Functional Neurorehabilitation using the Hybrid Assistive Limb (HAL): A First Experience in the United States

Abstract

Introduction: The Hybrid Assistive Limb (HAL, Cyberdyne, Japan) facilitates voluntary, user-driven ambulation through a neurologically-controlled system based on bioelectrical signals derived from the user. This allows for the repeated execution of physiologically faithful gait patterns, crucial to recovery in cases of neurologic motor deficit. In this series, we present the first three patients in the United States to undergo HAL neurorehabilitation training. Patient and methods: A case series of three patients participating in a single-center prospective, interventional pilot study, suffering neurologic motor deficits secondary to spinal cord infarct following a pulmonary embolism (patient 1), multiple sclerosis (patient 2) and the surgical resection of a petroclival meningioma (patient 3). The patients underwent 60 sessions of body weight-supported treadmill training in the HAL over the course of 12 weeks. Measures of functional ambulation (10 Minute Walk Test, 10MWT) were performed out of the HAL before and after each session and at the 12 week and 6 month follow-up. Timed Up & Go (TUG) test was performed each week. Treadmill data (time, distance) while in HAL was recorded at each session. Measures of endurance (6 Minute Walk Test, 6MWT), risk of fall (TUG), balance impairment (Berg Balance Scale) and improvements in walking performance (Walking Index for Spinal Cord Injury II, WISCI II) were measured at baseline, after 12 weeks and at 6 months follow-up. Results: Patients 2 and 3 completed 60 visits, patient 1 completed 56 visits. All patients achieved markedly increased treadmill paces, improved functional scores, increased distance in the 6MWT and decreased TUG times at 6-month follow-up. In the 10MWT, all patients achieved a clinically significant decrease in time and steps and showed improvements in the required assistance level to perform the test. Patients 1 and 3 showed improvement on the Berg Balance Scale. Patient 2 had no change between baseline and 6-month follow-up. Only minor adverse effects were reported, including skin abrasions and irritation secondary to chaffing of the HAL unit and EMG electrodes. Conclusion: These data show that HAL training is both feasible and effective in the neurorehabilitation of patients suffering neurologic motor deficits secondary to trauma and/or pathological/neurodegenerative processes after they have undergone normal rehab. A greater number of patients are required to meaningfully assess the differences in improvement from baseline, based upon underlying pathologies.