Aetiology

The aetiology of abducens nerve palsy depends on whether the sufferer is an adult or a child:

In adults the common causes are:

• tumour - e.g. nerve is compressed on the sharp edge of the petrous temporal bone with raised intracranial pressure, but it may also be directly compressed by a tumour in the cerebellopontine angle. Raised intracranial pressure may result in bilateral palsy.
• trauma - commonly affected in fractured base of skull
• cerebrovascular accidents - e.g. Millard Guber syndrome
• diabetes may cause mononeuritis complex - bilateral or unilateral palsy
• Wernicke's encephalopathy - bilateral
• idiopathic

Frequent causes in children:

• following mastoid and middle ear infections
• brain stem tumour
• infective, e.g. suppurative middle ear disease causing unilateral trigeminal pain and VI nerve palsy
• birth injury or trauma