COMPARATIVE EFFECTS OF HIGH AND LOW FREQUENCY TRANSCUTANEOUS ELECTRICAL NERVE STIMULATION ON UPPER LIMB SPASTICITY, HAND DEXTERITY AND FUNCTIONAL INDEPENDENCE IN STROKE SURVIVORS

Abstract

Upper limb spasticity and poor hand dexterity may affect functional independence in stroke survivors. High or low frequency Transcutaneous Electrical Nerve Stimulation (TENS) can be used in rehabilitating hand function after stroke, but it is not clear which is more effective. This study was carried out to compare the effects of high and low frequency TENS on upper limb spasticity and hand dexterity in stroke survivors. Interrelationships among functional independence, upper limb spasticity and hand dexterity were also investigated. This quasi-experimental study involved 49 consenting stroke survivors recruited from the outpatient Physiotherapy clinics of Federal Medical Centre, Umuahia and University of Port-Harcourt Teaching Hospital, Nigeria. Participants were consecutively assigned to either Low Frequency TENS Group (LFTG; n=24) or High Frequency TENS Group (HFTG; n=25). However, 18 and 20 participants in the LFTG and HFTG, respectively completed the six-week treatment period. The Low frequency TENS and high frequency TENS were applied to the wrist flexors in both groups. Participants also received conventional physiotherapy for stroke. Outcomes assessed at baseline, 2nd, 4th, and 6th week included: spasticity using Modified Ashworth Scale, functional independence using Functional Independence Measure, hand dexterity using Jebsen Hand Function Test. Data were analysed using descriptive statistics, Spearman correlation coefficient. Wilcoxon signed rank and Kruskal-Wallis test at p=0.05. At baseline, there was no significant difference in duration of stroke, hand dexterity, functional independence and spasticity between the two groups. The pre-treatment spasticity at each session were not different between LFTG and HFTG across the six weeks. The post-treatment spasticity for the LFTG compared with HFTG for 2nd week (3.2 ± 0.8 vs 2.6 ± 0.6), 4th week (3.1±0.5 vs 2.7±0.6) and 6th week (3.1±0.6 vs 2.6±0.6) were significantly different, respectively. Spasticity significantly reduced in the HFTG pre-treatment to post-treatment from (3.2±0.6 to 2.8±0.6) at baseline, from (3.1±0.6 to 2.7±0.7) at 2nd week from (3.1±0.6 vs 2.7±0.5) at 4th week and from (3.1±0.6 to 2.6±0.6) at 6th week. There were no significant differences in hand dexterity and functional independence between LFTG and HFTG over the treatment period. However, significant within-group changes were observed between pre and post intervention scores for hand dexterity (LFTG: 16.4±2.5 vs 15.3±2.8) and (HFTG: 16.3±3.2 vs 15.3±3.2), and functional independence, (LFTG: 84.7±18.7 vs 86.6±17.6) and (82.2±20.1 vs 86.2±18.6) respectively. Only hand dexterity was significantly correlated to functional independence (r=- 0.4) in this study. High and low frequency transcutaneous electrical nerve stimulation exerted similar effects on hand dexterity and functional independence. However, high frequency stimulation reduced spasticity better than the low frequency transcutaneous electrical nerve stimulation. Either of the two can be used in the management of hand dexterity and functional independence in stroke survivors.