Abstract
Stereotactic radiosurgery, including gamma knife surgery, has been widely performed as minimally invasive treatment for arteriovenous malformation (AVM). While its safety and efficacy have been well reported, some problems also have been reported. Patients who undergo radiosurgery must wait for a few years from the time of treatment and remain exposed to the risk of bleeding until obliteration of the AVM is confirmed, and technical limitations may lead to incomplete administration of the intended treatment. In addition, severe complications are occasionally reported. Here, we present a case of obstructive hydrocephalus caused by aqueductal stenosis in a 63-year-old man who underwent gamma knife surgery for AVM around the pineal body 8 years previously. On visiting our department, he presented with mild disturbance of gait and consciousness. Other physical and neurological examinations were unremarkable. CT demonstrated dilatation of the lateral ventricles and the third ventricle. Because the aqueduct of the midbrain and fourth ventricle were not dilated, obstructive hydrocephalus due to localized aqueductal stenosis was suspected. Endoscopic neurosurgery was performed and stenosis in the aqueduct of the midbrain caused by a membrane-like structure was confirmed. Aqueductal stenosis occurred as a result of inflammation following gamma knife surgery, which extended to the cicatricial tissue and eventually caused a stenosed aqueduct of the midbrain. After the endoscopic third ventriculostomy, the hydrocephalus improved and no recurrence has appeared since. To the best of our knowledge, there have been no previous reports of obstructive hydrocephalus attributable to aqueductal stenosis caused by inflammation following gamma knife surgery.
