Neurological - Cranial Nerves

Question 1

Clinical signs on general inspection?

Answer 1

Speech problems (glossopharyngeal/vagus)
Facial asymmetry (facial)
Eyelid abnormalities (oculomotor)
Pupillary abnormalities (dilated = oculomotor)
Strabismus (lazy eye)
Limb abnormalities

Question 2

Objects or equipment on general inspection?

Answer 2

Walking aids (gait issues), hearing aids, visual aids, prescriptions

Question 3

Causes of anosmia?

Answer 3

Mucus blockage of nose, head trauma, genetics, Parkinson’s, COVID-19

Question 4

Causes of decreased visual acuity?

Answer 4

Refractive errors, amblyopia, cataracts or corneal scarring, age-related macular degeneration, optic neuritis

Question 5

Afferent limb of pupillary reflex

Answer 5

Sensory input (light) -> retina -> optic nerve -> ipsilateral pretectal nucleus

Question 6

Efferent limb of pupillary reflex

Answer 6

Motor - pretectal nucleus -> Edinger-Westphal nuclei on both sides
Each EW nucleus then gives rise to efferent fibres -> oculomotor nerve -> ciliary sphincter = constriction

Question 7

Limbs of pupillary reflex tested by each pupillary reflex test?

Answer 7

Direct - ipsilateral afferent limb, ipsilateral efferent limb
Consensual - contralateral efferent limb
Swinging light - relative afferent limb defects

Question 8

Abnormal pupillary responses?

Answer 8

Marcus-Gunn pupil (relative afferent pupillary defect) - shine light into bad eye = bilateral impaired restriction (afferent pathway impaired)

Unilateral efferent defect - extrinsic compression of oculomotor nerve (afferent limb intact so contralateral consensual constriction intact, just impairment of ipsilateral efferent pathway)

Question 9

Colour vision deficiencies?

Answer 9

Optic neuritis (red)
Vitamin A deficiency, chronic solvent exposure

Question 10

6 muscles of the eye + innervations?

Answer 10

Superior/inferior/lateral/medial rectus
Superior/inferior oblique (opposite action to intuitive)

Superior oblique - trochlear (IV)
Lateral rectus - abducens (VI)
All others - oculomotor (III)

Question 11

Oculomotor nerve palsy?

Answer 11

Down and out +/- ptosis and mydriasis

Question 12

Trochlear nerve palsy?

Answer 12

Vertical diplopia (double vision looking downward as superior oblique can’t pull the eye down)

Question 13

Abducens nerve palsy?

Answer 13

Horizontal diplopia (double vision looking outward as lateral rectus can’t pull eye laterally/temporally)
Also convergent squint

Question 14

Explain difference between conductive and sensorineural hearing loss

Answer 14

Conductive - sound unable to transfer at any point throughout structure of ear (outer ear, external auditory canal, tympanic membrane, middle ear/ossicles)
Sensorineural - dysfunction of cochlea and/or vestibulocochlear nerve