ANSC 325 - Midterm 2 - Lecture 4

• Head and mental status

• Gait and posture

• Neck and forelimbs

• Trunk

• Tail and anus

Neuro exam should assess these 5 categories

• Sensory

• Integration

• Motor systems (upper vs lower motor neurons)

Divisions of neuro examination should include (3)

Upper Motor Neuron

• Brain to spinal cord in CNS

• Weakness or paralysis

• Spasticity

• Increased muscle tone (hypertonia)

• Over-response reflexes (hyperflexia)

Lower Motor Neuron

• Spinal cord to structure (muscle, organ, etc.)

• Decreased of absent muscle tone (hypotonia or atonia)

• Decreased or absent or areflexia)

• Muscle atrophy

• Mentation and alertness

• Cranial nerve function

Neurological exam - Head and Mental Status assesses (2)

• Alert

• Depression

• Stupor

• Coma

Four consciousness levels

Alert

Level of Consciousness

• Aware of environment-normal

• Aware and awake

Depression

Level of Consciousness

• Awake but unresponsive to the environment 

Stupor

Level of Consciousness

• Asleep except when aroused: needs to be aroused by strong (i.e. noxious) stimulus: pain, loud noise, bright light 

• Asleep, but will wake up

Coma

Level of Consciousness

• Deep state of unconsciousness and animal can not be aroused with noxious stimuli

CN II

Cranial Nerve - Optic

• Related to pupillary reflex

• Function: vision

• Assessment: menace response and pupillary light reflex, lesions cause blindness and loss of pupillary light reflex

CN III

Cranial Nerve - Oculomotor

• Related to pupillary reflex

• Function: pupillary constriction, extra ocular muscles

• Assessment: pupillary light reflex, pupil size, eye position, lesions cause ventral strabismus, loss of PLR

CN VIII

Cranial Nerve - Vestibulocochlear

• Related to head dropping, vestibular disease

• Function: posture, balance, hearing

• Assessment: head and eye position (strabismus) and nystagmus, lesions cause nystagmus, head tilt, balance loss, deafness

CN VII

Cranial Nerve - Facial

• Related to facial nerve tone and lip dropping

• Function: motor to muscles of facial expression

• Assessment: facial symmetry, palpebral blink, ear and muzzle/lip movement, lesion causes facial paralysis, loss of palpebral reflex, blink, dry eye

CN XII

Cranial Nerve - Hypoglossal

• Related to difficulty eating and drinking and not pulling tongue back when pulled

• Function: motor to tongue

• Assessment: tongue stretch and symmetry, lesions cause atrophy and paralysis

CN IX

Cranial Nerve - Glossopharyngeal

• Related to difficulty swallowing, saliva/mucous coming out

• Function: Sensory and motor to pharynx

• Assessment: Ability to swallow, lesions cause dysphagia and displaced soft palate

CN X

Cranial Nerve - Vagus

• Related to difficulty swallowing, saliva/mucous coming out

• Function: sensory and motor to pharynx and larynx

• Assessment: ability to swallow, laryngeal movement, lesion causes dysphagia, laryngeal paralysis, displaced palate

Standing Sway Test

Test of posture during neurological exam

• apply pressure of the shoulder: Horse should always maintain balance initially leaning into the examiner, then the horse should step away 

• Should be resistant and come back to original position

Thoracic limb test

Test of posture during neurological exam

• lift thoracic limb and force horse to hop on the down leg: some examiners consider this a test dangerous to both owner and the horse 

• Take front limb and lift, unstable

• Not very safe

Tail pull test

Test of posture during neurological exam

• pelvic limb weakness

  • Should be able to readjust back

0

Modified Mayhew Scale - Grade __

• No neurological deficits

1

Modified Mayhew Scale - Grade __

• Neurological deficits just detected at normal gait, but worsened by backing, turning, loin pressure, or neck extension

2

Modified Mayhew Scale - Grade __

• Neurological deficits easily detected at the walk and exaggerated by backing, turning, loin pressure, or neck extension

3

Modified Mayhew Scale - Grade __

• Neurological deficits prominent at the walk with a tendency to buckle or fall with backing, turning, loin pressure, or neck extension

4

Modified Mayhew Scale - Grade __

• Stumbling, tripping, and falling spontaneously at a normal gait

5

Modified Mayhew Scale - Grade __

• Horse recumbent

Cutaneous trunci reflex

• Part of trunk part of neurological exam

• Responses of spinal reflexes between thoracic nerve of the brachial plexuses and CN8-T1

• Localize spinal cord injuries

Cauda Equina Syndrome (Gegenerative Lumbosacral Stenosis)

• Penis extending - not retracted in prepuce

• Backend dropped (tail head dropped)

• Dying and dead ganglion

Cerebrospinal puncture

• Collection fluid from subarachnoid space- indication of inflammation, infection, neoplasia, hemorrhage within the brain and spinal cord 

• 2 sites:

  • Lumbosacral

  • Atlantooccipital

Lumbosacral

Site of Cerebrospinal Puncture

• Sedate (standing) horse 

• Base of spine

• Below foramen magnum

Atlantooccipital

Site of Cerebrospinal Puncture

• Anesthetized horse

• Higher up

• Where spinal cord is leaving the skull

• Above foramen magnum

• Riskier