Viscoelastic characteristics of muscles in neuroleptic treated patients

Abstract

Muscle tone (stiffness) is dependent on mechanical properties of fibers and neuronal activity. Neuroleptics determine changes in muscles characteristics. It is possibly to measure quantitative changes of contraction and relaxation using myotonometer. AIM: to clear up the possibility to evaluate subclinical extrapyramidal side effects of antipsychotic (neuroleptic) drugs in muscle tone changes. Method. MYOTONOMETER, designed and constructed by VAIN at the TARTU UNIVERSITY (Estonia) was used in the investigation. The frequency (FR) and the logarithmic decrement (DC) of damped oscillations of the muscles m.extensor carpi (EX) and m.trapezium (TR) (pars horizontalis) in sitting, relaxed state and m.biceps brachii (BC) in sitting relaxed and contracted states were recorded among the 17 patients of psychiatric department. Measurements were repeated 2-3 times in period of 7-12 days. 8 patients (age 32-59) received moderate or submaximal doses of neuroleptics (>3 weeks) with or without correctors were compared with 9 controls (age 7-62) treated without antipsychotics, with antidepressants and tranguiliants. Results. There was no evident difference of FR (reflecting muscle tone or stiffness) and DC (damping, elastic characteristic of muscle) in EX and TR muscles in both groups in relaxed state: neuroleptic EX-FR 14,02±0,82, DC 1,06±0,4; TR-FR 11,09±0,24,DC 0,98±0,32; control EX-FR 14,5±0,94, DC 1,05±0,28; TR-FR 11,65±0,5, DC 0,93±0,16. IN BC relaxed tone and decrement was similar: neuroleptic-FR 11,07±0,12: DC 1,06±0,1, control - FR 11,2±0,16;DC 0,84±0,16. IN contracted BC ability to contract and to relax turned worse in neuroleptic group FR 13,05±0,22, DC-1,17±0,08 than in control FR 15,64±0,21 and DC 0,75±0,11. Derivative parameters - stiffness (IS) and damping (ID) indexes - higher numbers demonstrate better ability to contract and to relax . Neuroleptic - IC 0,19±0,06, ID 0,81±0,12, control-IS 0,4±0,07, ID 1,25±0,32 (statistically significant.