The features of sensorimotor integration in patients with levodopa-induced dyskinesia in Parkinson’s disease

Abstract

Introduction. Parkinson’s disease (PD) is characterized not only by motor but also by a number of nonmotor symptoms, such as sensory, vegetative, and psycho-emotional disorders. Objective. To study the states of the somatosensory system and the sensorimotor integration in patients with levodopa-induced dyskinesia (LID). Materials and methods. Fifty-two patients with LID associated with PD (Hoehn and Yahr stage III–IV) and 29 patients free of dyskinesia were examined. The somatosensory evoked potentials (SSEPs) and blink reflex (BR) were studied. Results. LID in PD were observed significantly more often among females than among males. No differences in disease duration and duration of levodopa administration were observed among patients free of dyskinesia and patients with LID. In the group of patients with LID, MRI examination showed increased brainstem reflex excitability. The acceleration of signal passing from the medulla oblongata to the cortex revealed according to the SSEP data in this group of patients is indicative of the increased reflex excitability at the spinal cord and brainstem, thalamic, and cortical levels. Significant differences in passage of sensory information were found between the two patient groups. Hence, in patients with LID, the latency N20 was 20 (19.6; 21.3) ms; P18, 16.0 (15.1; 16.6) ms; and N13, 13.7 (13.1; 14.8) and was reliably shorter than in the group of patients free of LID, where the latency N20 was 20.9 (20; 21.4) ms; Р18, 16.9 (16.2; 17.6); and N13, 14.2 (13.5; 15.2) ms. Conclusions. The revealed alterations in parameters of blink reflex and SSEPs are hypothetically genetically determined in patients with LID. Objectification of these disorders at the earliest stages of the disease can help in assessing their role as predictor factors for development of LID. Allowance for these factors will make it possible to choose an appropriate treatment strategy and reduce the risk of complications associated with drug therapy.