Sixth nerve palsy
 

Most cases of sixth nerve palsy seen in the examination has an obvious esotropia making the diagnosis easy. However, in mild palsy the best way to demonstrate its  presence is by cover/uncover test with distant fixation.  The affected eye has a convergent squint (this may not be obvious in mild or partially recovered sixth nerve  palsy). On cover/uncover test, the eye shows esotropia which is worse for distance than near. On ocular motility  testing, the affected eye has limited abduction. There is a A pattern esotropia on upgaze (this is because the lateral rectus acts best as an abductor on elevation). In the examination: there may be abnormal head posture with face turn to the affected side if asked for further examination mention that you would like to perform blood pressure check, urine  test for diabetes and fundal examination for papilloedema. If the patient wears hearing aid, consider  middle ear infection as a cause but this is now rarely seen  (see question below).

Questions:

1. Where about is the lesion located in a patient with a sixth nerve palsy plus the following features:

a. bilateral optic disc swellings

answer
This is a false localizing sign and the patient is likely to have a mass lesion causing raised intracranial pressure

b. hearing loss the facial pain

answer
Petrous apex. The most common pathology is otitis media. This is termed Gradenigo's syndrome

c. ipsilateral gaze palsy with facial nerve palsy, Horner's syndrome and deafness

answer
Dorsolateral pons. The most common cause is occlusion of the anterior inferior cerebellar artery. This is also called Foville's syndrome

d. ipsilateral Horner's syndrome only

answer
Cavernous sinus. The sixth nerve and the sympathetic nerve travel together in the cavernous sinus and can therefore be affected earlier than other nervse.

e. ipsilateral facial nerve palsy with contralateral hemiparesis

answer
Anterior paramedian pons. The commonest cause is cerebrovascular accident. The combined signs form the  Millar-Gubler's syndrome

2. What treatment options are available for unresolved sixth nerve palsy?

answer
The main problem is diplopia and this can be treated either surgically or non-surgically:
Non-surgical treatment:
prism can be used to correct the diplopia
Surgical:
Botulinum toxin
ipsilateral medial rectus weakening procedure combined with strengthening of the ipsilateral lateral rectus muscle
vertical transposition of the muscles

Return to the main page