A study of isolated and multiple cranial nerve palsies.

Introduction There are several cranial nerves which are supplying the eye. They are namely the second, third, fourth, fifth, sixth, and seventh nerves. They are concerned with the eye movements, pupillary reactions corneal sensation and lid movements. Restricted eye movements can be due to paralysis of those cranial nerves which are responsible for ocular movement. The ocular motor nerves are third nerve [oculomotor nerve],fourth nerve[trochlear nerve], and the sixth nerve[abducent nerve].So a paralytic squint can occur from paralysis of these nerves[neurogenic] or from neuromuscular origin[myasthenia gravis] or from myopathic origin or from restrictive origin. Clinically differentiating these etiologies is important because their treatment also differs. In our study we are concerned with paralytic squint [where angle of deviation varies with different gaze positions] of neurogenic origin .Such nerve palsies can involve the ocular motor system at various levels from nucleus to the effector organ, that is, the extra ocular muscles.There are six extra ocular muscles controlling the eye movements, namely medial, lateral, superior,and inferior recti and superior and inferior oblique muscles. AIM OF THE STUDY: To analyse the various etiologies and pathogenic factors leading to multiple ocular motor nerve paralysis. To analyse the common clinical patterns arising in the background of acquired multiple ocular motor nerve palsy . To analyse the recovery pattern in multiple ocular motor nerve palsies and to compare this with that of isolated nerve palsies. MATERIALS AND METHODS: The study was conducted at the Regional institute of ophthalmology and Government Ophthalmic Hospital in Chennai. The period of study was from august 2003 to September 2005. All patients with paralytic squint have been included in the study . Congenital cranial nerve palsies have been excluded . Patients with incomitant squint due to myogenic, myasthenic and restrictive causes have been excluded . DISCUSSION: Ocular motor nerve palsy either isolated or multiple can lead to certain diagnostic and therapeutic dilemma ,i.e, whether to treat the primary cause or not, when to treat and when to interfere with regard to ocular complaints. SUMMARY: Of the 80 cases taken for the study, more than 80 percent of cases have occurred between 21 and 70 years. The maximum number of isolated nerve palsies occurred between 21and 60 years .In particular ,third nerve palsy cases occurred in maximum numbers between 21 and 60 years, while sixth nerve cases occurred with a uniform distribution in the age groups between second and eighth decades .The maximum number of multiple nerve palsy cases have occurred between 41 and 80 years. CONCLUSION: The sixth cranial nerve palsy is the commonest nerve palsy and it is followed by third nerve palsy and fourth nerve palsy. Among the multiple nerve palsy cases ,one or all the three nerves can be involved depending on the etiology causing it