Effect of the Multifidus Muscle Twitch on the Long Term Effect of Radiofrequency Lumbar Medial Branch Neurotomy

Facet joint syndrome has been described as a common cause of lumbar back pain. To achieve prolonged therapeutic effect in patients with lumbar facet joint syndrome, radiofrequency (RF) medial branch neurotomy is commonly performed. When performing RF neurotomy, needle placement in correct position is very important. For this reason, identification of sensory stimulation and multifidus muscle twitching by using the electrode have been commonly performed. However, there were no previous reports regarding relationship between prognosis of RF neurotomy and multifidus muscle twitching in combination of sensory stimulation. The purpose of this study was to evaluate the prognostic value of multifidus twitching when sensory stimulation was achieved while performing RF needle neurotomy in patients with lumbar facet syndrome.

The investigators have collected data and chart from the patients who were diagnosed facet joint syndrome and underwent lumbar RF medial branch neurotomy between January 2009 and June 2014.

RF was performed using sensory stimulation and multifidus twitching to confirm the position of RF needle. When numeric pain intensity score decreased less than half of the initial pain score, the procedure was regarded as effective and the duration was followed and recorded for each patients.

When multifidus twitching was observed in a voltage less than 1.0 to 2.0 times of the sensory stimulation (≤ 0.5V), the positioning of the RF needle will be regarded as adequate. The most appropriate cutoff value will be determined by univariate analysis. The patients will be grouped according to the adequacy of RF needle position while performing RF medial branch neurotomy ('complete' when all needles were placed adequately, 'partial' when one of the needles for a facet joint medial branch was placed inadequately, 'none' when there were both needles positioned inadequately for a facet joint) The relationship between the long term effect of RF neurotomy (longer than 6 months) and the groups will be analyzed.