AN EXPERIMENTAL technique piloted in Scotland to help stroke patients regain the use of their arms has shown promising results.
Vagus nerve stimulation (VNS), which aims to encourage the growth of new neural connections in the brain, was shown to help patients in Glasgow improve arm function by a greater degree than standard physiotherapy alone.
The two-year trial, which recruited 20 patients in Glasgow and Newcastle with long-term arm weakness after their stroke, involved the implantation of a small electrical device - similar to a pacemaker - into the participants' chests.
It is then connected to the vagus nerve in the neck using thin wires that are also implanted into the patient.
Scientists chose to stimulate the vagus nerve since it connects to structures in the brain that are involved in recovery from injury.
The idea was to take advantage of neuroplasticity - the natural ability of the brain to form new neural, or "nerve", connections.
Additional patients are now being invited to participate in a larger clinical trial in the United States. Participants will be drawn from communities in Dallas, Houston and Minneapolis.
Dr Jesse Dawson, of the Institute of Cardiovascular and Medical Sciences at Glasgow University, led the trial efforts.
He said: "There are no proven treatments beyond general rehabilitation strategies to improve hand function after stroke. A few methods may benefit the shoulder-elbow function, but nothing yet has worked to improve hand function.
"Vagus nerve stimulation has been suggested as a way of utilising neuroplasticity in the brain to drive the growth of new neural connections related to a specific body movement. This involves implanting a nerve stimulator, which provides electrical impulses during physiotherapy sessions.
"Our initial study demonstrates that VNS paired therapy holds promise. Greater improvements in arm function were observed in patients using VNS paired therapy compared to participants using traditional rehabilitation alone."
He said they needed to conduct larger trials to confirm the findings and determine if the widespread adoption of the technique could benefit post-stroke patients with upper limb weakness.
"These initial results are certainly encouraging and warrant further investigation," he said.
A stroke occurs as a result of a loss of blood supply to a part of the brain, leading to tissue death and loss of functions controlled by the affected brain area.
The study recruited volunteers who had suffered ischaemic stroke at least six months earlier with moderately severe arm problems.
The patients were split into two groups, one group receiving intensive physiotherapy alone, the other receiving physiotherapy paired with VNS.
They were scored at the end on their arm function.
The scores of VNS treated patients were six points higher than those who did not receive VNS in addition to their physiotherapy.
The trial was run in partnership with Texas-based biomedical company MicroTransponder, which developed the trademarked Vivistim device. A similar VNS device made by another company has been used for over 17 years to treat more than 80,000 people with epilepsy.
All patients received therapy three days a week for six weeks. Each session took two hours and involved many repetitions of different tasks as part of the standard physiotherapy.
For the patients receiving combined physiotherapy and VNS, a brief half-second of stimulation is delivered while the patients perform rehabilitative tasks.
The brief stimulation is initiated by a push button trigger held by the therapist, which then sends a wireless signal to the implanted device via a laptop computer and wireless transmitter.
The primary aim of the study was to assess safety and feasibility ahead of the planned large-scale trial. No safety issues were identified.
Anyone interested in taking part in future VNS stroke trials in the UK should call 0141 211 2176 or email: mvls-armweakness@glasgow.ac.uk
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