Cranial Nerve Examination and Differential Diagnosis Flashcards
What are the four stages evaluation of the cranial nerves can be divided into?
1 Assessment of symmetry of the face
2 Eyes (neurophthalmic examination)
3 Facial sensation
4 Gag reflex.
When a reflex is assessed, it will mostly evaluate the brainstem with…?
An afferent and efferent pathway
What change is seen in the following with forebrain lesion abnormalities:
A) Mental status?
B) Cranial nerves?
A) Altered mentation/change in behaviour
B) Contralateral lack of menace with normal PLR
What change is seen in the following with forebrain lesion abnormalities:
A) Posture/gait
B) Postural reaction?
A) Normal gait with poss abnormal posture
B) Contralateral deficits
What change is seen in the following with forebrain lesion abnormalities:
A) Spinal reflexes/muscle tone
B) Sensation
C) Other symptoms possibly seen? (2 - neuro)
A) Normal to increased contralaterally
B) Facial and body contralateral absent to decreased
C) Seizures/hemi-neglect syndrome
What change is seen in the following with brainstem lesion abnormalities:
A) Mental status?
B) Cranial nerves?
A) Altered
B) 3 - 12
What change is seen in the following with brainstem lesion abnormalities:
A) Posture/gait
B) Postural reaction?
A) Tetra/hemi paresis/plegia
B) Affected all 4 limbs/one side
What change is seen in the following with brainstem lesion abnormalities:
A) Spinal reflexes/muscle tone
B) Sensation
C) Other symptoms possibly seen? (not neuro!)
A) Normal to increased in all four limbs or ipsilaterally
B) Possible cervical hyperaesthesia
C) Poss cardiac/resp abnormailites
The two cranial nerves involved in the symmetry of the face are ?
trigeminal (CN V) and facial (CN VII) nerves.
The trigeminal nerve is sensory for the A) and motor for the B) through its mandibular branch.
A) entire face (cutaneous, cornea, nasal septum and oral cavity)
B) masticatory muscles
The facial nerve is innervating the A) of the face and sensory for the
A) muscles of the expression
B) rostral part of the palate and tongue.
Testing the palpebral reflex involves which nerves? (2)
facial (CN VII) and trigeminal (CN V) nerves.
Afferent nerve of the palpebral reflex?
Trigeminal (V)
Efferent nerve of the palpebral reflex?
Facial (VII)
The facial nerve has parasympathetic fibres supplying?
Lacrimal glands
Dysfunction of the facial nerve parasympathetic fibres can cause what? (2)
KCS (dry eye) and xeromycteria (dry nose)
PLR efferent pathway?
Oculomotor (III)
PLR afferent pathway?
Optic (II)
Aside from a lesion affecting the PLR pathways, the PLR can de decreased or absent in cases of? (3)
Iris atrophy
Drugs to dilate pupils
Light source of insufficient intensity.
Which nerves are involved in the menace response?
II and VII
How to perform a menace response?
The menace response is elicited by waving the hand toward one eye and blindfolding the other, creating a visual threat, the response is involving the awareness of the patient and should elicit the closure of the eyelid.
When is the menace response more reliable in cats?
When not blindfolded
Define nystagmus
Nystagmus is the involuntary rhythmic oscillation of the eyeball.
The extraocular muscles are controlled by which nerves? (3)
oculomotor nerve (CN III), trochlear nerve (CN IV), and abducens nerve (CN VI).
Physiological nystagmus can be elicited how?
moving the head from side to side and up and down.
When is pathological nystagmus seen?
At rest
However, in some cases no abnormal eye movement is seen at rest but can be observed if the vestibular system is challenged.
How could you then look for pathological positional nystagymus?
change the head position or have the patient on its back
How to assess facial sensation? (2)
Corneal reflex
Nasal stimulation
How to perfom the corneal reflex?
a damp cotton bud to touch the sclera of the eye and then evaluating closure of the eyelids and retraction of the globe.
Which nerves does the corneal reflex involve? (2)
ophthalmic branch of the trigeminal nerve (CN V)
facial nerve (CN VII)