Cranial Nerve lesions Flashcards
The Olfactory Nerve - Cranial nerve 1: sensory
The olfactory nerve is a series of bipolar neurons that passes through the cribriform plate of the ethmoid bone to the olfactory bulb
Reduced taste and smell but not to ammonia as it stimulates the pain fibres in the trigeminal nerve
E.g. Trauma, tumour meningitis
The optic nerve - cranial nerve 2: Sensory
Axons of the retinal ganglion cells and at the optic chiasm the nasal fibres decussate, optic canal
Leads to vision loss of visual field defects
Monocular sight impairment: MS, giant cell arteritis
Bilateral - neurosyphilis
Bitemporal hemianopia: Optic chiasm compression e.g. ICA aneurysm, pituitary adenoma or craniopharyngioma
Homonymous hemianopia: Loss of the same half of the visual field on the opposite side of the lesion - lesions will be in the optic tract e.g. lateral geniculate nucleus or optic radiations
Optic neuritis : Pain on movement, loss of red, loss of central vison - demyelination, syphilis, sinuses
Optic atrophy - MS and retinitis pigmentosa, syphilis
Papilledema - raised ICP e.g tumour, abscess, encephalitis , inflammation, ischaemia
Pupillary lesions?
The afferent limb of the pupillary reflex is made up of the optic nerve and prectectal nucleus and the afferent is via the Edinger Westphal nucleus
Anisocoria - uneuqal but can be due to horners syndrome ( carotid dissection, 3 nerve palsy )
3 nerve palsy : Unilaterally large pupil
Impaired pupillary light reflex: Oculomotor and optic
Non reactive is a bad sign !
What in horners syndrome?
Miosis ( small pupil ), partial ptosis and anhidrosis
The Oculomotor 3 nerve? Motor
Emerges from the brainstem on the medial crus cerebi - superior orbital fissure
Fixed dilated sign + ptosis and outward deviation of the eye
DM , GCA, syphilis, raised ICP - uncal herniation , 4 eye muscles and levator palpebrae superioris
Trochlear : 4 : Motor -
Diplopia due to weakness of down and in the patient usually tilts there head away from the affected side
Superior oblique and superior orbital fissure
Diabetes, trauma, HTN infarction
Trigeminal : Ophthalmic Division?
Superior orbital fissure
Supplies the skin over the medial nose forehead, eye and does the corneal reflex ( involuntary blinking elicted by corneal stimulation) , scalp sensation
What’s in the cavernous sinus?
O: Oculomotor
T: Trochlear
O: Ophthalmic division of the trigeminal nerve
M: Maxillary branch
C: Internal carotid artery
A: Abducens
T: Trochleor
Trigeminal Maxillary division?
Foramen Rotundum
Cheeks, lower eye lid, nasal mucosa, upper lip teeth and palate
Trigeminal Mandibular:
Lose sensation in the anterior 2/3 of the tongue, skin sensation over the mandible and lower teeth
Lose motor to the muscles of mastication - masseter , temporalis and pterigoids ( weakness of jaw clenching and side to side )
Trigeminal neuralgia, herpes zoster
Foramen ovale
Abducens nerve:
Superior orbital fissue
Motor
Lateral rectus so eye is deviated medially
MS,
Facial nerve 7?
External acoustic meatus
Loss of taste to the anterior 2/3 of the tongue , facial weakness in LMN the forehead is paralysed in UMN forehead is spared , loss of external ear sensation
Lacrimal , submandibular and sublingual glands
LMN: Bells palsy, polio, zoster, lymes
UMN: Stroke and tumour
Vestibulocochlear nerve 8?
Unilateral sensoneural deafness, tinnitus
Passes through the internal acoustic meatus
Acoustic neuroma, neurofibroma, herpes zoster
Glossopharyngeal nerve9?
Unilateral lesions dont do much but bilateral - pseudobulbar palsy
Posterior 1/3 of the tongue taste and sensation, middle ear, carotid body and sinus
Motor to parotid gland and stylopharyngeus
Jugular foramen
Trauma, braisntem lesions, Guillian barre
Vagus nerve - 10?
Jugular foramen
Palatal weakness - nasal speech and regurgitation, hoarsness , loss of voice
Most muscles of the pharynx, larynx, taste from the epiglottis, abdominal and thrracic viscera
trauma, brainstem, GBC, polio
