Percutaneous radiofrequency neurotomy of the lumbar medial branch is a widely accepted treatment for pain of the lumber intervertebral joints. However its success rate has varied among authors. One reason for this inconsistency is the lack of method for objective evaluation of whether the nerve has been sufficiently denervated or not. This study has made possible real time and accurate monitoring of whether electrocauterization is properly executed or not.

The subjects were 50 patients with law back pain persisting for 3 months or longer in whom facet block or medial branch block of posterior ramus was only temporarily effective. They ranged in age from 19 to 76 years (mean 54 years) and were followed up for 1 year to 7 years and 1 month (mean 2 years and 9 months). In our percutaneous radiofrequency neurotomy, the target point of denervation is defined as the groove between the mammillary process and accessory process (1) and complex muscle action potentials (CMAPs) of multifidus muscles are used as an index for objective evaluation of the effects of denervation.

Improvements were observed immediately after the treatment in 39 patients (78%). The effects of this treatment, once attained, remained over a long period, and the duration of effects was 18–20 months as estimated by the cumulative success rate calculated using the Kaplan-Meyer method.

Patients must be carefully selected for percutaneous radiofrequency neurotomy to be consistently effective, all the more because the procedure is simple. However, it is a reliable method for denervation of the lumbar medial branch and long-term relief from pain can be expected. This therapy, therefore, is an effective alternative for the treatment of chronic pain due to lumbar intervertebral arthropathy that resists conservative treatments and disturbs daily living.