Pain in Hereditary Neuromuscular Disorders and Myasthenia Gravis: A National Survey of Frequency, Characteristics, and Impact

Abstract

The aim of our study was to evaluate pain frequency, intensity, and disability levels in a population with neuromuscular disorders (NMD). Of 862 questionnaires mailed to outpatients treated at 10 centers, 511 (300 men and 211 women) responded with answers suitable for analysis (response rate: 59.3%). Patients had Duchenne or Becker muscular dystrophy, type 1 myotonic muscular dystrophy, facioscapulohumeral muscular dystrophy, metabolic myopathy, or myasthenia gravis (MYA). The questionnaire packet included numeric scales for pain intensity and relief, the Brief Pain Inventory, the Saint Antoine Pain Questionnaire, and a scale to assess disability. More than two-thirds of the 331 patients (67.3%) suffered pain during the last three months. The mean number of days with pain was 18.4+/-15.1 days. The mean pain intensity was 4.8+/-2.5. Pain was usually diffuse (153 patients, 44%) and intermittent (228, 71%). Pain intensity varied by the NMD diagnosis; the most severe pain was observed in metabolic myopathy (13/27 patients suffered severe pain, 49%) and in MYA (16/42, 38%). Approximately three-quarters of patients had fewer than 10 days of inactivity due to pain during the last three months, and 98% had fewer than 30 days. Our study indicates that pain is frequent in hereditary muscle disorders and MYA. Mean intensity is moderate. Pain in NMD patients should be systematically assessed.

Pain characterization in Duchenne muscular dystrophy

“…However, considering studies with disabled patients, most samples are by convenience 11 . Furthermore, Lager et al 1 and Guy-Coichard et al 7 presented data from DMD and Becker muscular dystrophy patients analyzed together (n = 38 and 128, respectively). Engel DMD: Duchenne muscular dystrophy; NDM: neuromuscular disease; BMD: Becker muscular disease; SMA: spinal muscular atrophy; BPI: brief pain inventory; VAS: visual analogue scales; *the paper had no information about each group separately; **the paper had no information about minimum and maximum age.…”

“…A variety of instruments was used in the reviewed studies to qualify and quantify pain. The most common instruments used in these studies were the Visual Analogue Scales (VAS) 1,5,15 and the Brief Pain Inventory (BPI) 1,6,7 . Other important factors are pain frequency and duration.…”

“…Other important factors are pain frequency and duration. Some studies conducted only an assessment of pain 1,2,5,6,7,14 . Another three studies analyzed pain at different times: pre and post two years of bisphosphonate therapy 13 ; before surgery and after six weeks, one year, and two years 15 ; and in six-month follow-ups 14 .…”

“…However, a growing number of studies indicate that chronic pain is a common symptom for people with neuromuscular diseases (NMD) 1,5,6 . Chronic pain may be common, even though it is not the primary concern of patients or doctors 7 . In some cases, pain can be the leading problem with adverse consequences on function and quality of life.…”

“…There are also causes that are difficult to recognize and assess that represent a therapeutic problem. Such causes are a result of fears of using certain substances in patients with a potential for cardiac or respiratory risk 7 . Knowledge about pain in children and adolescents with DMD is limited in terms of frequency, intensity, location, discomfort and the impact on function and quality of life.…”