An implantable upper extremity neuroprosthesis in a growing child with a C5 spinal cord injury

Abstract

Objectives: To implement a functional electrical stimulation (FES) hand neuroprosthesis called the Freehand System in a growing child with spinal cord injury (SCI) using extra lead wire to accommodate limb growth, and to evaluate the performance of the Freehand System during the subject's maturation. Setting: Pediatric orthopedic hospital specializing in SCI rehabilitation. Subject: Ten-year-old female patient with a C5 level SCI. Method: The Freehand System was implanted. Eight electrodes were implanted to targeted forearm and hand muscles to provide grasp and release function. The lead wire associated with each electrode was pathed subcutaneously up the arm with 4 cm of extra lead distributed throughout the path to accommodate expected limb growth. All leads were attached to a stimulator placed in the upper chest. Measures of lead unwinding, limb growth, stimulated muscle strength, and hand function were made at 6 and 16 months after implant. Results: By 16 months post implant, the upper limb growth plates were closed and humeral and radial bone growth combined was 2.7 cm from the time of surgery. For all eight leads, lead unwinding in the upper arm was approximately 1.2 cm and was comparable to humeral bone growth (1.4 cm). Lead unwinding in the lower arm was also measurable for the two electrodes in hand muscles. Six of eight electrodes maintained grade 3 or better stimulated muscle strength throughout the growth period according to a manual muscle test. Of the two other electrodes, one appeared to have lost function due to depletion of excess lead. However, hand function with FES was comparable at 6 and 16 months post implant suggesting that growth did not negatively impact performance with the FES system. Hand function with FES was improved over voluntary hand function as well. Using the Freehand System, a pinch force of approximately 15 N was achieved compared to 1.3 N of voluntary tenodesis pinch force. Scores on the Functional Independence Measure (FIM) increased by 9 points when FES was used as compared to voluntary function. Improvements occurred primarily in eating and grooming. Independence in writing was achieved only with FES. Conclusions: For this child, hand function with the Freehand System was sustained over the growth period and was a signi®cant functional improvement over voluntary hand function. By using excess lead wire, the Freehand System was successfully implemented before skeletal maturity, aording the child improved hand function earlier than would be otherwise indicated.

Functional electrical stimulation therapies after spinal cord injury

“…Although individuals with cervical SCI may be provided assistive devices or orthoses to complete their functional tasks, this alternative paradigm is compensatory and does not improve motor functional gains. Restoration of UE function has been attempted through hand surgery [63][64][65][66][67], somatosensory stimulation [68,69], and functional electrical stimulation via upper extremity neuroprostheses [70][71][72][73][74][75].…”

“…2) of upper extremity neuroprosthesis technology (Freehand system) was reported in the mid-1980s and involved implantation of 8-epimyseal electrodes in wrist and hand muscles, including flexor digitorum profundus (FDP) and superficialis (FDS), flexor pollicis longus (FPL), adductor pollicis (ADP), abductor pollicis brevis (AbPB), extensor digitorum communis (EDC), extensor pollicis longus (EPL); one electrode was sutured to the subcutaneous fascia near the clavicle for sensory feedback [74]. The primary goal of the implanted electrodes was to achieve myoelectric control to improve hand grasp and elbow extension in individuals with cervical SCI [71,[73][74][75][76][77][78][79]. More recently, Kilgore et al [72] have developed a second-generation neuroprosthesis that consists of 12 stimulating electrodes, 2 EMG signal recording electrodes, an implanted stimulator-telemeter device, an external control unit and a transmit/receive unit (see Fig.…”

“…Kilgore KL et al (72) Neuroprosthesis with implanted myoelectric control that consists of 12 stimulating electrodes, 2 EMG signal recording electrodes, an implanted stimulatortelemeter device, an external control unit, and a transmit/receive coil helped to restore basic hand functions. Smith BT et al (75) Implantation of the free hand system in 10 year old female with C5 SCI appeared to be successful in improving hand function over voluntary control. Growth did not appear to interfere with the FES system/ Alon G and McBride (80) The efficacy and safety of NESS hand-master neuroprothesis was determined in individuals with C5/C6 SCI Needham et al (82) FES ACE improved voluntary strength and control of elbow extensors after 8 weeks of training.…”

Evaluation of Muscle Strength in Medullar Injury: A Literature Review

“…100 Unspecified scales with scoring from 0 to 5 were used in three studies. 89,90,94 These scales use six-point grading with the force of gravity as a reference of resistance to movement. 100 As regards the survey about strength assessment in clinical practice, 42 of the 44 questionnaires sent were returned.…”

Evolution of Neuroprosthetic Approaches to Restoration of Upper Extremity Function in Spinal Cord Injury

“…10 Results of the first clinical trial have been previously published by Peckham and colleagues. [11][12][13][14][15][16][17] A second-generation neuroprosthesis internalized the control source using myoelectric recording electrodes to capture voluntary signals to control opening and closing of the hand. [18][19][20][21] In addition to implanting the control source, this system provided four additional channels of stimulation to refine additional functional activities.…”