Efficacy and validity of radiofrequency neurotomy for chronic lumbar zygapophysial joint pain

Study Design. A prospective audit. Objective. To establish the efficacy of lumbar medial branch neurotomy unde r optimum conditions. Summary of Background Data. Previous reports of the efficacy of lumbar medi al branch neurotomy have been confounded by poor patient selection, inaccur ate surgical technique, and inadequate assessment of outcome. Methods. Fifteen patients with chronic low back pain whose pain was relieve d by controlled, diagnostic medial branch blocks of the lumbar zygapophysia l joints, underwent lumbar medial branch neurotomy. Before surgery, all wer e evaluated by visual analog scale and a variety of validated measures of p ain, disability, and treatment satisfaction. Electromyography of the multif idus muscle was performed before and after surgery to ensure accuracy of th e neurotomy. All outcome measures were repeated at 6 weeks, and 3, 6, and 1 2 months after surgery. Results: Some 60% of the patients obtained at least 90% relief of pain at 1 2 months, and 87% obtained at least 60% relief. Relief was associated with denervation of the multifidus in those segments in which the medial branche s had been coagulated. Prelesion electrical stimulation of the medial branc h nerve with measurement of impedance was not associated with outcome. Conclusions. Lumbar medial branch neurotomy is an effective means of reduci ng pain in patients carefully selected on the basis of controlled diagnosti c blocks. Adequate coagulation of the target nerves can be achieved by care fully placing the electrode in correct position as judged radiologically. E lectrical stimulation before lesioning is superfluous in assuring correct p lacement of the electrode.