Small Unruptured Intracranial Aneurysm (≤5 mm) Associated with Epilepsy: Report of 2 Cases and Literature Review.

BACKGROUND: Owing to the continuing improvements in imaging technology, an increasing number of epileptogenic small (≤5 mm) unruptured intracranial aneurysms (sUIAs) are being diagnosed. However, these sUIAs have not been systematically described and reviewed until now.

CASE DESCRIPTION AND LITERATURE REVIEW: We report 2 patients with sUIAs who initially presented with complex partial seizures. Scalp electroencephalography identified the seizure activity as arising from the mesial temporal/frontal areas, but conventional magnetic resonance imaging (MRI) was normal in both patients. The diagnosis of sUIA was achieved by cerebral angiography. One of the patients had idiopathic seizures and sustained a subarachnoid hemorrhage before the final diagnosis of sUIA. Both of the patients were treated by surgical clipping without resection of the adjacent discolored brain tissue, and the seizures were controlled after surgery. Furthermore, we thoroughly reviewed the relevant literature. We analyzed a total of 5 documented cases, including out 2 cases, and described the clinical characteristics, diagnosis, underlying mechanism, treatment, and prognosis of epileptogenic sUIA.

CONCLUSIONS: The seizures caused by sUIAs are most likely related to subclinical hemorrhages. Angiography may be helpful in identifying seizures associated with sUIA in patients with normal conventional MRI findings. For epileptogenic sUIA with normal preoperative MRI, clipping without damaging the surrounding brain tissue may be sufficient to resolve this complex issue.