The transcallosal approach for lesions affecting the lateral and third ventricles. Surgical considerations and results in a series of 42 cases.

The study was carried out on a series of 42 patients who underwent surgery through a midline approach. Lesions were in the anterior part of the third ventricle in 32 cases, in the frontal horns in 6, in the trigone in 3, and in both lateral and third ventricles in 1 case. The third ventricle was approached through Monro's foramen in 22 cases and through an interfornicial route in 9 cases. Surgical mortality occurred in 2 cases (5%). Permanent morbidity occurred in another 2 cases (5%): it consisted of slight intellectual deterioration in one case and slight fixed pyramidal signs in the other. Transient mutism was the most frequently observed postoperative complication. Thirty-one patients were reviewed and submitted to neuropsychological tests in the late postoperative period to investigate the presence of intellectual deterioration or disturbances in the interhemispheric transfer of motor, somataesthetic and visual information. All patients showed only the presence of short-term memory disturbance. Furthermore, 12 patients tested before surgery also showed the presence of short-term memory deficits in the preoperative period. We conclude that a midline approach is the most direct and safe route to the third ventricle as well as to the frontal horns and trigone.