Bilateral Priming Accelerates Recovery of Upper Limb Function After Stroke

Abstract

Background and Purpose— The ability to live independently after stroke depends on the recovery of upper limb function. We hypothesized that bilateral priming with active–passive movements before upper limb physiotherapy would promote rebalancing of corticomotor excitability and would accelerate upper limb recovery at the subacute stage. Methods— A single-center randomized controlled trial of bilateral priming was conducted with 57 patients randomized at the subacute stage after first-ever ischemic stroke. The PRIMED group made device-assisted mirror symmetrical bimanual movements before upper limb physiotherapy, every weekday for 4 weeks. The CONTROL group was given intermittent cutaneous electric stimulation of the paretic forearm before physiotherapy. Assessments were made at baseline, 6, 12, and 26 weeks. The primary end point was the proportion of patients who reached their plateau for upper limb function at 12 weeks, measured with the Action Research Arm Test. Results— Odds ratios indicated that PRIMED participants were 3× more likely than controls to reach their recovery plateau by 12 weeks. Intention-to-treat and per-protocol analyses showed a greater proportion of PRIMED participants achieved their plateau by 12 weeks (intention to treat, χ 2 =4.25; P =0.039 and per protocol, χ 2 =3.99; P =0.046). ANOVA of per-protocol data showed PRIMED participants had greater rebalancing of corticomotor excitability than controls at 12 and 26 weeks and interhemispheric inhibition at 26 weeks (all P <0.05). Conclusions— Bilateral priming accelerated recovery of upper limb function in the initial weeks after stroke. Clinical Trial Registration— URL: http://www.anzctr.org.au . Unique identifier: ANZCTR1260900046822.

Motor Priming in Neurorehabilitation

“…However, they may produce similar effects that may include increased excitability or normalization of inhibition, which coincide with improvements in motor behavior. 13 Methods of priming the motor cortex that are most relevant to rehabilitation include: (1) stimulation-based priming; 14-22 (2) motor imagery and action observation; 23-28 (3) manipulation of sensory input; 29-31 (4) movement-based priming; 7, 32-36 and (5) pharmacology-based priming. 37 Studies examining priming for the primary motor cortex (M1) are increasing in number.…”

“…32-35 In neurologically healthy subjects, mirror-symmetric movements, but not alternating movements, were associated with improvements in motor performance and interhemispheric disinhibition. 7 Active-passive bilateral therapy (also known as bilateral priming) uses a low-tech device known as “the rocker” which was first described by Stinear and Byblow.…”

Bilateral Transcutaneous Electrical Nerve Stimulation Improves Lower‐Limb Motor Function in Subjects With Chronic Stroke: A Randomized Controlled Trial

“…The mechanisms that mediate the effects of bilateral intervention in subjects with stroke include rebalancing interhemispheric inhibition,20, 21, 22 activating the homologous neural networks in both hemispheres,23, 24 and recruiting the neural networks of the contralesional hemisphere 17, 23, 25. The use of transcranial magnetic stimulation in subjects with stroke, in which the maximum voluntary contraction of the nonparetic hand was combined with less‐forceful contraction of the paretic hand, increased the cortical excitability of the ipsilesional motor representation area of the hand when compared with contraction of the paretic hand alone 24.…”

“…Current evidence shows that bilateral intervention recruits spare neural substrates to enhance motor recovery17, 20, 21, 22, 23, 24, 25; we thus hypothesized that the application of TENS over both paretic and nonparetic legs (Bi‐TENS) might induce greater and earlier improvement in lower‐limb motor function than the use of Uni‐TENS in subjects with stroke. A literature search revealed that no study has compared the efficacy of Bi‐TENS+TOT and Uni‐TENS+TOT on motor recovery after stroke.…”

Non-invasive brain stimulation for stroke recovery: ready for the big time?

“…Second, there are a number of experimental approaches under investigation which aim to increase the effects of training by enhancing the potential for use-dependent plasticity. These ‘primers’ of the motor system might include drugs (eg, fluoxetine2), specific forms of activity (active–passive bilateral arm training,3 aerobic exercise4) and non-invasive brain stimulation (eg, transcranial direct current stimulation, tDCS5 6). None of these interventions should be thought of as treatments, but rather as tools for enhancing the effects of conventional practice-based treatment, which in the case of post-stroke motor impairment is currently physical therapy.…”