Aetiological analysis of ocular motor nerve (III, IV and VI) palsies

INTRODUCTION: A perfect alignment between the motor system of two eyes is responsible for viewing an object as single. The extraocular muscles of both eyes work in co-ordination. When any one or more of these falter, it may manifest as double vision , deviation of eyes or sometimes with pain. Patients may sometimes present to the ophthalmologist for one of these complaints ,may be referred by another physician or be seen accidentally while they just come for a routine checkup. This may be one of the first manifestation of a serious emergency like a posterior communicating artery aneurysm or a multisystem disease like diabetes. So every case has to be evaluated and its probable etiology identified. Here lies the role of an ophthalmologist to decide whether follow up and observation will suffice or may require emergency intervention by a neurosurgeon. AIM OF THE STUDY: 1. To study the disease patterns, etiologies and pathogenesis of the infranuclear lesions of III, IV and VI cranial nerves (the ocular motor nerves) 2. To study the relationship of glycemic and hypertensive control in ischemic ocular motor nerve palsies. 3. To compare the usefulness of the various investigative techniques 4. To study the recovery pattern of the nerve palsies MATERIALS & METHODS: The cases studied included those patients with neurogenic ocular motor nerve palsies who present to the ophthalmology department, Government Rajaji Hospital, Madurai as well as those who were referred from other departments like diabetology, neuromedicine, neurosurgery or the surrounding primary and secondary health care centres. All age groups and both sexes were included. A complete ophthalmological workup was done. Inclusion Criteria : 1. All infranuclear ocular motor nerve palsies 2. III, IV, VI cranial nerves alone or in combination. Exclusion Criteria : All supranuclear, nuclear nerve palsies, myogenic and restrictive neuropathies SUMMARY: Of the 50 cases studied, the age group ranged from 2-72 years. 80% of cases were in the 15-60 years group. IV nerve palsy occurred in 15-45 year group commonly. VI nerve palsies occurred in a wide range. There was a slight preponderance in males (54%) than in females (46%). The right eye was involved in (44%) 22 cases, left eye in (42%) 21 cases and both eyes involved in 7 cases (14%) 6 due to VI nerve palsy and 1 case of IV nerve palsy. CONCLUSION: The following conclusions were made from the above observations 1. The cranial nerve palsies occur in a wide age group but was more common between 15-60 years 2. Laterality was not significant 3. Unilateral cases were commoner than bilateral cases 4. Gender difference was not significant 5. VI nerve palsy was the commonest, followed by III nerve, next IV nerve and multiple nerve palsy least common. 6. Of all, the vascular etiology was the commonest. Trauma was the next common. 7. Diabetes and hypertension were common associations either alone or together. Poor systemic control of the above was associated with nerve palsies 8. Those with vascular ocular motor nerve palsies belonged to older age group (45-60 years) when compared to those with trauma who presented at an earlier age. 9. Nearly one – fifth of the cases were undetermined. 10. Neuroimaging done in the early period for all indicated cases improved the diagnostic possibilities. Due to the cost of the tests and patient’s affordability, it could not be done in a few patients. MRA and angiography can improve the detection rates, if done at an early period and reduce the number of undetermined cases. 11. Nearly three fourths had complete or partial recovery 12. A careful history, general and complete ophthalmological workup with necessary basic investigations have to be done in all cases. Timely neuroimaging and specialist opinion are necessary although financial problems have restrained and facilities have to be improved