P.18.9 Pain in patients with myotonic dystrophy: Comparison between type 1 and type 2

Myotonic dystrophy is a dominantly inherited disorder with multisystem clinical features. In Czech Republic (Central Europe), the type 2 (MD2) is more frequent than type 1 (MD1). Both types share some clinical features, but also have substantial differences in the clinical manifestation. Muscle pain is very frequent in both types, but it is considered as a typical feature of MD2. The aim of the study is to compare the musculoskeletal pain between MD1 and MD2. Seventy patients from the Czech Myotonic disorders registry ReaDy (21 persons with MD1 and 49 suffering from MD2) participated. Short-Form McGill Pain Questionnaire (SF-MPQ) and Brief Pain Inventory (BPI-SF) were administered and evaluated. Patients with MD1 were significantly younger than patients with MD2 (36.6 vs. 56.0 years in the time of the examination), but the disability was on the same level. MRC sum score (148 pts vs. 153 pts), six-minute walk test (347.5 m vs. 392.5 m). Muscle pain was very frequent in both groups 52.4% in MD1 and 59.2% in MD2. The intensity was nearly the same (Visual Analogue Scale: 32.9 mm vs. 28.6 mm, Numeric Rating Scale: 2.8 pts vs. 2.7 pts). The most frequent descriptors of the pain were also similar in both groups: aching (57.1% vs. 44.9%) and tiring-exhausting (47.6% vs. 49.0%). The least frequent was punishing-cruel pain (9.5% vs. 6.1%). Among all items of both questionnaires the significant difference was found only in gnawing pain, which was not present in any patient with MD1, but in 20.5% persons with MD2 ( p  = 0.027). The BPI showed the same impact and interference of pain with common activities in both groups. The most influenced item was “normal work” (3.8 pts in MD1 and 3.6 pts in MD2). No significant difference of intensity, frequency, descriptors of pain, and impact was found between patients with MD1 and MD2.