What is the pathophysiology of abducens nerve palsy (sixth cranial nerve palsy)?

Updated: Nov 19, 2018
  • Author: Michael P Ehrenhaus, MD; Chief Editor: Edsel Ing, MD, MPH, FRCSC  more...
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Answer

Only the ipsilateral lateral rectus that is solely innervated by the involved peripheral sixth cranial nerve is affected; therefore, only deviations in the horizontal plane are produced. In isolated cases of peripheral nerve lesions, no vertical or torsional deviations are present. Central nervous system lesions of the abducens nerve tract are localized easily secondary to the typical findings associated with each kind of lesion. Damage to the sixth nerve nucleus results in an ipsilateral gaze palsy. The lack of a contralateral adduction defect makes it easy to differentiate a nuclear lesion from a fascicular or nonnuclear lesion. [2]

Abducens palsy can be a false localizing sign with lesions that cause increased intracranial pressure and stretching of the sixth nerve as it ascends the clival area.

Abducens nerve palsy is frequently seen as a postviral syndrome in younger patients and as an ischemic mononeuropathy in the adult population.


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