Cranial Nerves Flashcards
Oculomotor nerve palsy
Complete compressive palsy will cause complete Ptosis, down and out, fixed dilated pupil (efferent defect and light unto affected pupil will still cause construction of contralateral pupil
Reduced movements all
Directions except adduction
Partial 3rd nerve palsy usually means pupil abnormalities and Ptosis not present (these nerve fibres lie on the outer rim of nerve and have a different blood supply)
May also be 4th nerve palsy - can tell 4th nerve intact with 3rd nerve palsy when ask patient to look down and away from lesion. The affected eye will intort (rotate onwards) if 4th nerve intact.
Ophthalmologia
False image normally less distinct
Diplopia occurs in positions that depend upon contraction of a weak eye muscle
A false image is projected in the direction of action of a weak muscle
Image separation increases in the direction of a weak muscle
Trochlear nerve
Double vision on looking down producing ‘twisted image’
A head tilt away from the side of trochlear nerve palsy
No obvious squint
Abducens nerve
Convergent squint
Diplopia with horizontal separation, maximal on attempted abduction of effected eye and disappears with adduction
No abnormality of pupil reaction
Internuclear ophthalmoplegia
Medial longitudinal fasciculus lesion in brainstem
Disconjugate horizontal gaze
Incomplete adduction of ipsilateral eye
Coarse jerky nystagmus of the opposite abducting eye
Trigeminal nerve
Angle jaw is supplied by C2 not the 5th nerve
Ophthalmic, maxillary and mandibular branches
Motor root supplies muscles of mastication. Masseters, temporalis, Opening jaw against resistance tests ptwrygoids. Here you would get jaw deviation towards side of weakness
Corneal reflex - say would do it. Often first sensory sign of V1 lesion
Jaw jerk - brisk on pseudobulbar palsy
Facial nerve
Small motor branch supplies stapedius causing hyperacuisis with a palsy.
Taste for anterior 2/3 tongue by chorda tympani.
Part of the 7th nerve nucleus supplying forehead gets supranuclear innervation from contralateral side so UMN lesion results in forehead sparing
Bells phenomenon (eyeball rolling up when trying to blink) is LMN phenomena as frontal sparing allows normal blinking
Causes of Unilateral LMN facial weakness
Bell’s palsy
Ramsay hunt (herpes zoster reactivation). Vesicles external auditory meatus or canal.
Stroke - brainstem lesion within 7th nerve nucleus
Demyelination
Space occupying lesion eg cerebellopontine angle (acoustic neuroma, cholesteatoma, neurofibromas. May also be cerebellar spines if compressed
Infection eg TB, Lyme disease
Nerve infiltration - sarcoidosis, lymphoma
Vasculitides
Causes of bilateral LMN facial weakness
Bilateral Bell’s palsy
Sarcoidosis, amyloidosis
Autoimmune: myasthenia gravis, vasculitis
Inflammatory: GBS
Facioscapulohumeral dystrophy, Myotonic dystrophy
Other congenital (mobius syndrome bilateral 6th and 7th palsies
Vestibular cochlear nerve
Hearing
Rinnes and Weber’s test
Cavernous sinus syndrome
Ipsilateral 3rd, 4th, 6th, and V1 (ophthalmic branch of 5th) and possibly V2
Ipsilateral complete / incomplete ophthalmoplegia (often painful) with dilated fixed pupil
Chemosis
Proptosis
Horners syndrome
Trigeminal sensory loss (V1 +/- V2)
Can be indistinguishable from superior orbital fissure syndrome except that V2 as well as V1 May be involved.
Causes:
Tumours
Infections (bacterial or fungal causing cavernous sinus thrombosis)
Internal carotid aneurysm
Granulomatous disease eg sarcoidosis, wegeners, PAN
Differential diagnosis:
Posterior communicating artery aneurysm with painful ophthalmoplegia Thyroid eye disease Vascular artery aneurysm Ophthalmic migraine Lesions involving orbital apex
Orbital apex syndrome / superior orbital fissure syndrome
Affects 3rd, 4th, 6th and V1 which all go through superior orbital fissure. If extends to orbital apex will involve optic nerve also which is orbital apex syndrome
Ophthalmoplegia V1 sensory disturbance Proptosis with large orbital lesions Horners syndrome Visual loss of orbital apex syndrome
Causes:
Inflammatory/vasculitic disorders: sarcoidosis, wegeners granulomatosis, GCA, Churg-Strauss
Superior orbital fissure fracture
Infections:
Nasopharyngeal tumours
Cerebellopontine angle lesion
CNs 5th 6th 7th 8th nerves with ipsilateral cerebellar signs
Features:
Absent corneal reflex Nystagmus 6th and 7th nerve palsies Sensorineural hearing loss Cerebellar signs Scar behind ear over petrous bone Headache, hydrocephalus or raised ICP from CSF obstruction
Causes:
Tumours of middle cranial fossa (acoustic neuroma, meningioma, cholesteatoma, glioma of pons, nasopharyngeal tumour)
Vertibrobasillar dolichoectasia
Meningeal infection from syphilus or TB
Jugular foramen syndrome
9, 10, 11
Absent gag reflex Ipsilateral reduces palatal movements Uvula drawn to opposite side Loss of posterior 1/3 tongue taste Wasted/weak sternocleidomastoid Headache, hydrocephalus, raised ICP Scar over petrous bone
Causes:
Neurofibroma or schwannoma of 9,10 or 11 nerve Meningioma Carotid body tumour (pulsatile tinnitus) Cholesteatoma Carcinoma Granulomatous disease Lymphoma
Differential diagnosis
A brainstem lesion affecting the lower nuclei would produce similar picture but with contralateral spinothalamic loss
