Priming Before Physical Therapy Facilitates Stroke Rehab

Daniel M. Keller, PhD

September 30, 2013

VIENNA, Austria — Bilateral priming facilitates upper-limb rehabilitation and accelerates recovery after stroke, a new study shows.

Through the use of a mechanical device designed for that purpose, the paretic hand is passively moved in a mirror-symmetric manner as the patient extends and flexes the nonparetic wrist.

"Bilateral priming has few contraindications, it takes little time to administer, and the device is portable and easy to use. You can easily integrate bilateral priming into your rehabilitation center," Winston Byblow, PhD, from the Centre for Brain Research, professor and deputy head of the Department of Sport and Exercise Science, and director of the Movement Neuroscience Laboratory at the University of Auckland, New Zealand, reported. Dr. Byblow is a named inventor on the patent of the device.

He points out that it could potentially be used at home before a physical therapy session.

He presented their findings with this approach here at the XXI World Congress of Neurology (WCN).

Priming Advantage

Priming device

Recovery after stroke reaches a plateau after 6 months and depends in part on the extent of cerebral damage. According to Dr. Byblow, priming the brain can disinhibit cortical areas adjacent to the lesion and promote neural plasticity.

Synchronous upper-limb movements can enhance disinhibition. He therefore designed the mechanical system by which movement of the nonparetic hand is transmitted to the paretic one to test the hypothesis that bilateral priming can enhance motor cortex function on the side of the lesion and accelerate recovery of hand and arm function.

Between November 2009 and March 2012, the researchers recruited patients with stroke at Auckland City Hospital into a randomized controlled trial within 21 days of stroke. Included were patients at least 18 years old with their first ischemic stroke in one hemisphere who required upper-limb rehabilitation.

Patients with complete sensory loss, cerebellar stroke, visuospatial neglect, or transcranial magnetic stimulation were excluded. Participants were randomly assigned to bilateral priming (n = 29) or control intervention (n = 28), which consisted of weak cutaneous electrical stimulation.

 
Bilateral priming has few contraindications, it takes little time to administer, and the device is portable and easy to use. Dr. Winston Byblow
 

The active intervention and control groups were well matched for age, sex, stroke severity, vascular risk factors, stroke lesion locations, use of thrombolysis, corticospinal tract integrity, predicted upper-limb recovery, and brain-derived neurotrophic factor genotype.

The patients received 15 minutes of priming or control intervention followed by 30 minutes of upper-arm therapy 5 days per week for 4 weeks. The priming patients averaged 1249 (range, 505 to 1896) wrist repetitions per day. Participants were assessed at 2, 6, 12, and 26 weeks using the Action Research Arm Test. Corticospinal tract integrity was confirmed with stimulation and imaging.

Fifty-one of 57 patients completed participation to 12 weeks. Compared with control patients, priming patients had a 3-fold greater likelihood of reaching 75% of their maximal recovery within 12 weeks, the primary endpoint of the trial.

By intention-to-treat analysis, the primed patients had an odds ratio of 3.2 (95% confidence interval, 1.1 - 10.7; P < .05) of reaching the primary endpoint compared with controls.

Dr. Byblow also reported that priming was associated with normalization of corticomotor excitability to a greater extent than with the control intervention.

He told Medscape Medical News that priming is not "just more therapy." He explained that "it's not task-specific and it can be completed without any active movement of the paretic upper limb." Furthermore, priming is distinct from bilateral training, he noted.

He said he expects the priming device could be commercially available for a few hundred dollars.

Stimulate the Brain

Asked to comment on the study, Rangrar Steen, MD, chair of the session on stroke rehabilitation and a retired neurologist who specialized in rehabilitation of spinal cord injuries when he was head of the Department of Neurology at one of the hospitals of the University of Oslo, Norway, said he thinks almost all efficacious stroke rehabilitation techniques get results in similar ways. The key is to stimulate the brain, then function can return.

Commenting on Dr. Byblow's technique, he said, "We have done it in some different ways...and he has done it in a very systematic way, and I think he showed that it has effect."

The difference is that Dr. Byblow has stimulated the brain to be more amenable to physical therapy even though the priming in itself is not the therapy.

Many techniques can work, and Dr. Steen said he believes that "You stimulate, and you get results. If the brain is stimulated, the function at least recovers better."

Dr. Byblow is a named inventor on the patent for the priming device. Dr. Steen has disclosed no relevant financial relationships.

XXI World Congress of Neurology (WCN). Free Papers 8. Presented September 22, 2013.

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