Premedication With Melatonin in Lumbar Medial Branch Block Procedure

Chronic low back pain is a common disease in industrialized countries which affect patients' productivity and quality of life. Currently, the estimated yearly prevalence of chronic low back pain in United States is 5-20%. Lumbar medial branch blocks (LMBB) are commonly used as a diagnostic tool for facet mediated chronic low back pain. This interventional pain procedure often occurs in the fluoroscopy suite. During this procedure, a physician inserts the needles to deliver local anesthetics such as lidocaine or bupivacaine to the nerves which innervate the lumbar facet joint.

Many patients experience anxiety before the LMBB procedure and require intravenous midazolam or fentanyl for sedation. In fact, in a retrospective review of over 8,000 interventional fluoroscopically guided pain procedures, the highest incidence of vasovagal episodes occurred with LMBB procedures. A nurse is required to administer these medications and monitor patient's vital signs. In addition, recovery from these medications can unduly prolong the patients visit and, in the case of fentanyl, can confound the diagnostic utility of the LMBB procedure by decreasing patient's pain.

In an effort to minimize the cost of administration, monitoring, time of recovery and maximize the diagnostic utility of LMBBs, a suitable alternative is required. Several randomized, double-blinded, controlled trials investigate the anxiolytic effect of melatonin before a surgery. Several other studies and review articles describe the use of melatonin for both sedation and anxiolysis in both adults and children. However, no studies to date describe the use of melatonin for anxiolysis or sedation for interventional pain medicine procedures.

Melatonin ((N-acetyl-5-methoxytryptamine) is an over-the-counter product which patients can take to reduce anxiety before a procedure; it is a hormone produced in the pineal gland and secreted into the blood and cerebrospinal fluid. Melatonin has several functions including the regulation of circadian rhythms and regulation of the reproductive axis and antioxidant activity. Exogenous melatonin has been used to treat insomnia and jet lag.

Inclusion criteria

• undergoing LMBB procedure
• both genders between the ages of 18-50

Exclusion criteria

• patients with active pregnancy (due to ionizing radiation)
• liver disease
• contraindications to LMBB procedure
• patient refusal
• localized or systemic infection
• low platelet count
• fibromyalgia
• use of sedative medications
• failure to comply with procedures
• investigator's determination that the assigned treatment is ineffective or unsafe
• appearance of unacceptable side effects in the subject