Wednesday, April 22, 2009

Quick references to the clinical presentation of cranial nerve lesions.

Olfactory Nerve- Anosmia,(loss of sense of smell) may result from head injuries in which cribriform plate of ethmoid bone is fractured.

Optic nerve:Visual field defects and loss of visual acuity may result from fractures in the orbit, lesion along the visual pathway and diseases of nervous system.

Oculomotor nerve:A lesion in the nerve causes strabismus ,ptosis of upper eyelid ,pupil dilatation,the movement of eye ball downward and outward on the damaged side,loss of accommodation for near vision and diplopia.

Trochlear nerve:In trochlear nerve paralysis,diplopia and strabismus occur.

Trigeminal nerve:Injury results in paralysis of muscles of mastication and loss of sensation of touch and temperature.Neuralgia of one or more branches of trigeminal nerve is called trigeminal neuralgia.(Tic douloureux)

Abducens nerve: With the damage to this nerve, the affected eyeball move laterally beyond the midpoint and the eye is usually directed medially.

Facial nerve:Injury produces paralysis of facial muscles called bell’s palsy,loss of taste and loss of ability to close the eyes even during sleep.

Vestibulocochlear nerve:Injury to the cochlear branch may cause tinnitus or deafness.Injury to the vestibular branch may cause vertigo,ataxia, and nystagmus.

Glossopharyngeal nerve:Injury results in difficulty during swallowing,reduced secretion of saliva,loss of sensation in the throat and loss of taste.

Vagus nerve:Damage to this nerve in the upper body interfere with swallowing,paralyses the vocal cords,and interrupts the sensation from many organs.

Acessory nerve:Damage to this nerve results in paralysis of sternocleido mastoid and trapezius muscle present with inability to raise the shoulder and turning the head.

Hypoglossal Nerve.Injury results in difficulty in chewing ,speaking and swallowing. The tongue when protruded turn towards the affected side and the affected side become atrophied,shrunken,and deeply furrowed.

Further reading

Cranial nerve examination

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