We hear about how often adults suffer from low back pain but with more and more jobs requiring repetitive motions like typing, scanning product labels, or grasping tools, arm pain is starting to move from the back seat to the front. Treatment tends to be conservative with antiinflammatories, physical therapy, and sometimes, steroid injections. In this study, the use of an antidepressant (Amitriptyline) for persistent arm pain associated with repetitive arm motions is examined.
The goal of the study was to see if Amitriptyline worked better than a placebo (sugar pill). Amitriptyline is often used successfully for patients with chronic low back pain. It has also been used for patients with headaches, nerve pain, and fibromyalgia. So, it makes sense that it might be equally effective in treating chronic arm pain.
The measures used to test how well Amitriptyline worked compared to a placebo pill were pain intensity and function. Function was measured using tests of grip strength, mood, and sleep. When researchers want to compare one specific treatment to another like this, they perform a double-blind, random-controlled trial. Double-blind means no one (patients or researchers) knew which type of pill each patient was given. Patients were randomly selected for each group using a computer program.
Only adults with overuse or strain of the muscles and/or tendons were included in the study. Many of them had been diagnosed with wrist or elbow tendonitis or carpal tunnel syndrome. Types of repetitive tasks linked with arm, wrist, or hand symptoms included computer work (keyboarding, using a mouse), playing a musical instrument, construction or assembly work, arts and crafts, house cleaning, or handwriting. Results were compared for Amitriptyline versus the placebo based on type of task causing the initial symptoms.
Anyone who had a known neurologic problem, arthritis, or specific injury to the arm was not included. Pills (Amitriptyline or placebo) were taken once daily at bedtime for eight weeks. Taking the pills at bedtime was advised because the Amitriptyline does tend to make people drowsy. The Amitriptyline pills given contained 25 mg of the drug, which is considered a low-dose.
Participants were tested at the start of the program and retested after three weeks, six weeks, and finally four weeks after the treatment was completed. They used a wide range of self-report questionnaires to assess sleep, pain, mood (anxiety or depression), and sense of well-being. Each person gave a report of any side effects from the “medication”. A handheld device called a dynamometer was used to test hand grip and finger pinch strength.
In the end what they found was that there wasn’t a difference in the effect on arm pain for either pill. The patients taking the Amitriptyline did gain strength and function compared with the placebo group. And the Amitriptyline group improved in their sense of well-being.
Despite taking the pill at bedtime, persistent drowsiness (into the morning upon waking up) remained the single most reported side effect. Almost half of the Amitriptyline group reported being affected by drowsiness, whereas only 15 per cent of the placebo group experienced this particular side affect. The longer the group took the Amitriptyline, the less daytime drowsiness bothered them.
The authors concluded that low-dose Amitriptyline is not more effective than a placebo pill in terms of pain control in the treatment of arm pain from repetitive overuse. But it does improve function and mood quickly. Amitriptyline has both analgesic (pain relieving) properties and acts as an antidepressant. Once the antidepressant took effect, the person felt better and could do more. When the study ended, arm function got worse again for the Amitriptyline group. That’s called a reversal of positive treatment effects and points to Amitriptyline being more effective than a placebo.
More study is needed to investigate the effectiveness of different dosages of Amitriptyline and over longer periods of time. Higher doses of the drug might reduce pain but there’s always the risk of worse side effects with more active drug ingredient. Still, this is the first study comparing Amitriptyline with a placebo for chronic arm pain caused by repetitive motion. Having another tool for treatment of this persistent pain may benefit some patients who do not respond to conservative care otherwise.