Anne M. Bryden

An Implanted Upper-Extremity Neuroprosthesis. Follow-up of Five Patients*

An implanted neuroprosthesis supplying functional neuromuscular stimulation was used to provide grasp and release to tetraplegic individuals. This article describes the results, at a minimum of three years, for the first five patients to have operative implantation of an eight-channel stimulator-receiver. All of the patients had a clinically complete spinal cord injury with motor function remaining at the level of the fifth or sixth cervical nerve root. In addition to implantation of the stimulator system, each patient had augmentative operations on the hand to improve function. The procedures included tendon transfers, side-to-side tendon anastomoses, arthrodesis of the interphalangeal joint of the thumb, and rotational osteotomy of the radius. The neuroprosthesis provides two grasp patterns controlled by voluntary motion of the shoulder or wrist. Functional evaluations included measurement of pinch force, a grasp-release test, evaluation of the level of functional independence, and usage surveys. Pinch force ranged from eight to twenty-five newtons. All five patients demonstrated functional grasp patterns, had increased independence, and were able to use the neuroprosthesis at home on a regular basis. The implanted stimulator has proved to be safe and reliable, with seven years as the longest time in situ at the time of writing.

An Implanted Upper-Extremity Neuroprosthesis Using Myoelectric Control

PURPOSE The purpose of this study was to evaluate the potential of a second-generation implantable neuroprosthesis that provides improved control of hand grasp and elbow extension for individuals with cervical level spinal cord injury. The key feature of this system is that users control their stimulated function through electromyographic (EMG) signals. METHODS The second-generation neuroprosthesis consists of 12 stimulating electrodes, 2 EMG signal recording electrodes, an implanted stimulator-telemeter device, an external control unit, and a transmit/receive coil. The system was implanted in a single surgical procedure. Functional outcomes for each subject were evaluated in the domains of body functions and structures, activity performance, and societal participation. RESULTS Three individuals with C5/C6 spinal cord injury received system implantation with subsequent prospective evaluation for a minimum of 2 years. All 3 subjects demonstrated that EMG signals can be recorded from voluntary muscles in the presence of electrical stimulation of nearby muscles. Significantly increased pinch force and grasp function was achieved for each subject. Functional evaluation demonstrated improvement in at least 5 activities of daily living using the Activities of Daily Living Abilities Test. Each subject was able to use the device at home. There were no system failures. Two of 6 EMG electrodes required surgical revision because of suboptimal location of the recording electrodes. CONCLUSIONS These results indicate that a neuroprosthesis with implanted myoelectric control is an effective method for restoring hand function in midcervical level spinal cord injury.

Durability of implanted electrodes and leads in an upper-limb neuroprosthesis

Implanted neuroprosthetic systems have been successfully used to provide upper-limb function for over 16 years. A critical aspect of these implanted systems is the safety, stability, and-reliability of the stimulating electrodes and leads. These components are (1) the stimulating electrode itself, (2) the electrode lead, and (3) the lead-to-device connector. A failure in any of these components causes the direct loss of the capability to activate a muscle consistently, usually resulting in a decrement in the function provided by the neuroprosthesis. Our results indicate that the electrode, lead, and connector system are extremely durable. We analyzed 238 electrodes that have been implanted as part of an upper-limb neuroprosthesis. Each electrode had been implanted at least 3 years, with a maximum implantation time of over 16 years. Only three electrode-lead failures and one electrode infection occurred, for a survival rate of almost 99 percent. Electrode threshold measurements indicate that the electrode response is stable over time, with no evidence of electrode migration or continual encapsulation in any of the electrodes studied. These results have an impact on the design of implantable neuroprosthetic systems. The electrode-lead component of these systems should no longer be considered a weak technological link.

Implanted Neuroprosthesis for Restoring Arm and Hand Function in People With High Level Tetraplegia

OBJECTIVE To develop and apply an implanted neuroprosthesis to restore arm and hand function to individuals with high level tetraplegia. DESIGN Case study. SETTING Clinical research laboratory. PARTICIPANTS Individuals with spinal cord injuries (N=2) at or above the C4 motor level. INTERVENTIONS The individuals were each implanted with 2 stimulators (24 stimulation channels and 4 myoelectric recording channels total). Stimulating electrodes were placed in the shoulder and arm, being, to our knowledge, the first long-term application of spiral nerve cuff electrodes to activate a human limb. Myoelectric recording electrodes were placed in the head and neck areas. MAIN OUTCOME MEASURES Successful installation and operation of the neuroprosthesis and electrode performance, range of motion, grasp strength, joint moments, and performance in activities of daily living. RESULTS The neuroprosthesis system was successfully implanted in both individuals. Spiral nerve cuff electrodes were placed around upper extremity nerves and activated the intended muscles. In both individuals, the neuroprosthesis has functioned properly for at least 2.5 years postimplant. Hand, wrist, forearm, elbow, and shoulder movements were achieved. A mobile arm support was needed to support the mass of the arm during functional activities. One individual was able to perform several activities of daily living with some limitations as a result of spasticity. The second individual was able to partially complete 2 activities of daily living. CONCLUSIONS Functional electrical stimulation is a feasible intervention for restoring arm and hand functions to individuals with high tetraplegia. Forces and movements were generated at the hand, wrist, elbow, and shoulder that allowed the performance of activities of daily living, with some limitations requiring the use of a mobile arm support to assist the stimulated shoulder forces.

Innovative Strategies for Improving Upper Extremity Function in Tetraplegia and Considerations in Measuring Functional Outcomes

Options for improving upper extremity function after tetraplegia have increased as a result of advancing science and technology. Subsequently, it becomes increasingly important to use a common language or approach for measuring outcomes. The International Classification of Function is a theoretical framework developed by the World Health Organization that can guide the comprehensive selection of restorative procedures and the measurement of resulting outcomes across all domains of health. Attention is needed in choosing appropriate outcome measures that detect the often subtle, yet significant, functional gains that affect all aspects of human function from the basics of movement to participation in life in a personally

Electrically stimulated elbow extension in persons with C5/C6 tetraplegia: A functional and physiological evaluation

OBJECTIVE To measure the effect of electrically stimulated triceps on elbow extension strength, range of motion, and the performance of overhead reaching tasks. SETTING Clinical research laboratory. PARTICIPANTS Four individuals with spinal cord injuries at the C5 or C6 motor level. INTERVENTIONS The participants, who already had an implanted upper extremity neuroprosthesis, were provided with elbow extension through functional electrical stimulation (FES) of the triceps brachii. MAIN OUTCOME MEASURES Comparisons of stimulated elbow extension to voluntary elbow extension: (1) evaluations of impairment such as range of motion and strength; (2) performance of a set of functional overhead reaching tasks that required elbow extension; (3) a usage survey (conducted by telephone) to examine use of triceps stimulation in the home and community. RESULTS All participants achieved greater range of motion and strength of elbow extension with stimulated triceps versus without. Overall functional task performance improved in 100% of the tasks tested for all but one participant, who showed improvement in 60% of the tasks. Participants reported using the triceps in at least one activity for at least 90% of the days the neuroprosthesis was donned.

An Implanted Neuroprosthesis for High Tetraplegia

Individuals with high tetraplegia (ASIA classification C4 or higher) have few options to restore upper extremity function. One promising alternative for restoring function to paralyzed muscles is the use of functional electrical stimulation (FES). Initial FES applications for individuals with high tetraplegia have been limited. A major difficulty encountered in the application of FES in high tetraplegia has been the inability to achieve shoulder stabilization and mobilization primarily due to the denervation of key muscles. Another major difficulty has been the limited alternatives to provide control of the stimulated limb. As a result of these difficulties, the functional outcomes of these initial systems have been limited. Advances in technology and surgical techniques have been made that may provide methods for overcoming these limitations. Muscle denervation can be addressed through neurotization techniques to improve voluntary function and increase the response of paralyzed muscles to electrical stim...

International spinal cord injury upper extremity basic data set version 1.1

Fin Biering-Sørensen, Chair of the International SCI Standards and Data Sets Executive Committee under the International Spinal Cord Society (ISCoS) and American Spinal Injury Association (ASIA). Member of ISCoS and ASIA. Anne Bryden, Armin Curt, member of ISCoS and ASIA. Jan Friden, Lisa A. Harvey, member of ISCoS and ASIA. M.J. Mulcahey, member of ISCoS and ASIA. Milos Popovic, member of ASIA. Arthur Prochazka, K. Anne Sinnott, Govert Snoek, member of ISCoS.

Implanted Neuroprosthesis for Assisting Arm and Hand Function after Stroke: A Case Study

Loss of arm and hand function is common after stroke. An implantable, 12-channel, electromyogram (EMG)-controlled functional electrical stimulation neuroprosthesis (NP) may be a viable assistive device for upper-limb hemiplegia. In this study, a research participant 4.8 yr poststroke underwent presurgical screening, surgical installation of the NP, training, and assessment of upper-limb impairment, activity limitation, and satisfaction over a 2.3 yr period. The NP increased active range of finger extension from 3 to 96 degrees, increased lateral pinch force from 16 to 29 N, increased the number of objects from 1 to 4 out of 6 that the participant could grasp and place in a Grasp-Release Test, and increased the Arm Motor Abilities Test score by 0.3 points. The upper-limb Fugl-Meyer score increased from 27 at baseline to 36 by the end of the study. The participant reported using the NP at home 3-4 d/wk, up to 3 h/d for exercise and household tasks. The effectiveness of the NP to assist with activities of daily living was dependent on the degree of flexor tone, which varied with task and level of fatigue. The EMG-based control strategy was not successfully implemented; button presses were used instead. Further advancements in technology may improve ease of use and address limitations caused by muscle spasticity.

Surgical Restoration of Arm and Hand Function in People with Tetraplegia

Improved hand and arm function is the most sought after function for people living with a cervical spinal cord injury (SCI). Surgical techniques have been established to increase upper extremity function for tetraplegics, focusing on restoring elbow extension, wrist movement, and hand opening and closing. Additionally, more innovative treatments that have been developed (implanted neuroprostheses and nerve transfers) provide more options for improving function and quality of life. One of the most important steps in the process of restoring upper extremity function in people with tetraplegia is identifying appropriate candidates - typically those with American Spinal Injury Association (ASIA) motor level C5 or greater. Secondary complications of SCI can pose barriers to restoring function, particularly upper extremity spasticity. A novel approach to managing spasticity through high-frequency alternating currents designed to block unwanted spasticity is being researched at the Cleveland FES Center and may improve the impact of reconstructive surgery for these individuals. The impact of these surgeries is best measured within the framework of the World Health Organizations International Classification of Function, Disability and Health. Outcome measures should be chosen to reflect changes within the domains of body functions and structures, activity, and participation. There is a need to strengthen the evidence in the area of reconstructive procedures for people with tetraplegia. Research continues to advance, providing more options for improved function in this population than ever before. The contribution of well-designed outcome studies to this evidence base will ultimately help to address the complications surrounding access to the procedures.