Investigating the Tolerability and Feasibility of tVNS Following aSAH

"* Pulse width - 25ms~* Frequency - device default (20 or 25Hz)~* Intensity - below pain threshold.~* Frequency - 45 minutes twice daily. On the basis of similarity to other studies, practicalities on the ward and clinical scenario~We have chosen a duration of 5 days based on the usual clinical pathway of inpatient management at the Royal Hallamshire Hospital, and have chosen to deliver the treatment twice daily to optimise the dose. This is a pilot study with feasibility outcomes and as such we will be exploring the feasibility of this treatment regimen.~The Parasym Device will be applied to the left tragus (figure 1) as this is the most common site for tVNS delivery in neurological studies and is associated with few afferents to the heart."

The active intervention will be compared to sham tVNS where the vagal nerve stimulator will be attached to the earlobe instead of the tragus, in keeping with evidence that this does not cause vagus nerve stimulation and is in line with sham methods used in other studies. We do not anticipate that patients will have the intervention long enough to become familiar with the common sensations associated with true tVNS intervention. At the end of the intervention period, participants will be asked if they thought they had received true of sham tVNS to understand the blinding ability of the sham.