Assessment of small sensory fiber function in myotonic dystrophy type 1.

BACKGROUND

Myotonic dystrophy type 1 (DM1) is a multisystem disorder affecting the peripheral nervous system. However, studies evaluating somatic small fiber sensory nerve function, which may contribute to pain in DM1, are lacking.

METHODS

Using quantitative sensory testing of the hand and foot, we evaluated Aδ and C-fiber function. Of 20 adult DM1 patients recruited, 16 were analyzed. Their results were compared with those of 32 age- and sex-matched controls.

RESULTS

No DM1 patient had diabetes mellitus or clinical evidence of small fiber neuropathy. In DM1, hand (P < .01) and foot (P = 0.02) warm detection thresholds were higher than those of controls. Cool detection thresholds were lower in the foot (P < .001).

CONCLUSIONS

Subclinical small sensory fiber dysfunction occurs in DM1 patients without large fiber neuropathy. Further research with other modalities is required to characterize these disturbances as disease modifying therapies are developed.