Primary epileptogenic unruptured intracranial aneurysms: incidence and effect of treatment on epilepsy

Seizures as the unique initial manifestation of unruptured intracranial aneurysms have rarely been documented and not systematically described until now.

The purpose of this large retrospective analysis was to focus on the incidence of primary epileptogenic aneurysms and the influence of treatment on epilepsy.

Within a 16-year period, 347 unruptured aneurysms were surgically treated at centers in Munich (1992-2002) and Düsseldorf (2003-2008), Germany. Of this patient population, 9 patients presented exclusively with epileptic seizures or epileptic equivalents. In 3 of them, a high-lying internal carotid artery aneurysm was diagnosed that was buried in the parahippocampal gyrus. In 4 patients, a middle cerebral artery aneurysm also created contact with the mediotemporal lobe adjacent to the parahippocampal gyrus. An anterior communicating artery aneurysm and a pericallosal artery aneurysm were diagnosed in 2 additional patients. Two patients with a middle cerebral artery aneurysm were initially incompletely occluded with Guglielmi detachable coils and continued to have epilepsy after the intervention. In all but 1 patient, the aneurysms were clipped and completely removed.

In all 8 patients operated on, there was no sign of hemorrhage intraoperatively but cortical gliosis was seen around the dome of the aneurysm. In all cases, the aneurysm and the surrounding gliosis, if existent, were surgically removed. Freedom from seizures without medication resulted for all patients after microsurgery.

Seizures as a presenting symptom of unruptured intracranial aneurysms are rare. There seems to be a preponderance of aneurysms anatomically related to the temporomedial region. Elimination of the aneurysm and perifocal gliosis provides the possibility of a cure for the epilepsy.