Use of transcranial random noise stimulation (tRNS) as an adjunct to reaching training in chronic stroke survivors with severe arm paresis: An exploratory pilot study.

INTERVENTION: The intervention group will receive 12 x 45‐minute training sessions with a physiotherapist (trainer) over 4‐weeks (3 sessions per week). Individualised training will involve repetitive and incrementally progressed task‐oriented reaching in sitting. Participants will be instructed to push their arm along a linear slide at a comfortable speed while receiving real‐time visual feedback of performance. To augment full range movement, electrical stimulation to muscles of the arm will be applied as required using the Empi 300PV unit (St Paul, MN, USA). Stimulation parameters will consist of a 1 second ascending ramp, and a 4 to 20 second duration of 200‐sec pulse width biphasic stimulation at 35 Hz. All training will be recorded by the trainer in a logbook. Training will be combined with transcranial random noise stimulation (tRNS). Stimulation will occur for the first 5‐seconds of each movement attempt to augment voluntary motor drive. Stimulation will be delivered by a battery‐driven non‐invasive brain stimulator (Neuroconn, Germany) through conductive rubber electrodes, placed in saline soaked sponges. The noise signal will contain all frequencies (101 – 640 Hz) up to half the sampling rate (1280 sps). The electrodes will be positioned over C3/C4 as per the 10/20 international system for EEG electrode placement: the stimulation electrode positioned over the ipsilesional primary motor cortex (M1) and the reference electrode positioned over the contralateral supra‐orbital region. All tRNS parameters will be recorded in a separate log by an unblinded intervener. The stimulating unit will be placed out of sight of the participant and trainer at all times. CONDITION: Stroke PRIMARY OUTCOME: Composite score of Motor Assessment Scale upper limb items 6‐8, which measure upper arm function, hand movements and advanced hand movements. SECONDARY OUTCOME: Muscle strength of elbow extension (triceps brachii) according to Manual Muscle Testing criteria. Muscle strength of wrist extension (extensor carpi radialis and ulnaris) according to Manual Muscle Testing criteria. Pain using the Ritchie Articular Index and 10‐point Visual Analogue Scale. Quality of life using the Stroke Specific Quality of Life Scale (normal and aphasia friendly version). ; Real‐world use of the arm in everyday tasks using the REACH (Rating of Everyday Arm‐Use in the Community and Home) measure. Resistance to passive movement using the Modified ashworth scale for elbow and wrist flexors Spasticity using the tardieu scale for elbow and wrist flexors. Structural (diffuse tensor imaging [DTI]) and functional (resting state functional‐magnetic resonance imaging [fcMRI]) connectivity of cortical motor regions using a 3T MRI. INCLUSION CRITERIA: All participants will be first time adult (greater than 18 years) stroke survivors who are 6 to 24 months post stroke who demonstrate severe upper limb paresis (as indicated by a Motor Assessment Scale item 6 score of less than 4 out of a possible 6 points). A minimum level of active movement consistent with a triceps brachii score of 2‐ is required, along with the ability to understand single stage commands. All participants will not have participated in any rehabilitation services for their arm for at least 2‐weeks prior to commencement of training.