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Biomedical subjects

T A Matyas

Publications and source records attributed to T A Matyas.

36 records · Page 2Linked to original sources
PubMed1993

Confounds of insensitivity and blind luck: statistical conclusion validity in stroke rehabilitation clinical trials.

We present theoretical analyses of some infrequently considered consequences of low power and quantitatively review power in 36 stroke rehabilitation clinical trials with multiple outcome variables. We demonstrate that low power affects the proportion of false alarms (type 1 errors) in the literature and probability of replication, not only the ability to detect true intervention effects; and that these consequences of low power are modulated by the probability that effective interventions have been preselected for study via theory and prior evidence. interventions have been preselected for study via theory and prior evidence. Rehabilitation trials showed low power to detect small, medium, or large treatment effects at alpha = 0.05 (0.09, 0.33, and 0.69, respectively). Effect sizes were generally small with adverse consequences on power. As expected, sample size was an important determinant of power. Power was lower for motor/reflex measures due to differences in sample sizes rather than effect sizes. These results and the conceptual analyses predict and address conflicting conclusions from stroke rehabilitation clinical trials.

Cerebrovascular Disorders↗
PubMed1993

Sensory loss in stroke patients: effective training of tactile and proprioceptive discrimination.

Although somatosensory loss following stroke is common, with negative consequences for functional outcome, studies of existing somatosensory retraining programs are limited by theoretical weaknesses, poor methodology, and negative findings. We, therefore, developed a new program for stroke patients and investigated its effect on tactile discrimination in four AB, single-case quasi-experiments and its effect on tactile and proprioceptive discrimination in four multiple-baseline experiments. Training involved specific, graded discrimination tasks, attentive exploration of stimuli with vision occluded, deliberate anticipation, and quantitative feedback. Graphic and statistical interrupted time-series analyses indicated that treatment produced improvements in seven of eight tactile time series and all four proprioceptive time series. Baseline improvement in one tactile time series prevented unequivocal evaluation of treatment effect. Improvements were clinically significant, discrimination in the affected hand becoming comparable to the other hand and normal performance. Therapeutic effects were maintained at 3-month to 5-month follow-up tests.

Adult↗
PubMed1993

The effect of training on physical therapists' ability to apply specified forces of palpation.

BACKGROUND AND PURPOSE: The aim of this study was to evaluate whether postgraduate physical therapy students studying manipulation could learn to accurately produce specific forces during palpation of an intervertebral joint. SUBJECTS: The 12 subjects (7 female, 5 male), aged 26 to 36 years (X = 29.5, SD = 2.9), had each completed a 4-year degree course in physical therapy and had worked between 3 and 10 years in clinical practice. All subjects were enrolled in a 12-month postgraduate manipulative therapy diploma course. METHODS: Subjects in the experimental group (n = 6) trained to apply specific forces of 1, 5, 10, 15, 20, and 25 kiloponds using bathroom scales. They practiced for 10 minutes per day for 30 days. Their ability to produce these forces on command was measured using a force platform as they applied posteroanterior passive accessory intervertebral joint movements to the lumbar spine of the healthy subjects. This testing was done prior to training (pretest), immediately after training (posttest), and 1 month following cessation of training (retention test). The control group subjects (n = 6) had no training with scales but were also students of the postgraduate manipulative physical therapy course. RESULTS: In comparison with the control group, the experimentally trained group showed reduced error in force production both immediately after training and 1 month later. This improvement was significant for the retention test. For the retention test, the experimental group subjects were also tested on the trained task (ie, their ability to apply specific forces to the scales). They developed higher levels of accuracy than did the control group. CONCLUSION AND DISCUSSION: Experimental training, therefore, was an effective addition to normal training, suggesting that therapists can learn to quantify applied forces, with significant implications for communication and evaluation of joint behavior.

Adult↗
PubMed1992

Negative transfer of training following brief practice of elbow tracking movements with electromyographic feedback from spastic antagonists.

This study aimed to overcome gaps in the literature by investigating effects of EMG feedback provided specifically from spastic muscles during antagonist phases of active movement, while controlling for the effects of practicing the movement and while testing for transfer of training without confounding several transfer phenomena. In a single training session, two groups of stroke patients practiced a pursuit tracking task by following a moving target with elbow flexion and extension, simultaneously attempting to reduce the activity of elbow flexors. Both groups tracked the target more accurately following training. Transfer tests failed to demonstrate effects of feedback on accuracy of tracking or on electromyographic activity during performance of the practiced task without feedback. Moreover, the group that was trained with electromyographic feedback exhibited negative transfer on variants of the practiced task: tracking faster or less predictable targets.

Biofeedback, Psychology↗
PubMed1992

Electrogoniometric feedback: its effect on genu recurvatum in stroke.

The purpose of this study was to determine the effect of combining electrogoniometric feedback with contemporary physical therapy procedures for treatment of genu recurvatum following stroke. Twenty-six patients suffering knee hyperextension resulting from cerebrovascular disorders were allocated to either a control group or an experimental group. Both groups received treatment for knee hyperextension during two consecutive phases. During phase I the control group received physical therapy and the experimental group received electrogoniometric feedback as an adjunct to physical therapy. In phase II both groups received physical therapy alone. Each phase lasted four weeks, during which time patients were treated 45 minutes daily, five days every week. Subjects in the experimental group showed greater reduction in knee hyperextension. This was particularly evident in phase II when the difference between groups for reduction in knee hyperextension reached statistical significance (U = 40, p = 0.011). These results suggest that the addition of electrogoniometric feedback to standard physical therapy enhanced the effectiveness of treatment for genu recurvatum in stroke.

Adult↗
PubMed1990

Postural control in standing following stroke: test-retest reliability of some quantitative clinical tests.

Despite their importance to stroke rehabilitation, appropriate clinical tests of postural control in standing appear to be inadequately developed. Several quantitative clinical tests, therefore, were constructed. These tests were used to measure functionally relevant aspects of postural control in standing in 24 stroke patients within a mean time interval of two months following a cerebrovascular accident. Subjects were tested in two stance positions (step and parallel) for five tasks that assessed their ability to withstand perturbations produced by self-generated body movements during functional activities. Intrasession reliability coefficients were very high (r = .94-.99). Intersession reliability coefficients were also high (r = .85-.94). Because the test battery requires minimal training and equipment, it can be easily applied in the clinical setting. The high reliability obtained justifies further evaluation of these tests, which appear to be very promising for use in stroke rehabilitation.

Activities of Daily Living↗
PubMed1990

Visual analysis of single-case time series: Effects of variability, serial dependence, and magnitude of intervention effects.

Visual analysis is the dominant method of analysis for single-case time series. The literature assumes that visual analysts will be conservative judges. We show that previous research into visual analysis has not adequately examined false alarm and miss rates or the effect of serial dependence. In order to measure false alarm and miss rates while varying serial dependence, amount of random variability, and effect size, 37 students undertaking a postgraduate course in single-case design and analysis were required to assess the presence of an intervention effect in each of 27 AB charts constructed using a first-order autoregressive model. Three levels of effect size and three levels of variability, representative of values found in published charts, were combined with autocorrelation coefficients of 0, 0.3 and 0.6 in a factorial design. False alarm rates were surprisingly high (16% to 84%). Positive autocorrelation and increased random variation both significantly increased the false alarm rates and interacted in a nonlinear fashion. Miss rates were relatively low (0% to 22%) and were not significantly affected by the design parameters. Thus, visual analysts were not conservative, and serial dependence did influence judgment.

Journal Article↗
PubMed1986

Facilitation of the maximum voluntary contraction in hemiplegia by concomitant cutaneous stimulation.

The effects of rapid brushing on the maximum voluntary contraction (MVC) and tonic vibratory reflex (TVR) of various muscles requiring facilitation (quadriceps, biceps femoris and tibialis anterior) were studied in two samples of hemiplegics. Brushing was studied under experimental and placebo conditions. In the first experiment, brushing produced significant facilitation of MVC and TVR in the quadriceps, replicating the findings of Spicer and Matyas (1980) and Matyas and Spicer (1980). However, the effect of the TVR failed to predict the gain in MVC that resulted from brushing. In the second sample of hemiplegics, brushing produced significant facilitation of the MVC and TVR in the biceps femoris but not in the tibialis anterior. The results for biceps femoris confirmed the results obtained with quadriceps. The failure to replicate this effect with tibialis anterior may have resulted from problems with the application of the stimulus to the relevant dermatome. Further exploration of the effect of cutaneous stimulation relating to this muscle is required to resolve this issue. The results of this experiment, with its replication of the facilitatory effect of brushing on TVR and MVC in two muscle groups, suggest that investigations of the effect of cutaneous stimulation on the acquisition and retention of voluntary movement should now take place.

Adult↗
PubMed1983

Facilitation of the isometric maximum voluntary contraction with traction. A test of PNF predictions.

Mean rectified electromyographic activity in vastus lateralis (VL) was recorded with surface electrodes during several Ss isometric maximum voluntary contractions performed in the PNF pattern of flexion-abduction-internal rotation, with the subject supine. The effects of longitudinally applied traction forces were compared in a within subject design employing latin square and counterbalanced presentation. Consistent with predictions, as traction force increased the group mean EMG showed a statistically significant increase. A brief survey using force platform measurements indicated that trained physical therapists tended to apply equal or greater forces than the 20 lb maximum used in the experiment.

Adolescent↗
PubMed1980

Facilitation of the tonic vibration reflex (TVR) by cutaneous stimulation.

Facilitation by cutaneous icing and brushing of the TVR elicited from the quadriceps femoris was studied in 15 normal subjects. Icing and brushing were studied under experimental and placebo conditions. In addition, TVR facilitation by each stimulus was examined during stimulation and 45-60 seconds after stimulation. The results confirmed that the cutaneous stimuli have a localized facilitatory action, with brushing being the stronger stimulus, as proposed by Rood (Goff, 1969). However, this effect was demonstrated only during stimulation and not 45-60 sec after stimulation, in contrast to the model proposed by Rood (1962).

Adult↗
PubMed1980

Facilitation of the tonic vibration reflex (TVR) by cutaneous stimulation in hemiplegics.

The study of TVR facilitation with cutaneous icing and brushing by Spicer and Matyas (1980) was replicated in 12 hemiplegics with paretic quadriceps femoris muscles. Icing and brushing were studied under experimental and placebo conditions. Facilitation of the TVR from quadriceps femoris was examined during stimulation and 45-60 sec after the end of stimulation. The results replicated the findings of Spicer and Matyas (1980): icing and brushing produced significant facilitation, with brushing being markedly more effective; the effects were observed only during stimulation but not after stimulation. Comparison of the facilitatory effect of brushing obtained in normal (Spicer and Matyas, 1980) and hemiplegic subjects indicated a more pronounced facilitation in the latter. An iverse relationship between baseline TVR amplitude and degree of facilitation was suggested by the combined evidence of the two studies.

Adult↗
PubMed1978

Conditioning under carbolonium bromide and D--tubocurarine chloride paralysis.

The findings of past research using d-tubocurarine chloride as a control procedure in heart rate conditioning have been equivocal. The present experiment compared classical heart rate conditioning under neuromuscular blockade by d-tubocurarine chloride, and a pharmacologically more specific blocker, carbolonium bromide. Both groups were compared to a placebo condition. The results indicated that carbolonium bromide and placebo treated animals acquired deceleratory cardiac conditional responses, but animals treated with d-tubocurarine chloride did not. Unconditional acceleratory responses were found in groups. The findings were discussed in relation to classical conditioning and the psychopharmacology of neuromuscular blockade.

Animals↗
PubMedDate not supplied

Can simultaneous bilateral movement involve the undamaged hemisphere in reconstruction of neural networks damaged by stroke?

Normalization of upper limb movement remains a difficult problem for a significant subpopulation of hemiplegic stroke patients. Clinical observations prompted investigation of a novel approach using simultaneous identical bilateral movements performed independently. We briefly report 12 controlled single-case experiments using multiple-baseline designs across three separate grasp/reach activities. Unilateral performance tests with the hemiplegic arm using the bilaterally trained actions demonstrated clinically and statistically significant improvements in movement patterns. These improvements were specific to the trained movement and well maintained. Using recent literature we develop a theoretical model proposing that bilateral simultaneous movement promotes interhemispheric disinhibition likely to allow reorganization by sharing of normal movement commands from the undamaged hemisphere. Disinhibition may also encourage recruitment of undamaged neurones to construct new task-relevant neural networks. The potential contribution of spared ipsilateral pathways in the damaged hemisphere, indirect corticospinal pathways and ipsilateral pathways from the undamaged hemisphere is discussed.

Aged↗
PubMedDate not supplied

When is a change a genuine change? A clinically meaningful interpretation of grip strength measurements in healthy and disabled women.

The aim of this study was twofold: 1) to use estimates of random and systematic error to ascertain the test-retest reliability of grip strength measurements obtained with the Jamar hand dynamometer in healthy and disabled women, and 2) to determine the size of the change required to detect a genuine change in grip strength for accurate and meaningful clinical interpretation. Previous research has shown grip strength measurements obtained with a Jamar hand dynamometer from healthy and disabled subjects on different occasions to be reliable. However, the test-retest reliability has been based on correlation coefficients rather than on the actual size of the test-retest differences required to detect a genuine change in grip. The test-retest reliability of maximum grip strength measurements in 32 healthy women and painfree grip in 10 disabled women with nonspecific regional pain (NSRP) was determined. Reliability, based on estimates of systematic and random error, was high in both subject groups. There was no statistically significant systematic error between tests. Test-retest measurement error was +/-5.7 kg (12.5 lb) and +/-5.9 kg (13.0 lb) in healthy and disabled subjects, respectively, 95% of the time. In this population of healthy women and women with NSRP, any change in grip of less than 6 kg (13.2 lb) could have occurred by chance. The results of our study suggest that a change of more than 6 kg (13.2 lb) is necessary to detect a genuine change in grip strength 95% of the time.

Adult↗