Biomedical subjects
S M Tuel
Publications and source records attributed to S M Tuel.
Correlation of motor control in the supine position and assistive device used for ambulation in chronic incomplete spinal cord-injured persons.
Neurocontrol of movement after spinal cord injury (SCI) is often spared, but few studies have investigated the chronic incomplete SCI patient. Multichannel surface electromyography (SEMG) can describe characteristics of neurocontrol during a series of volitional and reflex events. The relationship of these neurocontrol characteristics to clinical function is incompletely described. This study, retrospectively, evaluated the relationship between neurocontrol patterns evoked by lower limb movement in the supine position and the assistive device used for ambulation in chronic, incomplete SCI persons. The records of 15 neurologically healthy (9 male, 6 female) and 36 incomplete SCI persons (27 male, 9 female) (C2-T10) were used. SEMG was recorded from both quadriceps, adductors, hamstrings, anterior tibialis and triceps surae muscles and displayed on a stripchart for analysis. SEMG patterns of activity recorded in the supine position during volitional, unilateral, multijoint (hip and knee flexion and extension) movement attempts were characterized, divided into seven groups and compared with the subjects' self-selected ambulation device (independent, cane, crutches, walker or nonambulatory). The neurocontrol patterns recorded in the supine position correlated well with the SCI subjects ambulatory assistive device. Marked decreases in motor unit output and/or loss of motor organization were found in the nonambulatory group. Coactivation of proximal muscles, poor timing of muscle activity and radiation of activity into contralateral muscles were also noted in subjects who required a walker or crutches. To a lesser degree, abnormal motor patterns were also noted in subjects who ambulated with a cane or independently.
Faculty departure from academic programs of physical medicine and rehabilitation.
Anecdotal reports suggest that substantial numbers of physiatrists leave academic positions each year, but the specific reasons why departure occurs from academic institutions are opaque. Academic program chairpersons were asked to identify individuals who had left their program in the previous 5 yr, and a confidential survey was sent to those persons. Program chairpersons who responded were from similar programs as chairpersons who did not respond, except they had greater numbers of nonphysiatrists on their faculty. Forty-nine completed surveys were returned. Respondents were generally junior faculty, who had practiced an average of 5.35 yr, and their previous academic position was the first one after residency. The most important reasons for leaving were for a better career opportunity, personal, low job satisfaction with administration and not enough financial reward. The most important changes at the previous institution that might have induced them to stay were fewer administrative/political problems, greater salary, more protected time for academics, effective mentor/role model and more support for research. Statistically significant differences were noted between those who moved to another academic position and those who went into private practice, between those who were in their first job v the second or later job, between program and nonprogram graduates who had long-term expectations and between men and women respondents. Recommendations for faculty retention are discussed.
Effect of mexiletine on spinal cord injury dysesthetic pain.
Severe pain occurs in 5-30% of the spinal cord-injured (SCI) population and is difficult to treat. Subarachnoid lidocaine has been used in selected patients with some success. Mexiletine, an analog of lidocaine that acts at Na+/K+ channels in the peripheral nerve, has been found effective in persons with diabetic dysesthetic neuropathy. The effect of mexiletine in the treatment of spinal cord dysesthetic pain was examined in this study. Fifteen patients were enrolled, and 11 patients completed the prospective, randomized, placebo-controlled, double-blind, crossover design trial. Inclusion/exclusion criteria were carefully defined. A 1-wk washout period was followed by a 4-wk drug trial of either mexiletine (450 mg/day) or placebo. This was repeated for the second medication in the second arm of the study. Patients were followed weekly with McGill and visual analog pain scales. Baseline, midpoint, and endpoint Barthel function scores were recorded. The Wilcoxon's signed-rank test and paired t test were used for statistical analysis. Results showed no significant effect of mexiletine on SCI dysesthetic pain scales or Barthel index. In conclusion, in this trial, mexiletine did not appear to decrease spinal cord injury-related dysesthetic pain.
Educational goals and objectives in physical medicine and rehabilitation for the medical school graduate. Association of Academic Physiatrists Undergraduate Education Committee Workgroup.
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Augmented sensory nerve action potentials during distant muscle contraction.
We previously reported that the median sensory nerve action potentials (SNAP) increased in amplitude during ipsilateral abductor pollicis brevis contraction. The objectives of the present project were to study the timing and origin of this phenomenon and to eliminate the possibility of local artifact. Ten normal subjects were recruited. The baseline was established using ten threshold stimuli, which were delivered to the median nerve at the wrist at 0.2 Hz. Using the same stimulus strength, the SNAP was recorded while the tibialis anterior was contracted at 25, 50, 75, and 100% of maximum force. Responses were signal-averaged. Results showed an increase in ipsilateral SNAP amplitude between baseline and maximum contraction of 6 +/- 2 microV (standard error, P = 0.004) and contralateral amplitude of 8 +/- 2 microV (standard error, P = 0.01). Statistical analysis was performed with analysis of variance for repeated measures and paired t test. The effect peaked between 0 and 10 min after contraction and lasted from 1.5 to more than 20 min after muscle relaxation. In conclusion, SNAP appear to be enhanced during and after muscle contraction. Theories concerning underlying causes for this event are discussed.
Late facilitation of the human soleus H reflex induced by sustained isometric maneuver.
Studying the effect of spinal cord reinforcement maneuvers (SCRMs) on H reflex assists in understanding aspects of motor control. Our objective was as follows: (1) to elucidate the effects of four neck positions (neck resting at neutral position (control); passive hyperflexion of the neck; hyperextension of the neck with simultaneous abdominal contraction; and sustained active neck hyperflexion); (2) to evaluate the temporal changes of soleus H reflexes repeatedly evoked after a period of sustained neck flexion. We used a prospective, intrinsically controlled trial of the effects of these SCRMs on the H reflexes and M-responses in ten healthy volunteers. Pre- and postmaneuver measures included H reflex and M-response latencies and amplitudes, H/M maximum amplitude ratio, and H threshold. The four maneuvers showed no significant effect on the H reflex or M-response measures. To investigate temporal changes in the H reflex amplitude, H reflexes were repeatedly evoked at two-minute intervals after a one-minute period of active neck flexion. The amplitude of the H reflex was enhanced (P = 0.0356; analysis of variance), and the post hoc least significant difference test was significant at four minutes postmaneuver. Peak magnitude of the H reflex occurred at four minutes after relaxation, and the response returned to pretest baseline at eight minutes. The results of this study document the time course of repeated H reflexes after SCRM, and the timing of the H reflex was found to be a contributing variable that should be considered in future study designs.
Functional improvement in severe head injury after readmission for rehabilitation.
Early rehabilitation has been shown to minimize complications and optimize functional outcomes in head-injured patients. Although cognitive, behavioural and vocational issues continue for years after injury, many investigations maintain that physical improvement is limited after 6 months. At 12 months after injury, expectations for physical improvement are generally limited. In addition, although repeated inpatient admissions for rehabilitation are common, gains in self-care and mobility skills during readmissions for rehabilitation have not been specifically investigated. In this retrospective study the records of 49 severely head-injured patients were evaluated. All were readmitted to an inpatient rehabilitation facility more than 12 months after injury. Barthel Index scores were obtained to evaluate physical function. Although previous studies would predict few improvements, in this study 53% (26 patients) showed improvement, and the difference between readmission and discharge Barthel scores was statistically significant (p = 0.0001). Gains were highly correlated with length of readmission, but not with age of patient, age at time of injury, length of coma, time since injury, or duration of previous rehabilitation. Patients with mid-range admission Barthel scores (21-85) demonstrated the largest gains, with 79% showing improvement. Gains averaged 11.2 points on the Barthel Index. Severely head-injured patients may show clinically significant improvement in physical function well after current standards predict a plateau.