Chapter

Disorders of cranial nerves

R.D.M. Hadden, P.K. Thomas and R.A.C. Hughes

in Oxford Textbook of Medicine

Published on behalf of Oxford University Press

Published in print May 2010 | ISBN: 9780199204854
Published online November 2012 | e-ISBN: 9780199570973 | DOI: http://dx.doi.org/10.1093/med/9780199204854.003.2412_update_002

Series: Oxford Textbooks

Disorders of cranial nerves

Show Summary Details

Preview

The 12 cranial nerves are peripheral nerves except for the optic nerve which is a central nervous system tract. Disorders of particular note include the following: Olfactory (I) nerve—anosmia is most commonly encountered as a sequel to head injury.

Third, fourth, and sixth cranial nerves—complete lesions lead to the following deficits (1) third nerve—a dilated and unreactive pupil, complete ptosis, and loss of upward, downward and medial movement of the eye; (2) fourth nerve—extorsion of the eye when the patient looks outwards, with diplopia when gaze is directed downwards and medially; (3) sixth nerve—convergent strabismus, with inability to abduct the affected eye and diplopia maximal on lateral gaze to the affected side. The third, fourth, and sixth nerves may be affected singly or in combination: in older patients the commonest cause is vascular disease of the nerves themselves or their nuclei in the brainstem. Other causes of lesions include (1) false localizing signs—third or sixth nerve palsies related to displacement of the brainstem produced by supratentorial space-occupying lesions; (2) intracavernous aneurysm of the internal carotid artery—third, fourth, and sixth nerve lesions. Lesions of these nerves can be mimicked by myasthenia gravis....

Chapter.  6097 words. 

Subjects: Neurology

Full text: subscription required

How to subscribe Recommend to my Librarian

Buy this work at Oxford University Press »

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.