Photo Credit: Sergey Nivens

The following is a summary of “Characterization of the neuropathic pain component contributing to myalgia in patients with myotonic dystrophy type 1 and 2” published in the August 2024 issue of Neurology by Schmitt et al.

Chronic pain is common in myotonic dystrophy (DM), including types DM1 and DM2. It is mainly characterized by progressive muscle weakness. The neuropathic mechanism underlying the pathway needs to be better studied. 

Researchers conducted a retrospective study investigating the characteristics of the neuropathic pain component contributing to the pathogenesis of chronic pain in DM.

They conducted a study on patients with DM1 (21 patients) and DM2 (32 patients). The patients completed a pain questionnaire, which included a brief pain inventory (BPI), PAIN-DETECT, and pain disability index (PDI). Neurological examination, nerve conduction studies (NCS), quantitative sensory testing (QST), dorsum of the right hand and right thigh, and skin biopsy were conducted to determine the intraepidermal nerve fiber density (IENFD), distal and proximal site of the lower extremity. The NCS and QST results at the thigh were compared to 27 HCs.

The results showed reduced thermal and higher mechanical pain sensitivity in patients with DM1, whereas DM2 had a thermal and mechanical detection loss. Pressure hyperalgesia was observed in both groups. Additionally, IENFD was reduced to 63% in DM1 and 50% in DM2. Slightly higher pain interference and disability were found in DM2, which was rather due to the age difference. 

They concluded the presence of similar pain mechanisms in both DM subcategories, although a tendency toward more pain sensitivity was observed in DM1 and sensory loss in DM2. Both QST and reduced IENFD highlighted the presence of peripheral nerve damage in DM. 

Source: frontiersin.org/journals/neurology/articles/10.3389/fneur.2024.1414140/full