Flashcards in Equine Neurological Examination Deck (21):
What are the aims of a neurological examination?
To determine the presence/absence of neurological disease and localise the lesion/lesions
What are the two different approaches you can use to a neurological exam?
Systemic approach testing each nerve group separately
Anatomic approach from head to tail
What information is important to gather from the history?
Was the horse looking/acting clumsy before it was found down?
Is there any respiratory disease? Is it a new horse?
Are there any other horses affected?
Are there any behavioural abnormalitites?
What should be done prior to the neurological exam?
A good clinical examination to see if there is any other reason for the horse to be down e.g. CVS/respiratory/locomotor
How is the forebrain assessed? What behaviours indicate something wrong?
Mentation - bright or depresed, responsivenss
Abnormal behaviours include circling, hyperaesthesia, head turn, odd postures/head pressing
What is the role of the cerebellum?
Control centre for ascending proprioceptive pathways and descending motor pathways
What signs are seen with cerebellar dysfunction?
Spastic or exaggerated movements
Absent or diminished menace response
Ataxia without weakness
What is the role of the brainstem?
Contains ascending proprioceptive pathways and descending upper motor neurones
Also contains cranial nerve nuclei
How does brainstem damage show clinically?
Weakness and ataxia
Any cranial nerve deficits
How do you test the cranial nerves?
PLR for optic nerve and parasympathetic fibres in CN III
Menace response tests optic nerve, optic chiasm, thalamus, opposite occipital cortex, facial nerve and nucleus and cerebellum
Vision assessed by walking horse round an obstacle course and a fundic exam
Strabismus indicates dysfunction in CN III, IV or VI
Retractor oculi reflex tests CN V and VI
Facial sensation and tone of masticatory muscles = CN V
Muscles of facial expression = CN VII
Head tilt and nystagmus = CN VIII
Swallowing, vocalisation, slap test and endoscopy = CN IX and X
What is ataxia?
Functional deficit associated with defective proprioception
What are the signs of ataxia?
Hypermetria, hypometria, dysmetria and truncal sway
What are the causes of ataxia?
Cerebellar dysfunction, vestibular dysfunction, brainstem/spinal cord lesions or peripheral nerve problems
How is ataxia in the horse graded?
0 = normal
1 = very mild
2 = mild-moderate
3 = moderate
4 = moderate-severe (risk of falling)
5 = down
What are the clues to look for to diagnose ataxia?
Pacing or circumduction
How do you differentiate ataxia from hind limb lameness?
Irregular irregularities as opposed to regular irregularities
What is paresis and how is it defined?
Weakness of either UMN or LMN origin
What is UMN paresis?
Inability to control muscles resulting in normal or increased tone and no muscle atrophy
What is LMN paresis?
Inability to contract the muscles resulting in muscle flaccidity and atrophy if chronic
How do you localise a spinal lesion in a horse?
Limb weakness and cutaneous trunci reflex