Anaesthesia for thermocoagulation of the globus pallidus.

Stage I. Stereotaxic radiological localization of the globus pallidus. The position of the globus pallidus is calculated from radiographs taken after lumbar air encephalography. For this procedure the patient is placed in the sitting position. A graduated metal frame is secured to the head by three drills penetrating the outer plate of the skull. Air is injected into the ventricular system by lumbar puncture and a lateral radiograph is taken. If this shows satisfactory filling of the ventricles with air, the patient is then placed supine with hanging head, in order to get the air into the region of the posterior commissure. Further lateral and antero-posterior views are taken and from these pictures the surgeon calculates the position of the globus pallidus in relation to the graduations on the metal frame.