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Biomedical subjects

R L Joynt

Publications and source records attributed to R L Joynt.

7 recordsLinked to original sources
PubMed1992

The source of shoulder pain in hemiplegia.

Shoulder pain is a common problem in hemiplegia. This preliminary study attempted to identify pain-producing structures by evaluating the results of injecting 1% lidocaine into several sites in the shoulder area. Sixty-seven patients with shoulder problems were identified, examined, and characterized. The amount of pain was related most to loss of motion; it was unrelated to subluxation, spasticity, strength, or sensation. Of 28 patients who received a subacromial injection, approximately one-half obtained moderate or marked relief of pain and improved range of motion, suggesting that the subacromial area of the shoulder is a location of pain-producing structure in a significant number of cases.

Age Factors↗
PubMed1991

Electromyography interference pattern decomposition.

Decomposition of an interference pattern enables examination of individual electromyography (EMG) motor units and their firing rates at more than minimal contraction forces. In this decomposition method, significant events with a constant occurrence (near motor unit action potentials) can be enhanced, and unwanted events (distant motor unit action potentials, artifacts) eliminated, by calculating the average accumulated change while sliding a fixed-width window along the digitized EMG interference pattern. Nonparametric statistical methods are then applied to these data to determine which information is significant at the .05 level. The exact duration of significant information is identified without the need for arbitrary thresholds and filters to eliminate unwanted information. Events are then classified into groups of similar events by comparing: (1) correlation coefficients, (2) point-to-point differences, (3) amplitudes, and (4) areas. The classification is further refined by the use of firing-rate information.

Action Potentials↗
PubMed1989

Correlation studies of velocity, amplitude, and duration in median nerves.

Nerve conduction velocity is the parameter most often attended to when performing nerve conduction studies, but amplitude and duration of the nerve potentials should also provide important information about the status of the nerve examined. This study compared the results of amplitude and duration measurement to nerve conduction velocity to determine whether or not the various parameters correlated. Using standard techniques, median nerve motor and sensory conduction studies were performed on 390 unselected patients. The results were analyzed and correlation statistics calculated between the parameters of velocity, duration, and amplitude. Amplitude and duration of evoked potential correlated relatively poorly with conduction velocity (r2 = 0.26). Sensory and motor fibers were often affected differently in cases with probable carpal tunnel syndrome (CTS). Proximal motor conduction velocity correlated best with distal evoked potential amplitude (r2 = 0.27) in the CTS cases. The use of residual latency appeared to add little helpful diagnostic information. It was concluded that different parameters measure different physiologic processes that are to a considerable degree independent of each other.

Carpal Tunnel Syndrome↗
PubMed1989

Differences in sensory conduction velocity between different sensory branches and segments of the median and ulnar nerves.

Abnormality of absolute values of median sensory conduction velocities and differences in conduction velocity between median and ulnar nerves are used as criteria for abnormality in the diagnosis of carpal tunnel syndrome. Detailed studies of sensory conduction in various median and ulnar branches and segments indicate that conduction velocities measured and calculated by standard methods are different in the different nerves, segments and branches. In particular, the velocity in the middle digit branch of the median nerve is slower than that in the index, and that in the 3-4 palmar branch is slower than that in the 2-3 palmar branch. Median and ulnar sensory conduction velocities are not well correlated in the same hand in the same individual, so comparison of these nerves for diagnostic purposes is subject to some risk. Palmar and digital conduction velocity in the same nerve may not be identical and the median nerve may have asymptomatic palmar slowing of no clinical significance. The conclusion that abnormality is present must take these factors into account.

Adolescent↗
PubMed1988

Computerized synthesis of electromyographic interference patterns.

Computer simulation is a process that appears to have wide application in many disciplines. Electromyographic (EMG) interference patterns can be computer-synthesized by inputting parameters of individual motor unit action potentials (MUAPs) such as amplitude, duration, and phases, and recruitment parameters of number of motor units, and the firing rate and its standard deviation. The resulting simulated EMG interference patterns can then be used to test hypotheses regarding the effect of alteration of the individual MUAP parameters on the interference pattern. An example of the usefulness of simulation is demonstrated by the analysis of the simulated patterns by the Fast Fourier Transform (FFT), which indicates that the major frequency band in the FFT results from the duration of the individual phases of the MUAP. The motor unit's recruitment rate is superimposed on the FFT envelope in the low-frequency end. The variability of the firing rate influences the distinctness of the low-frequency peaks. The MUAP amplitude and number of motor units in the recruitment pattern are reflected in the FFT power. Simulation appears to be a useful tool for further investigation and development of EMG signal analysis techniques.

Action Potentials↗
PubMed1976

Dantrolene sodium: long-term effects in patients with muscle spasticity.

Seventy-seven patients with muscle spasticity secondary to central nervous system pathology were treated with dantrolene sodium for periods of up to two years. The drug was effective in reducing muscle spasms, clonus, muscle tone, and the force of muscle contraction elicited by Achilles tendon tap and tibial nerve stimulation, but improvement of function was seen less often. The incidence of side-effects was considerable, and poses a problem regarding patient acceptance of drug treatment.

Adolescent↗