfunction has gradually decreased from approximately 30% in early series, to 1–4% [31, 33, 82, 131]. Facial nerve function of grade 1 or 2 according to the House-Brackmann system may therefore be expected in more than 96% of patients [67, 97, 131]. Similarly, trigeminal nerve function can be preserved in 95–97%, and as the prescribed dose to the tumour margin has been gradually lowered, post-irradiation trigeminal dysfunction is now rare [31, 32, 97]. Hydrocephalus may develop in 2–4% of VS patients treated by GKR [84, 92], and it should be suspected in a patient complaining of unsteadiness developing months or years after treatment. The underlying mechanism is uncertain, but it may be seen in medium-sized tumours, and thus is unrelated to CSF obstruction. Since it may also be seen in some untreated medium-sized tumours, the contribution of GKR to hydrocephalus development in VS patients is uncertain [106]. Post-GKR neoplasia, either as a second tumour or a malignant change in the treated lesion has been reported in a few cases [6, 40, 57, 63, 121, 122]. It is to be 654 expected that among the large number of patients treated worldwide by GKR for benign lesions, some will develop a malignant brain tumour or a meningioma at a later stage. Meningioma is the intracranial neoplasm usually associated with previous irradiation [18, 111], but an association with previous GKR has not been documented. Health-related quality of life in VS patients Today, VS may be regarded as a chronic disease which is only rarely life-threatening. Instead, the tumour causes discomfort and leads to hearing loss. Therefore, information about HRQOL during the course of treatment and conservative management is highly relevant for this group of patients. Quality of life is measured by validated generic or disease-specific questionnaires and is increasingly being used as secondary and even primary endpoints in clinical studies [13, 126, 127]. Generic questionnaires, which are applicable for patients with many conditions, allow comparisons between patient groups and a reference population [64, 65, 135]. Some studies utilize questionnaires addressing symptoms that are typically found in operated patients (see e.g. [1, 7, 48, 71, 95, 100, 102, 104, 109, 110, 116, 120, 133, 137] but to our knowledge a validated disease-specific questionnaire has not been reported for VS. Instead, the generic questionnaires SF-36 [9, 12, 22, 70, 73, 83, 84] and Glasgow Benefit Inventory (GBI) [83, 84, 88, 116] predominate. SF-36 can be used to distinguish among various stages of illness, and large scale reference data is available in many countries for comparison with ageand sex-matched controls. The GBI questionnaire requests the subject to compare QOL before and after a specific event (for example the diagnosis or treatment of VS). Three recent studies report on the QOL in untreated VS patients [70, 83, 116]. In a study of patients managed over a 15-year period, Sandoraam and co-workers demonstrated that patients managed conservatively reported better QOL than patients receiving GKR or microsurgery [116]. MacAndie and Crowther demonstrated that QOL in VS patients managed conservatively is similar to other patients with vestibulo-cochlear complaints [70]. In our prospective study of 199 untreated VS patients we investigated the impact of symptoms and tumour size on QOL, which was below normative values across six out of eight subscales of SF-36. We found that the overall predictor of reduced QOL in untreated VS patients was vertigo, which discriminated QOL across all SF-36 and two out of three GBI subscales. When patients were E. Myrseth et al. grouped according to tumour size, tinnitus or reduced hearing, less difference between groups was seen in the reported QOL [83]. Most of our knowledge about QOL in VS patients derives from retrospective studies of patients who received treatment (usually surgery) several years earlier. The responders usually reported QOL lower than norms. Somewhat surprisingly, poor facial nerve function associates only weakly with a reduction in QOL [12, 73, 84]. Only a few studies report on the QOL after GKR [84, 116]. In our study, we found a slightly better QOL outcome in the GKR than in the surgery group [84]. In the study by Regis and co-workers comparing GKR and surgery, the authors reported better QOL following GKR, but the questionnaires used were not validated [102]. One may speculate that patients managed conservatively are at risk of the QOL being reduced if treatment is necessary at a later stage because of a growing tumour. Two studies show that in patients who received treatment because conservative treatment failed, QOL was no worse than in patients who received treatment initially [10, 116]. When studying treatment of any disease, prospective pre-treatment baseline data are valuable. To our knowledge, studies comparing QOL before and after treatment, and during the course of conservative management of VS seem to be lacking, and should be undertaken. Treatment decision and clinical management Although the choice of treatment in VS patients is a controversial issue, the treatment decision process has been poorly investigated. A recent study of 139 VS patients managed at the Mayo Clinic showed that 23% of the patients chose ‘‘watchful waiting’’, 36% underwent GKR, and 40% underwent surgical tumour removal [98]. The authors found that the discipline of the attending surgeon was a predictor for the choice of treatment, and small tumour size and high age were predictors for conservative treatment. As discussed before, the criteria for successful treatment of VS rely on tumour control rates and cranial nerve preservation. Despite the large amount of studies concerning treatment results, studies comparing treatment methods are based on no better than class 3 evidence [89], with one recent exception of class 2 evidence showing better results (facial nerve function, complications, hearing preservation) for GKR than for surgery [99]. Few centres, if any, can offer VS patients 655 Treatment of vestibular schwannomas all available surgical methods and GKR. Clinicians recommend a treatment modality depending on what is available at their institution, and will convey that to the patients. It is our opinion that the alternatives ought to be presented to the patients in an unbiased fashion, and then discussed thoroughly with them [108]. Moreover, patients are more knowledgeable about their disease and treatment options than previously, and it is difficult to conduct prospective randomised studies. At the Haukeland University Hospital, Department of Neurosurgery, the Gamma knife was established in 1988 as the 5th centre worldwide. During the next 12 years, a total of 219 Norwegian VS patients were treated, 103 with GKR, and 116 with microsurgery [84]. Conservative treatment was used in a small number of selected patients [81]. GKR or microsurgery was administered to tumours 30 mm, and microsurgery (MS) to tumours >30 mm in the CPA. The choice of method depended on patient preference and the medical condition. Patients with vertigo were predominantly treated with surgery. In 2001, we launched a new treatment algorithm dividing patients into four categories, based on CPA tumour size and tumour growth: – – – – <5% risk of shunt-requiring hydrocephalus. Complaints and QOL probably unchanged. Very low risk of radiation-induced neoplasia. No recovery period necessary. MS: – Total tumour resection in more than 90%. – GKR of growing residual tumour is possible. – Facial nerve function is dependent of tumour size; 80% H-B grade 1 or 2. – Facial nerve reconstruction to HB grade 3 is possible. – Total hearing loss except in some small tumours. – Complaints and QOL probably unchanged. – Mortality <1%. – About 3 months to full recovery. Until January 2006, 301 patients with VS referred to our unit (Fig. 1) have signed a written consent and thus been enrolled into a prospective research program on 1. <20 mm, single observation or no growth – Conservative management. 2. <20 mm and growth on serial scans – GKR or MS. 3. 20–25 mm, single observation – GKR or MS. 4. >25 mm – MS. Conservative management involves outpatient consultation and contrast axial=coronal thin slice MRI at 6 and 12 months and then annually. In a few elderly category 2 patients with growing canalicular tumours we adopted a ‘‘wait and scan’’ approach. Although we established a limit of 25 mm for recommending GKR, tumours up to 30 mm were treated in a few patients who had a strong wish to avoid surgery. In the elderly, or medically ill patients, a few even larger lesions have received GKR treatment. These exceptions apart, the algorithm was applicable to nearly all patients. Patients in categories 2 and 3 received standardised information given orally by one of the authors about treatment alternatives as follows: GKR: – 90–95% tumour control. – Later surgery possible, but probably more difficult (in relation to dissection of VII nerve). – Facial nerve palsy very rare. – Gradual hearing loss may occur. Fig. 1. Age distribution in 301 VS patients referred to the otoneurosurgical group. Mean: 57.0 years Table 5. Primary and secondary treatment in 301 patients with vestibular schwannoma (see text for details) Wait and scan GKS Microsurgery Total Primary management Secondary management 165 81 55 301 20 3 2 25 Indicates that following initial decision to wait and scan, either GKR or microsurgery were given to 20 (ten in each) patients. 656 E. Myrseth et al. VS, approved by the regional Medical Ethical Committee. Out of 165 patients who were initially included into the wait and scan program, MS and GKR each were given later to two groups of ten patients. During the period, 136 patients received primary treatment (55 with MS and 81 by GKR (Table 5). In order to investigate the choice of treatment in patients with newly diagnosed VS, we conducted a prospective study during the years 2001 out 2005. Patients with tumours 25 mm or less to be treated were presented with the options of either choosing treatment themselves or undergoing randomisation. Information was presented about the treatment alternatives as above. If medical conditions or age (70-year limit) contraindicated surgery, only GKR was used, and these patients were excluded. Data collection and analysis was carried out according to a pre-defined protocol. Out of 71 patients who fulfilled the inclusion criteria, only seven patients accepted randomisation. Altogether 64 consenting patients with tumours 25 mm or less did not accept randomisation but fulfilled the criteria for a free choice between GKR and surgery. Among the data collected in the period 2001–2006, we analysed if one particular treatment was preferred, or if any of the following, i.e., age, sex, tumour size or hearing function (Gardner–Robertson A þ B grouped together against C þ D) were different between the 2 groups. Altogether 45 patients chose GKR and 19 surgery (P< 0.001), (Table 6). The groups did not differ significantly in the distribution of any of the four parameters tested. Several conclusions may be drawn from the above study. First, since only seven patients accepted randomisation, class I evidence for GKR versus MS for VS will require a randomised multicentre study. However, if given the above information, patients may decide on the treatment choice themselves. Although no prospective data collection was used to investigate this, we observed that many patients needed more than one consultation with the attending doctor. Frequently, the first consultation, which was carried out in an outpatient setTable 6. Characteristics and individual treatment choice of 64 patients with VS N Male=female Age Tumour size (mm) Gardner Robertson A þ B Gamma knife Surgery P 45 23=22 53.9 (9.2 SD) 15.9 (5.0 SD) 47.1% 19 7=12 50.3 (12.7 SD) 17.3 (5.9 SD) 48.6% 0.001 n.s n.s n.s n.s ting, was followed by a telephone consultation one to two weeks later. The second important finding in this study is that GKR was preferred by a significantly higher proportion of patients than those choosing surgery. This may not be surprising, since the complication rate is lower, no recovery period is necessary, and the risk of therapy failure is low and within the same range for both alternatives. We think it is necessary to inform patients about both options of treatment, and let the patient decide, even if their preferred treatment is not an option available in the same institution. Conclusion Vestibular schwannoma is a benign tumour which usually either grows slowly or remains unchanged for many years. The complaints are usually mild, and may persist despite treatment. As the average size of newly diagnosed tumours is less than 20 mm, treatment is only rarely a life-saving procedure. Instead, treatment aims at preventing morbidity caused by growth. Tumour control rate, facial nerve function and hearing preservation are the traditional endpoints of VS treatment, but vertigo, unsteadiness, tinnitus and health-related quality of life should be reported as well. There is definitely a need for prospective comparative studies. To be justified, VS treatment should lead to an outcome better than the natural course. When treatment is indicated, surgery and Gamma Knife Radiosurgery are alternatives. Although prospective comparative studies are lacking, both methods have a cure rate of 90–98% and patients should be informed about each alternative. The original work presented here indicates that given balanced, unbiased information, a majority of patients prefer GKR if treatment is indicated. Consequently, the questions ‘‘why, when and how’’ need to be discussed with the patient before treatment is undertaken. References 1. Andersson G, Ekvall L, Kinnefors A, Nyberg G, Rask-Andersen H (1997) Evaluation of quality of life and symptoms after translabyrinthine acoustic neuroma surgery. Am J Otol 18: 421–426 2. Andersson G, Kinnefors A, Ekvall L, Rask-Andersen H (1997) Tinnitus and translabyrinthine acoustic neuroma surgery. Audiol Neurootol 2: 403–409 3. Arriaga MA, Chen DA (2001) Facial function in hearing preservation acoustic neuroma surgery. Arch Otolaryngol Head Neck Surg 127: 543–546 4. Axelsson A, Ringdahl A (1989) Tinnitus – a study of its prevalence and characteristics. Br J Audiol 23: 53–62 5. Baguley DM, Moffat DA, Hardy DG (1992). What is the effect of translabyrinthine acoustic schwannoma removal upon tinnitus? J Laryngol Otol 106: 329–331 Treatment of vestibular schwannomas 6. Bari ME, Forster DM, Kemeny AA, Walton L, Hardy D, Anderson JR (2002) Malignancy in a vestibular schwannoma. Report of a case with central neurofibromatosis, treated by both stereotactic radiosurgery and surgical excision, with a review of the literature. Br J Neurosurg 16: 284–289 7. Bateman N, Nikolopoulos TP, Robinson K, O’Donoghue GM (2000) Impairments, disabilities, and handicaps after acoustic neuroma surgery. Clin Otolaryngol Allied Sci 25: 62–65 8. Bauch CD, Lynn SG, Williams DE, Mellon MW, Weaver AL (2003) Tinnitus impact: three different measurement tools. J Am Acad Audiol 14: 181–187 9. Baumann I, Polligkeit J, Blumenstock G, Mauz PS, Zalaman IM, Maassen MM (2005) Quality of life after unilateral acoustic neuroma surgery via middle cranial fossa approach. Acta Otolaryngol 125: 585–591 10. Bederson JB, von Ammon K, Wichmann WW, Yasargil MG (1991) Conservative treatment of patients with acoustic tumors. Neurosurgery 28: 646–650 11. Berliner KI, Shelton C, Hitselberger WE, Luxford WM (1992) Acoustic tumors: effect of surgical removal on tinnitus. Am J Otol 13: 13–17 12. Betchen SA, Walsh J, Post KD (2003) Self-assessed quality of life after acoustic neuroma surgery. J Neurosurg 99: 818–823 13. Bottomley A, Flechtner H, Efficace F, Vanvoorden V, Coens C, Therasse P, Velikova G, Blazeby J, Greimel E (2005) Health related quality of life outcomes in cancer clinical trials. Eur J Cancer 41: 1697–1709 14. Briggs RJ, Fabinyi G, Kaye AH (2000) Current management of acoustic neuromas: review of surgical approaches and outcomes. J Clin Neurosci 7: 521–526 15. Briggs RJ, Luxford WM, Atkins JS, Hitselberger WE (1994) Translabyrinthine removal of large acoutsic neurinomas. Neurosurgery 34: 785–790 16. Bronstein AM (2004) Vision and vertigo: some visual aspects of vestibular disorders. J Neurol 251: 381–387 17. Buchman CA, Chen DA, Flannagan P, Wilberger JE, Maroon JC (1996) The learning curve for acoustic tumor surgery. Laryngoscope 106: 1406–1411 18. Cohen A, Modan B (1968) Some epidemiologic aspects of neoplastic diseases in Israeli immigrant population. 3. Brain tumors. Cancer 22: 1323–1328 19. Collins MM, Johnson IJ, Clifford E, Birchall JP, O’Donoghue GM (2003) Postural stability of preoperative acoustic neuroma patients assessed by sway magnetometry: are they unsteady? Laryngoscope 113: 640–642 20. Coulson SE, Croxson GR, Adams RD, O’Dwyer NJ (2005) Reliability of the ‘‘Sydney,’’ ‘‘Sunnybrook,’’ and ‘‘House Brackmann’’ facial grading systems to assess voluntary movement and synkinesis after facial nerve paralysis. Otolaryngol Head Neck Surg 132: 543–549 21. Cross JJ, Baguley D, Antoun NM, Moffat D, Prevost AT (2006) Reproducibility of volume measurements of vestibular schwannomas – a preliminary study. Clin Otolaryngol 31: 123–129 22. da Cruz MJ, Moffat DA, Hardy DG (2000) Postoperative quality of life in vestibular schwannoma patients measured by the SF36 Health Questionnaire. Laryngoscope 110: 151–155 23. Darrouzet V, Martel J, Enee V, Bebear JP, Guerin J (2004) Vestibular schwannoma surgery outcomes: our multidisciplinary experience in 400 cases over 17 years. Laryngoscope 114: 681–688 24. Deen HG, Ebersold MJ, Harner SG, Beatty CW, Marion MS, Wharen RE, Green JD, Quast L (1996) Conservative management of acoustic neuroma: an outcome study. Neurosurgery 39: 260–264 25. Dieterich M (2004) Dizziness. Neurologist 10: 154–164 657 26. Ebersold MJ, Harner SG, Beatty CW, Harper CM Jr, Quast LM (1992) Current results of the retrosigmoid approach to acoustic neurinoma. J Neurosurg 76: 901–909 27. Elsmore AJ, Mendoza ND (2002) The operative learning curve for vestibular schwannoma excision via the retrosigmoid approach. Br J Neurosurg 16: 448–455 28. Fahy C, Nikolopoulos TP, O’Donoghue GM (2002) Acoustic neuroma surgery and tinnitus. Eur Arch Otorhinolaryngol 259: 299–301 29. Fielder H, Denholm SW, Lyons RA, Fielder CP (1996) Measurement of health status in patients with vertigo. Clin Otolaryngol Allied Sci 21: 124–126 30. Flickinger JC, Kondziolka D, Lunsford LD (1996) Dose and diameter relationships for facial, trigeminal, and acoustic neuropathies following acoustic neuroma radiosurgery. Radiother Oncol 41: 215–219 31. Flickinger JC, Kondziolka D, Niranjan A, Lunsford LD (2001) Results of acoustic neuroma radiosurgery: an analysis of 5 years experience using current methods. J Neurosurg 94: 1–6 32. Flickinger JC, Kondziolka D, Niranjan A, Maitz A, Voynov G, Lunsford LD (2004) Acoustic neuroma radiosurgery with marginal tumor doses of 12 to 13 Gy. Int J Radiat Oncol Biol Phys 60: 225–230 33. Flickinger JC, Lunsford LD, Linskey ME, Duma CM, Kondziolka D (1993) Gamma knife radiosurgery for acoustic tumors: multivariate analysis of four year results. Radiother Oncol 27: 91–98 34. Foote KD, Friedman WA, Buatti JM, Meeks SL, Bova FJ, Kubilis PS (2001) Analysis of risk factors associated with radiosurgery for vestibular schwannoma. J Neurosurg 95: 440–449 35. Gardner G, Robertson JH (1988) Hearing preservation in unilateral acoustic neuroma surgery. Ann Otol Rhinol Laryngol 97: 55–66 36. Givre A, Olivecrona H (1949) Surgical experiences with acoustic tumors. J Neurosurg 5: 396–407 37. Glasscock ME III, Hays JW, Minor LB, Haynes DS, Carrasco VN (1993) Preservation of hearing in surgery for acoustic neuromas. J Neurosurg 78: 864–870 38. Glasscock ME III, Kveton JF, Jackson CG, Levine SC, McKennan KX (1986) A systematic approach to the surgical management of acoustic neuroma. Laryngoscope 96: 1088–1094 39. Grayeli AB, Guindi S, Kalamarides M, Garem HE, Smail M, Rey A, Sterkers O (2005) Four-channel electromyography of the facial nerve in vestibular schwannoma surgery: sensitivity and prognostic value for short-term facial function outcome. Otol Neurotol 26: 114–120 40. Hanabusa K, Morikawa A, Murata T, Taki W (2001) Acoustic neuroma with malignant transformation. Case report. J Neurosurg 95: 518–521 41. Hardy DG, MacFarlane R, Baguley D, Moffat DA (1989) Surgery for acoustic neurinoma. An analysis of 100 translabyrinthine operations. J Neurosurg 71: 799–804 42. Harner SG, Beatty CW, Ebersold MJ (1993) Headache after acoustic neuroma excision. Am J Otol 14: 552–555 43. Hasegawa T, Kida Y, Kobayashi T, Yoshimoto M, Mori Y, Yoshida J (2005) Long-term outcomes in patients with vestibular schwannomas treated using gamma knife surgery: 10-year follow up. J Neurosurg 102: 10–16 44. House JW, Brackmann DE (1985) Facial nerve grading system. Otolaryngol Head Neck Surg 93: 146–147 45. Howitz MF, Johansen C, Tos M, Charabi S, Olsen JH (2000) Incidence of vestibular schwannoma in Denmark, 1977–1995. Am J Otol 21: 690–694 46. Hwang SK, Kim DG, Paek SH, Kim CY, Kim MK, Chi JG, Jung HW (2002) Aggressive vestibular schwannomas with postoperative rapid growth: clinicopathological analysis of 15 cases. Neurosurgery 51: 1381–1390 658 47. Inoue HK (2005) Low-dose radiosurgery for large vestibular schwannomas: long-term results of functional preservation. J Neurosurg 102 Suppl 111–113: 111–113 48. Inoue Y, Ogawa K, Kanzaki J (2001) Quality of life of vestibular schwannoma patients after surgery. Acta Otolaryngol 121: 59–61 49. Isaacson B, Kileny PR, El-Kashlan HK (2005) Prediction of longterm facial nerve outcomes with intraoperative nerve monitoring. Otol Neurotol 26: 270–273 50. Iwai Y, Yamanaka K, Ishiguro T (2003) Surgery combined with radiosurgery of large acoustic neuromas. Surg Neurol 59: 283–289 51. Jackson CG, McGrew BM, Forest JA, Hampf CR, Glasscock ME III, Brandes JL, Hanson MB (2000) Comparison of postoperative headache after retrosigmoid approach: vestibular nerve section versus vestibular schwannoma resection. Am J Otol 21: 412–416 52. Kanzaki J, Inoue Y, Ogawa K (2001) The learning curve in postoperative hearing results in vestibular schwannoma surgery. Auris Nasus Larynx 28: 209–213 53. Karjalainen S, Nuutinen J, Neittaanmaki H, Naukkarinen A, Asikainen R (1984) The incidence of acoustic neuroma in and autopsy material. Acta Otorhinolaryngol Belg 240: 91–93 54. Kentala E, Pyykko I (2000) Vestibular schwannoma mimicking Meniere’s disease. Acta Otolaryngol Suppl 543: 17–19 55. Kentala E, Pyykko I (2001) Clinical picture of vestibular schwannoma. Auris Nasus Larynx 28: 15–22 56. Koperer H, Deinsberger W, Jodicke A, Boker DK (1999) Postoperative headache after the lateral suboccipital approach: craniotomy versus craniectomy. Minim Invasive Neurosurg 42: 175–178 57. Kubo O, Chernov M, Izawa M, Hayashi M, Muragaki Y, Maruyama T, Hori T, Takakura K (2005) Malignant progression of benign brain tumors after gamma knife radiosurgery: is it really caused by irradiation? Minim Invasive Neurosurg 48: 334–339 58. Lalwani AK, Butt FY, Jackler RK, Pitts LH, Yingling CD (1994) Facial nerve outcome after acoustic neuroma surgery: a study from the era of cranial nerve monitoring. Otolaryngol Head Neck Surg 111: 561–570 59. Lanman TH, Brackmann DE, Hitselberger WE, Subin B (1999) Report of 190 consecutive cases of large acoustic tumours (vestibular schwannomas) removed via the translabyrinthine approach. J Neurosurg 90: 617–623 60. Levo H, Blomstedt G, Pyykko I (2004) Postural stability after vestibular schwannoma surgery. Ann Otol Rhinol Laryngol 113: 994–999 61. Linskey ME, Flickinger JC, Lunsford LD (1993) Cranial nerve length predicts the risk of delayed facial and trigeminal neuropathies after acoustic tumor stereotactic radiosurgery. Int J Radiat Oncol Biol Phys 25: 227–233 62. Lockwood AH, Salvi RJ, Burkard RF (2002) Tinnitus. N Engl J Med 347: 904–910 63. Loeffler JS, Niemierko A, Chapman PH (2003) Second tumors after radiosurgery: tip of the iceberg or a bump in the road? Neurosurgery 52: 1436–1440 64. Loge JH, Kaasa S (1998) Short form 36 (SF-36) health survey: normative data from the general Norwegian population. Scand J Soc Med 26: 250–258 65. Loge JH, Kaasa S, Hjermstad MJ, Kvien TK (1998) Translation and performance of the Norwegian SF-36 Health Survey in patients with rheumatoid arthritis. I. Data quality, scaling assumptions, reliability, and construct validity. J Clin Epidemiol 51: 1069–1076 66. Luetje CM (2000) Spontaneous involution of acoustic tumors. Am J Otol 21: 393–398 67. Lunsford LD, Niranjan A, Flickinger JC, Maitz A, Kondziolka D (2005) Radiosurgery of vestibular schwannomas: summary of experience in 829 cases. J Neurosurg 102[Suppl 195–199]: 195–199 E. Myrseth et al. 68. Lynn SG, Bauch CD, Williams DE, Beatty CW, Mellon MW, Weaver AL (2003) Psychologic profile of tinnitus patients using the SCL-90-R and Tinnitus Handicap Inventory. Otol Neurotol 24: 878–881 69. Lynn SG, Driscoll CL, Harner SG, Beatty CW, Atkinson EJ (1999) Assessment of dysequilibrium after acoustic neuroma removal. Am J Otol 20: 484–494 70. MacAndie C, Crowther JA (2004) Quality of life in patients with vestibular schwannomas managed conservatively. Clin Otolaryngol Allied Sci 29: 215–218 71. Magliulo G, Zardo F, Damico R, Varacalli S, Forino M (2000) Acoustic neuroma: postoperative quality of life. J Otolaryngol 29: 344–347 72. Malis L (1998) History. In: Malis LI (ed) Acoustic neuroma. Elsevier New York, pp 4–7 73. Martin HC, Sethi J, Lang D, Neil-Dwyer G, Lutman ME, Yardley L (2001) Patient-assessed outcomes after excision of acoustic neuroma: postoperative symptoms and quality of life. J Neurosurg 94: 211–216 74. Matthies C, Samii M (1997) Management of 1000 vestibular schwannomas (acoustic neuromas): clinical presentation. Neurosurgery 40: 1–9 75. Mirz F, Jorgensen B, Fiirgaard B, Lundorf E, Pedersen CB (1999) Investigations into the natural history of vestibular schwannomas. Clin Otolaryngol Allied Sci 24: 13–18 76. Mirz F, Pedersen CB, Fiirgaard B, Lundorf E (2000) Incidence and growth pattern of vestibular schwannomas in a Danish county, 1977–1998. Acta Otolaryngol Suppl 543: 30–33 77. Moffat DA, Baguley DM, von Blumenthal H, Irving RM, Hardy DG (1994) Sudden deafness in vestibular schwannoma. J Laryngol Otol 108: 116–119 78. Moffat DA, Hardy DG, Grey PL, Baguley DM (1996) The operative learning curve and its effect on facial nerve outcome in vestibular schwannoma surgery. Am J Otol 17: 643–647 79. Moffat DA, Jones SE, Mahendran S, Humphriss R, Baguley DM (2004) Referral patterns in vestibular schwannomas – 10 years on. Clin Otolaryngol Allied Sci 29: 515–517 80. Mohyuddin A, Vokurka EA, Evans DG, Ramsden RT, Jackson A (2003) Is clinical growth index a reliable predictor of tumour growth in vestibular schwannomas? Clin Otolaryngol Allied Sci 28: 85–90 81. Moller P, Myrseth E, Pedersen PH, Larsen JL, Krakenes J, Moen G (2000) Acoustic neuroma-treatment modalities. Surgery, gammaknife or observation? Acta Otolaryngol Suppl 543: 34–37 82. Muacevic A, Jess-Hempen A, Tonn JC, Wowra B (2004) Results of outpatient gamma knife radiosurgery for primary therapy of acoustic neuromas. Acta Neurochir Suppl 91: 75–78 83. Myrseth E, Moller P, Goplen F, Wentzel-Larsen T, Lund-Johansen M (2006) Untreated vestibular schwannoma: vertigo is a powerful predictor for health-related quality of life. Neurosurgery 59: 67–76 84. Myrseth E, Moller P, Pedersen PH, Vassbotn FS, Wentzel-Larsen T, Lund-Johansen M (2005) Vestibular schwannomas: clinical results and quality of life after microsurgery or gamma knife radiosurgery. Neurosurgery 56: 927–935 85. Nader R, Al Abdulhadi K, Leblanc R, Zeitouni A (2002) Acoustic neuroma: outcome study. J Otolaryngol 31: 207–210 86. Neff BA, Ting J, Dickinson SL, Welling DB (2005) Facial nerve monitoring parameters as a predictor of postoperative facial nerve outcomes after vestibular schwannoma resection. Otol Neurotol 26: 728–732 87. Neuhauser HK, von Brevern M, Radtke A, Lezius F, Feldmann M, Ziese T, Lempert T (2005) Epidemiology of vestibular vertigo: a neurotologic survey of the general population. Neurology 65: 898–904 Treatment of vestibular schwannomas 88. Nikolopoulos TP, Johnson I, O’Donoghue GM (1998) Quality of life after acoustic neuroma surgery. Laryngoscope 108: 1382–1385 89. Nikolopoulos TP, O’Donoghue GM (2002) Acoustic neuroma management: an evidence-based medicine approach. Otol Neurotol 23: 534–541 90. Nissen AJ, Sikand A, Welsh JE, Curto FS, Gardi J (1997) A multifactorial analysis of facial nerve results in surgery for cerebellopontine angle tumors. Ear Nose Throat J 76: 37–40 91. Nordahl SH, Aasen T, Dyrkorn BM, Eidsvik S, Molvaer OI (2000) Static stabilometry and repeated testing in a normal population. Aviat Space Environ Med 71: 889–893 92. Noren G (1998) Long-term complications following gamma knife radiosurgery of vestibular schwannomas. Stereotact Funct Neurosurg 70 Suppl 1: 65–73 93. Ogawa K, Kanzaki J, Ogawa S, Tsuchihashi N, Inoue Y (1991) Acoustic neuromas presenting as sudden hearing loss. Acta Otolaryngol Suppl 487: 138–143 94. Paek SH, Chung HT, Jeong SS, Park CK, Kim CY, Kim JE, Kim DG, Jung HW (2005) Hearing preservation after gamma knife stereotactic radiosurgery of vestibular schwannoma. Cancer 104: 580–590 95. Parving A, Tos M, Thomsen J, Moller H, Buchwald C (1992) Some aspects of life quality after surgery for acoustic neuroma. Arch Otolaryngol Head Neck Surg 118: 1061–1064 96. Perez N, Martin E, Garcia-Tapia R (2003) Dizziness: relating the severity of vertigo to the degree of handicap by measuring vestibular impairment. Otolaryngol Head Neck Surg 128: 372–381 97. Petit JH, Hudes RS, Chen TT, Eisenberg HM, Simard JM, Chin LS (2001) Reduced-dose radiosurgery for vestibular schwannomas. Neurosurgery 49: 1299–1306 98. Pogodzinski MS, Harner SG, Link MJ (2004) Patient choice in treatment of vestibular schwannoma. Otolaryngol Head Neck Surg 130: 611–616 99. Pollock BE, Driscoll CL, Link MJ, Gorman DA, Bauch CD, Mandrekar JN, Krecke KN, Johnson CH (2006) Patient outcomes after vestibular schwannoma management: a prospective comparison of microsurgical resecion and stereotactic radiosurgery. Neurosurgery 59: 77–85 100. Pritchard C, Clapham L, Davis A, Lang DA, Neil-Dwyer G (2004) Psycho-socio-economic outcomes in acoustic neuroma patients and their carers related to tumour size. Clin Otolaryngol Allied Sci 29: 324–330 101. Raut VV, Walsh RM, Bath AP, Bance ML, Guha A, Tator CH, Rutka JA (2004) Conservative management of vestibular schwannomas – second review of a prospective longitudinal study. Clin Otolaryngol Allied Sci 29: 505–514 102. Regis J, Pellet W, Delsanti C, Dufour H, Roche PH, Thomassin JM, Zanaret M, Peragut JC (2002) Functional outcome after gamma knife surgery or microsurgery for vestibular schwannomas. J Neurosurg 97: 1091–1100 103. Rickenmann J, Jaquenod C, Cerenko D, Fisch U (1997) Comparative value of facial nerve grading systems. Otolaryngol Head Neck Surg 117: 322–325 104. Rigby PL, Shah SB, Jackler RK, Chung JH, Cooke DD (1997) Acoustic neuroma surgery: outcome analysis of patient-perceived disability. Am J Otol 18: 427–435 105. Robinson SK, McQuaid JR, Viirre ES, Betzig LL, Miller DL, Bailey KA, Harris JP, Perry W (2003) Relationship of tinnitus questionnaires to depressive symptoms, quality of well-being, and internal focus. Int Tinnitus J 9: 97–103 106. Rogg JM, Ahn SH, Tung GA, Reinert SE, Noren G (2005) Prevalence of hydrocephalus in 157 patients with vestibular schwannoma. Neuroradiology 47: 344–351 107. Rosenberg SI (2000) Natural history of acoustic neuromas. Laryngoscope 110: 497–508 659 108. Rutherford S, King A (2005) Vestibular schwannoma management: what is the ‘‘best’’ option? Br J Neurosurg 19: 309–316 109. Ryzenman JM, Pensak ML, Tew JM Jr (2004) Patient perception of comorbid conditions after acoustic neuroma management: survey results from the acoustic neuroma association. Laryngoscope 114: 814–820 110. Ryzenman JM, Pensak ML, Tew JM Jr (2005) Headache: a quality of life analysis in a cohort of 1,657 patients undergoing acoustic neuroma surgery, results from the acoustic neuroma association. Laryngoscope 115: 703–711 111. Sadetzki S, Modan B, Chetrit A, Freedman L (2000) An iatrogenic epidemic of benign meningioma. Am J Epidemiol 151: 266–272 112. Samii M, Matthies C (1997) Management of 1000 vestibular schwannomas (acoustic neuromas): surgical management and results with an emphasis on complications and how to avoid them. Neurosurgery 40: 11–21 113. Samii M, Matthies C (1997) Management of 1000 vestibular schwannomas (acoustic neuromas): hearing function in 1000 tumor resections. Neurosurgery 40: 248–260 114. Samii M, Matthies C (1997) Management of 1000 vestibular schwannomas (acoustic neuromas): the facial nerve–preservation and restitution of function. Neurosurgery 40: 684–694 115. Sampath P, Holliday MJ, Brem H, Niparko JK, Long DM (1997) Facial nerve injury in acoustic neuroma (vestibular schwannoma) surgery: etiology and prevention. J Neurosurg 87: 60–66 116. Sandooram D, Grunfeld EA, McKinney C, Gleeson MJ (2004) Quality of life following microsurgery, radiosurgery and conservative management for unilateral vestibular schwannoma. Clin Otolaryngol Allied Sci 29: 621–627 117. Sanna M, Khrais T, Russo A, Piccirillo E, Augurio A (2004) Hearing preservation surgery in vestibular schwannoma: the hidden truth. Ann Otol Rhinol Laryngol 113: 156–163 118. Santarius T, D’Sousa AR, Zeitoun HM, Cruickshank G, Morgan DW (2000) Audit of headache following resection of acoustic neuroma using three different techniques of suboccipital approach. Rev Laryngol Otol Rhinol (Bord) 121: 75–78 119. Saunders JE, Luxford WM, Devgan KK, Fetterman BL (1995) Sudden hearing loss in acoustic neuroma patients. Otolaryngol Head Neck Surg 113: 23–31 120. Schaitkin BM, Young T, III, Robertson JS, Fickel V, Wiegand DA (1991) Facial reanimation after acoustic neuroma excision: the patient’s perspective. Laryngoscope 101: 889–894 121. Shamisa A, Bance M, Nag S, Tator C, Wong S, Noren G, Guha A (2001) Glioblastoma multiforme occurring in a patient treated with gamma knife surgery. Case report and review of the literature. J Neurosurg 94: 816–821 122. Shin M, Ueki K, Kurita H, Kirino T (2002) Malignant transformation of a vestibular schwannoma after gamma knife radiosurgery. Lancet 360: 309–310 123. Smouha EE, Yoo M, Mohr K, Davis RP (2005) Conservative management of acoustic neuroma: a meta-analysis and proposed treatment algorithm. Laryngoscope 115: 450–454 124. Stewart TJ, Liland J, Schuknecht HF (1975) Occult schwannomas of the vestibular nerve. Arch Otolaryngol 101: 91–95 125. Strasnick B, Glasscock ME III, Haynes D, McMenomey SO, Minor LB (1994) The natural history of untreated acoustic neuromas. Laryngoscope 104: 1115–1119 126. Szende A, Leidy NK, Revicki D (2005) Health-related quality of life and other patient-reported outcomes in the European centralized drug regulatory process: a review of guidance documents and performed authorizations of medicinal products 1995 to 2003. Value Health 8: 534–548 127. Taphoorn MJ, Stupp R, Coens C, Osoba D, Kortmann R, van den Bent MJ, Mason W, Mirimanoff RO, Baumert BG, Eisenhauer E, Forsyth P, Bottomley A (2005) Health-related quality of life in 660 128. 129. 130. 131. 132. 133. 134. 135. 136. 137. 138. 139. 140. 141. 142. 143. 144. E. Myrseth et al.: Treatment of vestibular schwannomas patients with glioblastoma: a randomised controlled trial. Lancet Oncol 6: 937–944 Tonn JC, Schlake HP, Goldbrunner R, Milewski C, Helms J, Roosen K (2000) Acoustic neuroma surgery as an interdisciplinary approach: a neurosurgical series of 508 patients. J Neurol Neurosurg Psychiatry 69: 161–166 Tos M, Stangerup SE, Caye-Thomasen P, Tos T, Thomsen J (2004) What is the real incidence of vestibular schwannoma? Arch Otolaryngol Head Neck Surg 130: 216–220 Tos M, Thomsen J (1984) Epidemiology of acoustic neuromas. J Laryngol Otol 98: 685–692 Unger F, Walch C, Schrottner O, Eustacchio S, Sutter B, Pendl G (2002) Cranial nerve preservation after radiosurgery of vestibular schwannomas. Acta Neurochir Suppl 84: 77–83 van Eck AT, Horstmann GA (2005) Increased preservation of functional hearing after gamma knife surgery for vestibular schwannoma. J Neurosurg 102 Suppl: 204–206 van Leeuwen JP, Braspenning JC, Meijer H, Cremers CW (1996). Quality of life after acoustic neuroma surgery. Ann Otol Rhinol Laryngol 105: 423–430 Walsh RM, Bath AP, Bance ML, Keller A, Tator CH, Rutka JA (2000) The role of conservative management of vestibular schwannomas. Clin Otolaryngol Allied Sci 25: 28–39 Ware JE Jr (2000) SF-36 health survey update. Spine 25: 3130–3139 Welling DB, Slater PW, Thomas RD, McGregor JM, Goodman JE (1999) The learning curve in vestibular schwannoma surgery. Am J Otol 20: 644–648 Wiegand DA, Fickel V (1989) Acoustic neuroma – the patient’s perspective: subjective assessment of symptoms, diagnosis, therapy, and outcome in 541 patients. Laryngoscope 99: 179–187 Wiegand DA, Ojemann RG, Fickel V (1996) Surgical treatment of acoustic neuroma (vestibular schwannoma) in the United States: report from the Acoustic Neuroma Registry. Laryngoscope 106: 58–66 Wiet RJ, Mamikoglu B, Odom L, Hoistad DL (2001) Long-term results of the first 500 cases of acoustic neuroma surgery. Otolaryngol Head Neck Surg 124: 645–651 Wowra B, Muacevic A, Jess-Hempen A, Hempel JM, MullerSchunk S, Tonn JC (2005) Outpatient gamma knife surgery for vestibular schwannoma: definition of the therapeutic profile based on a 10-year experience. J Neurosurg 102 Suppl: 114–118 Yamakami I, Uchino Y, Kobayashi E, Yamaura A (2003) Conservative management, gamma-knife radiosurgery, and microsurgery for acoustic neurinomas: a systematic review of outcome and risk of three therapeutic options. Neurol Res 25: 682–690 Yardley L, Dibb B, Osborne G (2003) Factors associated with quality of life in Meniere’s disease. Clin Otolaryngol Allied Sci 28: 436–441 Yates PD, Jackler RK, Satar B, Pitts LH, Oghalai JS (2003) Is it worthwhile to attempt hearing preservation in larger acoustic neuromas? Otol Neurotol 24: 460–464 Yoshimoto Y (2005) Systematic review of the natural history of vestibular schwannoma. J Neurosurg 103: 59–63 tumours: hearing preservation. It is the result of improved microsurgery that the goalposts have moved, allowing hearing preservation to be the relevant factor for those who present sufficiently early. Paradoxically, surgery is now undermined by the outcome of less invasive methods. As most patients present with progressive hearing loss, despite the lack of high level statistical proof they suspect what the future holds without any intervention. At the same time they are increasingly aware of the radiosurgical hearing preservation in large series [1, 2]. Hearing loss after the ‘‘watch and wait’’ policy (just as after microsurgery or radiosurgery) should be considered failure of management. Contrary to quality of life data presented in this paper this single issue often clinches the decision for many younger patients. As the authors quite rightly point out, the choice of treatment is often determined by the local availability of techniques with the alternatives only vaguely mentioned to the patient. In this day and age it is quite possible for patients to be referred to another centre (specialising in microsurgery of the skull base or radiosurgery) if necessary. In fact, it should be considered negligent if such alternatives are not truly provided. The study presented here is commendable for its detached and honest standardised patient information which makes their results credible. References 1. Regis J, Pellet W, Delsanti C, Dufour H, Roche PH, Thomassin JM, Zanaret M, Peragut JC (2002) Functional outcome after gamma knife surgery or microsurgery for vestibular schwannomas. J Neurosurg 97(5): 1091–1100 2. Rowe JG, Radatz MW, Walton L, Hampshire A, Seaman S, Kemeny AA (2003) Gamma knife stereotactic radiosurgery for unilateral acoustic neuromas. J Neurol Neurosurg Psychiatry 74(11): 1536–1542 Andras Kemeny Sheffield In this comprehensive review, the authors discuss the spectrum of clinical presentation for a vestibular schwannoma and the various management options. They provide a good overview of what is known regarding the natural history for such tumors if untreated. We agree that this is a reasonable choice for older patients, who may not require any tumor care during their remaining life. However, for younger patients, there is a growing experience showing that tumor irradiation may lead to better cranial nerve outcomes (i.e., hearing preservation) than observation. Thus observation may not be a wise choice in a young patient. As for the controversy over resection versus radiosurgery, there are now four matched cohort studies, including one performed by these authors, showing similar or better outcomes in the Gamma knife radiosurgery patients. Although a randomized trial is not likely to be conducted, there is sound level two evidence supporting radiosurgery for smaller volume tumors. In addition, the long-term data for radiosurgery continues to be published [1]. We need such information for after all forms of management. Reference Comments The authors present an overview, much like a didactic chapter, for the presentation and management of acoustic neuromas on the apropos of their study. As they allude to in the paper, the history of management of these tumours progressed from trying to save the patients’ life, to keeping the neurological deficit to the minimum. Initially surgeons were happy to just minimize the deficit to the cerebellum and brainstem, later attempting and achieving increasing functional facial nerve preservation, progressing to the current aim for many small and medium-sized 1. Kondziolka D, Nathoo N, Flickinger JC, Niranjan A, Maitz AH, Lunsford LD (2003) Long-term results after radiosurgery for benign intracranial tumors. Neurosurgery 53: 815–822 Douglas Kondziolka Pittsburgh Correspondence: Dr. Erling Myrseth, Department of Neurosurgery, Institute of Surgical Science, Haukeland University Hospital, University of Bergen, N-5021 Bergen, Norway. e-mail: [email protected]
© Copyright 2024