Efficacy of interactive manual dexterity training after stroke: a pilot single-blinded randomized controlled trial

Abstract

Objective: To compare the efficacy of Dextrain Manipulandum™ training of dexterity components such as force control and independent finger movements, to dose-matched conventional therapy (CT) post-stroke.

Methods: A prospective, single-blind, pilot randomized clinical trial was conducted. Chronic-phase post-stroke patients with mild-to-moderate dexterity impairment (Box and Block Test (BBT) > 1) received 12 sessions of Dextrain or CT. Blinded measures were obtained before and after training and at 3-months follow-up. Primary outcome was BBT-change (after-before training). Secondary outcomes included changes in motor impairments, activity limitations and dexterity components. Corticospinal excitability and short intracortical inhibition (SICI) were measured using transcranial magnetic stimulation.

Results: BBT-change after training did not differ between the Dextrain (N = 21) vs CT group (N = 21) (median [IQR] = 5[2-7] vs 4[2-7], respectively; P = 0.36). Gains in BBT were maintained at the 3-month post-training follow-up, with a non-significant trend for enhanced BBT-change in the Dextrain group (median [IQR] = 3[- 1-7.0], P = 0.06). Several secondary outcomes showed significantly larger changes in the Dextrain group: finger tracking precision (mean ± SD = 0.3 ± 0.3N vs - 0.1 ± 0.33N; P < 0.0018), independent finger movements (34.7 ± 25.1 ms vs 7.7 ± 18.5 ms, P = 0.02) and maximal finger tapping speed (8.4 ± 7.1 vs 4.5 ± 4.9, P = 0.045). At follow-up, Dextrain group showed significantly greater improvement in Motor Activity Log (median/IQR = 0.7/0.2-0.8 vs 0.2/0.1-0.6, P = 0.05). Across both groups SICI increased in patients with greater BBT-change (Rho = 0.80, P = 0.006). Comparing Dextrain subgroups with maximal grip force higher/lower than median (61.2%), BBT-change was significantly larger in patients with low vs high grip force (7.5 ± 5.6 vs 2.9 ± 2.8; respectively, P = 0.015).

Conclusions: Although immediate improvements in gross dexterity post-stroke did not significantly differ between Dextrain training and CT, our findings suggest that Dextrain enhances recovery of several dexterity components and reported hand-use, particularly when motor impairment is moderate (low initial grip force). Findings need to be confirmed in a larger trial. Trial registration ClinicalTrials.gov NCT03934073 (retrospectively registered).

Keywords: Dexterity; Finger training; Hand use; RCT; Stroke; Upper limb.

Fig. 1

Participant flow through the longitudinal post-stroke study (CONSORT flow chart)

Fig. 2

Post-stroke recovery of dexterous hand use. Box and block test (BBT) score as outcome measure across time (training) and groups (Dextrain group vs. CT, conventional therapy group). A Primary outcome, BBT-change at post-training (T1-T0), did not differ between Dextrain and CT groups. BBT-change at 3-months follow-up (T2-T0) also did not differ between groups. B Within-group BBT scores compared to reference values in healthy control subjects (N = 30) at T0 (baseline), T1 (post-training) and T2 (follow-up); Dextrain and CT groups significantly improved BBT score with training (T1); the CT group showed retention of BBT gains at T2, while the Dextrain group showed further improvement at T2. *P < 0.05. C Degree of initial motor impairment and therapy-mediated gains in dexterous hand use. Exploratory analysis after median-splitting the groups according to Fmax% on T0 (line = median, box = 25–75%, whisker = min/max). Dextrain training was more beneficial in patients with moderate motor impairment (Low subgroup) than those with mild motor impairment (High maximal force subgroup; Z = − 2.32, P = 0.02). There was no significant difference in BBT-change between Low and High subgroups within the CT group. The Low motor impairment group also improved more in BBT-change after Dextrain than conventional therapy (Mann–Whitney U Test, P < 0.05)

Fig. 3

Training effects on components of manual dexterity. A Box plots showing mean (line), CI95% (box) and min–max (whiskers) of change scores in dexterity components. Change in maximal tapping speed was significantly greater in Dextrain compared to CT group. B Finger force tracking error also improved more in Dextrain compared to CT group. C Reaction time change: faster reaction times after training in the Dextrain group compared to CT group (positive change indicates faster times). *P < 0.05 (Student t-test)

Fig. 4

Transcranial magnetic stimulation (TMS) results. A Example of the neuronavigation map obtained in a subject during recruitment curve measures. Heat map indicates consistent cortical location of successive stimulations during testing in one patient. This ensured stable cortical location of stimulation over left M1 (red area). Below, an example motor evoked potential in 1DI after single-pulse TMS (in black) and after paired-pulse (conditioned) stimulation (in grey). The difference in MEP size between single and paired pulse stimulations was used to calculate SICI%. B Change in SICI% after training (negative values depict reinforced inhibition). The majority of patients showed stronger SICI after training, and the degree of SICI% change correlated significantly with change in BBT (T1-T0; Spearman Rho = − 0.80, P = 0.006)