Differential diagnosis of disorders manifesting with tremor on the basis of their clinical and neurophysiological characteristics

To search for additional methods of differential diagnosis of essential tremor (ET) and early-stage Parkinson’s disease (PD), a clinical, psychometric, tremorometric, stabilometric and electrooculografic study was carried out in PD, ET and age-matched controls. Patients with ET had bilateral distribution of predominantly postural-kinetic tremor with slight prevalence in one hand, and limb tremor often combined with head tremor. PD was characterized by asymmetric debut of clinical manifestations, as well as by rest and postural tremor with slight hypokinesia and rigidity. The frequency of rest and postural tremor was significantly higher than in the PD group. Stabilometry revealed improvement of postural stability in “Target-test” in patients with PD. In the dynamic “Evolventatest” patients with PD showed smaller statokinetic curve length and lower center-of-motion velocity compared to healthy subjects. No stabilometric changes were found in ET patients. In contrast to ET, patients with PD were characterized by significant increase in latencies of saccadic eye movements and fraction of multi-step saccades; eye movements lateralization was revealed on stage I of PD. Discussed is significance of the obtained data for clinical practice.