Large Animal Neurology. Joe Mayhew

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СКАЧАТЬ sensation Quick adjustment ~2–7 days Paralytic state with cradling Partial seizures—just face, jaw Mentation/sensorium Forebrain Midbrain Response to environment Sleep attacks more common than epilepsy Cardiovascular syncope very rare Adjustment ~24 h Head posture and movement Neck Forebrain—head and neck turn Vestibular—head tilt Tremor—check eyeballs Stiff/twisted neck Head tilt (VIII) verses head turn (forebrain) Head tremor—cerebellar Head/neck ataxia—cerebellar/spinal Head shaking—trigeminal Flexed head posture and ataxic movements normal Cranial innervation CN II – XII Brainstem Cervical sympathetic supply Evaluate regions of head Fundic examination Repeat test for subtle asymmetries Reevaluate when totally relaxed Menace deficit <7 days Eye rotation dorsomedial Body Neck and forelimbs C₁–T₂ Particularly asymmetry Only flexor reflex useful Hopping All reflexes Hyperreflexia normal Crossed extension normal Trunk and hindlimbs T₃–S₂ L₄—femoral n. L₅—cranial gluteal n. L₆–S₁—sciatic n. Particularly asymmetry Patellar reflexes usefulFlexor reflex useful All reflexes Hyperreflexia Crossed extensor reflex Extensor thrust response Tail Ca₁₊ Extension and flexion Perineum, anus, rectum, and bladder S_1–5 S1–2 is common fracture site Gait and posture ORTHOPEDIC PROBLEMS! Neuromusculoskeletal VIDEO! Shoulder and hip atrophy common Possible analgesic trial SEPSIS! Positional CP deficits Brainstem, spinal cord, and sensory nerves Manual placement of feet/limbs noncontributory Prematurity Extensor weakness Brainstem, spinal cord, and PNS Especially final motor neuron lesion Extensor strength dominant Flexor weakness Brainstem, spinal cord, and PNS Ataxia Spinal ataxia Irregular position and placement Cerebellar ataxia Hypermetria characteristic; F > H Normal to degree Vestibular gait Crouched posture Deliberate (predictable) stepping Wide‐based, staggering gait Normal to degree

      CP, conscious proprioception; CN, cranial nerve.

Head

For the routine large animal patient examination, evaluate what one can from a distance, preferably before the patient is disturbed, for the first observations of behavior, mentation and head, neck, trunk, and limbs. Head and neck deviations need to be assessed closely by straightening the neck along the midline to determine what neck and head asymmetry may be present. Allow the patient to smell an (often peppermint‐tainted) hand for introduction and observe the face, particularly eyes and associated structures, for an expressional response. Then, examine the parts of the head and neck for the evaluation of cranial nerve function (Table 2.3).

Table 2.3 Assessment of cranial nerve function

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Cranial nerve	Major function	Normal reflex/response/assessment
I	Olfactory		Sense of smell	Challenging—most odors also stimulate CNV
II	Optic		Afferent pathway for vision and light	Menace response. Pupillary light reflex. Swinging light test Dazzle response
III	Oculomotor		Pupillary constriction Upper eyelid levator muscle Extraocular muscles	Pupillary light reflex Induced eyeball movement Medial movement of globe Ptosis rarely apparent
IV	Trochlear		Extraocular muscle (dorsal oblique)	Ventrolateral rotation of globe
V	Trigeminal Sensory	Sensory to head, face, and tongue	Ear, eyelid, and lip (facial) reflexes Pain perception: head, nasal septum, and rostral tongue
		Motor	Motor to muscles of mastication	Chewing, jaw tone, and muscle mass (temporalis, masseter, and pterygoid)
VI	Abducens		Extraocular muscle (retractor oculi) Extraocular muscle (lateral rectus)	Induced eyeball retraction Eyeball retraction (corneal reflex) Lateral movement of globe
VII	Facial		Motor to muscles of facial expression	Ear, eyelid and lip (facial) tone, reflexes, and movementFacial expression and symmetry
VIII	Vestibular		Afferent branch of vestibular system	Head posture. Induced eyeball movement. Normal vestibular nystagmus. Normal gait. Blindfold test
	Cochlear		Hearing	Ear movement in response to noise (Preyer reflex)
IX	Glossopharyngeal