NAVLE Veterinary Neurology — Questions and Answers
Question 1: A 5-year-old Dachshund presents with sudden-onset paraplegia, absent deep pain perception in both pelvic limbs, and urinary retention. The lesion localizes to T3-L3 myelopathy. MRI confirms an acute Hansen Type I disc extrusion at T12-T13. The most important prognostic indicator for functional recovery is:
- Duration of clinical signs before surgery
- Severity of disc extrusion on MRI (Grasso scale grade)
- Presence or absence of deep pain perception in the pelvic limbs (Correct answer)
- Age of the patient at time of surgery
Correct answer: Presence or absence of deep pain perception in the pelvic limbs
Presence of deep pain perception (DPP) is the single most important prognostic factor in spinal cord injury from IVDD. Dogs that retain DPP have >90% chance of functional recovery with decompressive surgery. Dogs that have lost DPP have approximately 50–60% recovery rates, and those with absent DPP for >48 hours have a significantly poorer prognosis. Duration matters but DPP status is the most critical indicator.
Question 2: A 7-year-old German Shepherd presents with progressive, non-painful pelvic limb ataxia and weakness over 12 months. The dog is ambulatory but shows proprioceptive deficits bilaterally. Spinal radiographs are normal. CSF is normal. Which diagnosis is most consistent with this presentation?
- Lumbosacral stenosis (cauda equina syndrome)
- Degenerative myelopathy (DM) (Correct answer)
- Fibrocartilaginous embolism (FCE)
- Meningomyelitis due to Neospora caninum
Correct answer: Degenerative myelopathy (DM)
Degenerative myelopathy (DM) in German Shepherds is a progressive, non-painful, symmetric upper motor neuron disease of late middle-age to older dogs, with normal imaging and CSF. It is associated with the SOD1 gene mutation. FCE is acute and often asymmetric. Lumbosacral stenosis causes pain and lower motor neuron signs. Neospora causes a painful, ascending LMN polyradiculoneuritis.
Question 3: A 3-year-old intact male cat presents with acute onset of pelvic limb paralysis, cold limbs below the stifle, absent femoral pulses bilaterally, and cyanotic nail beds. The most likely diagnosis is:
- Fibrocartilaginous embolism (FCE) of the thoracolumbar spinal cord
- Aortic thromboembolism (ATE) secondary to hypertrophic cardiomyopathy (Correct answer)
- Traumatic spinal cord injury with T3-L3 myelopathy
- Botulism with flaccid tetraplegia
Correct answer: Aortic thromboembolism (ATE) secondary to hypertrophic cardiomyopathy
Aortic thromboembolism in cats classically presents as the 'SAD' triad: Sudden onset, Asymmetric or bilateral pelvic limb paresis/paralysis, and Devastating pain. Cold, paralyzed limbs with absent femoral pulses and cyanotic nail beds (ischemia distal to the thrombus at the aortic trifurcation) are pathognomonic. Most cases have underlying hypertrophic cardiomyopathy. FCE is painless; spinal trauma has a history of injury.
Question 4: A lesion causing ipsilateral hemiparesis, ipsilateral facial paralysis (CN VII), and ipsilateral loss of the menace response with intact vision best localizes to which neuroanatomical site?
- Contralateral cerebral cortex (forebrain)
- Ipsilateral cerebellum (cerebellar hemisphere)
- Ipsilateral brainstem (pons/medulla) (Correct answer)
- Ipsilateral C1-C5 spinal cord segment
Correct answer: Ipsilateral brainstem (pons/medulla)
Cranial nerve VII (facial) nucleus is located in the pons. A lesion in the ipsilateral pons/medulla causes ipsilateral CN VII palsy (facial paralysis), ipsilateral hemiparesis (UMN, because corticospinal tracts haven't crossed yet at this level), and ipsilateral menace loss (cerebellar/pontine relay for menace). A forebrain lesion would cause contralateral deficits. Cerebellar lesions cause ataxia, not weakness or CN VII signs.
Question 5: Polioencephalomalacia in adult cattle most commonly results from which underlying cause, distinct from the thiamine deficiency seen in sheep and young ruminants?
- Molybdenum toxicity causing copper depletion
- High dietary sulfur intake causing hydrogen sulfide (H2S) neurotoxicity (Correct answer)
- Vitamin A deficiency causing increased CSF pressure
- Sodium ion toxicosis (salt poisoning) following water deprivation
Correct answer: High dietary sulfur intake causing hydrogen sulfide (H2S) neurotoxicity
In adult cattle, PEM is increasingly associated with high dietary sulfur (from distillers grains, gypsum water, or sulfur supplements), which promotes rumen production of hydrogen sulfide — a neurotoxin that causes cortical necrosis. While thiamine deficiency also occurs in cattle, high-sulfur PEM is the emerging predominant cause and is sulfur-diet-associated rather than thiaminase-related. Sodium toxicosis causes cerebral edema/herniation rather than laminar cortical necrosis.
Question 6: An 8-month-old kitten presents with intention tremors of the head, broad-based stance, hypermetria, and falling toward the right. The neurologic examination is otherwise normal with no weakness. Which region of the nervous system is affected?
- Right cerebral hemisphere (forebrain)
- Right side of the cerebellum (Correct answer)
- Right vestibular apparatus (peripheral)
- Right C1-C5 spinal cord segment
Correct answer: Right side of the cerebellum
Intention tremors, hypermetria, and broad-based stance without weakness are signs of cerebellar disease. Falling/rolling ipsilaterally (toward the lesion side) with a unilateral cerebellar lesion reflects ipsilateral cerebellar hemispheric dysfunction (cerebellum has ipsilateral control). Forebrain lesions cause contralateral deficits with normal gait quality. Peripheral vestibular disease causes head tilt and nystagmus without hypermetria or intention tremor.
NAVLE Veterinary Neurology
A 5-year-old Dachshund presents with sudden-onset paraplegia, absent deep pain perception in both pelvic limbs, and urinary retention.
The lesion localizes to T3-L3 myelopathy.
MRI confirms an acute Hansen Type I disc extrusion at T12-T13.
The most important prognostic indicator for functional recovery is: