The primary aim is to characterize the prevalence, severity and quality of musculoskeletal nociceptive pain in adult patients with neuromuscular disorders (NMD). The secondary objectives are to evaluate whether severity and distribution of muscle pain is associated with muscle function, and to assess whether muscle pain is associated with alterations of muscle elasticity and muscle stiffness. Results of patients with neuromuscular disorders will be compared to age- and gender-matched healthy volunteers. Approx. 70 patients with neuromuscular disorders and 20 healthy volunteers will be enrolled, including patients with the following neuromuscular disorders: histologically confirmed inclusion body myositis (IBM), genetically confirmed late-onset Pompe disease (LOPD), genetically confirmed spinal muscular atrophy type 3 (SMA3), genetically confirmed facio-scapulo-humeral muscle dystrophy (FSHD), genetically confirmed myotonic dystrophy type 1 or type 2 (DM1, DM2). The duration of patient recruitment will be around 12 months.

The explorative, cross-sectional low-interventional pilot study evaluates the prevalence, severity and quality of musculoskeletal nociceptive pain in participants with defined neuromuscular disorders (NMD). Adult participants with the following neuromuscular disorders will be included: histologically confirmed inclusion body myositis (IBM), genetically confirmed late-onset Pompe disease (LOPD), genetically confirmed spinal muscular atrophy type 3 (SMA3), genetically confirmed facio-scapulo-humeral muscle dystrophy (FSHD) and genetically confirmed myotonic dystrophy type 1 or type 2 (DM1, DM2). 20 healthy participants will be enrolled as a control group. The Beck depression inventory fast screen (BDI-FS) will be used as a screening. If there is a possibility of major depression (with a BDI ≥4), patients will be excluded from the study. So only patients with BDI-FS score ≤3 at screening will be enrolled. Patients will be asked to complete the following validated disease-related and quality-of-life questionnaires: German Pain Inventory (module A and abbreviated module S and L and V), Brief Pain Inventory (BPI) and Fatigue Severity and Disability Scale (FSS). Demographic and disease related data will be obtained. A neuromuscular examination will be conducted. A clinical evaluation of muscle strength using the MRC-Scale (Medical Research Council-Scale) will be performed on both sides deltoid muscles, biceps brachii muscles, triceps brachii muscles, hip flexors, hip extensors, quadriceps femoris muscles, foot extensor and foot flexor muscles as well as axial muscles and neck flexors and extensors. The Quick Motor Function Test (QMFT) with 16 items will be performed to assess muscle and movement functions of the participants. To ensure a high level of objective measurement, muscle strength will also be assessed by using handheld dynamometry. The following muscle groups will be tested: arm abduction, elbow flexion, elbow extension, hip flexion, hip extension, knee extension, knee flexion, foot extension, foot flexion. A six-minute-walk test (6MWT) will be performed once. Additionally, first signs of muscle pain or muscle cramps will be recorded (including the quality and intensity of pain). The Borg scale to rate dyspnea will be administered before starting the 6MWT and after completing the 6MWT. For diagnosis of myofascial pain, a Pressure Pain Threshold test by using a pressure algometer is included for the trapezius, deltoid and supraspinatus muscles, the rectus femoris muscles, and the tibialis anterior muscles until the patient feels any sensation of pain. Measurement of muscle stiffness, muscle tone, relaxation periods and viscoelasticity of selected muscles will be assessed by a myotonometer. Data collected in this study will be reported using summary tables, figures, and patient data listings. Differences between the patients and the healthy volunteers will be analyzed.

Inclusion Criteria

• The participant is willing and able to provide signed informed consent.

• The participant is able and willing to perform study-related assessments.

• The participant is ≥18 years of age

• The participant has one of the following diagnoses:

  • histologically confirmed inclusion body myositis (IBM), or
  • genetically confirmed late-onset Pompe disease (LOPD), or
  • genetically confirmed spinal muscular atrophy type 3 (SMA3), or
  • genetically confirmed myotonic dystrophy type 1, or
  • genetically confirmed myotonic dystrophy type 2, or
  • genetically confirmed facio-scapulo-humeral muscle dystrophy (FSHD).

Exclusion Criteria

• The participant is participating in another clinical study or using an investigational treatment.
• The participant, in the opinion of the Investigator, is unable to adhere to the requirements of the study.
• The participant has currently a severe depression, assessed by the Beck depression inventory fast screen (BDI-FS) with a score ≥ 4

Approximately 70 patients with defined NMD (see inclusion criteria) will be enrolled. For a control group, 20 healthy volunteers will be enrolled. All patients must be ≥ 18 years of age.