Development of a Quantitative Hand Grasp and Release Test for Patients With Tetraplegia Using a Hand Neuroprosthesis Kathryn Stroh Wuolle, BS, Clayton 1. Van Doren, PhD, Geoffrey B. Thrope, BS, Michael W. Keith, MD, P. Hunter Peckham, PhD, Cleveland, OH We developed a quantitative grasp and release test for assessing a hand neuroprosthesis in C5 and C6 level tetraplegic patients. The objectives were (1) to determine if a patient’s hand performance with the neuroprosthesis exceeded a defined, clinically acceptable baseline, (2) to compare performance with and without the neuroprosthesis, (3) to measure the consistency of performance over time, and (4) to compare performance among patients. In the test, patients grasped, moved, and released one of six different objects as many times as possible in five 30-second trials for each object, with and without the neuroprosthesis. Unlike earlier tests, the objects and the task were chosen to span a range of difficulties appropriate for CS and C6 tetraplegic patients using a hand neuroprosthesis. Data from five patients showed that performance with the neuroprosthesis was above the baseline; performance improved with the neuroprosthesis, although it was not generally consistent across sessions; and the neuro- prosthesis helped C5 patients manipulate most objects and helped C6 patients primarily with more difficult objects. (J Hand Surg 1994;19A:209-218.) Over the past 12 years, 50 tetraplegic patients have been implemented with the Case Western Re- serve University-Veterans Administration Medical Center (CWRU-VAMC) portable hand neuropros- thesis.‘,* The patients have injuries at the CS or C6 neurological level (American Spinal Injury Associa- From the Case Western Reserve University Rehabilitation En- gineering Center, MetroHealth Medical Center, Cleveland VA Medical Center, and Departments of Orthopaedics and Biomedi- cal Engineering, Case Western Reserve University, Cleveland, OH. Supported in part by the Rehabilitation Research and Develop- ment Service of the Department of Veterans Affairs and Grant H133E80020 from the National Institute on Disability and Reha- bilitation Research. Received for publication Nov. 11, 1991; accepted in revised form July 9, 1993. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the sub- ject of this article. Reprint requests: Kathryn Stroh Wuolle, OTR/L, CHT, Case Western Reserve University Rehabilitation Engineering Center, Room H601. MetroHealth Medical Center, 2500 MetroHealth Drive, Cleveland. OH 44109-1998. tion guidelines31 and are in grouns 0, I, or 2 (0 or Cu) according to the interna%onal classification for surgery of the hand in tetraplegia4. CS patients (group 0 or 1) have some active shoulder control and elbow flexion and a passive tenodesis grasp where force is generated as the finger flexors are stretched in response to passive opening of the hand (e.g., when a large object is wedged in the hand). C6 pa- tients (group 2) have some shoulder control, elbow flexion. and voluntary wrist extension, which pro- vides them with an active tenodesis grasp as op- posed to a passive tenodesis grasp. The neuropros- thesis enhances independence in activities of daily living (ADL)’ by giving users unimanual control of lateral and palmar grasp and release. Paralyzed hand and forearm muscles are stimulated electrically via percutaneous” or implanted7,8 electrodes. The stim- ulation is controlled typically by movement of the contralateral shoulder using an external shoulder angle transducer and associated electronics. Elevat- ing the shoulder closes the hand by increasing flexor The Journal of Hand Surgery 209