Effectiveness of Neuromuscular Electrical Stimulation After Stroke

35 Hz Versus 50 Hz Frequency Stimulation Effects on Motor Recovery in Older Adults After Stroke. A Randomized Clinical Trial

A Randomized Clinical Trial (RCT) was conducted to determine the effects of two neuromuscular electrical stimulation protocols with different stimulation frequencies on motor recovery in older adults with spastic hemiparesis after a stroke.

Impairment of the upper limb is one of the most frequent consequences of stroke and directly impacts on the patient's functional status and quality of life. It is estimated that less than 50% of stroke survivors will recover arm function, which will exert a great economic, social and personal toll.

Neuromuscular electrical stimulation (NMES) is one of the techniques suggested for upper limb recovery in stroke patients. However, after considering the bibliographic background, more studies are required in order to test its effectiveness, to establish the most efficient NMES protocols and to assess the characteristics of the patients who can benefit the most from this treatment. With this regard, the parameters of the stimulation are currently subject to debate, and more data are needed to optimize the application of this treatment. The aim of this study was to evaluate and compare the effects of two neuromuscular electrical stimulation protocols with different stimulation frequencies on motor impairment, kinaesthetic sensation, functional motor ability, activities of daily living, and quality of life in older adults with spastic hemiparesis suffering a stroke.

To cope with the objective of the present study, RCT was conducted. Subjects who met inclusion criteria were recruited from a hospital rehabilitation unit. After the screening and signed consent, participants were randomly allocated to the control group or one of both experimental groups. NMES was applied on wrist and finger extensors for 30 minutes, 3 sessions per week for 8 weeks. The electrostimulation protocols were only differentiated in the parameter of the stimulation frequency, 35 Hz or 50 Hz, depending on the experimental group to which the patient belonged to. Outcome measures were collected at the beginning, after 4 and 8 weeks of treatment, and after a follow-up period (4 weeks).

Inclusion Criteria:

• Age ≥ 60 years
• Post-stroke spastic hemiparesis
• Mild-moderate hand impairment
• A score ≤ 3 on the modified Ashworth scale for wrist and finger flexors
• Active wrist extension ≥ 5º from the resting position
• Wrist extension response to stimulation
• Post-stroke period < 18 months
• Clinical stability
• Mini-Mental State Examination score ≥ 23

Exclusion Criteria:

• Previous hemiparesis due to stroke
• Dermatological reactions with the application of stimulation
• Significant sensory deficits in the affected arm
• Previous musculoskeletal problems of the hand
• Treatment with the botulin toxin
• Anti-spastic medication usage
• Cardiac pacemaker, implanted electronic device, or metal implants in the affected arm
• Complex regional pain syndrome
• Severe aphasia, history of epileptic seizures, psychiatric disorder or important alterations of behavior
• Severe visual impairment
• Any comorbid neurological disease
• Important deformity or obesity that affects the application of the NMES
• Potentially fatal cardiac arrhythmia or another decompensated heart disease
• Systemic infectious process, cancer or another terminal disease