Dose-response Effects of Neuromuscular Electrical Stimulation on Upper Extremity Function in Patients with Stroke
Date Issued
2011
Date
2011
Author(s)
Hsu, Shu-Shyuan
Abstract
Stroke is a leading cause of mortality and disability in adult population. Paralysis of upper extremity is a major sequela after stroke and it limits the patient’s ability of performing activity of daily life independently. More than half of stroke survivors demonstrate moderate to severe arm dysfunction 6 months after stroke, and only 5% to 20% can fully recover. Past researches have shown that training programs emphasizing task-oriented, active participation and massive repetition are more effective for patients with stroke in improving upper extremity function. Yet these types of intervention typically require voluntary movement by the patients and hence can not be applied to patients in the acute flaccid stage or to patients with severe arm weakness. Thus, alternative assisted therapy, such as neuromuscular electrical stimulation (NMES), is generally applied clinically to facilitate motor recovery in early stage after stroke.
Neuromuscular electrical stimulation (NMES) is an accessible modality in clinical setting and it can be applied to patients in flaccid stage. It has been proposed that electrical stimulation enhances motor recovery of upper extremity after acute stroke. With the use of NMES, patients with limited active movement can practice the movement to a fuller range, and patients with no or limited movement can receive abundant sensory input, which may facilitate reorganization of the central nervous system. But the dose of electrical stimulation varied widely among studies.The total hours of stimulation dosage may range from as little as 6 hours over 2 weeks to as much as 220 hours over 12 weeks. In addition, the long treatment duration proposed by the literature is not practical in common clinical settings. Issues of rationales for clinical applications of specific treatment parameters, such as treatment intensity or treatment dose have become the focus of current research in the field of stroke rehabilitation. The purpose of this study is to investigate the effects of different doses of NMES on upper extremity function in acute stroke patients with severe motor deficit and to investigate whether any dose-response of NMES and to find the minimal dosage applicable in clinical settings.
This was an assessor-blind block randomized controlled study. During the period of May 2004 to December 2008, 95 stroke patients with unilateral involvement were recruited from two academic medical centers. Subjects were allocated randomly to the control group or each of the three NMES groups of varying dosages (15, 30, and 60 minutes per session). All subjects received regular inpatient rehabilitation. Treatment groups received additional NMES treatment sessions for 4 weeks, 5 times per week. Outcome measures included the upper extremity motor section of the Fugl-Meyer Motor Assessment Scale (FMA_UE), Action Research Arm Test (ARAT), and Motor Activity Log (MAL). The FMA_UE and ARAT were assessed at baseline, after 4 weeks of treatment, and at 2 months follow-up. The MAL was assessed only at follow-up. Quality of life (SSQOL, EQ5D), ADL function (Barthel index), and upper limb motor function (FMA, ARAT, MAL) were evaluated at one year post stroke.
The results showed that: (1) NMES facilitates motor function recovery of affected upper extremities after stroke and the improvement was maintained at 2 month follow-up; (2) There was a trend toward improvement in the MAL scores in the NMES groups at 2-month follow up; (3) The minimal effective dosage was 5 hours of NMES for improvement of upper limb function in stroke patients; (4) There was a positive relationship between actual stimulation dosage of NMES and upper limb functional recovery. Increasing the stimulation dose of NMES led to greater improvement in the ARAT score at follow-up; (5) No significant difference was found between NMES groups and the control group in quality of life, ADL and upper limb function at post stroke 2-year follow-up.
There were some limitations in the present study. The NMES dosage in our study was limited to 0 to 20 hours. This range is narrower than those used in most studies. We thought that our range was more practical for clinical application. However, our result cannot be generalized to clinical practices where the total treatment time exceeds 20 hours, nor can our results be applied to treatment programs exceeding 1 hour/session. More studies are needed to develop the dose-response curve and to find the optimal NMES dosage or minimal effective dosage in improving upper limb function. Another concern was that treatment dose had been defined as the product of stimulation time per session, treatment frequency, or treatment duration. Future studies should investigate varying combinations of treatment dose administration for designing intervention programs suitable for clinical practice. The clinical value of this study is to provide the references in NMES intervention program design for stroke patients with severe motor deficits in clinical practice and point out some viewpoints regarding dose-response relation between NMES and functional outcome in future studies.
Subjects
stroke
upper limb function
electrical stimulation
dosage of electrical stimulation
dose-response
Type
thesis
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