Improvement in Sitting Balance by Exercises With a Standing Unstable Board Combined With Transcutaneous Electrical Nerve Stimulation to the Neck: A Study of Two Cases

Unstable board training and neck muscle stimulation have each been shown to improve sitting balance in stroke patients, but their combined effects remain unclear. This case report investigated whether transcutaneous electrical nerve stimulation (TENS) applied to the neck enhances the effectiveness of unstable board training on lateral sitting balance in individuals with severe subacute stroke. Two stroke survivors who required substantial assistance with activities of daily living participated in an alternating AB design intervention. In period A, both patients received conventional physiotherapy and unstable board training; in period B, neck TENS was included to the same program. Each physical therapy session lasted 40 minutes, consisting of 20 minutes of conventional physiotherapy and 20 minutes of unstable board training. During unstable board training, the non-paralyzed lower limb was placed on an unstable board, whereas the paralyzed limb, stabilized with a knee-ankle-foot orthosis, was placed on a stable surface. Patients performed weight-shifting and multidirectional reaching tasks under supervision. In period B, TENS was applied to the paralyzed sternocleidomastoid muscle at 100 Hz and 200 µs pulse width for 20 minutes during unstable board training. Righting reaction angles and center of pressure displacement were measured in the sitting position. Both outcomes improved to a greater extent in period B than in period A, particularly in the patient with milder sensory and motor impairments. These findings suggest that TENS applied to the neck may enhance sensory integration and postural adaptation when combined with unstable board training. The greater effect observed in the case with preserved somatosensory function implies that individual patient characteristics may influence the effectiveness of this combined intervention. This approach may offer a safe and potentially effective method to improve sitting balance in stroke patients with severe motor deficits. Further studies with larger samples and neurophysiological assessments are needed to confirm these preliminary observations.