25/06/2010 DIPARTIMENTO DI NEUROCHIRURGIA SECONDA UNIVERSITÀ DI NAPOLI DIRETTORE: PROF. ALDO MORACI Processi espansivi dell’angolo ponto-cerebellare Borders of cerebellopontine angle Internal auditory canal Compartments of CN VII and VIII CN V, VI, IX, X and XI Vascular structrures John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 1 25/06/2010 Unilateral sensorineural hearing loss Sudde so eu a hearing ea g loss oss Sudden se sensorineural Unilateral tinnitus Vestibular symptoms Facial hypesthesia and weakness Diplopia Hoarseness, dysphagia, aspiration John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Thorough cranial nerve exam Extra ocular movements Extra-ocular Funduscopic exam Facial motor and sensory function Pneumatic otoscopy/Weber/Rinne Hitselberger’s sign Gag/TVC/SCM and trapezius John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 2 25/06/2010 Pure tone and speech discrimination audiometry Impedance audiometry Rollover acoustic reflex tone decay Auditory A dito brainstem b ainstem evoked e oked response esponse (ABR) Vestibular testing (ENG) John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 CT MRI John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 3 25/06/2010 Benign slow growing tumors from Schwann cells surrounding CN VIII 10% of the intracranial tumors and >90% of the CPA tumors Incidence 0.1 to 2.5 per 100,000 Associated with neurofibromatosis Rate of growth 0.2 to 4.0 mm per year John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Centered on IAC, spherical, enlarge the medial IAC, IAC acute bone-tumor bone tumor angle CT: isodense and enhances with contrast Inhomogeneous due to cystic degeneration or intratumoral hemorraging MRI: isointense or hypointense on T1 and T2, b tb but becomes markedly k dl enhanced h d on T1T1 gadolinium John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 4 25/06/2010 Observation Surgery for small intracanalicular tumors Surgery for medium-sized tumors (1-3 cm) Surgery for only-hearing ear Surgery for bilateral acoustic neuromas (Neurofibromatosis-type II) John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 15% of intracranial tumors and 3% of CPA tumors Arise from cells lining the arachnoid villa Benign and do not metastasize, but locally aggressive because they invade bone Signs and symptoms referable to site of involvement John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 5 25/06/2010 Eccentric to IAC hyperostosis at medial IAC Hemispherical and sessile with obtuse bonebone tumor angle CT: hypodense with calcification with marked enhancement; homogeneous MRI: isointense/hypointense on T1, but only moderate enhancement on T1-gad g John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Several histologic subtypes syncytial transitional fibrous angioblastic sarcomatous Surgical excision with removal of underlying bone John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 6 25/06/2010 Hamartomatous vascular malformations se from o ge cu ate ga g o o e IAC C Arise geniculate ganglion or at tthe Closely associated with the facial nerve MRI: hyperintense on T2 CT: intratumoral bone spicules and “honeycomb” pattern of surrounding bone Treatment is surgical excision John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Facial nerve schwannoma Cholesteatoma (epidermoid) Lipoma Arachnoid cyst John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 7 25/06/2010 Advantages No retraction of cerebellum Allows good identification of CN VII Allows good exposure of IAC Less risk of CSF leak Disadvantages Hearing is sacrificed Technique John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Advantages Excellent for intracanalicular tumors, tumors especially at the lateral end of the IAC Hearing preservation is possible Extradural with low risk of CSF leak Disadvantages Lack of access to CPA and posterior fossa Need to retract temporal lobe Technique John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 8 25/06/2010 Advantages Disadvantages Hearing preservation is possible Access to CPA A Limited access to lateral IAC/Fundus Difficult to repairing or grafting CN VII Increased risk of air embolism/CSF leak/post-op headache Cerebellar retraction is necessary Technique John K. Yoo, M.D. Jeffrey T. Vrabec, M.D., 1997 Scaricato da www.sunhope.it 9 25/06/2010 Scaricato da www.sunhope.it 10 25/06/2010 Scaricato da www.sunhope.it 11 25/06/2010 Scaricato da www.sunhope.it 12 25/06/2010 Scaricato da www.sunhope.it 13 25/06/2010 Scaricato da www.sunhope.it 14 25/06/2010 Scaricato da www.sunhope.it 15 25/06/2010 Scaricato da www.sunhope.it 16 25/06/2010 Scaricato da www.sunhope.it 17 25/06/2010 Scaricato da www.sunhope.it 18 25/06/2010 Scaricato da www.sunhope.it 19 25/06/2010 Scaricato da www.sunhope.it 20 25/06/2010 Scaricato da www.sunhope.it 21 25/06/2010 Scaricato da www.sunhope.it 22 25/06/2010 Epidermoid tumours are developmental anomalies, presenting as benign masses anomalies that arise when retained ectodermal implants from the closing neural tube (normal developmental cells) are trapped within the growing brain, usually in the third and fourth week of gestation. Scaricato da www.sunhope.it 23 25/06/2010 They are probably caused by incorrect disjunction disj nction of neuroectodermal ne oectode mal cells from f om cutaneous ones, and thus are not neoplastic masses, masses but can be considered, and are sometimes called, "ectodermal ectodermal heterotopia heterotopia". In this sense they are similar to dermoid masses, with the only difference being that dermoids also have mesodermal cells. Epidermoids are uncommon primary intracranial, mainly extra-axial, intradural masses (representing 0.2-1% of all intracranial neoplasms). They are benign and slowlygrowing usually presenting, because of this reason, in early to mid-adulthood. In this case the tumor had an intra intra-axial axial localization localization, which is unusual. The most common location is the CPA (40%), and these lesions represent 5-7% of all CPA tumours. Osborn,1991 Scaricato da www.sunhope.it 24 25/06/2010 Epidermoids grow very slowly, thus the patient often presents late in the course of the disease with symptoms similar to those of any mass lesion in the same location. Additionally, they may present with recurrent episodes of aseptic (nonbacterial) meningitis caused by rupture of the cyst contents contents. Other symptoms include fever fever, headaches, and neck stiffness. Osborn,1991 The treatment of ECs relies exclusively on surgery. In the cerebellopontine angle, it may be a technical challenge. challenge While approaching the cyst, the surgeon has to negotiate around particularly brittle cortex and vessels. Scaricato da www.sunhope.it 25 25/06/2010 The lesion often is intimately adherent to all cranial nerves and vessels of the region region. i Bridging B id i veins i are stretched t t h d over the th tumor and may bleed after debulking of the cyst. Anatomical landmarks may be lost because of the size of the tumor. A 38-year-old man with a 12-month history of tinnitus in the right ear, unsteady gait, and vestibular signs on the right. T1-weighted MRI (TR, 400 ms; TE, 12 ms; EX, 2). Careful study of the signal in the cyst and comparison with the CSF allow distinction from arachnoid cysts. Scaricato da www.sunhope.it 26 25/06/2010 Proton-density MRI (TR, (TR 2000 ms; TE, TE 50 ms; EX, 2) in the axial plane. Note the different signal of cyst content (straight arrow) and CSF (curved arrow). T2-weighted MRI (TR, 2000 ms; TE 100 ms; EX, 2) in th axial the i l plane. l Scaricato da www.sunhope.it 27 25/06/2010 The only definitive treatment of epidermoid tumours is surgery, and they are referred to as "pearly tumours" because of their glistening white appearance on surgery. Total removal is considered the ideal option, option as partial removal leads to recurrence. However, total removal is often associated with significant morbidity in the postoperative period and there is controversy regarding the optimal extent of removal. The whole of the capsule p should ideallyy be removed with microscopic dissection, but adherence of the capsule to the important neurovascular structures in and around the tumour, tumour such as cranial nerves, brain stem, or important vessels in the CPA, often leads to its incomplete removal. removal Scaricato da www.sunhope.it 28 25/06/2010 Management These meningiomas may arise from any area of the dura on the p posterior surface of the petrous p bone. At operation p four general categories are found: 1.Anterior to the internal auditory meatus, displacing the seventh and eighth nerves posteriorly and inferiorly. 2.Between the internal auditory meatus and the jugular foramen, displacing the seventh and eighth nerves superiorly. 3S 3.Superior i to t th the iinternal t l auditory dit meatus t , displacing the seventh and eighth nerves anteriorly in the large tumors. 4.Surrounding the internal auditory meatus, with the seventh and eighth nerves engulfed in the tumor. Scaricato da www.sunhope.it 29 25/06/2010 In the past I often utilized angiography when a cerebellopontine angle meningioma was suspected. However, for most of these meningiomas it is now not necessary, necessary because the MRI usually gives all the information needed and in most patients the blood supply comes primarily through the dural attachment. Embolization has not been a consideration. This 41-year-old woman noted increased numbness in the left side of her face and decreased hearing in her left ear. MRI axial TI images after gadolinium show the typical appearance of a meningioma, with the flat surface against the petrous bone and the dural "tails." This tumor is arising anterior to the left internal auditory meatus. It may extend into the internal auditory meatus, as seen here. Scaricato da www.sunhope.it 30 25/06/2010 This 40-year-old woman had progressively decreased hearing in her left ear and discomfort around her ear and the side of her head. There was normal recovery. MRI axial TI images after gadolinium show a large meningioma arising posterior to the left internal auditory meatus. The microsurgical removal of CPA meningioma can be done by a suboccipital, translabrynthine, or middle fossa approach. approach pp Good results from all three approaches have been reported by experienced groups of neurosurgeons. For most patients we have preferred the suboccipital (posterior posterior fossa) fossa approach because of the wide visualization it allows, the ability to save hearing in appropriate app op ate cases, and a d the t e good results esu ts we ea and d others have reported. In a few patients with no useful hearing and intracanalicular tumors or with tumors extending a few millimeters into the posterior fossa, we have used a translabrynthine approach. Scaricato da www.sunhope.it 31 25/06/2010 I use the supine position with the ipsilateral shoulder slightly elevated and the head turned to the opposite side. This approach has worked well for visualization of the important anatomical structures, tumor removal, comfort of the operator, and avoidance of problems with air embolism or hypotension hypotension. Other surgeons have used the sitting position and achieved good results. The key considerations in the operation include: 1. Exposure of the tumor as described in acoustic neurinoma. 2. Interruption of the blood supply along the dural attachments. 3. Internal decompression combined with careful dissection of the tumor capsule from the brainstem and cranial nerves. Scaricato da www.sunhope.it 32 25/06/2010 Cerebellopontine Angle Meningiomas aRemoval bOutcome Anterio r 14 Posterio r 13 RS T 10 1 ST 18 T 1 Complications Good Anterio r 34 Posterio r 15 Fair 3 0 Permane nt deficit Cerebella Poor 4 (4) 0 r infarction Meningitis Deat h 1 0 CSF leak Anterio r 3 Posterio r 0 1 0 1 0 1 0 Recurrenc e 5 Anterior 0 Posterior aT,, total removal RST, radical subtotal removal ST, subtotal removal bGood, free of major neurological deficit and able to return to previous activity level Fair, independent but not able to return to full activity because of new neurological deficit or significant preoperative deficit that did not fully recover Poor, dependent. Yasargil et al. (1980) reported that 27 of 30 patients had a good result and in 27 the tumor was "radically radically excised. excised " Sekhar and Jannetta (1987) reported total removal in 14 of 22 patients, with no operative mortality and a good outcome in 16. Samii and Ammirati (1991) reported total removal of all 24 tumors located posterior to the internal auditory meatus, meatus with a good outcome for 22 patients. Of 32 patients with tumors anterior to the internal auditory meatus, 29 had the tumors totally removed and 28 had a good outcome. Scaricato da www.sunhope.it 33 25/06/2010 Scaricato da www.sunhope.it 34