New Research to Help MS Pain
By Ted Brown, MD
EvergreenHealth MS Center
Once, pain was thought not to be a symptom of multiple sclerosis (MS). It is now recognized as a common symptom in patients with MS, with almost 50% experiencing clinically significant pain at some time during the course of the disease, and as the presenting symptom in approximately 20%. Pain in MS is most commonly due to nerve damage (i.e. “neurogenic pain”), which usually presents as a continuous burning or tingling discomfort in the limbs.
Lower limbs are most frequently involved, followed by the trunk (euphemistically called the “MS hug”) and upper limbs, and it occurs with insidious onset. Nerve pain in the face is most often a stabbing intermittent pain, which may start abruptly. Other potential causes of pain include musculoskeletal pain (for example, due to tight muscles) and visceral pain, such as discomfort from constipation. Often the pain problem is complex and, despite treatment, many patients with MS have ongoing pain or develop a chronic refractory pain syndrome.
The MS Center at EvergreenHealth recently completed a single-center study to treat MS pain using an antidepressant medication, duloxetine (Cymbalta®). Duloxetine is approved for use in other pain conditions including fibromyalgia, chronic musculoskeletal pain and diabetic neuropathy. It is believed to act in the central nervous system.
In our study, 38 people with chronic MS pain were randomized 1:1 to receive Duloxetine or matched Placebo. The dosing regimen was 30mg daily for one week, then 60mg daily for five weeks. Patients kept daily pain diaries throughout the study, recording their average and worst daily pain levels on a scale from 0-10. The primary outcome measure was change in Worst pain for Week 6 relative to baseline. Other measures included depression ratings, sleep quality score and quality of life measures.
As expected, the legs were most commonly reported pain location. Not everyone could tolerate the medication and there were more drop-outs in the duloxetine group than in the placebo group. Fourteen (78%) patients randomized to Duloxetine and 19 (95%) randomized to placebo completed treatment. Among those who completed treatment. Worst pain at 6 weeks was reduced by 29% for Duloxetine vs. 12% for placebo, a significant difference (p=0.016). Average daily pain at 6 weeks was reduced by 39% on Duloxetine compared to 10% in the placebo group (p=0.002). Patients randomized to Duloxetine also had significantly greater reductions in average daily pain at weeks 2 and 4, and in worst daily pain at week 4.Change in Subject Global Impression favored Duloxetine, although there were no significant changes (week 6 vs. baseline) or between-group differences for other quality of life measures, depression or sleep quality.
This study has already been reported at a national meeting (Consortium of MS Centers) and is hopefully going to be published. It showed that duloxetine is not always well tolerated, but it may provide relief of MS pain. The study was small, and the results should not be over-interpreted.
Currently, the MS Center at EvergreenHealth is doing another pain study. This time, we are looking at reducing pain related to injection of any of the approved subcutaneous MS medications (glatiramer acetate [Copaxone] and interferon beta medications). We are testing an anesthetic patch applied to the skin prior to injection of the MS medication. Contact MS Center study coordinator Carey Gonzales at 425.899.5374 for more information.