Thomas Mathews

Musculoskeletal responses of spinal cord injured individuals to functional neuromuscular stimulation-induced knee extension exercise training.

This study was conducted to evaluate a newly designed functional neuromuscular stimulation (FNS)-induced knee extension (KE) exercise system that incorporates the most desired features of previously described systems by determining the musculoskeletal responses of spinal cord injured (SCI) individuals to training. A specially designed chair and electrical stimulator were fabricated for FNS-induced KE resistance exercise. Surface electrodes were placed over motor points of the quadriceps muscles, and KE was alternated between legs at an average rate of 6 KE/min/leg. KE testing protocols were developed for pre- and post-training evaluations of performance, and 12 SCI subjects exercise-trained up to three times per week for 36 sessions using a progressive resistance load at ankle level. Pre- and post-training evaluation data were statistically compared using a 0.05 level for significance. Quadriceps muscle performance (strength x repetitions) improved for both legs in all subjects as indicated by significant increases in load resistance and repetitions over the 36-session training period (right leg mean = 1156.0 versus 1624.8 kg.reps, left leg mean = 1127.3 versus 1721.1 kg.reps). In addition, knee range of motion significantly increased (right leg mean = 134 versus 146 degrees, left leg mean = 133 versus 144 degrees). Thigh skinfold, thigh girth, body weight and bone density were not significantly changed. The lack of decrease in bone density in some subjects suggests that the training may retard the rate of bone loss which typically occurs with SCI. No injuries or problems were encountered during testing and training.(ABSTRACT TRUNCATED AT 250 WORDS)

Change in aerobic fitness of patients with multiple sclerosis during a 6‐month training program

Twenty‐three individuals with multiple sclerosis (MS) participated in a 6‐month exercise training program; 11 ambulatory (AMB) and 8 semi‐ambulatory (SEMI). Four persons with MS served as non‐exercising controls (C). A test of maximal aerobic power (VO2max) was administered at baseline to all subjects. AMB and SEMI subjects exercised on alternating days for 30 minutes, at 55‐60% VO2max using either a commercially available recumbent or upright combination leg/arm bicycle ergometer. At the end of 12 and 24 weeks, exercising subjects were re‐evaluated. The C group was only re‐evaluated at 24 weeks. The results show that the AMB and SEMI groups experienced a +20% and +5% improvement in VO2max, respectively. The C group averaged a 12% decline in VO2max during the 6 months. These data demonstrate the possibility that although exercise improves cardiovascular fitness of some persons with less severe MS, this beneficial response may not apply to the more severely impaired patient. Nevertheless, improved cardiova...

Physiologic responses of paraplegics and quadriplegics to passive and active leg cycle ergometry.

The purposes of this study were three-fold: (a) to determine acute physiologic responses of spinal cord injured (SCI) subjects to peak levels of leg cycle ergometry utilizing functional neuromuscular stimulation (FNS) of paralyzed leg muscles, (b) to determine the relative contributions of passive and active components of FNS cycling to the peak physiologic responses, and (c) to compare these physiologic responses between persons who have quadriplegia and those who have paraplegia. Thirty SCI subjects (17 quadriplegics and 13 paraplegics) performed a discontinuous graded FNS exercise test from rest to fatigue on an ERGYS 1 ergometer. Steady-state physiologic responses were determined by open-circuit spirometry, impedance cardiography with ECG, and auscultation. In the combined statistics of both groups, it was noted that peak FNS cycling significantly increased (from rest levels) mean oxygen uptake by 255%, arteriovenous O2 difference VO2 and VE, Q and a-vO2 and VCO by 69%, and stroke volume by 45%, while total peripheral vascular resistance decreased by 43%. Mean peak power output for paraplegics (15 W) was significantly higher than for quadriplegics (9 W), eliciting higher peak levels of pulmonary ventilation and sympathetically mediated hemodynamic responses such as cardiac output, heart rate, and systolic and diastolic arterial blood pressure. Passive cycling without FNS produced no statistically significant increases in physiologic responses above the resting level in either group.

Metabolic and hemodynamic responses to concurrent voluntary arm crank and electrical stimulation leg cycle exercise in quadriplegics

This study determined the metabolic and hemodynamic responses in eight spinal cord injured (SCI) quadriplegics (C5-C8/T1) performing subpeak arm crank exercise (ACE) alone, subpeak functional electrical stimulation leg cycle exercise (FES-LCE) alone, and subpeak FES-LCE concurrent with subpeak ACE (hybrid exercise). Subjects completed 10 minutes of each exercise mode during which steady-state oxygen uptake (VO2), pulmonary ventilation (VE), heart rate (HR), cardiac output (CO), stroke volume (SV), mean arterial pressure (MAP), arteriovenous oxygen difference (a-v O2 diff), and total peripheral resistance (TPR) were determined. Although mean VO2 for both ACE alone and FES-LCE alone was matched at 0.66 l/mi, individualized power outputs ranged from 0-30 W (mean = 19.4 +/- 1.3) and 0-12.2 W (mean = 2.3 +/- 0.6), respectively. Hybrid exercise elicited significantly higher VO2 (by 54 percent), VE (by 39-53 percent), HR (by 19-33 percent), and CO (by 33-47 percent), and significantly lower TPR (by 21-34 percent) than ACE or FES-LCE performed alone (P less than or equal to 0.05). Stroke volume was similar between hybrid exercise and FES-LCE alone, and these two exercise modes evoked a significantly higher SV (by 41-56 percent) than during ACE alone. These data clearly demonstrate that hybrid exercise creates a higher aerobic metabolic demand and cardiac-volume load in SCI quadriplegics than either subpeak levels of ACE or FES-LCE performed separately. Therefore, hybrid exercise may provide more advantageous central cardiovascular training effects in quadriplegics than either ACE or FES-LCE alone.

The current status of tardive dystonia

Tardive dystonia (TDt), a persistent dystonia associated with exposure to neuroleptic drugs, is an uncommon disorder. It differs from tardive dyskinesia (TDk) in epidemiology, clinical features, risk factors, pathophysiology, course, prognosis, and treatment outcome. TDt seems to develop faster and is more painful, distressing, and disabling than tardive dyskinesia. In this article, evidence is reviewed on the face, descriptive, construct, and predictive validity of this iatrogenic complication of antipsychotic drugs. It is suggested that TDt should not be lumped together with TDk. It deserves a separate nosological status as an independent diagnostic category. The subclassification of TDt into various subtypes based on coexistence of other movement disorders is suggested.

Acute hemodynamic responses of spinal cord injured individuals to functional neuromuscular stimulation-induced knee extension exercise

The purpose of this study was to determine and compare acute hemodynamic responses of spinal cord injured (SCI) quadriplegics (quads), and paraplegics (paras) during a graded-intensity knee extension (KE) exercise test utilizing functional neuromuscular stimulation (FNS) of paralyzed quadriceps muscles. Seven quads and seven paras (N = 14) performed a series of 4-minute stages of bilateral alternating FNS-KE exercise (approximately zero to 70 degree range of motion at the knee and 6 KE/min/leg) at ankle loads of 0, 5, 10, and 15 kg/leg. Physiologic responses were determined with open-circuit spirometry, impedance cardiography, and auscultation. Comparing rest with peak FNS-KE for both groups combined, FNS-KE exercise elicited significant (p less than 0.05) increases in oxygen uptake (130 percent), pulmonary ventilation (120 percent), respiratory exchange ratio (37 percent), arteriovenous oxygen difference (57 percent), cardiac output (32 percent), stroke volume (41 percent), mean arterial pressure (18 percent), and rate-pressure product (23 percent). Heart rate increased significantly by 11 percent from the 5- to the 15-kg/leg stages. Physiologic responses of quads and paras were very similar, except for lower (p less than 0.05) arterial pressures, rate-pressure product, and peripheral vascular resistance in quads. This graded FNS-KE exercise up to the 15-kg/leg load induced relatively small but appropriate increases in aerobic metabolism and cardiopulmonary responses that appear to be safe and easily tolerated by quads and paras. Arterial pressure needs to be monitored carefully in quads to prevent excessive hypertension or hypotension. Although FNS-KE exercise has been shown to elicit peripheral adaptations to improve muscle strength and endurance, it is probably not an effective central cardiovascular training tool for all but the least fit SCI individuals. This information is important for understanding the effects of FNS use during more complex activities such as cycling and ambulation.

Proposed research diagnostic criteria for neuroleptic malignant syndrome

Many sets of diagnostic criteria have been proposed for neuroleptic malignant syndrome (NMS) but there is a lack of uniformity. No universally agreed criteria exist currently for research purposes, thus making comparisons across studies very difficult. Most of them have flaws and detect too many false-positives based on an over-inclusive definition. The estimates of incidence rates of NMS vary because of differences in the sensitivity threshold of the diagnostic criteria used. A new set of diagnostic criteria is proposed for research purposes. It is hoped that with this set of stringent research diagnostic criteria, future epidemiological, aetiological and treatment research studies on NMS will be more meaningful and comparable across studies. For routine clinical purposes, the clinicians should continue to use their clinical acumen, sound clinical judgement and discretion. To avoid premature aetiological closure and broaden treatment options, we also propose renaming this syndrome descriptively as drug-induced hyperthermic catatonia (DIHC).

Efficiency of FNS leg cycle ergometry

The efficiency of electrically induced leg cycle ergometry performed by spinal-cord-injured (SCI) subjects was compared to voluntary leg cycle ergometry performed by able-bodied (AB) subjects at power output (PO) levels of 6-42 W. Twenty SCI (nine quadriplegics and 11 paraplegics) and twenty AB subjects exercised on a leg cycle ergometer. SCI subjects received functional neuromuscular stimulation (FNS) of paralyzed leg musculature, while AB subjects pedaled voluntarily. Subjects performed a discontinuous, progressive intensity exercise test with 6-W (for SCI) or 12-W (for AB) PO increments between stages. Each exercise bout was 5 min in duration and was followed by a 5-min rest period. Steady-rate oxygen uptake (VO/sub 2/) and respiratory exchange ratio (RER) values were determined by open-circuit spirometry during the final minute of each stage. Gross, net, work, and data efficiencies were calculated for each PO. These efficiencies ranged from 2 to 14% for FNS cycling by SCI subjects and from 4 to 34% during voluntary cycling by AB subjects. At most POs, efficiencies for FNS cycling were significantly lower (by approximately one-half) than those for voluntary cycling. Despite the apparent energy-wastefulness or inefficiency of FNS leg cycle ergometry, the relatively high metabolic rates elicited by the exercise may be advantageous to SCI individuals seeking aerobic (cardiopulmonary) training effects.<<ETX>>

Physiologic responses of SCI subjects to electrically induced leg cycle ergometry

The purpose of this study was to determine steady-state physiologic responses of spinal-cord-injured (SCI) subjects to electrically induced leg-cycle ergometry, and to compare these responses to those of able-bodied (AB) individuals performing voluntary leg-cycle ergometry at the same power output (PO) levels. Twelve SCI subjects and 6 AB subjects exercised on a microprocessor-controlled functional neuromuscular stimulation (FNS) cycle ergometer. FNS of paralyzed leg muscles was delivered via skin-surface electrodes over the quadriceps, hamstring, and gluteal muscle groups. Subjects performed several 5-min bouts of progressive intensity cycling (6- or 12-W increments) at 50 r.p.m. Each bout was followed by a 5-min rest period. Oxygen uptake, pulmonary ventilation, and heart rate were significantly higher for the SCI group at each PO level. The data suggest that this FNS exercise may elicit metabolic and cardiopulmonary responses from FNS-trained SCI individuals that are of similar magnitudes to those elicited from AB individuals during jogging exercise. The authors therefore hypothesize that this mode of FNS exercise training may promote higher levels of aerobic fitness in many SCI individuals than can be obtained by conventional arm exercise (e.g. wheelchair propulsion, cranking).<<ETX>>

Animal model of spinal cord infarction induced by cholesterol embolization

Though several animal models of ischemic brain infarction have been developed, no animal model of purely ischemic spinal cord infarction exists. In humans, such paralysis often occurs as a complication of aortic surgery. While working on an animal model of cholesterol embolic renal disease, the authors produced an animal model of ischemic spinal paralysis by direct intraortic injection of cholesterol suspension. With histologic examination of spinal cords of the paralyzed rats, prominent cholesterol crystals were found obliterating the lumen of the anterior and/or posterior spinal arteries. Spinal cord infarction was seen most prominently in the lateral columns and anterior horns, though other areas also were affected. Permanent paraplegia developed in most rats, but transient paralysis developed in a few, followed by partial or full recovery. This model of spinal infarction in non-anesthetized rats can be used to study the pathophysiology and therapy of spinal infarction.