RELATIONSHIP BETWEEN REACTION TIME AND AMPLITUDE CHANGES OF THE H-REFLEX IN THE PERFORMANCE OF SIMPLE MOTOR TASK IN PATIENTS WITH THYROTOXICOSIS

Abstract

The authors examine the dependence between reaction time as an indicator of change at cerebral level and H-reflex amplitude change being a relative index of excitability level in the spinal cord during the preparation of a simple voluntary movement in thyrotoxicosis patients. Electrophysiological investigations are carried out after identifying the disease and prior to the beginning of causal therapy. Patients are comfortably seated on a chair in a dark room and respond to light signal from a blitz-lamp and it was determined reaction time. Simultaneously with light signal presentation, nervus tibialis in the popliteal fossa of the same leg is excited to evoke H-reflex. One-day signal programme consists of a total of 120 light signals divided into three equal blocks. H-reflex amplitude evoked only once for every light signal is compared with control H-reflex amplitude. Its decrease or increase is read. Reaction times are grouped according to the extern of corresponding H-reflex amplitude increase or decrease. Data obtained serve to construct relation curve between reaction time and H-reflex amplitude changes. This relation curve differs in nature from the curve when healthy subjects under the same experimental conditions are tested.

Keywords

• reaction time
• H-reflex amplitude change
• thyrotoxicosis
• voluntary movement