Electrical stimulation of antagonist muscles after botulinum toxin type A for post-stroke spastic equinus foot. A randomized single-blind pilot study

Background: Botulinum toxin type A (BoNT-A) injection is an effective treatment for lower-limb spasticity and should be offered as first-line treatment for focal manifestations. Although its possible role has been hypothesized, the efficacy of electrical stimulation (ES) of antagonists of the injected muscles for improving clinical outcome after BoNT-A injection remains to be established. Objectives: This randomized single-blind pilot study aimed to investigate the efficacy of ES of antagonist muscles as adjunct treatment after BoNT-A injection to plantar flexor muscles in hemiplegic patients with spastic equinus foot. Methods: After BoNT-A injection at triceps surae, patients were randomly allocated to 2 groups: group 1, single ES session on injected muscles plus 5 sessions of ES on antagonist muscles, and group 2, single ES session on injected muscles alone. Both groups underwent daily physical therapy for 60 min for 2 weeks (5 days/week). Assessments were performed before treatment (T₀) and at 10 days (T₁), 20 days (T₂), and 90 days (T₃) after treatment. Our primary outcome was gait velocity at a comfortable speed at T₂ (10-m walk test [10MWT]). The following were secondary outcomes: triceps surae spasticity (Modified Ashworth Scale), ankle passive range of motion (pROM), strength of tibialis anterior muscle, and 2-min walk test (2MWT). Results: The 30 patients enrolled were randomly allocated to the 2 groups: 15 in group 1 and 15 in group 2. At T₁, T₂ and T₃, both groups showed a significant reduction in muscle tone and an increase in ankle pROM (P < 0.05). At T₂ and T₃, both groups showed a significant increase in 10MWT and 2MWT. The groups did not significantly differ in tibialis anterior strength or primary or secondary outcome measures. Conclusions: ES of antagonist muscles does not improve clinical outcomes in the post-stroke spastic equinus foot after BoNT-A injection.