Abducens Nerve Palsy (Sixth Cranial Nerve Palsy) Clinical Presentation

Updated: Oct 10, 2017
  • Author: Michael P Ehrenhaus, MD; Chief Editor: Edsel Ing, MD, MPH, FRCSC  more...
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Presentation

History

Clinical history of abducens nerve palsy includes the following:

  • Binocular diplopia (worse at distance or lateral gaze)
  • Esotropia
  • Head-turn
  • Vision loss
  • Headache, vomiting, pain, or facial numbness
  • Trauma
  • Symptoms of vasculitis, particularly giant cell arteritis
  • Hearing loss
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Physical

Physical findings of abducens nerve palsy include the following:

  • An esodeviation that increases on ipsilateral gaze and is often greater at a distance; prism measurements in different positions of gaze can reveal the magnitude of misalignment and its incomitance (asymmetry)
  • An isolated abduction deficit
  • Slowed ipsilateral saccades
  • Papilledema (if increased intracranial pressure)
  • Altered sensation in the V1 or V2 distribution with cavernous sinus lesions
  • Nystagmus (usually in children, ie, secondary to pontine glioma)
  • Otitis media
  • Petrous bone fracture
  • Tender, enlarged, nonpulsatile temporal arteries in giant cell arteritis
  • Horner syndrome (Foville brainstem syndrome, carotid oculosympathetic plexus involvement in cavernous sinus)
  • Contralateral hemiparesis may be seen in brainstem syndromes that involve the sixth cranial nerve (Millard-Gubler syndrome and Raymond syndrome)
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Causes

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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