Pain Prevalence in Multiple Sclerosis
Abstract & Commentary
By Gregg L. Caporaso, MD, PhD, Assistant Professor of Neurology and Neuroscience, Weill Cornell Medical College. Dr. Caporaso reports no financial relationship relevant to this field of study.
Synopsis: Pain is a common symptom in patients with multiple sclerosis that significantly impairs quality of life yet is often inadequately treated.
Source: Hadjimichael O, et al. Persistent pain and uncomfortable sensations in persons with multiple sclerosis. Pain. 2007;127:35-41.
Pain is among the most common symptoms in patients with multiple sclerosis (MS), but reports on the prevalence of pain in this population have differed. Hadjimichael and colleagues have now performed a community-based study of the prevalence of pain in MS and its impact on patients' lives. Questionnaires asking about pain and uncomfortable sensations were mailed to the 18,725 participants in the North American Research Committee on MS Patient Registry. Of the 54% of patients who responded to the questionnaire, nearly 75% reported experiencing some pain in the previous month. The demographics and pain characteristics of those responding to the present survey were similar to those of non-responding patients in the Registry based upon earlier questionnaires.
Thirty-five percent of participants experienced mild to moderate pain (occasional or frequent pain that affects daily activities) and 13% had severe or totally disabling pain (daily pain that either necessitated a modification in or prevented daily activities). The most common sites of pain were the legs (30%), back (16%), feet (16%), arms (13%), head (12%), neck (10%), and face (3%). In addition, the quality of pain varied by body location — spasms were most common with leg pain, aching with back or neck pain, and tingling or burning with foot pain. Severe pain was more often reported by women and by individuals whose education was limited to high school. Pain severity strongly correlated with disability (p < 0.0001) as determined by a patient self-report instrument, the Patient-Determined Disease Steps (Mult Scler. 1999;5:349-354.). It also correlated significantly with interference in daily life, including affects on mood, ability to walk or move about, sleep, work, enjoyment of recreational activities, and enjoyment of life in general (Medical Outcomes Study Pain Effects Scale). Other characteristics that were associated with severe pain were worsening MS symptoms over the past year, 4 or more body sites affected by pain, pain lasting more than 5 years, and constant pain. Multiple pain sites were the strongest predictor of pain severity upon stepwise regression analysis.
Individuals with severe pain were more likely to make healthcare visits (82% compared with 60% of those with mild pain). Neurologists were most often seen for pain-related symptoms, with 39% of those with mild pain, 43% with moderate pain, and 47% with severe pain seeking neurological care. Primary care physicians were the next most often visited (14% to 25%), followed by pain specialists (10%), physical therapists (8%), and psychologists (6%). Two-thirds of patients used medications for their pain, with 20% taking 3 or more drugs. Although over-the-counter drugs such as aspirin, ibuprofen, or acetaminophen were most commonly used, prescription analgesics (eg, opioids or anticonvulsants) were taken by 32% of individuals with mild pain, 39% with moderate pain, and 50% experiencing severe pain. Patients with severe pain rated the least satisfaction with their physicians' management of their pain, with 35% reporting dissatisfaction.
Lower extremity dysesthesias, backache, neuralgias, Lhermitte's symptom, and muscle spasms are common forms of pain in individuals with MS. Previous reports have estimated the prevalence of pain in MS patients to be 13% to 86%. The present study represents the largest community-based investigation to date and further highlights the significant impact of pain symptoms in patients with multiple sclerosis. Though pain strongly correlated with disability, the cross-sectional nature of the study's survey did not allow a causal relationship to be determined. However, the participants did acknowledge that pain interfered to a significant degree with their ability to move about, pursue recreations, and enjoy life.
Perhaps the most striking finding of this survey is the apparent underutilization of healthcare and medications by individuals with MS who experience pain. Only 3.6% of patients with moderate to severe pain had reported visiting a pain specialist. Indeed, fully 18% of those with severe pain had not sought any care at all. No explanation is given for this statistic, but one might speculate that some patients with severe pain had sought care and received treatment in the past without adequate relief of their symptoms, their negative experience thus discouraging them from seeking further care. The authors therefore encourage routine screening for pain in patients with MS as well as continuous reassessment. Numerous medications are available to treat pain and related symptoms in patients with MS (ie, non-opioid analgesics, opiates, muscle relaxants, anticonvulsants, antidepressants, and anxiolytics), as are a range of non-pharmacological treatments (eg, physical therapy, psychological counseling, biofeedback, massage therapy, and acupuncture). Given the varying nature of pain and the frequent co-existence of pain at more than one body site reported in this study, a multimodal approach to pain may well be warranted in many patients with MS.