Motor unit number estimation: sample size considerations.

A computer model of the motor unit number estimation procedure was developed to evaluate the sampling error associated with estimates of the number of motor units in muscles. Two different distributions were used to model the motor unit amplitude distribution and were chosen in such a manner that they qualitatively matched the distributions observed under both normal and neurogenic conditions. As expected, the results indicated that estimation error decreases as a function of sample size. However, the relationship between these two variables was nonlinear in the sense that successive increases in sample size lead to progressively smaller decreases in estimation error. The results also indicated that the shape of the motor unit amplitude distribution plays an important role. Specifically, estimates obtained using the distribution modeling normal muscle were generally higher than the actual number of motor units in the muscle, which was not the case for the distribution modeling neurogenic muscle. In addition, the neurogenic distribution was associated with much smaller estimation error, suggesting that motor unit number estimation is well suited to the analysis of neurogenic disease processes.

Pressure ulcer prophylaxis in elderly patients using polyurethane foam or Jay wheelchair cushions.

A significantly lower proportion of the patients in the Jay group (25%) experienced pressure ulcer formation during the three months of observation as compared to the foam group (41%). No statistically significant differences were found between groups on the location, severity, or healing duration of the pressure ulcers. Most lesions (65%) were limited to persistent erythema of intact skin, and healed in three to four weeks. Significantly higher proportions of patients in the Jay groups (7%) rejected their cushion because of discomfort as compared to foam (1%). The incidence of pressure ulcers was significantly higher among those patients who experienced peak interface pressures recorded at 60 mmHg or higher, had low Norton scores (< or = 11), or were malnourished.

Assessment of an infra-red non-contact sensor for routine skin temperature monitoring: a preliminary study.

The accuracy and reproducibility of a new non-contact sensor for monitoring skin temperature was examined. Thirty measurements taken by the device were compared with those taken by a commonly used thermocouple contact sensor. The result was a very high correlation coefficient (r = 0.9999). This accuracy was achieved with the probe held at an angle of 90 degrees 1 cm from the skin. Changes in angle and distance were found to contribute to measurement error. Little difference was found between 39 pairs of measurements taken of the left and right sides of subjects. However, intra-subject variability was noted with respect to the dermotomal segmental fields. Inter-tester reliability analysis resulted in a correlation of r = 0.937 involving two independent testers and 26 pairs of measurements. These preliminary data will be used for power calculations to study further the device which we found to be simple to operate, portable, and practical for routine clinical use. This sensor may have applications in the diagnosis of nerve and vascular disorders and in prospective monitoring of skin conditions such as bony areas at risk of pressure ulcers.

Development and clinical evaluation of a computerized limb volume measurement system (CLEMS).

Limb edema is a common problem in both rehabilitation and acute care settings. In the past, attempts to determine an optimal management strategy for limb edema have been limited by the lack of accurate, noninvasive, rapid, clinical tools for quantifying limb volumes. The water displacement method is slow and difficult to use in the clinical setting. Furthermore, water displacement requires that the limb be in a dependent position. The tape measure method is unreliable because it is difficult to position the tape measure on a swollen limb. The development and evaluation of a new tool called the computerized limb volume measurement system (CLEMS) is described. The shape and volume of a limb or limb segment can be rapidly measured by CLEMS, independent of limb position. The limb volumes generated by CLEMS were compared to volumes determined by water displacement and by a tape measure. Volumes of eighteen legs (plaster, nonedematous and edematous) were measured using CLEMS, water displacement, and the tape measure. In all cases, the CLEMS and water displacement methods showed close agreement. CLEMS was found to be a reliable and valid new method of determining limb volume; whereas, the tape measure method was found to be invalid. This new tool allows clinicians to measure the efficacy of different treatment strategies in the management of limb edema.

Effectiveness: a neglected dimension in the assessment of rehabilitation devices and equipment.

Effectiveness is a term used by research methodologists when referring to the attributes of a new health care intervention (e.g. device, medication, or procedure) which if lacking may result in its rejection despite its efficacy and efficiency. Administrators and consumers increasingly require evidence to ensure that a proposed new product or manoeuvre not only 'works' (efficacy, efficiency) but is 'practical' (effective). Yet, effectiveness data are rarely described in research literature or adequately measured. Common effectiveness qualities that might be considered in the formal evaluation of new rehabilitation devices and equipment are cost, convenience to the user ('user-friendliness'), and compliance with the local standards. This article identifies some of the most important variables related to these attributes and suggests strategies for appropriate data collection and analysis. A comparison of two products evaluated in an institutional setting is used to illustrate the suggested method.

A tongue force measurement system for the assessment of oral-phase swallowing disorders.

A computer-aided measuring system using a highly sensitive beam transducer has been developed to provide a quantitative, reliable measure of tongue strength. This tool has application in both the diagnosis and treatment of dysphagic patients with oral-stage dysfunction. The device is customized to comfortably adapt to each individual. Audiovisual feedback is used to enhance subject interest and motivation. The device has proven reliable in measurements of upward and side tongue thrust in six able-bodied subjects measured during five separate sessions. It has also been used with two dysphagic patients.

A review of techniques employed to estimate the number of motor units in a muscle.

Being the smallest functional units under neural control, motor units play an integral role in muscle physiology. However, at the present time, there does not exist any widely accepted technique for quantifying or estimating the number of motor units in a muscle. Specifically, the existing techniques are the increment-counting technique, a technique based on spike-triggered averaging, and a macro-EMG based technique which vary in invasiveness from noninvasive to highly invasive, respectively. We discuss each of these techniques, along with their associated shortcomings, in detail.

Effects of chronic cerebellar stimulation (CCS) setting on the gait and speech of a spastic cerebral palsy adult.

A single (N = 1) spastic cerebral palsy adult who had experienced Chronic Cerebellar Stimulation (CCS) for 9 years without any change in the stimulator settings was assessed at six different stimulator settings. These voltage settings varied from 0 volts to 40 volts and frequencies of stimulation from 0 to 200 Hz. Stimulation was with bipolar rectangular pulses with less than 0.2 C/mm2 charge per phase. Responses measured at each setting were quantitative gait, speech, and somatosensory evoked potential measurements. Additional clinical assessments were done by a neurologist and speech therapist. Alteration in stimulator settings occurred 1 week apart to allow for stabilization and all assessments were completed in the same sequence each day. None of the individual stimulator settings were known to any of the assessors or to the patient. The results showed consistently that the patient's gait and speech were poorest when the stimulator was switched off completely. Switching on the stimulator caused improved function according to all assessments. There was consistent improvement in gait and speech when the rate of the cerebellar stimuli was high (for voltages between 0 and 40 V). Changing the voltage (within the range 0 to 40 V), while keeping the frequency of stimulation constant, did not appear to have as much effect. This preliminary evaluation suggests that the technique of CCS is safe and can improve function in a measurable manner.

Visual neglect and extinction: a new test.

A new computerized test for visual neglect and extinction was developed and evaluated by testing twenty-five patients with right-hemisphere cerebrovascular accidents. The test consisted of a series of unilateral or bilateral lights on a semicircular array to which the subject responded by pushing a button. A computer controlled the sequence of stimuli and stored the responses. Results of the computer test were compared to conventional occupational therapy and beside clinical tests. Extinction was present in 16 subjects on the computerized test, and in 11 on the clinical test. Neglect was present in 13 subjects on the computerized test, in seven subjects on the occupational therapy test, and in five subjects on the clinical test. The computerized test was more sensitive than the other tests. On both computerized and clinical testing, all subjects with left-sided neglect also had left-sided extinction, but not all subjects with extinction had neglect. Neglect may represent a more severe manifestation of an underlying perceptual defect that produces both neglect and extinction.

Angle-angle diagrams in above-knee amputee and cerebral palsy gait.

This paper presents the results of further research relating to quantitative analyses of angle-angle diagrams associated with an above-knee (A/K) amputee and a cerebral palsied (C.P.) subject. The quantification and physical interpretations of the parameters extracted from the angle-angle diagrams not only provided a valuable adjunct to visual assessment of the gaits but also elicited significant information regarding overall coordination and control during each gait.

Angle--angle diagrams in the assessment of locomotion.

This paper includes original research relating to kinematic information presented in the form of knee-angle/hip-angle diagrams. Cyclic loops which had been utilized in the past mainly for their visual representation have been quantified using a shape recognition technique. Quantitative analyses of angle-angle diagrams associated with 5 normal subjects were carried out. The quantification and physical interpretations of the parameters extracted from the angle-angle diagrams provided a valuable adjunct to visual assessment of the gaits.