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Radiofrequency lumbar zygapophysial (facet) joint denervation: a preliminary report of a new concept.

This is a preliminary report of a new concept of lumbar medial branch neurotomy by measurement of minimal sensory threshold. This technique is not recommended for routine clinical use until further controlled data are available. The lumbar zygapophysial joints (Z-joint) or facet joints, are a potential source of low back pain. In general, the principle innervation of the Z-joint is the medial branch of the posterior primary ramus of the same level as the target Z-joint as well as the level above. Denervation of the multifidus as evaluated by electromyography has become a measurement of successful Z-joint denervation. Two drawbacks to this method are that it takes one to several weeks for denervation potentials to develop and thus does not give the physician any sense of successful denervation intra-operatively. The other is that the Z-joint is innervated by the sensory fibers of the medial branches. As a result, the multifidus may be successfully denervated as demonstrated by electromyography but the Z-joints may be inadequately denervated. As a result, this technique describes measurement of minimal sensory threshold prior to lesioning and seeking to double that threshold as an additional, intra-operative measure of successful sensory denervation of the Z-joint.