Neurological Examination - Cranial Nerves - for Medical Student OSCE
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General inspection:
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Abnormal or asymmetrical pupils: II, III
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Ptosis, strabismus (squint), abnormal eye position: III
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Poor articulation of words: V, VII, X, XII
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General asymmetry, muscle atrophy, facial droop: VII
I Smell bottles
II Acuity: Snellen chart
Neglect
Visual fields
Colour vision: Ishihara colour test plates
Pupils:
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Size, shape, symmetry (Horner’s syndrome, ptosis)
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Reaction to light (direct, consensual, alternating) (direct + consensual: hand placed to mask light between eyes.) What is a relative afferent defect? (Alternating light)
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Accommodation (if reaction to light is poor)
Ophthalmoscopy:
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Tropicamide
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Optic disc: pale / swollen? (Swollen optic disc, maybe with enlarged blind spot = papilloedema due to raised intracranial pressure)
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Follow vessels outwards to view each quadrant
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Change focus: lens and cornea
III, IV, VI
Eye movements: pursuit, to test for nerve palsy or poor saccades
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III palsy: ptosis, large pupil, eye down and out
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IV palsy: diplopia on looking down and in. Head tilting compensates
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VI palsy: horizontal diplopia on looking out.
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Nystagmus: if more in the abducting eye, MS may be the cause. N.B. various causes of nystagmus
V Sensation:
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3 branches: ophthalmic, maxillary, mandibular. Compare to sternum.
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Corneal reflex
Muscles of mastication (masseter and temporalis). Jaw jerk. Motor palsy: ‘open your mouth’ ? jaw deviates to side of lesion
VII Screw up eyes (and resist)
Raise eyebrows
Show teeth
Puff out cheeks (and resist)
Open jaw against hand
Forehead has bilateral representation in the brain. Therefore, upper 1/3 not affected by UMN lesion. However, all of one side of face affected in LMN lesion. All cranial nerves have bilateral representation except for CNVII
VIII Begin by examining the external auditory meatus
Whisper numbers, for repetition; mask by rubbing fingers
Tuning fork (256 or 512 Hz tuning fork): air should conduct the sound better than the bone
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Weber’s test: high on forehead, in midline – tests bone conduction – sensorineural deficits1
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Unilateral conductive deafness: sound seems louder in deaf ear (sensorineural apparatus has become more sensitive)
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Unilateral sensorineural deafness: sound louder in unaffected ear
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Rinne’s test: over mastoid process then about 1cm from external auditory meatus – tests air conduction – conductive deficits2
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Bone conduction better than air conduction ? conductive deficit
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Balance: induction of positional nystagmus (not carried out)
IX Gag reflex (side of pharynx)
Cough
XI Sternocleidomastoid: turn head against resistance
Trapezius: shrug shoulders against resistance
XII Tongue movement: deviates to side of lesion.
Further tests:
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Neurological examination of UL and LL
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Fundoscopy (ophthalmoscopy)
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Otoscopy
Bulbar and pseudo-bulbar problems: ‘bulbar’ = medullary = IX, X, XI, XII.
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Bulbar: LMN: wasting and fasciculation. Dysarthria, dysphagia3, nasal regurgitation.
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Pseudo-bulbar: UMN
Cerebellar disease
Caused by MS, stroke, alcohol, space occupying lesions (tumour, aneurysm, abscess, granuloma, cyst) and anti-convulsant medications. Signs and symptoms: DANISH:
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Dysdiadochokinesia or dysmetria
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Ataxic gait
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Nystagmus (worse in direction of lesion)
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Intention tremor
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Slurred speech
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Hypotonia
Symptoms are worse on ipsilateral side, although vermis lesions cause bilateral problems e.g. axial imbalance / truncal ataxia
1 Sensorineural hearing deficit: due to cochlear / VIII nerve damage
2 Conductive hearing deficit: due to lesion of external auditory meatus, tympanic membrane, middle ear cavity or ossicles ? sounds unable to reach cochlea
3 Dysphagia: difficulty swallowing
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Date: Fri, 22 Jan 2010 Time: 4:01 PM
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