The pathophysiological mechanism of<unk>  with increased intracranial pressure has traditionally been said to be stretching of the nerve in its long intracranial course, or compression against the petrous ligament or the ridge of the petrous temporal bone. Collier, however, was “unable to accept this explanation”, his view being that since the<unk>  nerve emerges straight forward from the brain stem, whereas other cranial nerves emerge obliquely or transversely, it is more liable to the mechanical effects of backward brain stem displacement by intracranial space occupying lesions. Brainstem Isolated lesions of the VI nerve nucleus will not give rise to an isolated VIth nerve<unk>  because paramedian pontine reticular formation fibers pass through the nucleus to the opposite IIIrd nerve nucleus. Thus, a nuclear lesion will give rise to an ipsilateral gaze<unk> . In addition, fibers of the seventh cranial nerve wrap around the VIth nerve nucleus, and, if this is also affected, a VIth nerve<unk>  with ipsilateral facial<unk>  will result. In Millard–Gubler syndrome, a unilateral softening of the brain tissue arising from obstruction of the blood vessels of the pons involving<unk>  and seventh cranial nerves and the corticospinal tract, the VIth nerve<unk>  and ipsilateral facial paresis occur with a contralateral hemiparesis. Foville's syndrome can also arise as a result of brainstem lesions which affect Vth, VIth and VIIth cranial nerves. Subarachnoid space As the VIth nerve passes through the subarachnoid space it lies adjacent to anterior inferior and posterior inferior cerebellar and basilar arteries and is therefore vulnerable to compression against the clivus. Typically<unk> es caused in this way will be associated with signs and symptoms of headache and/or a rise in ICP. Petrous apex The nerve passes adjacent to the mastoid sinus and is vulnerable to mastoiditis, leading to inflammation of the meninges, which can give rise to Gradenigo's syndrome. This condition results in a VIth nerve<unk>  with an associated reduction in hearing ipsilaterally, plus facial pain and paralysis, and photophobia. Similar symptoms can also occur secondary to petrous fractures or to nasopharyngeal tumours. Cavernous sinus/Superior orbital fissure The nerve runs in the sinus body adjacent to the internal carotid artery and oculo-sympathetic fibres responsible for pupil control, thus, lesions here might be associated with pupillary dysfunctions such as Horner's syndrome. In addition, III, IV, V1, and V2 involvement might also indicate a sinus lesion as all run toward the orbit in the sinus wall. Lesions in this area can arise as a result of vascular problems, inflammation, metastatic carcinomas and primary meningiomas. Orbit The VIth nerve's course is short and lesions in the orbit rarely give rise to isolated VIth nerve<unk> es, but more typically involve one or more of the other extraocular muscle groups.
Sixth nerve palsy
Fourth nerve palsy
Facial nerve paralysis
Central facial palsy
Bulbar palsy
Ulnar neuropathy
Median nerve palsy
Axillary nerve palsy