Reconstruction of the cervical spine following anterior vertebral body resection: a mechanical analysis of a canine experimental model.

In some quadriplegic patients whose acute spinal injury consists of a vertebral body fracture with bony retropulsion anteriorly and ligamentous damage posteriorly, it is appropriate to perform a decompression of the injured spinal cord by excision of the fractured body. Reconstruction of such a spine to achieve immediate and ultimate stability can be quite difficult. This is a report of mechanical testing using a canine in vitro experimental model to simulate different general types of reconstruction systems applicable to the spine destabilized as above. The results explain some of the previously noted failures of the traditional anterior strut grafting procedures. In addition, one of the reconstruction systems tested (anterior and posterior tension bands compressing an anterior strut graft into place) appeared to have sufficient immediate stability to eliminate the need for a halo-vest in the postoperative period. If such a reconstruction system were to prove clinically applicable, it would be quite beneficial to the quadriplegic patient in his rehabilitation.

Erythema and skin temperature following continuous sitting in spinal cord injured individuals.

Pressure sores are a severe and costly problem for many disabled individuals. There is a need for quantitative tools to assess damage produced by external loads on human skin and underlying tissues. Clinically, intensity and size of skin erythema have been used as indicators of tissue damage. Temperature is a quantifiable measure, and various studies have investigated the thermal response to localized pressure. The purpose of this study was to measure the effect of "long-term sitting" on skin temperature and erythema, in a situation that closely approximated what a spinal cord injured individual encounters on a regular basis. The resulting data indicated that: 1) a consistent skin temperature pattern occurred after pressure relief from the seated position; 2) skin temperature of experimentally-induced erythematous areas often remained elevated, even after one hour of pressure relief; and, 3) a qualitative, but not quantitative, correlation exists between erythema size and intensity and skin temperature. Implications of this research include the potential use of temperature to: 1) monitor the effectiveness of various strategies being used to prevent the development of pressure sores; and, 2) predict incipient tissue damage.

Electrical muscle stimulation for pressure variation at the seating interface.

A new method is proposed for pressure sore prevention using electrical muscle stimulation (EMS). Potential mechanisms through which EMS may act for this purpose are discussed, including both short-term/dynamic and chronic effects. Measurements of maximum pressure variation in three able-bodied subjects using low levels of stimulation were performed. Pressure distribution changes were also measured. Fatigue effects on pressure redistribution were studied for four able-bodied subjects as well as for one C4, complete spinal cord injured individual. The results indicate that EMS produces sizeable pressure reduction under the ischial tuberosity, with redistribution occurring over other parts of the seating surface in able-bodied subjects. Fatigue effects were not observed in the four able-bodied subjects even after prolonged stimulation. Fatigue was observed with the spinal cord injured subject, but only after extensive stimulation. These studies demonstrate the feasibility of using EMS at relatively low intensity to vary seating interface pressure. The results warrant continued investigation of EMS to assist in pressure sore prevention.

Commercial software as the basis for an augmentative communication system on a personal computer.

Many severely speech-impaired individuals have a need or desire to maintain the capability for computerized speech generation while performing a variety of other computer-supported tasks such as word processing, financial analysis, or database management. Criteria are presented for augmentative communication systems that both incorporate a personal computer (PC) and provide capabilities for voice output to satisfy this requirement. Current approaches to such systems are categorized and reviewed in light of these criteria. A new method is then described in which word processing or other appropriate PC software is used for speech production, providing a natural integration of written and spoken communication. The approach separates the computer access and voice output functions to allow great flexibility in the choice of an alternative access system. This flexibility combined with appropriate exploitation of PC software features has the potential to yield a high communication rate as well as maximum compatibility with application software.

Independently activated talking tracheostomy systems for quadriplegic patients.

Patients who require mechanical ventilator support use cuffed tracheostomy tubes to facilitate prolonged, intermittent, positive-pressure ventilation. The air flow provided by these cuffed tracheostomy tubes bypasses the vocal cords, preventing verbal expression by the patient. Specially designed cuffed tracheostomy tubes are available that restore air flow across the vocal cords without compromising a patient's ventilation. These tracheostomy tubes require an air control port to be covered when air flow is needed by the patient to produce speech. Individuals with neuromuscular impairment usually require an attendant to activate the control port. Electromechanical systems have been developed to allow independent activation of the air flow by the patient. Both freestanding and wheelchair-based systems are described.

Telephone communication system for handicapped individuals.

Simple low-cost telephone systems for independent use by individuals with limited upper extremity function are described. The systems can be easily assembled from readily available telephone components. Communication is accomplished through a telephone amplifier and uses operator-assisted dialing. Use requires the manipulation of only two switches. One switch connects the amplifier to the phone line; the other dials the operator. "Dial (0)" telephone systems, costing less than $100, are readily affordable for many handicapped individuals.

Electric muscle stimulation for pressure sore prevention: tissue shape variation.

This study measured changes in tissue shape and deformation at the seating interface produced by electric muscle stimulation (EMS) of the gluteus maximus. The purpose of the study was to investigate the application of EMS for pressure sore prevention. Limitations of pressure measurements for analysis of load distribution are discussed and a rationale developed for using tissue shape and deformation to further characterize the seating interface. Ultrasonic imaging of the seating interface is described under three conditions: buttocks suspended, external load applied with no EMS, and external load applied with bilateral EMS of the buttocks. Results show that low level stimulation of the gluteus maximus produces substantial changes in the shape of the loaded buttocks and an external contour more nearly shaped like the suspended buttocks. It is concluded that EMS produces buttock tissue undulation and shape reconfiguration which may assist in preventing pressure sores over the seating surface.

Blood flow in the gluteus maximus of seated individuals during electrical muscle stimulation.

Blood flow was measured under the ischial tuberosites of seated individuals during electrical stimulation of the gluteus maximus muscles. Eight able-bodied and six spinal cord injured subjects were studied. Muscle blood flow was measured via radioactive tracer (133xenon) clearance. Retention of xenon in adipose tissue prevented accurate measurement of blood flow in cutaneous and subcutaneous tissue. Average muscle blood flow for both subject groups was increased during stimulation as compared to rest. All subjects showed an increase in muscle blood flow during stimulation. The statistical significance from a paired student t-test was greater for able-bodied subjects (p less than .05) than for spinal cord injured subjects (p = .12). The increase in muscle blood flow produced by electrical muscle stimulation in seated individuals supports the hypothesis that electrical muscle stimulation can help prevent pressure sores.