Pure sylvian fissure arteriovenous malformations

Pure sylvian fissure arteriovenous malformations (AVMs) are vascular malformations confined to the sylvian fissure without parenchymal involvement. Because the branches of the middle cerebral artery are arteries of passage and the margins between the AVM and the insula cortex may be ill defined, many surgeons regard pure sylvian fissure AVMs as inoperable. The authors reviewed their surgical experience with eight patients harboring pure sylvian fissure AVMs to determine the incidence of operative morbidity.

All eight patients experienced seizures, five (63%) had headaches, and three (38%) experienced hemorrhages. Preoperatively, six patients (75%) were normal neurologically and two (25%) had neurological deficits. Five (63%) of eight sylvian fissure AVMs were located in the dominant hemisphere. The size of the nidus ranged from 6 to 27 cm3 (mean 14 cm3). Complete removal of the AVM was documented by postoperative angiography in every case. Seizures were reduced or eliminated and headaches were relieved in all affected patients. Transient neurological deficits, which included aphasia, short-term memory loss, and hemiparesis, occurred in four patients (50%). Within 3 months, all patients were functioning independently with no new neurological deficits. The status of two patients who had had preoperative neurological deficits improved postoperatively. Neuropsychological testing showed no new cognitive deficits.

With appreciation for transient instances of postoperative morbidity, the outcome was excellent in all patients. The authors thus advocate microsurgery as the primary treatment for pure sylvian fissure AVMs.