Lois D. Hedman

Sensory dysfunction following stroke: incidence, significance, examination, and intervention.

Abstract Recent studies have provided evidence of the widespread incidence of sensory dysfunction following stroke. The importance of these findings lies in the association between sensory loss poststroke and poorer outcomes in motor capacity, functional abilities, length of inpatient stay, and quality of life. Since literature suggests that clinicians can use information about clients’ sensory status to predict rehabilitation outcomes and select appropriate interventions, the accuracy of somatosensory assessment is extremely clinically relevant. However, many of the clinical tests that are commonly used to examine sensation have not been found to be valid or reliable. Emerging evidence supports the efficacy of several interventions that target the sensory systems. This article reviews the incidence, significance, examination, and interventions for sensory dysfunction following stroke and summarizes the important characteristics of interventions directed at somatosensation.

Triggering of protective stepping for the control of human balance: age and contextual dependence

Human stepping is a commonly executed control strategy for maintaining standing balance in the natural environment. Aging changes in the initiation triggering of both voluntary (longer latency) and perturbation-induced (shorter latency) stepping are associated with falling, and are a complex function of altered sensorimotor, neuromuscular, and cognitive system factors. The aim of this study was to determine the effect of contextual uncertainty about balance stability on the triggering of protective stepping in young and older individuals. Subjects initiated forward stepping during simple reaction time and waist-pull perturbation conditions with and without contextual uncertainty about balance stability. The results showed that, regardless of age, the initiation timing for triggering both voluntary and induced stepping was delayed substantially (100-300 ms) by the presence of balance uncertainty, and that age-associated timing differences were exacerbated with contextual uncertainty. The initiation timing of the first step liftoff for perturbation-induced stepping did not reflect entirely an immediate necessity or last resort strategy to balance instability determined directly by specific sensory input, but rather a decision to step. Moreover, the time to liftoff onset for perturbation-induced stepping was similar for the old and young with contextual certainty, and occurred 130 ms earlier for the old than for the young when balance stability was uncertain. Overall, we concluded that older individuals can retain a residual capacity to sustain stationary standing stability as a function of the prevailing task conditions, and that the reduced timing threshold with age may involve a pre-selected strategy triggered earlier by non-specific event-related sensory input rather than specific movement-related information.

Effects of home-based sensory and motor amplitude electrical stimulation on arm dysfunction in chronic stroke

Objective: To examine the effects of a home-based arm exercise programme of sensory and motor amplitude electrical stimulation. Design: Non-concurrent, multiple-baseline, single-subject design. Subjects: Ten adults with chronic arm hemiparesis following stroke. Subjects ranged in age from 38 to 74 years and were 2-16 years post stroke. Three subjects had right-sided involvement; seven had left. Intervention: Subjects completed an eight-week, individualized, home programme of neuromuscular and sensory amplitude electrical stimulation. All subjects engaged in stimulation-assisted task-specific exercises for 15 minutes 2 -3 times daily. Participants with sensory deficits received an additional 15 minutes of sensory amplitude stimulation twice daily. The Action Research Arm Test was used to examine arm function; the Stroke Rehabilitation Assessment of Movement was used to examine movement quality; and the Modified Ashworth Assessment of Spasticity was used to examine muscle tone. Results: A statistically significant improvement was demonstrated by six of the 10 subjects on the Action Research Arm Test, and five subjects on the Stroke Rehabilitation Assessment of Movement. Four subjects had ≥ 10% improvement on the Modified Ashworth Assessment of Spasticity. Two subjects demonstrated significant improvement on all three outcome measures; six subjects improved on two or more measures; and seven subjects improved on one or more measure. Subjects who improved on two or more measures tended to have had more recent onset of stroke, were older and had higher baseline motor and functional capacity. Conclusion: Subjects with chronic stroke can experience impairment and functional improvements following a home-based programme of motor and sensory amplitude electrical stimulation.

Neuromuscular electrical stimulation during task-oriented exercise improves arm function for an individual with proximal arm dysfunction after stroke.

Hedman LD, Sullivan JE, Hilliard MJ, Brown DM: Neuromuscular electrical stimulation during task-oriented exercise improves proximal arm dysfunction after stroke. Am J Phys Med Rehabil 2007;86:592–596. This case report examined the effectiveness of a home program using neuromuscular electrical stimulation (NMES) during voluntary task-oriented exercise to achieve functional and impairment improvements for an individual with primarily proximal arm paresis after a stroke. The subject initially achieved a Fugl–Meyer Assessment (FMA) score of 58/66, but she reported minimal functional use of her involved, dominant arm. The 6-wk intervention consisted of NMES-assisted task practice involving repetitive reaching for and manipulation of small objects for three daily 15-min sessions. The subject applied NMES to the deltoid and triceps brachii muscles to augment shoulder flexion and abduction and elbow extension during task practice. Outcome measures included the FMA, the Action Research Arm Test (ARAT), and the Motor Activity Log Quality of Movement subscale (MAL-QOM). The FMA remained unchanged, but the ARAT and MAL-QOM showed improvements, from the beginning to the conclusion of the intervention, that were maintained at 6-wk follow-up.

Electromyographic analysis of postural responses during standing leg flexion in adults with hemiparesis

The purpose of this study was to examine muscle activation patterns during standing leg single leg flexion in adults with hemiparesis. Specifically, the electromyographic activation patterns of the flexing limb biceps femoris and gluteus medius, and the stance limb gluteus medius muscles were analyzed as a function of whether the muscles were paretic or not. Delayed activation of the affected flexing side gluteus medius, as compared with unaffected flexing side gluteus medius, resulted in it being activated simultaneous with the flexing biceps femoris rather than preceding it as was previously found in healthy subjects. This suggests a temporal change in the sequential mode of coordination of the postural and intended components of the task. In addition, the magnitude of the electromyographic integrals of both the affected and unaffected flexing side gluteus medius in the early propulsive phase of the task was significantly reduced in comparison with healthy subjects. These alterations can be attributed to spatial alterations in the sequential form of organization or to a shift to a different mode of neural control in order to perform a relatively novel task. These results suggest a potential adaptive capacity in these individuals.

Afferent stimulation provided by glove electrode during task-specific arm exercise following stroke

Background: Sensory amplitude electrical stimulation (SES) and repetitive task practice reduce impairments and arm dysfunction when delivered separately following stroke. Objective: To determine if home-based, task-specific arm exercise was more effective when administered concurrent with SES. Methods: Thirty-eight subjects with chronic stroke and mean Fugl-Meyer Assessment (FMA) score 28/66 (15–45) participated. Subjects were randomly assigned to an SES (n = 20) or sham stimulation (n = 18) group. Subjects engaged in task-based home exercise for 30 minutes, twice daily, for four weeks while wearing a glove electrode on the impaired hand. Experimental subjects received SES while control subjects received sham stimulation during exercise. Primary outcome measures: FMA and Arm Motor Ability Test (AMAT). Results: There were no significant between-group differences for outcome measures. There was a significant difference between the pre- and post-test scores in the SES group AMAT median time (P = 0.003 95% confidence interval (CI): −14.304, −6.365; effect size: 0.84). Practice time was not associated with changes in outcomes. Subjects with more sensorimotor dysfunction had significantly greater improvements on AMAT median time (P = 0.037). There was a significant relationship between baseline FMA score and FMA change score (r = 0.402; P = 0.006). Conclusions: This study describes a unique SES delivery system via glove electrode that enabled delivery of SES during home-based arm task practice in stroke survivors. Task practice with concurrent SES did not demonstrate significantly better effects than task practice with sham stimulation, however there was a trend for greater improvement in one activity measure.

Locomotor Requirements for Bipedal Locomotion: A Delphi Survey

Background Bipedal locomotor control requirements may be useful as classifications for walking dysfunction because they go beyond gait analysis to address all issues contributing to walking dysfunction. Objective The objective of this study was to determine whether locomotor experts could achieve consensus about the requirements for bipedal locomotion. Design and Methods Locomotor experts from physical therapy and other related professions participated in an electronic mail Delphi survey. Experts recommended additions, deletions, rewording, and merges for 15 proposed locomotor requirements in round 1. In rounds 2 and 3, panelists commented on and rated the validity, mutual exclusiveness, and understandability of each requirement. Consensus was defined a priori as: (1) 75% or more panelists agree or strongly agree that a requirement is valid, mutually exclusive, and understandable in round 3; (2) no difference between round 2 and 3 ratings with kappa coefficients ≥.60; and (3) a reduction in panelists who commented and convergence of comments between rounds 1 and 3. Content analysis and nonparametric statistics were used. Results Fifty-eight panelists reached full consensus on 5 locomotor requirements (Initiation, Termination, Anticipatory Dynamic Balance, Multi-Task Capacity, and Walking Confidence) and partial consensus for 7 other requirements. There were no significant differences in ratings between rounds 2 and 3, and there was a decrease in the percentage of panelists who commented between rounds 1 and 3. Limitations The studys 6-month time frame may have contributed to panelist attrition. Conclusions Locomotor experts achieved consensus on several bipedal locomotor requirements. With validation, these requirements can provide the framework for a clinically feasible and systematic diagnostic tool for physical therapists to categorize locomotor problems and standardize intervention for walking dysfunction.

An initial exploration of the perceptual threshold test using electrical stimulation to measure arm sensation following stroke

Objective: To explore the viability of the perceptual threshold test using electrical stimulation to measure light touch sensation in the hands of stroke survivors. Design: Descriptive study. Setting: University research laboratory. Subjects: Twenty-nine adult community-dwelling chronic stroke survivors. Main measure(s): Perceptual threshold test using electrical stimulation, stroke rehabilitation assessment of movement, Nottingham sensory assessment for stereognosis, action research arm test, Fugl-Meyer assessment of sensation and motor activity log 14. Results: Perceptual threshold test using electrical stimulation mean threshold values were 1.23 (0.6) milliamperes (range 0.5–3.5) for the uninvolved side and 1.68 (0.91) milliamperes (range 0.5–4.5) for the involved side. The perceptual threshold test using electrical stimulation demonstrated excellent intra-rater reliability (intraclass correlation coefficient = 0.896 – uninvolved; 0.829 – involved). There was a statistically significant difference between the perceptual threshold test using electrical stimulation mean threshold values for the uninvolved and involved arms (P = 0.003), but this significance did not hold for subjects who had normal sensation as measured by the Fugl-Meyer assessment of sensation (P = 0.083). Low to nonexistent correlations were found between the perceptual threshold test using electrical stimulation and other measures of sensation, arm movement, activity and participation. Conclusions: The perceptual threshold test using electrical stimulation is a reliable and clinically feasible test with the potential to identify sensory capacity in stroke survivors with substantial sensory loss. Electrical sensory thresholds do not reflect overall sensory function or motor capabilities in stroke survivors.