Medial trigonal arteriovenous malformations.
A retrospective analysis of 48 patients of medial paratrigonal arteriovenous malformations (AVMs) which constituted 18% of the total 258. AVMs surgically managed in our institute for 16 years was carried out to study their clinical presentation, radiological features, operative approaches and functional outcome. While hemorrhage was the initial presenting symptom in 35, it was longstanding headache in 10, focal seizures in two and progressive weakness in one. However, 41 of these presented with bleed at the time of admission to our hospital and in 15 there was history of multiple bleeds. Twelve and eleven patients had field cut and hemiparesis respectively. Arterial supply to the malformation was quite uniform with posterior (43 patients) and anterior cerebral (25 patients) being the most frequent source. Venous drainage was predominantly into the galenic system (70%). Preoperative embolization was carried out in six patients. While the AVM was excised through a parasagittal interhemispheric approach in 34 patients, the nidus was approached through a direct transcortical (superior parietal lobule) approach in fourteen patients. There was only one operative mortality. Twelve patients whose preoperative fields were normal developed field cut postoperatively. An improvement of the preoperative field deficit was noted only in one patient. While eight of the ten patients with preoperative weakness improved and remained independent the remaining two were moderately disabled. Only two of the 10 patients who developed postoperative weakness remained severely disabled. Our operative results suggest that these AVMs which are prone to recurrent bleeds can be resected with acceptable morbidity. Hemianopia resulting from bleed or surgery is unlikely to improve.