Neurological Exam Large Animals Flashcards
What is the aim of the neurological exam?
Determine presence or absence of neurological disease (vs. musculoskeletal issue)
What are the 2 approaches to the neurological examination?
What is the most suitable approach for neurological assessment of the horse?
Systematic (modality) approach
Anatomic approach - head to tail
Combination of systematic and anatomic approaches is most suitable for the neurological assessment of horses
Where is white matter vs. grey matter in the brain vs. the spinal cord?
White matter - inside brain, outside spinal cord
Grey matter - outside brain, inside spinal cord
Label this photo of the spinal cord
What does the white matter consist of?
Myelinated nerve axons (traveling from cell bodies)
What does the grey matter consist of?
Neuron cell bodies
Supportive cells (astrocytes, glial cells, etc.)
Afferent is the _______ pathway while Efferent is the _______ pathway
(motor/sensory)
Afferent = sensory
Efferent = motor
What part of a neuro exam is ESSENTIAL?
Accurate history
What is the typical mentation of a horse with a forebrain problem? What kind of behavior do they have?
Mentation - Bright or depressed
Abnormal behavior - Circling, Hyperasthesia, Head turn, Odd postures, yawning
What is the function of the cerebellum?
Control center for ascending proprioceptive pathways and descending motor pathways (fine tunes control signals from higher centers)
How common is cerebellar disease in the horse?
Very rare
What are the signs of cerebellar disease in the horse?
Spastic or exaggerated movements
Absence or diminished menace response
Intention tremor
Ataxia with weakness
Which horse breed is predisposed to cerebellar disease and why?
Arabian Foals/Arabian Crosses
Autosomal recessive inherited genetic neurological condition which causes progressive death of neurons in the cerebellum
What structures does the brainstem include?
Pons and Medulla
Reticular formation
Cranial nerve nuclei
What does the reticular formation control? What common substance works here?
Controls level of consciousness (site of action of caffeine)
What are the ascending and descending pathways in the brainstem?
What does this mean about the symptoms associated with brainstem dysfunction?
Ascending proprioceptive pathways
Descending motor neuron pathways
Weakness and ataxia
Which cranial nerves originate in the brainstem?
How do we evaluate the cranial nerve nuclei?
Cranial nerves testing
What is afferent and efferent limb of the pupillary light reflex?
Afferent - optic nerve CN II
Efferent - oculomotor nerve CN III (parasympathetic fibers)
Does the animal need to be conscious for pupillary light reflex to occur?
No - reflexes are involuntary
What is important to remember about consensual pupillary response in pupillary light reflex testing?
Can be difficult to evaluate in horses/farm animals
Does the animal need to be conscious for menace response to occur?
Yes - responses require perception of stimulus at level of forebrain
What are the steps/structures involved in the menace response?
Perception of stimulus → optic nerve CN II → Optic chiasm → Thalamus → Opposite occipital cortex → facial nerve CN VII and nucleus → Cerebellum
What is the optic chiasm?
Part of the brain where the optic nerves cross