What are the causes 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

Not all abduction deficits are cranial nerve VI palsies. Mimickers are orbital lesions, medial wall fractures, Duane syndrome, thyroid-associated orbitopathy, myasthenia gravis, and spasm of the near reflex. [4]

  • Elevated intracranial pressure can result in downward displacement of the brainstem, causing stretching of the sixth nerve secondary to its anatomic location within the Dorello canal. This is believed to be the reason that about 30% of patients with pseudotumor cerebri have an isolated abducens nerve palsy and explains how lesions remote from the sixth cranial nerve can cause abducens paresis (false localizing sign).
  • Subarachnoid space lesions can be causes of abducens nerve palsy (eg, hemorrhage, infection, inflammation, space-occupying tumor, cavernous sinus mass). Inflammatory (eg, postviral, demyelinating, sarcoid, giant cell arteritis)
  • Vascular
  • Metabolic (eg, vitamin B, Wernicke-Korsakoff syndrome)
  • Neoplasm (children) - Pontine glioma
  • Infectious (eg, Lyme disease, syphilis)
  • Congenital absence of the sixth nerve (eg, Duane syndrome) [5]
  • Trauma, particularly if it results in a torsional head motion [6, 7, 8, 9]
  • Post–lumbar tap [10]

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