Transient Complete Unilateral Oculomotor Nerve Palsy following Clipping of Ruptured Anterior Communicating Artery Aneurysm: An Abstruse Phenomenon.

Background: Aneurysmal subarachnoid hemorrhage may be associated with different cranial nerve palsies, with oculomotor nerve palsy (ONP) being the most common. ONP is especially associated with posterior communicating artery aneurysms, due to the anatomical proximity of the nerve to the aneurysmal wall. Anterior communicating artery (Acom) aneurysms are very unlikely to produce ONP due to the widely separated anatomical locations of Acom and oculomotor nerve.

Case description: Here we describe the case of a 60-year-old nondiabetic lady who presented with Acom aneurysmal subarachnoid hemorrhage having a World Federation of Neurosurgical Societies (WFNS) grade I. She underwent an uneventful right pterional craniotomy and clipping of the aneurysm, except for a short period of controlled rupture of the aneurysm. Postoperatively she developed complete ONP on the right side, though her sensorium was preserved. Computed Tomogram and Magnetic Resonance Imaging scans of the brain did not yield any useful information regarding its etiology. She was conservatively managed and kept on regular follow-up. She had a gradual recovery of ONP in the following order: pupillary reaction, ocular movements, and finally ptosis. On postoperative day 61, she had complete recovery from ONP.

Conclusion: We describe a very unusual case of complete ONP following Acom aneurysm clipping and its management by masterly inactivity.