Characteristics of somatosensory evoked potentials in patients with dystonia of the upper limb
Interest in the study of somatosensory evoked potentials (SSEP) in patients with dystonic hyperkinesis of the upper limbs (DHUL) is justified by a number of publications in recent literature on the presence of sensor-motor disintegration in the pathogenesis of primary dystonia. We conducted the SSEP study in 63 patients: 42 (66.7%) patients had writer's cramp (WS), 7 patients (11.1%) - isolated dystonia of the upper limb, in 14 (22.2%) patients WS was one of the symptoms of multifocal dystonia or segmental dystonia, 32 healthy persons were included in the control group. The SSEP analysis revealed a significant decrease of the amplitude peak of the N20 when stimulating the dominant arm in the group of patients with DHUL, which was 1.63 (1.05, 3.05) μV if compared to the control group, where the analogous index was 2.12 (1. 85; 3.94) μV (P<0,05). Our study proves that patients with DHUL have a disorder of sensory afferentation, according to SSEP.The obtained data together with the literature reviews suggest the existence of a defect in the perception and processing of sensory information in patients with dystonia of the upper limb.