The Effect of Destruction of the Corticospinal Tract in the Human Cerebral Peduncle Upon Motor Function and Involuntary Movements

slightly back to the mid portion of the temporalis, the temporalis fascia and muscle are split, and self-retaining retractors placed. The temporalis is stripped from the zygoma, thus affording additional exposure at the floor of the middle fossa. An approximately circular craniectomy about 4 cm in diameter is made, based on the floor of the middle fossa. The dura is opened close to the base and reflected medially. The temporal lobe is slowly retracted and the occasional bridging vein clipped and cut. The pia about the incisura is then opened. The peduncle is seen with its junction with the pons represented by a change in texture of the presenting nervous tissue. The posterior cerebral artery is also apparent coursing around the mesencephalon. An avascular area is selected and the pia opened with a Bard Parker :~ 11 blade. The lesion is made with a Penfield dissector :~ 1 which contains a disc 7 mm in diameter. The disc is placed through the opening in the pia and moved back and forth so that the resulting lesions have been no more than 7-8 mm deep but usually 8-10 mm wide. Results Fourteen pedunculotomies were performed on 11 patients with various movement disorders (Table 1). There was one death (7%) and one transient third nerve palsy. The results in the four cases of Huntington's chorea were poor; two patients had neither hemiplegia nor change in abnormal movements, one had moderate hemiplegia with little relief of symptoms, and one, a very poor operative risk, died. On the other hand, the four patients with choreothetosis, the two with hemiballismus, and the one with dystonia all fared better. Six patients