A case of unruptured aneurysm of the internal carotid artery presenting as olfactory hallucinations

BACKGROUND: Olfactory hallucination, a symptom of medial temporal lobe epilepsy, is rarely associated with unruptured intracranial aneurysms. CASE DESCRIPTION: We encountered this situation in a 70-year-old woman with an unruptured aneurysm at the bifurcation of the internal carotid and posterior communicating artery. We were able to achieve epileptic control by craniotomy clipping and medial temporal lesionectomy. CONCLUSION: According to our knowledge, previous reports are limited to cases of large middle cerebral artery aneurysms compressing the lateral orbitofrontal cortex, and this is apparently the first report of a case where olfactory hallucinations occurred from direct stimulation of the entorhinal cortex by an internal carotid and posterior communicating artery bifurcation aneurysm. We examined the pathophysiology underlying the development of olfactory hallucinations. We found craniotomy clipping and focal resection to be useful from the standpoint of seizure control. Whether seizure control can also be obtained with intracranial aneurysm coiling should be investigated in the future.