Posterior Communicating Artery Aneurysm in a 20 Year Old Boy Presenting as Non-Isolated Third Nerve Palsy

Abstract

Objective: The need for neuroimaging in non-isolated third nerve palsy remains uncertain. Even with associated partial pupillary involvement, the possibility of aneurysm is said to be low. We highlight the need for vigilance for possible life-threatening aneurysms in cases of non-isolated third nerve palsies. Method: Case report of a 20 years old boy who presented with drooping of the left upper eyelid, double vision and dull
headache. Examination showed moderate ptosis, 300 exotropia and limited extraocular movements of the left eye. Quantitative pupillary measurement revealed 1mm anisocoria with decreased left pupillary light response.
Result: A clinical diagnosis of left third and fourth cranial nerve palsies from intracranial space-occupying lesion was made. Computed tomography and computed tomography angiography confirmed left posterior communicating artery aneurysm.
Conclusion: Any degree of pupillary involvement in third nerve palsy, whether isolated or not should warrant neuroimaging in view of the high mortality risk from intracranial aneurysms.

Niger Med J. Vol. 50, No. 3, July – Sept., 2009: 68 – 70.

Key words: third nerve palsy, partial pupillary involvement,
aneurysm.