Functional electrical stimulation (FES): muscle histochemical analysis

Functional electrical stimulation (FES) has been used in Brazil since 1989 to obtain functional improvement in paraplegic patients' orthostasis and locomotion. The aim of this paper is to evaluate the histochemical changes observed in the quadriceps femoris muscle following the use of FES. We studied four patients with traumatic spinal cord lesions at T4-10 level, Frankel A, all within 12-24 months postlesion. They were all submitted to FES using the following criteria: square-wave, 20-30 Hz frequency, pulses of 0.003 seconds, time of stimulation 5 seconds, resting interval 10 seconds. The stimulation was applied during 90 consecutive days, 30 minutes each time, twice daily. The interval between the stimulations was 6 hours. Quadriceps muscle biopsies were performed before and after the use of FES. We used ATPase technique for the histochemical analysis, where three different dying patterns can be observed for the three types of muscular fibres (I, IIa and IIb). The two samples from each patient were analysed measuring the fibres' diameters and their index of atrophy, and counting the total number of each type of fibre in each sample. The mean total number of fibres in each sample was 256 +/- 12.3. The results showed that the sizes of the three types of fibres were not modified with the use of FES; the number of type IIa fibres increased in a significant fashion, after using of FES.