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The Nervous System
And its associated diseases
Diseases of Brain: Trauma
Dog skull and brain
1º Trauma—Direct trauma to
brain tissue
2º Trauma: edema, hemorrhage
(↑ intracranial pressure)
Brain: Trauma
• Signs:
– Seizures
– Blood in eyes, ears, nose, oral cavity
– Loss of consciousness or decrease in response to external
stimuli
– Shock, coma, altered respiratory patterns
• Dx
– Hx of trauma (HBC, falling)
– Chem. panel to rule out other metabolic diseases
Brain: Trauma
• Treatment—aimed at reducing 2° effects (edema)
– Osmotic agents: Mannitol (20-50%) IV slow bolus
– Diuretics: Furosemide IV q4h
– Anti-seizure Rx if needed: Diazepam, Phenobarbital
• Client info
– Some brain injury is irreversible
– Dog in coma >48 h usually does not survive
– Worsening neuro signs → bad prognosis
Idiopathic Vestibular Disease
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Signs
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Loss of balance
Head tilt
Nystagmus
Disorientation
Ataxia
Vomiting/anorexia
Signalment: Dogs (middle aged)
and cats, acute
Idiopathic Vestibular disease
http://www.youtube.com/watch?v=Y25T7dZ77T4&feature=related
Idiopathic Vestibular Disease
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Dx
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Clinical signs
Blood work to r/o other diseases of nervous system
Ear exam to r/o inner ear infection
Rx
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Treatment is not recommended; does not alter course of
disease (antibiotics, steroids often given to cover possible
causes not found by PE and lab work)
Clinical signs resolve in 3-6 wks
Brain: Neoplasia
•
Enlarging mass in brain; causes compression of healthy
tissue or replacement with cancerous tissue
•
Signs (usually progressive)
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Depends on tumor location
Seizures increasing in frequency and intensity
Vestibular signs (depending on location)
Tremors, ataxia
Brain: Neoplasia
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Dx
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Systematic screening for tumors in other organs
CBC, chem panel
Radiographs
CSF tap to assess increased cerebral spinal pressure
Ophthalmic exam may indicate optic nerve edema
Computed tomography (CT) scanning or magnetic resonance
imaging (MRI) to locate tumor
Brain: Neoplasia
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Rx—
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Surgical removal of superficial single lesions
Radiation therapy
Chemotherapy; efficacy varies with tumor type (lymphomas
respond well; other less so)
Anti-seizure medication (Phenobarbital PO 2-3 times/day)
Corticosteroids—prednisone
Client info
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Unless tumor is surgically removed, medications will not
cure disease
Symptoms will worsen as tumor grows larger
Epilepsy
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Signs of seizure
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short aura (stare into distance,
seek comfort/protection from
Click for video
someone, vocalize)
seizure lasts 1-2 min; may consist of total body muscle
twitching with extended arms and legs and arching of
neck dorsally (opisthotonus)
dog will be disoriented/blind for a few minutes
may be a single event (no veterinary intervention
needed) or followed shortly by other seizures (status
epilepticus- requires veterinary intervention)
may be incited by certain events
normal at other times
• http://www.thepetcenter.com/gen/epilepsy.ht
ml
Epilepsy
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Dx
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CBC, chem panel—r/o metabolic diseases causing seizures
hypoglycemia
hypocalcemia
hepatic encephalopathy (failure to detox blood)
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Shunt
Cirrhosis
Pb poisoning
Radiographs—r/o head trauma or hydrocephalus
CT scan or MRI—r/o space-occupying lesion in brain
Rx—directed at cause if one can be found
– treat if >1 every mo or two (Rx will not completely stop
seizures)
– Phenobarbital is TOC
Status Epilepticus
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Signs—prolonged, uninterrupted seizures
Rx
– Diazepam (2-10 mg to effect); can be repeated over
several minutes
• Phenobarbital – Time to steady state blood levels: 10-14 days
– Side effects: sedation, ataxia, PU/PD/PP, hepatotoxicity, blood
dyscrasias (Rare)
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Establish an open airway
IV cath with IV fluids to keep an open vein
Monitor blood Ca and glucose; treat is needed
Monitor body temp; if elevated, treat appropriately
If cerebral edema is suspected, treat with mannitol
(IV)
Phenobarbital—IV or IM
Epilepsy
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Client info—
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Epilepsy is an incurable disease
Even with treatment, animal may still seize;
• goal is to reduce frequency and intensity of seizures
Spaying/neutering will remove any hormonal influence on
seizures
Medications will probably be required for life
Most animals that seize can live a normal life
If seizure free for 6-9 mo, may reduced or discontinued Rx
Spinal Cord
• Function
– Nerve fibers carry signals between brain and rest of
body
• Anatomy
– Like brain, protected by hard covering, the vertebral
canal
Spinal Cord: Anatomy
Like brain, spinal cord enclosed in hard covering
IVDD problem in both humans and canine
Anatomical differences—cervical same; lumbar—human bears weight, canine doesn’t
Attached rib (thorax) helps stabilize the IV joint; worse at T-L junction (dogs)
Degenerative Disc Disease: Humans
Degeneration of disk occurs with age
Dries out, shrinks (we get shorter as we age)
IV Disk Disease: Anatomy
Normal spinal column and disk
1/3 thickness
nucleus fibrosus
Prolapsed disk
Intervertebral Disk Disease
• Etiology
– IVD dries out with age → hardened, less compliant
– ↑Pressure from jumping
– Occurs most commonly in cervical, caudal thoracic,
and lumbar vertebrae
Intervertebral Disk Disease
• Hansen TYPE I: Nucleus pulposus herniates
upward; narrowest part of annulus fibrosus
– TYPE I: Most common in chondrodystrophic (“faulty
development of cartilage”) breeds
• Dachshunds, shih tzus, Lhasa apsos, beagles, basset
hounds (poodles also affected)
• Acute onset
• Can occur at any age, but generally younger dogs
Intervertebral Disk disease
• Hansen TYPE 2: dorsal protrusion of the
annulus into the spinal canal
– Common in older dogs and nonchondrodystrophic
breeds
• Occurs over a longer period of time
• Clinical signs may be less severe
• Generally older dogs
Intervertebral Disk Disease
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Signs:
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Pain
Paresis/paralysis; nerve function is lost in this order:
• Proprioception—largest fibers; most susceptible to
pressure; signs are ataxia
• Motor fibers—next smallest fibers; signs are
weakness/paresis
• Cutaneous sensory fibers—small; require a lot of pressure
to disrupt function; decreased panniculus reflex
• Deep pain fibers—smallest fibers; require the most
pressure to disrupt; loss is associated with poor prognosis
Intervertebral Disk Disease
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Severity of clinical signs depends on:
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Speed at which disk material is deposited
Degree of compression
Duration of compression
IVDD – Paralysis of rear legs
Cervical IVDD
Loss of Deep Pain
IVDD Dx: Spine X-Rays
Normal
horse’s head
consistent IV space
Subluxation L2-3
(old lesion)
IV Disk Disease: Myelogram
Which disk space?
IV Disk Disease: Myelogram
Which disk space?
Cervical IVDD
Myelogram: Disk herniation at C2-3 (narrowed IV space, narrowed spinal canal)
IVDD
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Rx TYPE I, acute onset
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Medical Rx is recommended for animals, with deep
pain intact, with or w/o neuro deficit
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Strict confinement—2 wk minimum (easy when dog
hurts; not so easy after steroids/other pain
medications take effect)
Nursing care
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High levels of corticosteroids is CONTROVERSIAL
Soft padded cage
Urinary cath or express bladder several times/day
Surgery is recommended for
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repeat offenders
No voluntary motor function
loss of deep pain (needs to be done QUICKLY!)
worsening neuro signs (poor Prognosis)
Laminectomy
IVDD: Possible sequela
IVDD
IVDD - rehabilitation
http://www.youtube.com/watch?v=7AkNVDc4
lig&feature=related
IVDD – Alternative/Optional Treatment
• Methocarbamol 15-20 mg/kg q 8hr
• High-dose Methylprednisolone sodium succinate
(CONTROVERSIAL!) and should be given within 8 hours
– Although there is proven benefit in humans, results have not
been proven in dogs
• Low dose prednisone – various regimens
• NSAIDS
– Carprofen, deracoxib, etodolac
• Gastroprotectants
• Acupuncture
Veterinary Acupuncture
• http://www.youtube.com/watch?v=ZJjZPnk_Mw&feature=related
• http://www.youtube.com/watch?v=vJIJDUQyOmw&f
eature=fvw
IVDD
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Client info
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Do not let susceptible breeds get overweight
Encourage animals to keep spine parallel to ground
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No jumping on/off couch
No begging on hind legs
No stair climbing
Loss of deep pain >24 h has poor prognosis
If surgery is done soon enough, there is a good Px of recovery
Almost half of animals treated medically will have recurrence
Extensive home care is required for medical and surgical
patients
Severe damage to spinal cord is not reparable