American Society for Peripheral Nerve

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Improvement in Functional Elbow Movement with a Myoelectric Orthotic Device: A Novel Application of a Post-CVA Assistive Rehabilitation Orthotic Device
Vahe Fahradyan, MD; Jonathan M Winograd, MD; Mark A Randolph, MAS
Massachusetts General Hospital, Boston, MA

Introduction: Nerve grafting, nerve transfers and free functioning muscle transfers (FFMTs) have lead to improved functional outcomes in brachial plexus injury (BPI) patients. Reports have shown that 41% of nerve transfers and 79% of the FFMTs for elbow flexion achieve ≥ M4 elbow flexion strength. However, there remains a substantial minority of patients with less favorable functional outcomes that need to be addressed further.
The MyoPro (Myomo Inc., Cambridge, MA, USA) is an FDA-cleared myoelectric elbow-wrist-hand orthosis that uses surface EMG signals from affected muscle groups to control a powered orthosis to assist with the movement of a paretic upper limb. This device was originally designed for the treatment of post-CVA upper extremity paresis, in patients who had incomplete recovery of muscle strength but preserved voluntary EMG signals. We describe the application of this orthosis for enhancement of elbow flexion and extension in patients with incomplete recovery from BPI with poor voluntary elbow movement.

Materials and Methods: Two patients from a single-surgeon practice have been evaluated for the suitability of the myoelectric functional orthotic device. Both patients are 37 year-old men who were involved in motor vehicle accidents, 14 and 17 years ago, that resulted in left and right brachial plexus injuries. Patient 1 initially had brachial plexus reconstruction by nerve transfers and secondarily a free functioning muscle transfer for restoration of elbow flexion and finger extension. Patient 2 underwent brachial plexus exploration and neurolysis only. Both patients failed to regain voluntary elbow movement. Evaluation showed 0 130 degree elbow passive range of motion in flail arms. Both patients had detectable EMG signals in the biceps or gracilis, and triceps muscles. Both patients underwent 30 minutes of training with the device, which provides powered assistance for elbow flexion and extension via motors attached to the exterior of the orthosis. After the training, patients were asked to perform voluntary assisted elbow flexion and extension.

Results: Both patients demonstrated voluntary active elbow flexion and extension from 0 to 115 degrees using EMG control signals from the gracilis and triceps in Patient 1, and from the biceps and triceps muscles in Patient 2.

Conclusion: Given the limited options available after definitive reconstruction, this myoelectric orthosis is a valuable option to improve the functional outcome in patients with BPI and poor return of voluntary elbow movement following reconstruction.

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