Influences of venous involvement on postoperative brain damage following the anterior interhemispheric approach

Background. The anterior interhemispheric approach offers us an excellent surgical view for suprasellar lesions. Following this approach, we occasionally encounter postoperative brain damage in the frontal lobes. To assess the determinants of such a complication, we undertook a clinical study. Method. Potential causes for such brain damage were evaluated in 28 consecutive patients with suprasellar tumours extirpated using this approach. We focused particularly on the influences of venous involvement during surgery. The draining territory index (DTI) was originally devised for estimating the extent of the draining area of the sacrificed bridging veins. Findings. CT evident brain damage was observed in five of 28 patients (17.8%), but only one patient (3.6%) showed clinically significant postoperative deficits. The patient's age, tumour pathology, tumour character, tumour size, duration of surgery, and radicality of the surgery did not affect the incidence of the brain damage. Of the twelve patients whose bridging veins were sacrificed during surgery, four (33.3%) showed brain damage in the frontal lobes. In contrast, such damage was observed in only one patient out of 16 (6.3%) whose bridging veins were preserved. Among the brain-damaged group, the average DTI of the sacrificed veins was significantly higher than that among the non-brain-damaged group. Interpretation. Venous involvement during surgery significantly aggravated postoperative brain damage following the anterior interhemispheric approach. The DTI was useful in predicting the risk of brain damage, and a large bridging vein with a DTI over 50% should not be sacrificed during surgery.