Direct Peroneal and Tibial Transcutaneous Electrical Nerve Stimulation for Improving Postural Control in European Women with Diabetic Polyneuropathy: A Randomized Controlled Trial

Background: Postural disability develops in almost all patients with diabetic polyneuropathy (DPN). While transcutaneous electrical nerve stimulation (TENS) has proven effective in regressing sensory and motor impairments, its efficacy in improving postural control remains insufficiently studied. Purpose: To evaluate and compare the efficacy of direct peroneal and tibial high-frequency low-amplitude (HFLA) TENS and low-frequency high-amplitude (LFHA) TENS in correcting DPN-related postural disability, among European female patients without a documented history of falls, motor deficits, or pronounced electromyographic impairments, using computerized static posturography and the tandem walk test. Materials and methods: In this single-center, three-arm, randomized controlled trial (registration number: ISRCTN47534508, 3 December 2024), we conducted a longitudinal prospective analysis of European women with DPN-related postural disability. All enrolled patients were non-fallers with no motor deficits and baseline compound muscle action potential (CMAP) amplitudes of the peroneal and tibial nerves of at least 1.5 mV. The intervention groups received HFLA TENS (n = 24) or LFHA TENS (n = 25), while the control group underwent sham TENS (n = 24). Primary endpoints were assessed via static posturography and the tandem walk test (TWT); secondary endpoints were evaluated using hypoesthesia and pain evaluation, the Modified Clinical Test of Sensory Interaction in Balance (mCTSIB), and electromyography. Assessments were performed before treatment, immediately post-treatment, and at the conclusion of a 2-month follow-up period. Results: Comparative analysis incorporating the Bonferroni adjustment demonstrated that LFHA TENS is significantly superior to HFLA TENS. Post-treatment, LFHA TENS induced a reduction in envelope area by 20.7% under the eyes-open (EO) condition (p < αadj; αadj = 0.0028) and 32.9% under the eyes-closed (EC) condition (p < αadj; αadj = 0.0028), alongside a 16.6% decrease in the Romberg uotient (RQ) (p < αadj; αadj = 0.0056). Furthermore, LFHA TENS elicited a significant 39.0% reduction in velocity of CoP sway (VCS) under the EO condition (p < αadj; αadj = 0.0042), and decreased total CoP sway excursion by an average of 35.8% (EO) (p < αadj; αadj = 0.0042) and 43.8% (EC) (p < αadj; αadj = 0.0042) compared to baseline. In contrast, no statistically significant changes in these parameters were observed after HFLA TENS. Ultimately, LFHA TENS outperformed HFLA TENS in improving postural stability by 7.04% under the EO condition (p < αadj; αadj = 0.0042) and by 25.5% under the EC condition (p < αadj; αadj = 0.0042) in both the tandem walk test (TWT) and the Modified Clinical Test of Sensory Interaction on Balance (mCTSIB). Notably, a statistically significant increase in the CMAP amplitude of the affected peroneal nerves by 22.2% was observed exclusively following LFHA TENS treatment (p < αadj; αadj = 0.0056). Conclusions: The clinical efficacy of direct peroneal and tibial TENS compared to sham stimulation in reducing postural disability during both static and dynamic conditions was established in European female patients with moderate-to-severe DPN and unremarkable EMG impairments. Comparative analysis reveals a clear therapeutic superiority of LFHA TENS over HFLA TENS, as evidenced by significantly greater improvements in both posturographic parameters (envelope area, total CoP excursion under EO and EC conditions, and VCS under the EO condition) and functional clinical tests (TWT and mCTSIB), demonstrating long-term stability for up to 2 months post-intervention.