Tactile sensory impairments and prehensile function in subjects with left-hemisphere cerebral lesions

Using sensory discrimination in a foraging-style task to evaluate human upper-limb sensorimotor performance

Object stiffness discrimination is fundamental to shaping the way we interact with our environment. Investigating the sensorimotor mechanisms underpinning stiffness discrimination may help further our understanding of healthy and sensory-impaired upper limb function. We developed a metric that leverages sensory discrimination techniques and a foraging-based analysis to characterize participant accuracy and discrimination processes of sensorimotor control. Our metric required searching and discriminating two variants of test-object: rubber blocks and spring cells, which emphasized cutaneous-force and proprioceptive feedback, respectively. We measured the number of test-objects handled, selection accuracy, and foraging duration. These values were used to derive six indicators of performance. We observed higher discrimination accuracies, with quicker search and handling durations, for blocks compared to spring cells. Correlative analyses of accuracy, error rates, and foraging times suggested that the block and spring variants were, in fact, unique sensory tasks. These results provide evidence that our metric is sensitive to the contributions of sensory feedback, motor control, and task performance strategy, and will likely be effective in further characterizing the impact of sensory feedback on motor control in healthy and sensory-impaired populations.

Effects of Sensory Deficit on Phalanx Force Deviation During Power Grip Post Stroke

The effect of sensory deficits on power grip force from individual phalanges was examined. The authors found that stroke survivors with sensory deficits (determined by the Semmes-Weinstein monofilament test) gripped with phalanx force directed more tangential to the object surface, than those without, although both groups had similar motor deficits (Chedoke-McMaster and Fugl-Meyer), grip strength, and skin friction. Altered grip force direction elevates risk of finger slippage against the object thus grip loss/object dropping, hindering activities of daily living. Altered grip force direction was associated with altered muscle activation patterns. In summary, the motor impairment level alone may not describe hand motor control in detail. Information about sensory deficits helps elucidate patients' hand motor control with functional relevance.

Occupational Therapy for Upper Limb Post-Stroke Sensory Impairments: A Survey

Purpose:

Upper limb post-stroke sensory impairments have an impact on a significant number of stroke survivors. There is limited research in this area and it is unclear how occupational therapists are addressing sensory impairments in clinical practice. This study aimed to investigate the clinical practice patterns of occupational therapists, perceived barriers to providing interventions and information sources used when addressing upper limb post-stroke sensory impairments.

Methods:

A survey was sent to 500 randomly selected occupational therapists in the United States.

Findings:

The majority of the 145 respondents reported frequently assessing sensation, and half reported providing interventions for sensory impairments. Interventions primarily focused on providing passive sensory stimulation followed by compensatory strategies. Most therapists provided patient/caregiver education about safety. Therapists cited lack of knowledge and skills, patients' short length of stay and lack of time as barriers to utilizing interventions. Most therapists reported not being up to date with current research and requested continuing education to support practice.

Conclusion:

This survey established a profile of American occupational therapists' practice with people with upper limb post-stroke sensory impairments. Therapists have a need for information and training in all aspects of the management of upper limb post-stroke sensory impairment. Further research, evaluating the effectiveness of interventions and exploring therapists' clinical decision making when choosing interventions, is also needed.

Effect of functional electrical stimulation with mirror therapy on upper extremity motor function in poststroke patients

BACKGROUND

Motor recovery of the upper extremity in stroke patients is an important goal of rehabilitation. In particular, motor recovery can be accelerated when physical and cognitive interventions are combined. Thus, the aim of this study was to investigate the effects of functional electrical stimulation (FES) with mirror therapy (MT) on motor function of upper extremity in stroke patients.

METHODS

Twenty-seven stroke patients were recruited, and the 23 subjects who met the inclusion criteria were randomly allocated into 2 groups: the experimental group (n = 12) and the control group (n = 11). Both groups received conventional rehabilitation training for 60 minutes/day and 5 days/week for 4 weeks. In addition, members of the experimental group received FES with MT and members of the control group received FES without MT for 30 minutes/day and 5 days/week for 4 weeks. Immediately before and after intervention, motor recovery was measured using the Fugl-Meyer (FM) assessment, Brunnstrom's motor recovery stage (BMRS), the Manual Function Test (MFT), and the Box and Block Test (BBT).

RESULTS

Significant upper extremity motor improvements were observed in the experimental and control groups according to the FM, BMRS, MFT, and BBT (P < .05). In particular, FM subscores for wrist, hand, and co-ordination and MFT subscores for hand function were more significantly improved in the experimental group (P < .05).

CONCLUSIONS

Motor functions of the upper extremity were improved by FES with MT versus controls. The study shows that FES with MT during poststroke rehabilitation may effectively improve motor functions of the upper extremity.

Interventions for sensory impairment in the upper limb after stroke

BACKGROUND

Sensory impairments significantly limit the ability to use the upper limb after stroke. However, little is known about the effects of interventions used to address such impairments.

OBJECTIVES

To determine the effects of interventions that target upper limb sensory impairment after stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched 8 October 2009), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2009, Issue 1), MEDLINE (1966 to January 2009), EMBASE (1980 to January 2009), and six further electronic databases to January 2009. We also handsearched relevant journals, contacted authors in the field, searched doctoral dissertation databases, checked reference lists, and completed citation tracking.

SELECTION CRITERIA

Randomized controlled trials and controlled trials comparing interventions for sensory impairment after stroke with no treatment, conventional treatment, attention placebo or with other interventions for sensory impairment.

DATA COLLECTION AND ANALYSIS

Two review authors selected studies, assessed quality and extracted data. We analyzed study data using mean differences and odds ratios as appropriate. The primary outcome we considered was sensory function and secondary outcomes examined included upper limb function, activities of daily living, impact of stroke and quality of life as well as adverse events.

MAIN RESULTS

We included 13 studies, with a total 467 participants, testing a range of different interventions. Outcome measures included 36 measures of sensory impairment and 13 measures of upper limb function. All but two studies had unclear or high risk of bias. While there is insufficient evidence to reach conclusions about the effects of interventions included in this review, three studies provided preliminary evidence for the effects of some specific interventions, including mirror therapy for improving detection of light touch, pressure and temperature pain; a thermal stimulation intervention for improving rate of recovery of sensation; and intermittent pneumatic compression intervention for improving tactile and kinesthetic sensation. We could not perform meta-analysis due to a high degree of clinical heterogeneity in both interventions and outcomes.

AUTHORS' CONCLUSIONS

Multiple interventions for upper limb sensory impairment after stroke are described but there is insufficient evidence to support or refute their effectiveness in improving sensory impairment, upper limb function, or participants' functional status and participation. There is a need for more well-designed, better reported studies of sensory rehabilitation.

Butler’s neuromobilizations combined with proprioceptive neuromuscular facilitation are effective in reducing of upper limb sensory in late-stage stroke subjects: a three-group randomized trial

Question: Are Butler’s neuromobilizations combined with proprioceptive neuromuscular facilitation and traditional post-stroke therapy more effective in reducing affected upper extremity sensory deficits in late-stage stroke subjects than proprioceptive neuromuscular facilitation combined with traditional therapy or traditional therapy alone?

Design: Pretest—posttest three-group randomized clinical experimental design.

Participants: A total of 96 late-stage stroke subjects were randomly assigned to three groups.

Intervention: The therapeutic programme in the control group was based on traditional post-stroke methods. The second group (experimental 1) received in addition individual therapy based on the proprioceptive neuromuscular facilitation method. The third group (experimental 2) received a combination: traditional therapeutic programme plus individual proprioceptive neuromuscular facilitation exercises plus neuromobilization of the affected upper extremity. All groups received 18 training sessions lasting about 45 minutes each.

Outcome measures: Assessment of the two-point discriminatory sense (distance between the tips of the compass when the subject indicated two-point sensation), stereognosia (identification up to 10 objects by touch) and thermaesthesia (using hot and cold cylinders on dermatomes C6—C8) were performed.

Results: Analysis of change scores showed that two-point discriminatory sense for experimental group 2 was significantly better than that in the two other groups (P<0.001). Similar results were registered for thermaesthesia (experimental 2 versus experimental 1 P<0.01; experimental 2 versus control P<0.001). For stereognosia the only significant difference was found between experimental group 2 and the control group (P<0.05).

Conclusion: In our subjects, application of Butler’s neuromobilizations combined with proprioceptive neuromuscular facilitation showed greater effectiveness in reducing sensory deficits than proprioceptive neuromuscular facilitation or traditional therapy alone.

Somatosensory recovery: A longitudinal study of the first 6 months after unilateral stroke

PURPOSE

The aim of this study was to characterize the recovery pattern of stroke patients in the first 6 months following stroke.

METHOD

Using the Rivermead Assessment of Somatosensory Performance (RASP), the Motricity index and the Barthel Activities of Daily Living (ADL) index, a case series of serial somatosensory and motor measurements was made on 18 patients with a diagnosis of a first ever stroke. Patients comprised 2 distinct groups, acute and subacute. The acute group were seen weekly for the first month post onset and the subacute group were seen monthly for 6 months. Participants were seen at hospital, regional rehabilitation unit and/or the participant's home. Standard local rehabilitation was given.

RESULTS

The somatosensory subtest of proprioception demonstrated the greatest level of recovery. No patient achieved full recovery on all somatosensory subtests. Motor and functional recovery demonstrated continual improvement over time, somatosensory recovery showed marked variation in subtests both within and between patients.

CONCLUSION

Of the 18 patients tested there were no consistent, generalizable, recognizable patterns of sensory recovery demonstrated.

Clinical measures of handgrip limitation relate to impaired pinch grip force control after stroke

This study examined whether clinical measures of handgrip limitation relate to laboratory measures of grip force impairment during a pinch grip, lift, and hold task post-stroke. Handgrip ability in 45 people with stroke who had residual grip ability was examined relative to 45 age-matched healthy adults. The clinical tests included items from a) the Jebsen Taylor Hand Function Test; b) the Motor Assessment Scale; c) the Functional Independence Measure (FIM); and d) a custom-designed survey about hand-use in daily life. The laboratory test was summarized by principal components: 1) Pre-Lift Delay and 2) Grip Force Dyscontrol. For the stroke group, a moderate to strong correlation was found between Pre-Lift Delay and each clinical measure of handgrip limitation (rs=0.70-0.85) except the FIM (rs=0.38-0.49). In contrast, Grip Force Dyscontrol was not associated with handgrip limitation on any of the clinical tests (rs=-0.08 to 0.18).

Impaired Discrimination of Surface Friction Contributes to Pinch Grip Deficit After Stroke

Background. Impaired sensation and force production could both contribute to handgrip limitation after stroke. Clinically, training is usually directed to motor impairment rather than sensory impairment despite the prevalence of sensory deficit and the importance of sensory input for grip control. Objective. The aim of this study was to investigate if sensory deficits contribute to pinch grip dysfunction beyond that attributable to motor deficits poststroke. Methods. The study enlisted 45 stroke participants and 45 healthy controls matched for age, gender, and hand dominance. Ability to differentiate surface friction (Friction Discrimination Test [FDT]), match object weight (Weight Matching Test [WMT]), produce grip force to track a visual target (Visually Guided Pinch Test [VGPT]), and perform a Pinch-Grip Lift-and-Hold Test (PGLHT) was quantified relative to normative performance, as defined by matched controls. The relationship between sensory ability (FDT, WMT) and altered PGLHT performance adjusted for motor ability (VGPT) after stroke was then examined using multivariate regression. Results. Deficits in FDT, WMT, and VGPT ability were present in at least half of the stroke sample and were largely independent across the variables. Poorer friction discrimination was significantly associated with longer latencies of grip-lift ( r = .34; P = .03) and grip force dysregulation ( r= .34; P= .03) after the impact of VGPT was statistically removed from PGLHT ability. However, performance on WMT did not relate to either PGLHT deficit. Conclusion. The findings indicate that impaired friction discrimination ability contributes to altered timing and force adjustment during PGLHT poststroke.

An fMRI study of somatosensory-implicated acupuncture points in stable somatosensory stroke patients

PURPOSE

To assess differences in brain responses between stroke patients and controls to tactile and electrical acupuncture stimulation using functional MRI (fMRI).

MATERIALS AND METHODS

A total of 12 male, clinically stable stroke patients with left side somatosensory deficits, and 12 age-matched male control subjects were studied. fMRI was performed with two different paradigms; namely, tactile stimuli and electrical stimulation at acupuncture points LI4 and LI11 on the affected side of the body. fMRI data were analyzed using SPM99.

RESULTS

Tactile stimulation in both patients and controls produced significant activation in primary and secondary sensory and motor cortical areas and cerebellum. Greater activation was present in patients than controls in the somatosensory cortex with both the tactile task and the acupuncture point (acupoint) stimulation. Activation was greater during the tactile task than the acupuncture stimulation in patients and normal controls.

CONCLUSION

Differences observed between patients and controls on both tasks may indicate compensatory over recruitment of neocortical areas involved in somatosensory perception in the stroke patients. The observed differences between patients and controls on the acupoint stimulation task may also indicate that stimulation of acupoints used therapeutically to enhance recovery from stroke, selectively activates areas thought to be involved in mediating recovery from stroke via functional plasticity. fMRI of acupoint stimulation may illustrate the functional substrate of the therapeutically beneficial effect of acupuncture in stroke rehabilitation.

Development of the Hand Active Sensation Test: reliability and validity

OBJECTIVE

To develop and establish the reliability and validity of a new quantitative functional measure of haptic perception in the hand, the Hand Active Sensation Test (HASTe).

DESIGN

Reliability was assessed by test-retest sessions. Validity was assessed via discriminant analysis, concurrent validity with 2-point discrimination and wrist position test, and receiver operating characteristic (ROC) curve construction.

SETTING

Subject preference.

PARTICIPANTS

Heterogeneous sample of 28 stroke survivors and 28 individually matched controls.

INTERVENTION

Subjects used 1 hand to manipulate HASTe objects that vary by weight or texture to complete 18 match-to-sample trials.

MAIN OUTCOME MEASURES

Two-point discrimination threshold, Wrist Position Sense Test (WPST) average error, and HASTe accuracy score.

RESULTS

Test-retest reliability was strong (intraclass correlation coefficient model 3,1 = .77). The HASTe score significantly discriminated the groups (t = 8.3, P < .001) and correlated with 2-point discrimination (r = -.67, P < .001) and WPST (r = -.60, P < .001). ROC curve area was .94 for test 1 and .92 for the average of 2 tests.

CONCLUSIONS

The HASTe is a reliable and valid functional measure of haptic perception, appears to detect impairment of haptic perception even in stroke survivors with no reported sensory deficits, and may provide valuable quantitative clinical data about complex sensory loss and hand function after stroke.

Grip force regulation during pinch grip lifts under somatosensory guidance: comparison between people with stroke and healthy controls

OBJECTIVES

To compare the timing and grip force application in a pinch grip task performed under somatosensory guidance in stroke and matched controls and to identify characteristics of impaired grip force regulation after stroke.

DESIGN

Matched-pairs control group.

SETTING

University research laboratory.

PARTICIPANTS

Forty-five people with stroke who could pick up a pen lid using a pinch grip and actively participated in rehabilitation and 45 adults without neurologic conditions or musculoskeletal or skin impairments affecting the hand, matched for age, sex, and hand dominance.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Timing and magnitude of grip forces applied during pinch grip lift and hold.

RESULTS

Prolonged time to grip and lift objects, and excessive grip force prior to commencing the lift occurred in approximately half of the contralesional (involved) hands of people with stroke. Fluctuating irregular forces and reduced adaptation of the grip safety margin were also observed. Excessive safety margins were not predominant after stroke. Extreme slowing and disorganized sequencing of the grip and lifting forces and difficulty maintaining a stable grip characterized severe dysfunction.

CONCLUSIONS

Delayed grip formulation and variable grip force application are key characteristics of grip dysfunction after stroke.

Noise-enhanced vibrotactile sensitivity in older adults, patients with stroke, and patients with diabetic neuropathy

OBJECTIVE

To test the hypothesis that vibrotactile detection thresholds in older adults, patients with stroke, and patients with diabetic neuropathy can be significantly reduced with the introduction of mechanical noise.

DESIGN

A randomized controlled study.

SETTING

A university research laboratory.

PARTICIPANTS

Twelve healthy elderly subjects (age range, 67-85y), 5 patients with stroke (age range, 24-64y), and 8 patients with diabetic neuropathy (age range, 53-77y).

INTERVENTIONS

Each subject's detection thresholds (ie, minimum level of stimulus to be detected) for a vibrotactile stimulus without and with mechanical noise (ie, random vibration with a small intensity) were determined by using a 4-, 2-, and 1-stepping algorithm. The stimuli were applied to the fingertip and/or to the first metatarsal of the foot.

MAIN OUTCOME MEASURE

Detection threshold for a vibrotactile stimulus.

RESULTS

The detection threshold at the fingertip for the vibration stimulus with mechanical noise was significantly lower than that without mechanical noise for all 12 elderly subjects, for 4 of the 5 patients with stroke, and all 8 patients with diabetic neuropathy. For the 8 patients with diabetes, mechanical noise also significantly reduced the vibrotactile detection threshold at the foot.

CONCLUSIONS

Reduced vibrotactile sensitivity in older adults, patients with stroke, and patients with diabetic neuropathy can be significantly improved with input mechanical noise. Noise-based techniques and devices may prove useful in overcoming age- and disease-related losses in sensorimotor function.

Using electrical noise to enhance the ability of humans to detect subthreshold mechanical cutaneous stimuli

Stochastic resonance (SR) is a phenomenon wherein the response of a nonlinear system to a weak input signal is optimized by the presence of a particular, nonzero level of noise. Our objective was to demonstrate cross-modality SR in human sensory perception. Specifically, we were interested in testing the hypothesis that the ability of an individual to detect a subthreshold mechanical cutaneous stimulus can be significantly enhanced by introducing a particular level of electrical noise. Psychophysical experiments were performed on 11 healthy subjects. The protocol consisted of the presentation of: (a) a subthreshold mechanical stimulus plus electrical noise, or (b) no mechanical stimulus plus electrical noise. The intensity of the electrical noise was varied between trials. Each subject's ability to identify correctly the presence of the mechanical stimulus was determined as a function of the noise intensity. In 9 of the 11 subjects, the introduction of a particular level of electrical noise significantly enhanced the subject's ability to detect the subthreshold mechanical cutaneous stimulus. In 2 of the 11 subjects, the introduction of electrical noise did not significantly change the subject's ability to detect the mechanical stimulus. These findings indicate that input electrical noise can serve as a negative masker for subthreshold mechanical tactile stimuli, i.e., electrical noise can increase the detectability of weak mechanical signals. Thus, for SR-type effects to be observed in human sensory perception, the noise and stimulus need not be of the same modality. From a bioengineering and clinical standpoint, this work suggests that an electrical noise-based technique could be used to improve tactile sensation in humans when the mechanical stimulus is around or below threshold. (c) 1998 American Institute of Physics.

Electromyogram-triggered neuromuscular stimulation for improving the arm function of acute stroke survivors: a randomized pilot study

OBJECTIVE

To assess the efficacy of electromyogram (EMG)-triggered neuromuscular stimulation (EMG-stim) in enhancing upper extremity motor and functional recovery of acute stroke survivors.

DESIGN

A pilot randomized, single-blinded clinical trial.

SETTING

Freestanding inpatient rehabilitation facility.

PATIENTS

Nine subjects who were within 6 weeks of their first unifocal, nonhemorrhagic stroke were randomly assigned to either the EMG-stim (n = 4) or control (n = 5) group. All subjects had a detectable EMG signal (>5 microV) from the surface of the paretic extensor carpi radialis and voluntary wrist extension in synergy or in isolation with muscle grade of <3/5.

INTERVENTION

All subjects received two 30-minute sessions per day of wrist strengthening exercises with EMG-stim (experimental) or without (control) for the duration of their rehabilitation stay.

MAIN OUTCOME MEASURES

Upper extremity Fugl-Meyer motor assessment and the feeding, grooming, and upper body dressing items of the Functional Independence Measure (FIM) were assessed at study entry and at discharge.

RESULTS

Subjects treated with EMG-stim exhibited significantly greater gains in Fugl-Meyer (27.0 vs 10.4; p = .05), and FIM (6.0 vs 3.4; p = .02) scores compared with controls.

CONCLUSION

Data suggest that EMG-stim enhances the arm function of acute stroke survivors.

Discriminative sensory dysfunction after unilateral stroke

BACKGROUND AND PURPOSE

Although sensory deficits caused by stroke have been reported occasionally, dysfunction of discriminative sensation has seldom been studied in patients with unilateral stroke. The frequency and modality of bilaterally impaired discriminative sensation also remain to be clarified.

METHODS

With the use of specifically designed methods, we tested discriminative sensations including texture discrimination, two-point discrimination, stereognosis, point localization, and position sense in 67 patients with acute unilateral stroke. The locations of the lesions were identified with the use of CT and/or MRI. Thirty-two age- and sex-matched healthy subjects were used as a control.

RESULTS

Impaired discriminative sensation was common in patients with unilateral stroke (detected in 57 of the 67 patients) regardless of lesion location except for patients with lateral medullary infarction. Discriminative sensation remained intact in only 3 of 25 patients who were initially diagnosed as having pure motor stroke on the basis of conventional sensory tests. Point localization and stereognosis were bilaterally impaired in 17 of 39 patients and 7 of 38 patients, respectively, regardless of the laterality of the lesion. Dysfunction of other sensory modalities was observed exclusively on the side contralateral to the lesion.

CONCLUSIONS

Discriminative sensory disturbances, which often occur bilaterally in some modalities, are common in patients with unilateral stroke even in those with intact sensory function on routine examination. The subtle disturbances of this sensation may explain, at least in part, the clumsiness of the patients that is not readily explained by conventional neurological tests.