Exam 6: Neuro Flashcards
Most critical part of clinical neurology
neuroanatomic diagnosis
No conscious proprioception in pelvic limb, no voluntary movement of pelvic limb, but normal patellar and withdrawal reflexes, thoracic limbs normal: which spinal cord segments?
T3 - L3 spinal segments
Acute Spinal Diseases: most common causes
- Trauma (external)
- Neoplasia
- Myelitis/meningitis
- Intervertebral Disk Disease
- Vascular
Don’t forget…
Look where you localize!!!
Things to note when considering neurological abnormalities:
Look for abnormalities of:
- Posture
- Appearance
What is a hyperkeratotic pad (“Hard Pad”) associated with?
Distemper has been associated w/ hyperkeratotic pad
Physiological causes of Muscle Atrophy
- Disuse (takes time, usually bilateral)
- Neurogenic (can be acute; 3-5 days after damage to a nerve)
- Primary myopathic
Paraspinal Muscle Atrophy
Often caused by discospondylitis
asymmetry of face
1) palpebral fissure differences
2) nasal filtrum deviation
(cranial nerve seven-facial nerve controls this)
opisthotinus
spasm of the muscles causing backward arching of the head, neck, and spine, as in severe tetanus, some kinds of meningitis, and strychnine poisoning.
Decerebrate rigidity
1) opisthotinus
2) extensor rigidity
3) stupor or coma
PATHOGNOMONIC for disease in the midbrain
CLINICAL signs suggest location, not specific disease
(cerebellar disease can look like this but they remain conscious since cerebellum doesn’t involve consciousness. They may do extensor movements intermittently.)
Decerebrate rigidity
Pathognomonic for MIDBRAIN LESION
- rare for animals to recover at this point
- could be heartworm thrombosis, Toxoplasma, FIP
Postural abnormalities
extended or flexed!!
Remember: decerebrate rigidity
Is pathognomonic for midbrain lesion!
But remember tetanus can also look like this. You would want to look immediately for a wound.
But remember spinal cord disease may also disrupt balance between flexors and extensors (i.e. cervical disc problem)
Muscle fibrosis ==> contraction
We can see extensor problems with damage to muscle (i.e. femoral fracture causing fibrosis of quadriceps)
Cushing’s disease and heavily muscled?
Being heavily muscled may cause a stiff stilted short and choppy gait, which is an extensor posture and gait. (Cushing’s disease may cause heavy muscling)
Shiff-Sherrington Posture
1) usually occurs with acute lesions in thoracolumbar area (i.e. fracture of T13-L1 area)
2) front limbs extended, pelvic limbs neutral or slightly flexed (not actively)
Extended Postures
1) neurologic disease (usually central)
2) muscle (skeletal?)
(Also consider tetanus)
Gastrocnemius muscle
Extends hock and is innervated by the sciatic nerve
-may see over flexion of the hock when something is wrong with the gastrocnemius muscle or the sciatic nerve (note if flexion is when they put weight on the limb or not weight on the limb)
Problem with gastrocnemius tendon
1) the superficial digital flexor tendon may be allowed to over-tense the toes
- the toes may be knuckled under and you may see over flexion of the hock at weight-bearing
Gastrocnemius tendon rupture
1) superficial digital flexor over-flexes
- causes knuckling of toes
Cranial tibial muscle
1) flexes the hock
2) is innervated by the sciatic nerve
3) it’s not common to get nerve avulsion with this muscle group
Decreased tone in the pelvic limb
1) indicates damage more likely is present in peripheral nerves
2) sciatic nerve arises from L6, L7, S1, and maybe S2
Fibrotic myopathy
PATHOGNOMONIC GAIT (it's like the only one in vet med neuro!) -The hock turns inward at the height of its elevation
1) semimemnranosus, semitendinosus, and sometimes gracilis muscles become fibrotic and prevent normal movement of the limb
2) German shepherds are over-represented with this disease
3) it’s musculoskeletal disease!! It’s not neurologic disease
4) it likely occurred due to damage of the muscle