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Biomedical subjects

R J Triolo

Publications and source records attributed to R J Triolo.

29 records · Page 2Linked to original sources
PubMed1992

The application of a modified neuroprosthetic hand system in a child with a C7 spinal cord injury. Case report.

A neuroprosthetic hand system developed at Case Western Reserve University has been modified for use by an 8 year old child with an incomplete C7 spinal cord injury. This system has been adapted to accommodate voluntary thumb and finger extension, and provides stimulated finger flexion and thumb position for lateral and palmar prehension. Three months were required to develop grasp with sufficient strength and coordination for functional use. This period consisted of: implantation and immobilization of percutaneous intramuscular electrodes; stimulated exercise of the muscles of the hand and forearm; programming grasp patterns; and system training. Functional assessments show that the neuroprosthetic hand system allows the subject to perform unilateral and bilateral tasks that were otherwise impossible or were previously performed bimanually. The ability to perform activities of daily living with one hand frees the contralateral upper extremity to be used either for balance which increases the work area, or to stabilize an object allowing manipulation with the instrumented hand. Telephone interviews suggest that the hand system is used on a consistent basis at home and school. This single subject application indicates that a stimulation system designed for adults with C5-6 spinal cord injuries can enhance hand function and facilitate independence in a child with a low level cervical lesion.

Activities of Daily Living↗
PubMed1992

Bipolar latissimus dorsi transposition and functional neuromuscular stimulation to restore elbow flexion in an individual with C4 quadriplegia and C5 denervation.

A bipolar latissimus dorsi transposition was performed on a 17-year-old male patient with a C4 spinal cord injury and complete peripheral denervation at C5. Electrical stimulation of the paralyzed but excitable latissimus dorsi provided elbow flexion that could not be achieved with the paralyzed and denervated elbow flexors. The muscle was attached from the coracoid to the ulna allowing the elbow to be flexed with the forearm and wrist maintained in the neutral position. Following a 6-week immobilization period, the transposed muscle was exercised daily with intramuscular stimulation to increase both strength and endurance. By the fourth month after surgery, the subject could control elbow flexion proportionally with contralateral shoulder elevation using a shoulder position transducer. Functionally, the subject was able to use the neuroprosthetic system to bring his hand to his mouth and feed himself with the aid of a universal cuff and a support to stabilize the shoulder.

Adolescent↗
PubMed1989

Tetanic responses of electrically stimulated paralyzed muscle at varying interpulse intervals.

The influence of stimulus interpulse interval (IPI) on torque output during electrically-evoked contractions was investigated for the knee extensor muscles of paralyzed subjects. The parameters measured were the rise time, magnitude, and relaxation time of the contraction at stimulus IPI's ranging from 62 to 7 ms. Torque output increased as IPI's were decreased from 62 to 15 ms. Peak torques were recorded at IPI's of 12-15 ms; IPI's less than these resulted in an insignificant loss of torque. Rise times decreased as IPI's were decreased. Relaxation time generally increased as IPI's were decreased with the longest relaxation times occurring with stimulation at an IPI of 12 ms. To demonstrate the influence of IPI on muscle fatigue, the effect of prolonged stimulation at short (12 ms) and long (50 ms) IPI's was also compared. After 30 s of stimulation with an IPI of 12 ms, mean torque had declined to 5 +/- 3 percent and after 30 s of stimulation with an IPI of 50 ms, mean torque had declined to 82 +/- 4 percent of the initial value. Knowledge of how stimulus IPI influences the response of paralyzed muscle to electrical stimulation may assist in the development of rehabilitation devices which utilize these technologies.

Electric Stimulation Therapy↗
PubMed1989

The theoretical development of a multichannel time-series myoprocessor for simultaneous limb function detection and muscle force estimation.

This paper details the theoretical development and simulation of a complete time-series myoprocessor which provides reliable and economical predictions of both the magnitude and direction of limb motion from the spectral content of the surface EMG. Treating multiple channels of surface EMG as a vector-valued autoregressive process incorporates spatially distributed information which extends the operating range of parallel filtering limb function classifiers and reduces their sensitivity to modeling conditions. Active joint moment is estimated simultaneously from the pooled variance of the prewhitened EMG generated during the classification procedure. Estimation from the prewhitened sequence imposes no additional computational requirements and extends optimal myoprocessors to include multiple channels of serially dependent data. Such a system may be applied to the control of actively powered prostheses or orthoses.

Artificial Limbs↗
PubMed1989

The experimental demonstration of a multichannel time-series myoprocessor: system testing and evaluation.

A multichannel time-series myoprocessor which combines the advantages of the parallel filtering limb function classifiers of Doerschuk et al. and the "optimal myoprocessor" muscle force estimators described by Hogan et al. have been developed and evaluated experimentally. Magnitudes and directions of knee movements were identified accurately and robustly from EMG sites intermediate to the major thigh muscles of intact individuals. Electrode placement criteria were tested, and system performance and sensitivity to contraction level as functions of channel number were computed. By including spatially distributed information into the structure of the processor, gains in accuracy and reliability over systems with fewer channels were demonstrated. Operating range increased with the number of channels included in the processor. Joint moment was estimated from multiple channels of temporally correlated data, extending and generalizing previously reported techniques. Identifying the parameters of AR models of the EMG at low levels of contraction resulted in more robust classification and joint moment estimation. Optimal electrode position could not be predicted a priori. The system may be applicable to the proportional control of myoelectric prostheses.

Adult↗
PubMedDate not supplied

A reusable, self-adhesive electrode for intraoperative stimulation in the lower limbs.

A suction-based stimulating electrode was designed and fabricated to allow intraoperative testing of lower-limb muscles during routinely scheduled surgical procedures. The suction device can adhere to a small exposure of muscle surface with reproducible contact forces and can maintain its geometric relationship to the underlying tissue for sufficient time to grade the resulting muscle contraction before removal and repositioning. When operated with a 10-cc syringe, the device can generate between 0 and 23 N of contact force; correlation between measured contact forces and those analytically predicted was 0.989. Preliminary animal testing indicates that the reusable device maintains its position over the nerve entry point even during vigorous active contractions of the stimulated muscle. Thus, it may be a valuable useful tool for locating the optimal site for a permanent electrode for functional electrical stimulation (FES) applications, as well as an ideal means of providing accurate and repeatable stimulation in various locations.

Animals↗
PubMedDate not supplied

Selectivity of intramuscular stimulating electrodes in the lower limbs.

Intramuscular (IM) electrodes have been used safely and effectively for decades to activate paralyzed muscles in neuroprosthetic systems employing functional electrical stimulation (FES). However, the response to stimulation delivered by these and any type of electrode can be limited by a phenomenon known as spillover, in which the stimulus intended to produce a contraction in a particular muscle inadvertently activates another muscle, causes adverse sensation, or triggers undesired reflexes. The purpose of this retrospective study was to determine the selectivity of monopolar intramuscular stimulating electrodes implanted in the lower limbs of individuals with motor and sensory complete paraplegia secondary to spinal cord injury (SCI) and to catalog the most common electrode spillover patterns. The performance records of 602 electrodes from 10 subjects who participated in a program of standing and walking with FES in our laboratory over the past decade were examined. Sixty percent (358) of these electrodes were "stable" (i.e., stimulated responses were consistent during the first 6 months postimplant), and 32% of all stable electrodes (113) exhibited spillover as noted in clinical and laboratory records. Common spillover patterns for eight muscle groups were tabulated and analyzed in terms of their functional implications. The beneficial (activation of synergistic muscles) or deleterious (activation of compromising reflexes, antagonists, or adverse sensation) effects of spillover were highly context dependent, with several potentially useful spillover patterns in certain phases of gait becoming undesirable and limiting in others. Knowledge of the selectivity of intramuscular electrodes and the patterns of spillover they exhibit should guide surgeons and rehabilitationists installing lower-limb neuroprostheses during the implantation process and allow them to better predict the ultimate functional usefulness of the electrodes they choose.

Electric Stimulation Therapy↗
PubMedDate not supplied

Preliminary performance of a surgically implanted neuroprosthesis for standing and transfers--where do we stand?

This paper describes the preliminary performance of a surgically implanted neuroprosthesis for standing and transfers after spinal cord injury (SCI) in an initial group of 12 volunteers with longstanding paralysis. The CWRU/VA standing neuroprosthesis consists of an 8-channel implanted receiver-stimulator, epimysial and surgically implanted intramuscular electrodes, and a programmable wearable external controller. After reconditioning exercise and rehabilitation with the system, most individuals with paraplegia or low tetraplegia were able to stand, transfer, and release one hand from a support device to manipulate objects in the environment or to perform swing-to ambulation in a walker. The effort and assistance required for transfers were reduced for users with mid-level tetraplegia, although the maneuvers were not independent. Neuroprosthesis users with tetraplegia and paraplegia alike benefited from the improvements in their general health derived from exercise, including reduced risk of decubiti and self-reported modulation of spasticity. Stimulated responses are stable and sufficiently strong for function, and implanted components are reliable with a 90% probability of epimysial electrode survival at 4 years post-implant. The techniques employed are repeatable and teachable, and suitable for multi-center clinical trial.

Electric Stimulation Therapy↗