[Cortical and spinal evoked potentials in parkinsonism. Part II. Somatosensory potentials evoked form the posterior tibial nerve].

In 20 patients with parkinsonism somatosensory evoked potentials were studied. The posterior tibial nerves were stimulated successively at the medial ankle. The averaged responses were recorded at the level of the L2 vertebra, C2 vertebra and in the central parietal area (Cz/Pz). The obtained data were compared with similar values in a control group. The conduction velocity in the sensory fibres of the tibial nerves was normal in both groups. No significant differences were found also between the patients and the controls in the latency of the spinal lumbar and cervical potentials, and the spinal conduction time (L2-C2) was normal. In the patients with parkinsonism the cortical evoked response N35 was significantly prolonged. Differences were noted also in the time of central conduction (C2-cortex) between the patients and the controls, but they were not significant statistically. The effects of disturbed dopamine metabolism on the electro-physiological processes in the peripheral and the central nervous system are discussed.