DISEASES OF THE NERVOUS SYSTEM
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Transcript of DISEASES OF THE NERVOUS SYSTEM
“I’ve wrestled with an alligator, I’ve tussled with a whale, I handcuffed
lightning, threw thunder in jail. Last night I murdered a rock,
injured a stone, hospitalized a brick. I’m so mean, I make medicine sick.
I’m gonna show you how great I am.”-Muhammad Ali
PART 2
SIGNALMENT: 4mth old, intact female Yorkshire Terrier; history of neck pain,Inability to stand/walk
CASE #5: Atlantoaxial Instability Signs
Toy and miniature breeds Reluctance to be patted on head Neck pain May have tetraparesis (weakness in all 4
limbs) or tetraplegia (paralysis in all 4 legs) Sudden death due to respiratory paralysis
Atlantoaxial Joint
Atlanto-Axial Joint
Atlantoaxial instability Diagnosis
Radiographs: lateral x-ray of neck in slight ventroflexion
avoid further spinal cord damage with positioning
Atlantoaxial Instability
CT scan:dens is marked by *
Normal toy breed dog Toy breed dog with atlantoaxial subluxation
X-rays of same dogs; note separation of C1 and C2 when dog’s neck is flexed in B
Narrowed spinal canal
Atlantoaxial Instability (Subluxation)
Treatment Medical
splint neck in extension with cage confinement x 6 w
treat like other spinal cord trauma
Surgical (if unresponsive to medical Rx) stabilize/decompress attach dorsal process of axis to arch of atlas fuse atlas and axis joint with pins and bone graft hemilaminectomy to relieve spinal cord
compression
Atlantoaxial Instability: Surgical Correction
Stabilization using screws and bone cement
Stabilization using trans-articularscrews
Atlantoaxial InstabilityClient info
prognosis is fair to good for animals with mild signs
animals should not be used for breeding; may be hereditary
CASE #6
Cervical Spondylomyelopathy: Wobbler’s
Cervical spinal cord compression as a result of caudal vertebral malformation or misarticulation.
Large breed dogs (Great Danes and Dobermans)Signs
Progressive hind-limb ataxia (wobbly gait) Pelvic limbs cross each other when walking Abduct widely/tend to collapse May drag toes (wears dorsal surface of nails) Impaired proprioception Signs may also be present in front limb Crouching stance with downward flexed neck Rigid flexion of neck; may have neck pain
Cervical Spondylomyelopathy: Wobbler Diagnosis
Radiographs to show malalignment and narrowing of spinal canal
Myelogram is essential to locate the region of compression
CT and MRI if available
Cervical Spondylomyelopathy: WobblerTreatment: without treatment, prognosis is
poor Medical
Anti-inflammatory doses of corticosteroids Neck brace Cage confinement
Surgical Decompression of spinal cord by laminectomy Stabilize vertebral column
screws and wire dorsally spinal fusion ventrally
Cervical Spondylomyelopathy: Wobbler
Client info Prognosis is guarded Most likely a hereditary disease Multiple levels of compression less favorable
prognosis than a single area of compression Surgery is risky and costly
Degenerative Myelopathy Etiology: unclear
May be autoimmune response to antigen in nervous sys
Degeneration of white matter in ascending and descending tracts
Signs Mainly in German Shep and Shep mixes (>5 yr) Progressive ataxia and paresis of hind limbs Loss of proprioception is first sign Dog “falls down” when trying to defecate Muscle wasting of back muscles along caudal
thoracic and lumbosacral areas Symptoms progress until animal is unable to support
weight on hind limbs
Degenerative Myelopathy
Degenerative Myelopathy Diagnosis
Neurologic Exam ↓ proprioception N-↑ patellar reflexes Lack of pain Normal sphincter tone; normal panniculus (pin
prick) reflex Radiographs usually normal
Treatment: none - symptoms will progress to paralysis
Degenerative Myelopathy Client info
Degenerative myelopathy is a progressive, incurable disease
Although symptoms are similar at early stages, it is a different disease from hip dysplasia
When dog cannot support weight, quality of life should be evaluated
Deafnessdamage to auditory pathway
chronic otitis rupture of tympanic membrane damage to middle ear (ossicles)
damage to auditory nervehereditary or congenital
bull terriers, Dobes, Rotts, Pointers, blue-eyed white cats, Dalmations, Aust Heelers, Aust shepherds, Eng setters, Catahoula
related to drug therapy aminoglycosides (gentamicin, streptomycin, kanamycin topical polymyxin B Chloramphenicol Chlorhexidine w/ centrimide
normal old age: usually due to atrophy of nerve ganglia or cochlear hair cells
Deafness Diagnosis
Inability to rouse sleeping animal with loud noise (e,g,. blast from air horn) is diagnostic
Treatment: No treatment is available in most cases Hearing aids are available for animals, but most will not
tolerate something in ear canal
Client info Hearing loss is permanent If hereditary, do not breed Animals can be taught to hand signals rather than words Animals should not be off leash when outside Hearing aids are available for dogs but are usually not
tolerated; would only be appropriate for hearing impaired
Laryngeal Paralysis 3 types (always be cautious of laryngeal paralysis because
of the chance of rabies)
Hereditary: seen in Bouvier des Flandres and Siberian Huskies
Seen at 4-6 mo of age Acquired: can occur from lead poisoning,
rabies, trauma, inflammation of vagus nerve 1.5 to 13 yr of age
Idiopathic: seen in middle-age to old large- and giant-breed dogs; castrated dogs and cats have a higher incidence than female and non-neutered males
Laryngeal Paralysis
Laryngeal Paralysis Signs:
Inspiratory stridor Resp distress Loss of endurance Voice change Dyspnea/cyanosis/complete resp collapse
Laryngeal Paralysis Diagnosis: laryngoscopy will show laryngeal
abductor m. dysfunction
Treatment: surgical intervention including: Arytenoidectomy Removal of vocal folds
Client info: prognosis is guarded to good; do not breed if hereditary
Coonhound Paralysis (Polyradiculoneuritis ) thought to be an immune response to an unknown etiologic factor
in raccoon saliva some dogs will get it 1-2 wk after exposure, others exposed to same
raccoon will not Signs: similar to tick paralysis and rabies
Weakness begins in hind limbs with paralysis progressing rapidly to a flaccid tetraplegia
Alert, afebrile animal Loss of spinal reflexes (patella tap, etc) Loss of voice; labored breathing; inability to lift head May die of respiratory failure May last for 2-3 mo (usually good Px)
Rx: supportive nursing care
Client info Dogs can be affected without exposure to raccoon May require long-term nursing care Some animals will regain total function, while more severely
affected animals may not
CASE #11
Tick Paralysis Cause: female tick (Dermacenter variablis, D.
andersoni) → salivary neurotoxin Neurotoxin interfered with Ach at neuromuscular jct Not seen in cats; humans are affected
Signs Gradual onset of voice changes and hind-limb ataxia
(motor deficit) progressing to a flaccid, ascending paralysis (1-3 d)
Sensation is intact Ticks on the dog
Treatment Remove ticks (manually or with dip)
Usually resolves in 1-3 d Supportive care until dog recovers
Ventilation required for resp paralysis
Idiopathic Facial Nerve Paralysis Etiology: unknown Occurrence
Cocker Spaniels, Corgis, Boxers, Eng Setter, DLH cats
Signs Older dogs (>5 y) Ear droop Lip paralysis Sialosis (drooling) Deviation of nose Collection of food in paralyzed side of mouth Absence of menace and palpebral reflex
Idiopathic Facial Nerve Paralysis
Treatment efficacy of corticosteroids unknown
Artificial tears to prevent corneal ulcers Keep oral cavity clear of food
Client info Cause is unknown Complete recovery does not usually occur May develop keratoconjunctivitis sicca (dry
eye) Animals may require life-long maintenance
Grey’s Anatomy Memory Center
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