Fig. 8. Technique of percutaneous controlled thermocoagulation of the trigeminal ganglion. A: Needle placement. B: Position of needle in the ganglion. (From Tew JM, Keller JT: Percutaneous rhizotomy in the treatment of intractable facial pain. In Lee JF (ed): Pain Management—Symposium on the Neurosurgical Treatment of Pain. Baltimore: Williams Wilkins, 1977:150–155.)