PubMed Health⌕ Search

Biomedical subjects

C S Lessard

Publications and source records attributed to C S Lessard.

12 recordsLinked to original sources
PubMed1992

Use of motor nerve conduction testing and vibration sensitivity testing as screening tools for carpal tunnel syndrome in industry.

Increased attention to carpal tunnel syndrome in industry has resulted in the development of several proposed screening tests. This investigation evaluated the use of two portable devices for measuring motor nerve conduction time and tactile sensitivity to 120 Hz vibration in a field setting. Forty-seven control participants, 63 manufacturing plant workers with and without symptoms of carpal tunnel syndrome, and 22 patients with physician-diagnosed carpal tunnel syndrome were tested with the NervePace electroneurometer and the Vibration II vibration threshold measurement device. Nerve conduction time differed significantly between the controls, the asymptomatic workers, and the participants with carpal tunnel syndrome or symptoms of carpal tunnel syndrome. The vibration threshold was higher in the carpal tunnel syndrome group than in the other groups; however, further examination of the data revealed no differences in threshold unless nerve conduction time exceeded the control mean by at least three standard deviations. The false-negative rates associated with the tests limit their usefulness in screening for carpal tunnel syndrome.

Carpal Tunnel Syndrome↗
PubMed1990

Oxygen consumption and cardiac response of short-leg and long-leg prosthetic ambulation in a patient with bilateral above-knee amputation: comparisons with able-bodied men.

This study measured oxygen uptake (VO2), minute ventilation (VE), and heart rate (HR) in a bilateral above-knee (AK) amputee and in three able-bodied controls during progressive treadmill exercise. Walking conditions for the amputee included using bilateral short-leg (SL) and long-leg (LL) prostheses. A progressive treadmill protocol to maximal capacity was used for the amputee and duplicated by the control subjects. An automated system was used to measure VO2, VE, and HR throughout exercise. Data analysis was restricted to the use of parameter averages and percentages to describe differences between experimental conditions. Maximal VO2 for the amputee averaged 23.3mL/kg-1/min-1 with the LL and 22.8mL/kg-1/min-1 with the SL prostheses, a negligible difference between conditions; however, exercise duration was 27% longer when using the SL prostheses. In addition, when averaged over the first four stages of exercise, VO2, VE, and HR were 24%, 32%, and 14% higher, respectively, when the LL prostheses were used. Treadmill walking by unimpaired controls averaged 47% and 79% more economical than walking with the SL or LL prostheses, respectively. These results demonstrate that the use of currently available AK prostheses requires significant energy expenditure, which limits their use to only the most physically fit individuals.

Adult↗
PubMed1987

Vestibular response to pseudorandom angular velocity input: progress report.

Space motion sickness was not reported during the first Apollo missions; however, since Apollo 8 through the current Shuttle and Skylab missions, approximately 50% of the crewmembers have experienced instances of space motion sickness. One of NASA's efforts to resolve the space adaptation syndrome is to model the vestibular response for both basic knowledge and as a possible predictor of an individual's susceptibility to the disorder. This report describes a method to analyze the vestibular system when subjected to a pseudorandom angular velocity input.

Humans↗
PubMed1987

Effects of proposed preflight adaptation training on eye movements, self-motion perception, and motion sickness: a progress report.

A program has been initiated to develop apparatus and procedures to preadapt astronauts to the sensory rearrangement associated with weightlessness in spaceflight. If space motion sickness is a consequence of adaptation to that sensory rearrangement, preflight training could afford astronauts significant relief from the motion sickness. The preflight adaptation trainer (PAT) was designed to produce rearranged relationships between visual and otolith signals analogous to those experienced in space. Investigations have been undertaken with three prototype trainers. The results indicated that exposure to the PAT sensory rearrangement altered self-motion perception, induced motion sickness, and changed the amplitude and phase of the horizontal eye movements evoked by roll stimulation. However, the changes were inconsistent. Appropriate measures of adaptation and protocols for producing the adaptation efficiently remain to be determined.

Adaptation, Physiological↗
PubMed1986

Analysis of nystagmus response to pseudorandom velocity input.

This report describes a method to analyse the vestibular system when subjected to a pseudorandom angular velocity input. A sum of sinusoids (pseudorandom) input lends itself to analysis by linear frequency methods. Resultant horizontal ocular movements were digitized, filtered and transformed into the frequency domain. Programs were developed and evaluated to obtain the auto spectra of input stimulus and resultant ocular response, cross spectra, the estimated vestibular-ocular system transfer function gain and phase, and coherence function between stimulus and response functions.

Computers↗
PubMed1985

Localization of current dipole within a sphere by magnetic measurements.

The principal objective of this study is the development of computer programs to determine the location and strength of neural electric activity within the brain from noninvasive magnetic field measurements at the surface of the head. This report presents theoretical calculations and computer programs derived from the method described by Williamson and Kaufman to determine the depth and strength of a current dipole in a sphere. From the location of the magnetic field radial component extremes, Br maximum and Br minimum, the orientation and location of the current dipole can be determined. The accuracy of the solution is dependent on precise location of of the magnetic field extremes as measured from the surface of a sphere, e.g. the head. To validate the program for locating the dipole, theoretical calculations and computer programs related to the total magnetic field vector resulting from a hypothetical current source within a homogeneous sphere were generated. The errors in calculations of the current dipole depth and strength are presented.

Brain↗