Comparative analyse of single motor unit pattern in healthy subjects and patients with neuromuscular disorders.

ABSTRACT

OBJECTIVE: The motor unit (MU) spike trains in human muscle contractions are an object to new mathematical processing. The aim is to identify the interspike interval relations characterizing normal and changed physiological states (neuro-muscular disorders). METHODS: MU activities in healthy subjects and patients with Schwartz-Jampel syndrome, neuromiotonia and Parkinson disease were investigated. Motor unit action potentials (MUAPs) were recorded by surface multielectrode with small leading-off area without provoking a burst of activity, as usually was observed during the needle electromyography study in patients with Schwartz-Jampel syndrome and neuromiotonia. RESULTS: Different single motor unit activity in healthy subjects and patients was observed. Discharge pattern of patients was basically changed. Disturbance of different parts of the motor system leads to the changes of temporal order of interspike interval. This permit us to suppose that the pattern of repetative neuronal discharges suggests an influence at a higher level than the muscle in all investigated patients but the reason of multiple discharges with an interimpulse interval of 2 to 10 ms probably originated in the muscle membrane. CONCLUSIONS: The comparative analysis of MU patterns in healthy subjects and patients with neuro-muscular disorders can help us to disclose inapparent connections between cortical and spinal level of motor control.