Premedication With Melatonin in Lumbar Medial Branch Block Procedure

Brief description of study

Lumbar medial branch blocks 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 and during the lumbar medial branch block procedure and require
intravenous midazolam or fentanyl for sedation. Intravenous or conscious sedation requires
one-to-one nursing care, monitoring, and recovery. In order to minimize the costs and time
requirements of intravenous sedation, a suitable oral medication which is readily available
and non-controlled would be ideal. Several randomized double-blinded, controlled trials have
investigated the anxiolytic effects of melatonin before a surgery; however no studies to date
have studied the anxiolytic effects of melatonin before less invasive interventional pain
procedures. This study is designed to evaluate the efficacy of melatonin for reducing anxiety
in patients undergoing a lumbar medial branch block procedure.

The study is a randomized, double-blinded, placebo-controlled trial with 40 patients in each
group: 2 mg melatonin, 10 mg melatonin and placebo. The primary outcome is anxiety reduction
in patients before undergoing the procedure. The primary outcome is measured by visual
numerical rating scale for anxiety and the Amsterdam Preoperative Anxiety and Information
Scale. Based on the results of previous studies, the investigators hypothesize that melatonin
may reduce anxiety in patients undergoing the procedure and be a suitable alternative to
intravenous sedation in the pain clinic for patients undergoing lumbar medial branch blocks.

Detailed Study Description

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.