Review of Cranial Nerves Flashcards
What would be the result of a lesion to CN I and what are the possible causes?
The result of this would be anosmia. Upper respiratory tract and sinus infections. Aging. Trauma causing fracture of the cribiform plate can lead to this condition and CSF rhinorrhea. Tumors of the frontal lobe can compress the tract.
What are possible causes of optic neuritis?
MS, exposure to toxic substance, infecitons, and diabetes.
How would compression of the optic sheath be caused and what would compression of each of its components result in?
CN II is an evagination of the diencephalon and therefore lies with in the optic sheath, an extension of the meninges. Increased intracranial pressure can cause compression.
Central retinal vein - papilledema
Optic nerve - blindness
Retinal artery - blindness due to loss of blood to retina`
How would occulomotor nerve palsy present and what would be causes of this lesion?
Paralysis of most EOM causing the eye to be held down and out or diplopia.
Paralysis of levator palpebrae muscle causing the ptosis.
Paralysis of sphincter pupillae causing mydriasis
Paralysis of ciliary muscle causing loss of accomodation
This lesion could be caused by an uncal herniation, cavernous sinus pathologies, aneurysms of posterior cerebral or superior cerebellar aa, increased intracranial pressure causing compression against temporal bone.
With compression of CN III the peripheral fibers (GVE-P) would be first affected.
How does diabetic neuropathy present at the eyes?
Microvascular injury of the vessels supplying CN III would cause diplopia and ptosis with pupillary sparing.
How would trochlear nerve palsy present?
Eye held slightly up and in with diplopia
How would abducent nerve palsy present and what is a typical cause of this?
Eye would be held adducted. Often affected in pathologies involving the cavernous sinus due to its course through the structure.
What are the results of a CN VIII lesions and possible causes?
This lesion would result in dizziness, tinnitis, and hearing deficits. Possible causes include acoustic neuromas.
How does glossopharyngeal neuralgia present and what are some possible causes?
This is a very rare condition which presents with sudden excruciating pain during swallowing, talking, or touching of palatine tonsil. Compression by AICA is a possible cause.
