Aphasia is an acquired communication disorder, characterised by difficulties with the
production and/or understanding of language. Stroke is the most common cause of aphasia
which affects approximately 30% of stroke survivors. Many individuals are left with
chronic deficits. Speech and Language Therapy (SLT) is the gold-standard treatment for
aphasia but access to therapy is limited beyond the first few months of recovery.
Individuals with chronic aphasia (>6 months) can benefit from SLT input. Computer-based
SLT can lead to improvements in word-finding for people with aphasia, many years after
stroke (Palmer et al., 2019). Improvements have not been found to translate to day-to-day
conversation.
Vagus Nerve Stimulation (VNS) paired with upper limb rehabilitation has proved beneficial
in chronic stroke. Transcutaneous Vagus Nerve Stimulation (tVNS) is a non-invasive
technique which involves stimulating a branch of the vagus nerve through the skin of the
ear, using a small earpiece. This technique is safe and has been approved for use in
headache. The use of tVNS in chronic stroke is currently being explored, with promising
findings when paired with upper limb rehabilitation exercises. To date, there are no
published studies exploring the use of tVNS in chronic aphasia. Pairing tVNS with an SLT
intervention may have the potential to promote language recovery in chronic stroke. An
indication of study feasibility may support the development of a larger RCT to explore
treatment efficacy.
This is a single centre, single blind, pilot randomised controlled trial. The primary aim
is to explore the safety, tolerability and feasibility of self-directed computer-based
SLT combined with tVNS, in individuals with chronic-stroke related aphasia. Secondary
aims include exploring any indication of effect of the intervention on word-finding
ability (trained words, generalisability to untrained words and conversation).
Additionally, the study aims to explore potential mechanisms of action.
Participants will be asked to use the stimulation device alongside computer-based SLT, at
home for 6 weeks. SLT training will include naming pictures of 30 personally relevant
words, selected by the participant prior to the commencement of the intervention and
uploaded onto the software. The SLT software (Step by Step) uses a self-guided errorless
learning approach and will be completed on an ipad. The researcher will check-in with the
participant each week to monitor any concerns, side effects and monitor engagement with
the programme.
Potential participants will be recruited from Sheffield, using the NHS PHIND database.
Accessible study invitations will be sent to potential participants. The Consent Support
Tool will be used to ascertain the most appropriate way to provide study information. All
participants will have capacity to consent to the study. Participants will be randomly
allocated (SealedEnvelope Ltd) to an active or sham tVNS group, stratified according to
language score. Participants will be blinded to group allocation.
The tVNS device will be applied to the ear (tragus or earlobe), depending on group
allocation. The tVNS device (Nurosym/ Parasym II) is a UKCE marked device, indicated for
off-label use in the current study. tVNS use is safe however it has been associated with
mild and transitory side effects such as pain or irritation at the stimulation site,
headache and nasopharyngitis (Redgrave et al 2018). Stimulation parameters are in line
with previous studies:
Language assessments will be taken at baseline, end of treatment (6 weeks) and at
follow-up (12 weeks). To explore potential mechanisms, blood samples, heart rate
variability (HRV) and pupillometry measures will be taken at baseline and end of
treatment. The Functional near infrared spectroscopy (fNIRS; LUMO, Gowerlabs) will be
used on a subset of participants to explore cortical activation in the frontal lobes in
response to tVNS at baseline and end of treatment (6 weeks). Outcome measures will be
undertaken by a trained member of the research team.