Heather Peters

Moving Forward by Stimulating the Brain: Transcranial Direct Current Stimulation in Post-Stroke Hemiparesis

Stroke remains a leading cause of disability worldwide, with a majority of survivors experiencing long term decrements in motor function that severely undermine quality of life. While many treatment approaches and adjunctive strategies exist to remediate motor impairment, many are only efficacious or feasible for survivors with active hand and wrist function, a population who constitute only a minority of stroke survivors. Transcranial direct current stimulation (tDCS), a type of non-invasive brain stimulation, has been increasingly utilized to increase motor function following stroke as it is able to be used with stroke survivors of varying impairment levels, is portable, is relatively inexpensive and has few side effects and contraindications. Accordingly, in recent years the number of studies investigating its efficacy when utilized as an adjunct to motor rehabilitation regimens has drastically increased. While many of these trials have reported positive and promising efficacy, methodologies vary greatly between studies, including differences in stimulation parameters, outcome measures and the nature of physical practice. As such, an urgent need remains, centering on the need to investigate these methodological differences and synthesize the most current evidence surrounding the application of tDCS for post-stroke motor rehabilitation. Accordingly, the purpose of this paper is to provide a detailed overview of the most recent tDCS literature (published 2014-2015), while highlighting these variations in methodological approach, as well to elucidate the mechanisms associated with tDCS and post-stroke motor re-learning and neuroplasticity.

Mental Practice Applying Motor PRACTICE and Neuroplasticity Principles to Increase Upper Extremity Function

The vast majority of stroke survivors exhibit residual impairments,1,2 with most reporting-associated quality of life decrements.3,4 The prevalence of these poststroke motor deficits and the overall burden of stroke are likely to rise exponentially attributable to an aging population and increases in the prevalence of many risk factors (eg, obesity, diabetes mellitus, smoking).5,6 In light of these trends, several promising motor interventions have been introduced, with many targeting upper extremity (UE) hemiparesis, given its widely appreciated impact. Yet, although several of these approaches appear efficacious, few therapeutic approaches showing promise in animal or early human trials are fully translated to regular clinical practice.7 Consistently, many contemporary motor rehabilitation strategies require high duration contact time8 and costly equipment,9 preventing their widespread clinical application, except among specialized rehabilitation and academic medical centers. Mental practice involves repetitive cognitive rehearsal of physical movements in the absence of physical, voluntary attempts. From a practical perspective, mental practice constitutes an attractive alternative to other rehabilitative approaches because it does not require physical rehearsal, can be performed without direct supervision, and requires minimal expense and equipment, facilitating ease of use. The brain’s ability to respond to repetitive, learning-based strategies even years after injury and well into adulthood also makes mental practice a favorable match for stroke, which tends to be a disease of the aged and because survivors frequently exhibit residual impairments for years postictus. We speculated that repetitive mental practice use, shown to trigger the same neural areas and musculature as physical practice of the same tasks,10–14 would cause substantive neural and motor changes in stroke survivors with UE deficits. Although used for decades in sport and exercise settings, this laboratory was the first to apply mental practice to increase learning …

Integrating Mental Practice with Task-specific Training and Behavioral Supports in Poststroke Rehabilitation: Evidence, Components, and Augmentative Opportunities

Stroke remains a leading cause of death, with most survivors experiencing long-term deficits in motor function. Upper extremity (UE) hemiparesis constitutes one of the most common and disabling poststroke impairments. Many contemporary rehabilitative methods target reacquisition of UE motor skills. One such intervention is mental practice (MP), which involves mental rehearsal without physical execution of the movement. MP has not been consistently integrated into clinical environments. This article discusses the scientific rationale for MPs, highlights evidence supporting their use, discusses components of the repetitive task-specific practice regimens accompanying MP, and discusses possible augmentative strategies and areas for research.

The National Institutes of Health Stroke Scale Lacks Validity in Chronic Hemiparetic Stroke.

BACKGROUND The National Institutes of Health Stroke Scale (NIHSS) is purported to be associated with long-term outcomes. This study determined the concurrent validity of the NIHSS with the Stroke Impact Scale (SIS), a previously validated measure of health status in chronic stroke survivors. METHODS The NIHSS and the SIS were administered to 147 subjects before participation in a multicenter, randomized, controlled trial. A Spearmans rho was used to determine correlations between NIHSS total score and (1) SIS physical dimension scores, (2) SIS overall perception of recovery scores, and (3) the SIS activities and independent activities of daily living (ADL/IADL) scores. SIS score variation and medians between subjects who scored a zero versus a nonzero on the NIHSS was also assessed. RESULTS There was no association between total NIHSS scores and SIS physical dimension scores, SIS overall perception of recovery scores, and SIS ADL/IADL scores (P = -.036, P = .782; P = -.039, P = .640; P = -.054, P = .520; respectively). Lastly, significant variation and similar median scores on the SIS were found between those scoring a zero on the NIHSS versus those who did not score a zero. CONCLUSIONS The NIHSS has no association with health status in chronic stroke and lacks association with measures of impairment and functional limitation. From these findings, we conclude that the NIHSS has poor validity to discern long-term poststroke outcomes and is not associated with health status. Because of possible limitation in the NIHSSs ability to accurately determine outcomes in this population, we recommend restriction of its use to the acute stage of recovery.

Changing Their Minds: Enhancing Poststroke Occupational Performance Using Transcranial Direct Current Stimulation

ABSTRACT Stroke remains a leading cause of disability, with survivors experiencing long-term decrements in independence and quality of life. Occupational therapists (OTs) employ numerous neurorehabilitative treatment approaches to remediate impairments that are impeding performance. OTs also use physical agent modalities to facilitate increased participation and success in therapy. One such modality is transcranial direct current stimulation (tDCS), a form a noninvasive brain stimulation that can be overlaid onto task practice and delivers a constant, low intensity current into the brain. tDCS is safe, portable, and efficacious in remediating a variety of deficits, yet is not consistently incorporated into clinical practice. The authors discuss the mechanisms, safety, evidence, and potential applications of tDCS to enhance outcomes for this growing population.

Navigated Transcranial Magnetic Stimulation: A Biologically Based Assay of Lower Extremity Impairment and Gait Velocity

Objectives. (a) To determine associations among motor evoked potential (MEP) amplitude, MEP latency, lower extremity (LE) impairment, and gait velocity and (b) determine the association between the presence of a detectable MEP signal with LE impairment and with gait velocity. Method. 35 subjects with chronic, stable LE hemiparesis were undergone TMS, the LE section of the Fugl-Meyer Impairment Scale (LE FM), and 10-meter walk test. We recorded presence, amplitude, and latency of MEPs in the affected tibialis anterior (TA) and soleus (SO). Results. MEP presence was associated with higher LEFM scores in both the TA and SO. MEP latency was larger in subjects with lower LEFM and difficulty walking. Conclusion. MEP latency appears to be an indicator of LE impairment and gait. Significance. Our results support the precept of using TMS, particularly MEP latency, as an adjunctive LE outcome measurement and prognostic technique.

Functional Brain Stimulation in a Chronic Stroke Survivor With Moderate Impairment.

OBJECTIVE. To determine the impact of transcranial direct current stimulation (tDCS) combined with repetitive, task-specific training (RTP) on upper-extremity (UE) impairment in a chronic stroke survivor with moderate impairment. METHOD. The participant was a 54-yr-old woman with chronic, moderate UE hemiparesis after a single stroke that had occurred 10 yr before study enrollment. She participated in 45-min RTP sessions 3 days/wk for 8 wk. tDCS was administered concurrent to the first 20 min of each RTP session. RESULTS. Immediately after intervention, the participant demonstrated marked score increases on the UE section of the Fugl–Meyer Scale and the Motor Activity Log (on both the Amount of Use and the Quality of Movement subscales). CONCLUSION. These data support the use of tDCS combined with RTP to decrease impairment and increase UE use in chronic stroke patients with moderate impairment. This finding is crucial, given the paucity of efficacious treatment approaches in this impairment level.

Task-Oriented Rehabilitation Program for Stroke

estimation of body water composition remains challenging in critically ill patients.4 We agree with Dr Azim and colleagues that evidence supporting the administration of acetazolamide as a respiratory stimulant in mechanically ventilated patients with COPD and metabolic alkalosis remains sparse.5 The DIABOLO trial helps clarify the issue by establishing the lack of respiratory stimulant effects following inhibition of the carbonic anhydrase enzyme by acetazolamide. Our study leaves unanswered the question of the specific inhibition of carbonic anhydrase isozymes I, II, IV, and XII. It would seem preferable to administer acetazolamide during the weaning period. However, weaning from mechanical ventilation, especially in the difficult-to-wean population included in the DIABOLO trial, may be discontinuous, rendering an accurate measuring of its duration difficult. Limiting carbon-dioxide retention at the time of intubation also seemed relevant. The study was therefore designed to enable investigators to administer the treatment on day 1 in case of mixed or pure metabolic alkalosis. Patients with COPD with mixed metabolic alkalosis were included in the trial. Previous modeling assessing the effect of acetazolamide on respiratory parameters was undertaken with mixed metabolic alkalosis.6 At the start of the trial, the investigatorsbelievedthatadecreaseinserumbicarbonatewasthemost important objective because acetazolamide essentially lowers serum bicarbonates. To take into account the presence of mixed acid-base balance disturbances (ie, chronic respiratory acidosis and metabolic alkalosis), metabolic alkalosis was defined by serum bicarbonate greater than 26 mEq1/L and a pH of 7.35 or higher. These cutoff values are close to findings at the bedside, as shown by the relatively high inclusion rate (382 per 694) during the DIABOLO trial. In addition, the transient nature of posthypercapnic alkalosis during intermittent positive pressure breathing may be overcome by the choice of relatively low levels of serum bicarbonate (>26 mEql/L) and pH (≥7.35) (ie, mixed alkalosis to trigger the administration of acetazolamide). Finally, a per-protocol analysis yielded similar results to those of the intention-to-treat analysis regarding significant findings (eTables 1 and 3 in the article), suggesting the 28% not receiving treatment did not affect the overall results.