We present the case of a 38-year-old female with subarachnoid hemorrhage due to a minor leak from an anterior communicating aneurysm. CT scans of the brain failed to detect the hemorrhage, and the patient was treated for menigitis for two weeks. At the onset of minor leaks, the patient developed headaches associated with nausea and loss of consciousness which lasted for a few minutes. A general physician gave the patient antibiotics and antiepileptic agents, after diagnosing meningitits, because the CT scans failed to reveal any evidence of hemorrhage. The patient's clinical symptoms gradually improved, but similar episodes occurred on the 11th and 20th day afterthe first, and she was referred to our clinic and admitted for precise clinical evaluation of her clinical symptoms. We also were unable to find any evidence of hemorrhage on CT scans. Since the patient's history strongly suggested subarachnoid hemorrhage, we performed a lumbar puncture and obtained bloody cerebrospinal fluid, confirming the diagnosis of subarachnoid hemorrhage. Cerebral angiography demonstrated an anterior communicating aneurysm, and on the same day, the neck of the aneurysm was successfully clipped. The patient's postoperative course was uneventful, and she was discharged on the 24th postoperative day without sequelae. Minor leaks from cerebral aneurysms reportedly occur relatively often within several weeks prior to amajor aneurysmal rupture. The detection of minor leaks is strongly correlated with an excellent prognosis, if minor leaks are found and treated before a major rupture. CT scanning is not always effective in detecting minor leaks. Lumbar puncture, however, is an important method of detecting them.
