Veterinary Neurology Quiz

Neurological Examination

• Reflexes are a part of the neurological examination to assess the integrity of the central and peripheral nervous system.
• Reflex arc is the neural pathway involved in mediating reflex actions, starting with a sensory receptor and ending with an effector organ.
• Sensory neurons involved in reflexes do not always pass through the brain, instead, they synapse in the spinal cord, allowing for faster reflexes.
• Myotatic reflexes are also known as stretch reflexes.
• Reflex tests assess the sensory and motor components of the reflex arc and the influence of descending motor pathways.
• Absence or depressed reflex indicates a complete or partial loss of sensory or motor nerves in the reflex arc, known as Lower Motor Neuron (LMN) lesion.
• Normal reflex suggests intact sensory and motor nerves.
• Exaggerated reflex indicates an abnormality in the descending pathways from the brain and spinal cord, known as an Upper Motor Neuron (UMN) lesion.
• Patellar reflex is the most reliable pelvic limb reflex, performed with the animal in lateral recumbency.
• Absence or depression of the patellar reflex indicates a lesion of the sensory or motor component of the reflex arc (LMN).
• Unilateral loss suggests a femoral nerve lesion, while bilateral loss suggests a segmental spinal cord lesion involving spinal cord segments L4-L6.
• Exaggerated patellar reflex and increased muscle tone suggest a lesion cranial to the L4 spinal cord segment (UMN).
• Proprioception is the ability to recognize the limb position, tested by observing gait, foot placement, and knuckling.
• Ataxia is lack of coordination without paresis, spasticity or involuntary movements.
• Hypotonia is abnormally decreased muscle tonicity or strength.
• Dysmetria is the inability to properly direct or limit movements.
• Hypermetria is movements that overreach the intended goal.
• Hypometria is movements that fall short of the intended goal.
• Purposeful movement is an animal's conscious attempt to move its legs, applicable to weakly ambulatory and non-ambulatory animals.
• Proprioceptive positioning is preformed by flexing the paw so the dorsal surface is on the floor. The animal should immediately return to position.
• Wheel-barrowing is performed by having the animal bear weight on the thoracic limbs while being supported under the abdomen.
• Hopping is tested by lifting one thoracic or pelvic limb and supporting the animal's weight on the remaining limb.
• Extensor postural thrust is performed by supporting an animal caudal to the scapula and observing its ability to extend pelvic limbs to support weight.
• Hemistanding and Hemiwalking are performed by elevating one side's front and rear limbs, observing the animal's ability to walk forward and laterally.
• Tonic neck reaction is observed by extending the head dorsally, eliciting extension of joints in thoracic limbs in a normal dog.
• Placing reactions are evaluated with and without vision.
  • Tactile placing involves covering the eyes and touching the distal thoracic limb to the edge of a table.
  • Visual placing allows the animal to see the table surface.
• Clonus is a sustained after-contraction or quivering observed or felt during reflex testing, often associated with chronic conditions.
• Deep pain perception is the most important prognostic test, indicating spinal cord integrity.
• Sensory evaluation should be performed last.
• Absence of deep pain indicates severe spinal cord damage with poor prognosis.
• Sensory function returns before motor function during recovery.
• Hyperpathia is an abnormally exaggerated response to painful stimuli, often found in pressure applied to spinous processes and paraspinal muscles.
• Cerebellum is responsible for coordination and balance.

Spinal Cord Localization

• Lesions below the foramen magnum are localized to specific regions of the spinal cord: cranial cervical, caudal cervical, thoracolumbar, lumbosacral, and sacral.

Cranial Cervical (C1-C5) Lesions

• Altered mental status
• Ipsilateral circling, pacing, head pressing
• Contralateral postural and proprioceptive deficits
• Contralateral cortical blindness (normal pupils and pupillary light reflexes)
• Contralateral UMN hemiparesis
• Seizure

Caudal Cervical (C6-T2) Lesions

• Altered mental status: aggression, disorientation, hyperexcitability, coma
• Contralateral postural and proprioceptive deficits
• Bilateral visual deficits
• Abnormalities of eating, drinking, sleeping, and temperature regulation (hypothalamus)

Thoracolumbar (T3-L3) Lesions

• Mental status may be normal to severe depression and coma
• Ipsilateral UMN hemiparesis or tetraparesis; may circle if ambulatory

Lumbosacral (L4-S3) Lesions

• Cranial nerve deficits involving cranial nerves V through XII
  • Trigeminal: motor and sensory (drop jaw/eyelid?)
  • Abducent: medial strabismus
  • Facial: facial paralysis
  • Vestibulocochlear: central vestibular signs; hearing loss
  • Glossopharyngeal/vagus: dysphagia, reduced gag reflex, laryngeal dysfunction
  • Hypoglossal: abnormal tongue movement

Sacral (S1-S3) Lesions

• Vestibular: Disoriented or unaltered mental status

• Ipsilateral head tilt, circling, rolling, falling, asymmetric ataxia, and incoordination

• Nystagmus (spontaneous or positional) with fast phase away from the side of the lesion

• Ipsilateral ventrolateral strabismus

• Requires differentiation from peripheral vestibular disease

  Cerebellar Lesions

• Unaltered mental status

• Ataxic gait, wide-based stance, dysmetria, head tremor, intention tremor, and truncal ataxia

• Visual but may have ipsilateral loss of menace response

• Hypermetric postural reactions, goose stepping gait

• Muscle tone, segmental reflexes, and sensation are unaltered