Management of paralytic strabismus.

This paper is limited to the consideration of acquired ocular palsies attributed to involvement of the cranial nerve pathways, i.e. lower motor neurone lesions. It is not concerned with supranuclear problems, retraction syndromes, myasthenia, dysthyroid eye disease, or blow-out fractures. The words palsy, paresis, and paralysis tend to be used interchangeably, but usually paresis means a mild and paralysis a severe degree of palsy. The cause of an isolated neurogenic ocular palsy is not always established but, in general terms, a IIIrd nerve palsy is often due to an aneurysm, a IVth nerve palsy to trauma, and a VIth nerve palsy to tumour or trauma. Autopsy studies of road accident victims by Heinze (I969) have shown that avulsion of the nerve rootlets from the surface of the brain stem may cause III, IV, or VI palsies. Other IlIrd nerve lesions were due to focal softening in discrete axonal bundles in the proximal segment of that nerve, and intraneural haemorrhage at the superior orbital fissure. VIth nerve lesions were either at the brainstem surface or at its intraorbital termination in the neuro-vascular hilum of the lateral rectus muscle. Only one patient had the VIth nerve damaged by the fractured tip of the petrous temporal bone. When it comes to apportioning significance to minor head trauma as the possible cause of oculomotor palsy, the recent study of Eyster, Hoyt, and Wilson (I 972) has shown that this may be an initial sign of a basal intracranial tumour. In children, a posterior fossa tumour must always be considered in cases of abducent palsy. The associated vestibular upset may lead to a fall and this injury may be accepted as the cause of the palsy without further search. Even Gradenigo's syndrome is not always due to middle ear infection but may be caused by a tumour. Two important causes in young adults are multiple sclerosis, and an unrecongized congenital ocular palsy that is becoming decompensated. Finally, virus infection is often invoked on slender evidence, particularly for recurrent VIth nerve palsies.