Neuro questions on the NAVLE typically require two steps: localize the lesion, then match it to a diagnosis. Get the UMN/LMN distinction and the localization chart memorized—everything else flows from there.
Neurolocalization: UMN vs LMN
UMN Signs (lesion above LMN pool)
- Spastic, stiff gait
- Hyperreflexia (exaggerated reflexes)
- Normal or increased muscle tone
- Crossed extensor reflex present
- Muscle atrophy: slow disuse (weeks)
LMN Signs (lesion at or below LMN pool)
- Flaccid, weak gait
- Hyporeflexia or areflexia
- Decreased or absent muscle tone
- No crossed extensor reflex
- Rapid neurogenic muscle atrophy (days)
Canine IVDD
Hansen Type I: Chondrodystrophic breeds (Dachshund #1, Beagle, Pekingese, Shih Tzu); nucleus pulposus extrusion; acute onset; any age. Hansen Type II: Large non-chondrodystrophic breeds; annulus fibrosus protrusion; chronic progressive; older dogs.
IVDD grading: Grade 1 (pain only) → Grade 5 (paralysis, absent deep pain). Deep pain is the most important prognostic indicator. Present = >90% recovery with surgery. Absent >48 hours = guarded prognosis (<50% with surgery). Treatment: Grade 1–2 = strict cage rest 4–6 weeks; Grade 3–5 = surgery within 24–48 hours improves outcomes significantly.
Wobbler Syndrome (Cervical Spondylomyelopathy)
Two populations: Great Danes (young, bony malformation C3–C5) and Dobermans (middle-aged/old, disc-ligament instability C5–C7). Classic presentation: hindlimb worse than forelimb, progressive ataxia ("wobbler" gait). Diagnosis: MRI or CT myelogram for definitive. Treatment: surgical decompression or medical management.
Seizure Management
Acute seizure (status epilepticus or cluster): diazepam 0.5 mg/kg IV (repeat ×2); if refractory → phenobarbital loading or propofol CRI. Maintenance: phenobarbital (therapeutic range 20–40 μg/mL; causes ALP elevation without true hepatotoxicity at therapeutic levels) or potassium bromide (adjunct, especially in dogs with hepatic concerns).
Cross-Species Neurological Conditions
Bovine PEM (Polioencephalomalacia): Thiamine deficiency; high-grain or high-sulfur diet; cortical necrosis → blindness, opisthotonus, circling, seizures. Treatment: thiamine IV (10–20 mg/kg), dramatic response if treated early. CSF: normal or mildly elevated protein, no pleocytosis.
Bovine Listeriosis: Listeria monocytogenes from silage; brainstem signs (CN V, VII, IX–XII); circling toward lesion side; treatment: high-dose penicillin G.
Equine EPM: Sarcocystis neurona; opossum is definitive host, horse is dead-end host; asymmetric ataxia and weakness; diagnosis: serum or CSF titers (SAG 2,4/3 IFAT); treatment: ponazuril (diclazuril alternative).
Equine Tetanus: Clostridium tetani; horse is MOST susceptible species; spastic paralysis, third eyelid prolapse, lockjaw, sawhorse stance; treatment: penicillin G, tetanus antitoxin, muscle relaxants (diazepam, guaifenesin).