RF Neurotomy in Chronic Cervicogenic Headache cal level lesion with good postoperative results. Some authors reported a lengthy operation time to denervate just one joint and, to practice third occipital neurotomy, about 90 min (5, 13). They do not rely on a stimulation test for adjusting electrode tip. However, we believe that through a stimulation tests, both sensory and motor threshold, surgeons can confirm the exact location of the electrode tip and reduce operation time. Also, a lengthy operation not only gives rise to patient discomfort caused by the prone position, but also results in a higher dose of radiation exposure to both the pa- tient and surgeon. Moreover, during the long operation, much needle manipulation may be necessary. In these cases, pain relief can be derived from other mechanisms including myo- fascial trigger point theory (14). Even with these adequate physiologic monitorings, the average duration of operation in our series was 19 min. The plane of insertion of electrodes is a critical factor. Electrodes must lie parallel to the nerve for the nerve to be incorporated in the radial lesion. Under these circumstances, however, the electrode must be within 2 mm of the nerve for adequate coagulation (18). With these clinical, anatomical, and technical considera- tions, we undertook an audit of our experience with this pro- cedure. The patients selected for the study were those who had significant pain relief without definitive complications or worsening of symptoms when diagnostic blocks were pre- operatively performed under stringent, controlled conditions. The procedure was based on antecedent anatomical studies of the target nerves; electrodes were introduced parallel to the target nerves, and multiple lesions were made to incor- porate the nerves. The limitations of this study lie in the fact that it was not a controlled, randomized study, and the num- ber of subjects was small. 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