PubMed Health⌕ Search

Biomedical subjects

P H Peckham

Publications and source records attributed to P H Peckham.

At least 19 recordsLinked to original sources
PubMed1999

Satisfaction with and usage of a hand neuroprosthesis.

OBJECTIVE: To measure the satisfaction with, clinical impact of, and use of an implantable hand neuroprosthesis. SETTING: Eight different medical centers. PARTICIPANTS: Thirty-four individuals with spinal cord injuries at the C5 or C6 motor level. INTERVENTIONS: Participants were implemented with a hand neuroprosthesis that provides grasp and release. The neuroprosthesis includes a surgically implanted stimulator, implanted electrodes sutured to the hand and forearm muscles, and an externally mounted controller. MAIN OUTCOME MEASURE: A survey was mailed to study participants, who were asked to respond to statements such as "If I had it to do over, I would have the hand system implanted again," using a 5-level Likert scale ("strongly agree" to "strongly disagree"). RESULTS: Eighty-seven percent of participants were very satisfied with the neuroprosthesis, 88% reported a positive impact on their life, 87% reported improvements in activities of daily living, and 81% reported improved independence. Participants reported using the neuroprosthesis a median of 5.5 days per week; 15 participants used the neuroprosthesis 7 days per week, and 5 participants reported not using the device. CONCLUSIONS: The neuroprosthesis was used by most participants. The neuroprosthesis performed satisfactorily, increased users' ability to perform activities of daily living and independence, and improved their quality of life.

Adolescent↗
PubMed1999

The function of the finger intrinsic muscles in response to electrical stimulation.

The actions of the dorsal interosseous, volar interosseous, and lumbrical muscles were investigated using applied electrical stimulation and recording the moments that were generated across the metacarpophalangeal joint in flexion/extension and abduction/adduction, the proximal interphalangeal joint in flexion/extension, and the distal interphalangeal joint in flexion/extension. These measurements were made isometrically at various joint angles and levels of stimulation with both able bodied subjects and persons who had sustained tetraplegia. It was determined that the dorsal interossei, including the first, were strong abductors of the fingers and generated a significant moment in metacarpophalangeal (MP) joint flexion and interphalangeal (IP) joint extension. The volar interossei were the primary adductors of the fingers, as well as providing a significant moment in MP joint flexion and IP joint extension. The lumbrical muscles were found to be MP joint flexors and IP joint extensors, although the moments that were generated were on average 70% lower than the interossei. The role of the lumbricals as finger abductors or adductors could not be determined from the data. This information on the actions and moment generating capabilities of the intrinsic muscles led to the incorporation of the interossei into electrically induced hand grasp provided by an implanted neuroprosthesis. The evaluation of the intrinsic muscles in the neuroprosthesis was accomplished by recording the moment generating capabilities of these muscles across each of the joints of the finger. These muscles were capable of generating moments that were 80-90% of the average attained by the able bodied subjects, and have provided a substantial improvement to the electrically induced hand grasp.

Adult↗
PubMed1998

Neurophysiologic evaluation of lower motor neuron damage in tetraplegia.

We quantitatively investigated the extent of damage to motor neurons in tetraplegic subjects. Numbers of motor units in the patients were significantly lower for thenar, wrist extensor, and biceps brachii as compared to controls. Reduction in counts occurred even when M-response amplitudes were normal. Standard electromyography suggested a surprising frequency of lower motor neuron dysfunction below the level of injury. These results confirm previous reports and add data on motor units in the biceps brachii.

Cell Count↗
PubMed1998

An externally powered, multichannel, implantable stimulator-telemeter for control of paralyzed muscle.

An implantable integrated stimulator and telemetry system has been developed. The system is capable of fulfilling the stimulus and telemetry needs of advanced functional neuromuscular stimulation (FNS) applications requiring multiple channels of stimulation and multiple channels of sensor or biopotential sensing. This system provides a command control structure, an inductive radio frequency link providing power to the implant device as well as two-way transcutaneous communication, an ASIC for decoding the command and for providing functional control within the implant, and modular circuitry providing the application specific implant functions. Biocompatible hermetic packaging, lead systems, and in-line connectors suitable for long-term implantation, provide encapsulation for the circuitry and access to the electrodes and sensors used in the application. The first implant configuration realized from this modular system is targeted for clinical implementation in persons with tetraplegia at the C6 level for restoration of hand function, using wrist position as the command control source. The implant device realized has ten channels of stimulation and telemetry used to control and sense a joint angle transducer implanted in the radio-carpal joint of the wrist. A prototype device has been fabricated and is undergoing testing in an animal.

Algorithms↗
PubMed1998

Functional neuromuscular stimulation for combined control of elbow extension and hand grasp in C5 and C6 quadriplegics.

Spinal cord injury sustained at the C5/C6 level leaves an individual without voluntary control of the muscles of the forearm, hand, or of the elbow extensors. The objective of this research project was to integrate functional neuromuscular stimulation (FNS) control of elbow extension with a previously developed system that provides hand grasp in order to increase the working volume in space in which users can perform functional tasks. Elbow extension control was achieved by detecting the position of the arm in space and determining the magnitude of the gravitational moment acting to oppose extension. An accelerometer was used as the command control source, and this sensor was placed over the ulna near the elbow joint to detect static (gravitational) acceleration, and therefore the gravitational moment acting about the elbow joint. This value determined the level of electrical stimulation required to activate the triceps muscles to full extension against these forces. Combined FNS control of elbow extension and hand grasp was implemented in two quadriplegic subjects. Both subjects were able to reach and grasp objects at locations in space which were unattainable without triceps activation.

Biomechanical Phenomena↗
PubMed1998

A comparison between control methods for implanted FES hand-grasp systems.

Implanted neuroprostheses employing functional electrical stimulation (FES) provide grasp and release to individuals with tetraplegia. This paper describes and compares three methods of controlling the stimulated hand movement: shoulder position, wrist position and myoelectric activity from the wrist extensors. Three experienced neuroprosthesis users were evaluated with each of the control methods by performing a grasp release test (GRT). A significant improvement was found between each functional electrical stimulation (FES) method and tenodesis without FES. No significant difference in overall performance was found between the three FES methods of control. Each method of control demonstrated advantages and disadvantages which depend upon characteristics of the individual patient. Factors which must be considered are injury level, voluntary wrist strength, proximal upper limb strength, the level of cognition of the patient, hand-grasp characteristics, cosmeses, importance of using both arms, and personal preference. Due to the unique characteristics of each controller type, it is advantageous to have each type available for the FES patients to adapt the system to the needs and desires of the individual patient.

Electric Stimulation Therapy↗
PubMed1998

A transducer for the measurement of finger joint moments.

A device capable of simultaneously measuring the isometric moments generated about the metacarpophalangeal (MP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints of all four fingers has been developed. The design utilizes a four-bar linkage to transmit moments, but not forces, to the device. This linkage allows the same device to fit a wide range of hand sizes without recalibration. The device was constructed out of aluminum bars which are strapped to each joint segment and to the back of the hand. Strain gauges mounted to the aluminum bars measure the bending moment on the device, which is directly related to the moment applied about the joint center of rotation. Because of the unique design of the device, it is not necessary to have accurate measurements of the joint center of rotation in order to get accurate moment information. A single device is capable of generating independent measurement of MP extension/flexion, PIP extension/flexion, and DIP extension/flexion. Four of these devices can be used to make simultaneous measurements of all the moments generated by all four fingers. The device also acts as a splint, allowing each joint to be positioned and locked at any angle through the range of motion of the joint. The device is accurate to within +/- 5.6% of each reading for moments from 10 N x cm to 100 N x cm and within +/- 2.0 N x cm for moments of 10 N x cm or less. If the device configuration is constrained, the accuracy can be improved to +/- 0.8% of full scale (100 N x cm) and +/- 0.21 N x cm for moments of 10 N x cm or less. The device can measure both flexion and extension moments up to 100 N x cm, and can allow the joints to be fixed at any angle from approximately 10 to 80 degrees.

Biophysical Phenomena↗
PubMed1997

Patient selection for an upper extremity neuroprosthesis in tetraplegic individuals.

One hundred and twenty persons with new onset traumatic tetraplegia consecutively admitted to our rehabilitation service were screened for consideration for use of an upper extremity neuroprosthesis. Strict inclusion criteria allowed only for participation of patients with ASIA impairment scale A, B or C injuries at the C5 or C6 level. One hundred and six persons were excluded from participation for the following reasons: five patients died, 27 had central cord syndrome, two had Brown-Sequard syndrome, 12 were injured at too high a level, 42 were injured at too low a level, two were excluded on the basis of motor incompleteness alone, four were excessively denervated, two had limited range of motion, one had overriding medical complications, seven had psychosocial issues making participation impractical, and two elected tendon transfer surgery. In total, 14 patients (representing 11.7% of all tetraplegic individuals and 50% of the C5 or C6 ASIA Impairment Scale A, B or C patients) were found to be candidates for the neuroprosthesis. Given the prevalence of tetraplegia, approximately 12,200 Americans would be candidates for the FES neuroprosthetic hand grasp system under the current research protocols. With both the expansion of current protocols to other diagnostic categories and further research and development, application of this neuroprosthesis to a considerable number of previously excluded subjects will likely be possible.

Adult↗
PubMed1997

Peripheral nerve stimulation for restoration of motor function.

This review paper discusses the use of electrical stimulation to restore function after upper motor neurone type of paralysis. It describes the basic physiology of electrical stimulation, the electrophysiology and biomaterials associated with using metal electrodes to deliver charge to living tissue, and also the adverse effects of stimulation. The central concepts of electrode applications, stimulus parameters, muscle fatigue, and stimulation control are covered. Next, a survey of clinical applications is made with focus on upper and lower limb applications. A concluding section mentions the current status of commercial products available for stimulation.

Bioprosthesis↗
PubMed1997

Tissue response to chronically stimulated implanted epimysial and intramuscular electrodes.

Twenty-four epimysial and 16 intramuscular electrodes were implanted in five adult dogs for periods ranging from 11 to 50 months. Chronic stimulation was applied to half of the electrodes for eight weeks near the end of the implantation period. The tissue response was rated by the amount and appearance of the fibrous tissue and inflammatory cells seen in the capsule lining the region of the electrode. The encapsulation tissues were composed primarily of collagen and fibroblasts and some macrophages and few other inflammatory cells. The epimysial electrodes exhibited more variation between and within electrodes, but had more of the better scores than the intramuscular electrodes. No difference in the distribution of scores was measured between the control and stimulated groups for the epimysial electrodes. While the scores for the intra-muscular electrodes varied very little, variance was sufficient to indicate a trend for poorer ratings with the application of chronic stimulation. Fibrous capsules were generally thinner under the epimysial electrodes than around the intramuscular electrodes. For both electrode types, the thickness was not correlated with the application or level of chronic stimulation. Thickness was shown to be positively correlated to the degree of loss of the sutures used to anchor the epimysial electrodes.

Animals↗
PubMed1997

The monitoring of tendon tension with an implantable intratendon probe and its use in the control of neuroprostheses.

The use of a probe measuring tendon tension for the purpose of controlling a neuroprosthesis suited to spinal cord injured persons is investigated. The implanted probe detected inwardly directed radial force exerted by the tendon as the result of longitudinal tension. Varying types of load were applied to the tendon in order to measure static and dynamic parameters of the probe within the tendon. The results are discussed with respect to the potential use of the probe, within an active muscle's tendon, as a hand grasp neuroprosthesis controller. In addition, use of the probe to monitor electrically stimulated paralyzed muscle for the augmentation of closed loop control schemes is discussed.

Achilles Tendon↗
PubMed1997

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.

Activities of Daily Living↗
PubMed1996

Tendon transfers and functional electrical stimulation for restoration of hand function in spinal cord injury.

Spinal cord injury at the C5 and C6 level results in loss of hand function. Electrical stimulation of paralyzed muscles is one approach that has demonstrated significant capacity for restoring grasp and release function. One potential limitation of this approach is that key muscles for stimulation may have lower motor neuron damage, rendering the muscles unexcitable. We have used surgical modification of the biomechanics of the hand to overcome this limitation. Tendon transfer of paralyzed but lower motor neuron intact muscles can compensate for potential function lost owing to muscles with lower motor neuron damage. Such procedures have been performed to provide finger extension, thumb extension, finger flexion, and wrist extension. Additional surgical procedures have been performed to enhance the function provided with electrical stimulation. These are side-to-side synchronization of the finger flexor and extensor tendons, the flexor digitorium superficialis Zancolli-lasso procedure, and thumb interphalangeal joint arthrodesis. These procedures have been performed in 11 patients with C5 and C6 level spinal injuries and functional electrical stimulation neuroprostheses. In these patients, 41 different functional electrical stimulation-related procedures were performed and 38 gave the desired result after surgery. One procedure resulted in no increase or decrease in function or muscle output, and two procedures resulted in a decrease in muscle force or joint range of motion. The issues that must be considered in performing functional electrical stimulation-related tendon transfers are discussed.

Electric Stimulation Therapy↗
PubMed1996

Tri-state myoelectric control of bilateral upper extremity neuroprostheses for tetraplegic individuals.

For the purpose of bimanual control of tetraplegic hands that have useful movement restored by a neuroprosthetic device, the use of myoelectric signals from bilateral sternoclei-domastoid muscles is proposed. Three state control has been proposed where each sternocleidomastoid controls its ipsilateral hand. Demonstration was made with spinal-cord-injured and nonspinal-cord-injured subjects providing three levels of activation that can be repeatably made with each of these muscles. The agonist and antagonist sternocleidomastoids during this command control were differentiated so that the desired hand will respond to a command. Neither normal head movements nor head position within its comfortable range of motion were shown to interfere with the proposed command. The provision of feedback was shown as important to provide robustness in the operation for the users selection of the right or left hand. The performance of spinal cord injured and noninjured persons using this controller was quantitatively measured through the completion of precision tracking tasks by the manipulation of on-screen virtual hands. All subjects were able to operate the controller with a degree of skill acceptable for completion of functional tasks with bilateral stimulated hand grasps. The sensitivity of the subjects performance to variation in controller parameters was also measured.

Arm↗
PubMed1996

Technology transfer of neuroprosthetic devices.

Despite long development periods for neuroprosthetic devices, the numbers in clinical use or clinical trials are rising, with an estimated 3,000 systems in use today. As they gain experience with the regulatory approval process, developers are learning to conduct research to best prepare for transfer of technology to industry. The track record of the first motor prosthesis to be approved by the United States Food and Drug Administration contains important lessons for a company planning to undergo the regulatory process. Throughout the development of a neuroprosthesis, the capabilities and preferences of the customers who will use it (physicians, surgeons, therapists, and end-users) should be sought out and used in device design. When a device has reached clinical application, particular attention is needed to maximize both the population who will use it and each individual's degree of use (optimal, partial, reluctant). Identification of person-technology mismatches can help to select training strategies and other interventions that can be applied to ensure a good rehabilitation outcome.

Clinical Trials as Topic↗
PubMed1994

Development of a quantitative hand grasp and release test for patients with tetraplegia using a hand neuroprosthesis.

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 C5 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 neuroprosthesis helped C5 patients manipulate most objects and helped C6 patients primarily with more difficult objects.

Adult↗