Experience with implanted electrodes.

Implant units, manufactured by Medtronic, Inc., have been implanted in 31 patients for treatment of drop-foot. The principal problem encountered in this series was inflammatory reaction. This was observed in seven patients, and was serious enough in five to require removal of the implant. On the positive side, there have been no failures of the implanted equipment for periods of up to 7.3 years, although there is currently a question on one patient. There has also been no documented damage to the nerve from chronic stimulation. Fine wire elctrodes have been implanted intraneurally in a series of animals and in three patients. Preliminary results look encouraging, and this approach seems to hold considerable promise for a new generation of electrode design.

A four-channel IBM PC/AT compatible biphasic pulse generator for nerve stimulation.

An IBM PC/AT compatible four-channel biphasic pulse generator has been developed to assist in functional electrical stimulation (FES) related research. Each channel uses a bipolar 12-bit digital-to-analog converter (DAC) to generate biphasic voltage pulses between +/- 5 VDC and three 16-bit timers to control first, second, and interphase durations. Two vectored interrupt generators are available for precise pulse timing control. Potential uses of this device include FES research, the characterization of the recruitment properties of percutaneous electrodes in multichannel stimulation systems, or as a subassembly in commercial medical devices requiring electrical simulation in an IBM PC/AT platform.

Open-loop control of the freely-swinging paralyzed leg.

An experimental model has been used to study issues that are relevant to the use of electrical stimulation to help paralyzed individuals walk. Modulated stimulation sequences for the quadriceps muscles were manually selected using an iterative trial-and-error procedure to cause the knee angle to follow a specific movement pattern (desired trajectory). Four paraplegic subjects were tested before and after an eight-week program in which the quadriceps were exercised daily with electrical stimulation. It was found that 12.6 +/- 2.9 iterations were required to approximate the desired trajectory. The average error of the final match between the actual and desired trajectories was 2.1 degrees +/- 0.7. Repeated responses were extremely consistent; the average difference between successive trials was less than 1 degree in 81 percent of the trials. When the stimulation sequence was repeated every 3 s for 50 cycles, however, there was a progressive degradation in the response, even in exercised legs, that demonstrated the limitations of open-loop control. Stimulus modulation envelopes for all four subjects were similar in shape (although varied in amplitude) indicating that the iterative process can be shortened by starting with an "average" modulation envelope. Stimulation sequences achieved accurate matches of the desired trajectory on subsequent days when adjusted by a simple gain factor. The relevance of these results to multichannel control of walking is discussed.

Recruitment data for nerve cuff electrodes: implications for design of implantable stimulators.

Recruitment characteristics of nerve cuff electrodes implanted in four cats for five months were measured. Monopolar, bipolar, and tripolar configurations were considered. Approximately twice the current was required to achieve a given response using the tripolar configuration as compared with monopolar stimulation. Bipolar stimulation also required more current than monopolar stimulation. Using the recruitment data, a number of strategies for modulating muscle tension were considered. It was shown that both pulse amplitude and pulse duration should be software-selectable to achieve adequate control of muscle tension when using either pulse amplitude modulation or pulse duration modulation. When using pulse amplitude modulation, it was found to be desirable to operate at a low pulse duration in the high end of the allowable range for pulse amplitude. For pulse duration modulation, one should operate at a low pulse amplitude in the high end of the allowable range for pulse duration. The effect of pulse amplitude and pulse duration step size on the maximum step change in muscle tension and the linearity of the recruitment curves were examined. The use of logarithmic steps in the modulation parameter was examined and was shown to result in improved controllability and linearity.

Spinal cord monitoring using evoked potentials recorded from feline vertebral bone.

A new recording method for continuous spinal cord monitoring has been developed at Rancho Los Amigo Hospital. Using peripheral nerve stimulation, spinal evoked potentials (SEPs) are recorded from cancellous bone of spinous processes. This neurologically noninvasive technique provides a highly reproducible and consistent signal, unaffected by biologic noise and surgical handling of the spinal column. Moreover, the evoked response is extremely sensitive to changes in functional integrity of the spinal cord. In experimental spinal cord injuries, produced by localized distraction of the spine, changes of the evoked responses were well correlated with the change in spinal cord function.

A 3-year clinical trial to compare efficacy of dentifrices containing 1.14% and 0.76% sodium monofluorophosphate.

A 3-yr daily supervised toothbrushing study with a double blind design was conducted to evaluate the anticaries effectiveness of a 1.14% sodium monofluorophosphate (MFP) dentifrice (1500 ppm F) compared to a 0.76% MFP dentifrice (1000 ppm F). This study began with nearly 4000 children, primarily aged 8-11, in grades 3-5, residing in a nonfluoridated community in Florida. A total of 2415 children completed 3 yr of the study, representing 61% of the children who began the study. The results indicate a statistically significant (P less than 0.001) anticaries benefit was derived over a 3-yr period from the use of the higher fluoride dentifrice (1500 ppm F) when compared to the positive control (1000 ppm F). Percent reductions in mean dental caries increments were 20.9%, 22.1%, 21.8%, 24.3%, and 35.2% for DMFT, DFT, DMFS, DFS, and DFS Interproximal, respectively.

A comparison of the effectiveness of the "Toothkeeper" and a traditional dental health education program.

A study was made of the effectiveness of two dental health education programs in an elementary school in Flint, Michigan. Following stratification by grades, random assignments of students were made by classrooms to either the Toothkeeper group or a "Traditional" group. No control groups were employed. Separate in-service training workshops were attended by the classroom teachers according to the education program to which they had been randomly assigned. An intensive 16-week program was conducted by the classroom teachers following the guidelines of the two programs. Dental examinations which included an assessment of plaque and gingivitis scores were conducted on all participants at baseline, at the end of 16 weeks, and at the conclusion of the school year, some seven months after the initiation of the program. Only minimal reductions in plaque scores were observed with either program and little comparative difference was found in the two programs at the end of the evaluation period. The Toothkeeper group experienced a somewhat greater reduction in plaque scores than the "Traditional" group during the intensive 16-week phase of the study, but these scores worsened from this time to the end of the school year. Gingivitis scores demonstrated more improvement than the reductions in plaque scores would indicate and may be related to the confounding factor of large numbers of children receiving dental treatment, especially prophylaxes during the course of this study. Differences in reductions in gingivitis between the two programs were not meaningful clinically.

The Pew National Dental Education Program at the University of Florida College of Dentistry.

The University of Florida College of Dentistry is located in a dynamic environment. Socially, economically, and demographically, the state of Florida manifests changes reflective of the entire nation, i.e., increasing numbers of elderly and minorities, a fluctuating, diversified economy, and altered cultural values. The explosive growth unique to this state has both positive and negative implications for all aspects of its culture and economy. The college resides in a maturing, research-oriented university facing vigorous competition from other major universities in the state. Within the Health Science Center, the college was occupied during the first decade of its existence with development of an innovative curriculum, and now it must turn its attention to a new emphasis on research and service. A process of strategic planning was conducted at the University of Florida College of Dentistry from January 1986 through June 1987. Four consultant groups representing the college, the university, organized dentistry in Florida, and outside consultants, were guided by a steering committee in a thorough evaluation of the external and internal environment of the institution.(ABSTRACT TRUNCATED AT 250 WORDS)

Is body powered operation of upper limb prostheses feasible for young limb deficient children?

The investigators measured efficiencies of body powered prehensors and cable control components of prostheses available for young children. Results indicated that the cable control systems and hook type prehensors have moderate to high efficiencies, but children's body powered hands have very low efficiencies. Measures of arm and shoulder strength of 3-5 year-old limb deficient children, both on the limb deficient and sound sides, were less than that reported in the sound sides, were less than that reported in the literature for normal children. The findings were examined in relation to children's strength available compared with prosthesis strength requirements. The comparison demonstrates a way to establish measurable efficiency targets for new prehensor designs. The article includes detailed findings on children's strength, and findings on efficiencies of the prehensors and cable control systems of children's upper limb prosthses. Sample calculations may be useful to future designers of body powered prehensors for young children. A more efficient body powered hand is especially needed. Preliminary calculations indicate that the use of currently available children's voluntary opening (VO), body powered hands is not feasible, given the low strength of young limb deficient children and the low efficiencies of the VO hands. The use of voluntary closing (VC) hands may be feasible but remains to be tested.

Laboratory and clinical tests of a prototype pressure sensor for clincial assessment of prosthetic socket fit.

Lower limb prosthetic socket fabrication is a highly refined process relying on the prosthetist's skill and experience. Despite their best efforts, patients often return with complications. Additionally, clinical application of technological advances for the quantification of biomechanical factors at the socket interface has not changed in practice. Measuring pressure levels at the stump/socket interface could provide valuable information in the process of prosthetic socket fabrication, fit and modification. This paper presents findings on the performance of a prototype capacitance pressure sensor designed for prosthetic socket use. Bench tests using compressed air were performed to measure accuracy, hysteresis and drift responses in both a flatbed chamber and a custom-modified pressure vessel. For the contoured testing, the sensors were placed on nine sites on a positive trans-tibial stump mould and enveloped with a silicone liner. Additionally, a preliminary clinical evaluation was performed with two trans-tibial amputee subjects at the nine sites during normal ambulation. Bench test results showed that the prototype capacitance sensor performed well in all categories, exhibiting a 2.42% (flatbed) and 9.96% (contoured) accuracy error, a 12.93% (flatbed) and 12.95% (contoured) hysteresis error, and a 4.40% (flatbed) and 6.20% (contoured) drift error. The clinical study showed that after three hours of continual use, no noticeable sensor drift occurred between pre and post-test calibration values. The results from this study were encouraging and the authors hope to conduct further laboratory and clinical trials to assess the influence of shear force and dynamic loading on sensor response.

Pouching of medications in the mouth: a case report.

Foods or medicines can be pouched or held in the mouth to prolong taste, enjoyment, or effect. This article describes a patient who pouches medications. The oral injury that occurred from this behavior is reported.

Effects of chlorhexidine spray on plaque and gingival health in institutionalized persons with mental retardation.

In this study, eight institutionalized males received a 0.12% chlorhexidine gluconate spray twice daily. A second group of eight males received a placebo spray in the same manner. The results indicated that pump-administered chlorhexidine spray can effectively reduce plaque and gingivitis in patients with mental retardation who are unable to brush their own teeth.

Pica: a peculiar behavior with oral involvement.

Pica is a behavior commonly displayed by children, pregnant females, and individuals with mental retardation. A population of institutionalized adults with mental retardation was assessed for pica. Of this population, 10.8% were identified with this behavior. Also, this article discusses aspects of pica and describes how this behavior can affect the mouth.

Tobacco and the institutionalized mentally retarded: usage choices and ethical considerations.

Patterns of tobacco use were observed among 749 people diagnosed with mental retardation residing in a state-operated facility. Specifically, individual preference for tobacco products and frequency of use were documented. Subjects were observed using several types of tobacco products: cigarettes, cigars, chewing tobacco, snuff, and cigarette butts. Approximately 7% (n = 52) used at least one form of tobacco; ten individuals used more than one tobacco product. Interestingly, 20.5% of the individuals diagnosed with mild or moderate mental retardation (n = 122) consumed tobacco products, a pattern of behavior that closely approximates that of the general population (20-24%). Ethical considerations pertaining to the availability of tobacco products to this special population are presented.

A survey of the availability of dental services to developmentally disabled persons residing in the community.

Public Law 88-164, enacted in 1963, has led to extensive deinstitutionalization of persons with mental retardation from a peak census of 194,650 in 1967 to 91,440 by 1988. This population now depends on the community-based health care system for medical and dental care. A survey conducted to determine the availability of dental care to the developmentally disabled residing in group homes located in north central Florida indicated that 40% of caretakers experienced difficulty in locating dentists willing to provide comprehensive dental services for residents. According to the caretakers, although 75% of the residents were cooperative dental patients, dentists were reluctant to provide services for a variety of reasons, including financial disincentives, inadequate knowledge and preparation, and a lack of proper equipment necessary to treat this group of special patients.

Work problems and accommodations reported by persons who are postpolio or have a spinal cord injury.

A number of studies have documented early functional declines in persons with a disability. The purpose of this study was to document (1) whether employees who are aging with their disability have experienced new work problems as a consequence of functional declines and (2) whether their work problems are being accommodated adequately. Ninety-six individuals with a disability (50 who are postpolio and 46 who had a spinal cord injury) were interviewed by phone. Each had worked at least 5 years postonset and was either currently working or unemployed for less than 5 years at the time of the interview. Forty-nine of the 50 persons who are postpolio reported they had experienced functional declines in recent years, and 41 of the 50 rated the severity of their disability greater than it was when they first began working. As a result of the functional declines they had experienced, most (90.9%) of their work problems were new and would not have been significant problems for them when they first began working. The situation was very different for the group with spinal cord injuries. Only a few members of that group had experienced functional declines that were causing new problems at work. A total of 480 work problems were reported by study participants. Three out of every eight problems did not have an accommodation satisfactory to the employee. The primary reason why a satisfactory solution was not provided was that no accommodation had been identified. Employers were generally supportive of the employee's need for accommodation; they paid for 59.1% of the accommodations that had a cost and refused to provide an accommodation for only 18 of the 480 problems.

Dental care for developmentally disabled.

There are an estimated 3.9 million developmentally disabled people in the United States, 300,000 of whom reside in Florida. Oral health is an issue relevant to the quality of life of these individuals. A person's self-esteem and interpersonal relations within the community, including employment and friendships, are directly affected by--and associated with a healthy mouth and smile. There are factors at both the individual and community levels that may inhibit accessibility to comprehensive dental care for developmentally disabled citizens. Parents, caretakers, public health workers, community agencies, and dentists have their unique perspectives on this issue.