Safety and tolerability of tVNS in MCI
redness, light-headedness, itching, reduction of systolic blood pressure, faintness, pain, tinnitus, headache
ADVERSE EVENTS, TINNITUS
The risk associated with use of the NEMOS © Cerbomed tVNS device is minimal as published data of the safety profile shows minimal adverse events. The most common adverse events reported include local skin tingling, burning, redness, itching, tinnitus or headache which occur in up to 18% of participants, and tends to resolve quickly after discontinuation of the use of the device [During the active and sham stimulation conditions, safety will be recorded by completion of the following:
Contemporaneous recording of any adverse events reported by participants whilst undergoing either active or sham stimulation.Likert-Based Questionnaires (See Additional File 2) will assess for established side effects previously reported with tVNS: pain, skin discomfort, tingling, headache and tinnitus. These will be administered both during active and sham stimulation.Detailed assessment of subjective (OH symptoms including faintness, light-headedness), peripheral (beat-to-beat blood pressure) and central (TSI) haemodynamic responses to active stand.
Briefly, participants will undergo active stand from supine to standing. After lying supine for 5 min, participants will be asked to stand as fast as they can. Beat-to-beat blood pressure and heart rate responses (assessed via the Finapres© NOVA) will be monitored during active stand and for three minutes after. To standardise assessments, all assessments are all taken at the same time each day, and all routine medications are taken as usual each morning. OH is defined by consensus as a sustained reduction of systolic blood pressure (SBP) of at least 20 mmHg or diastolic blood pressure (DBP) of 10 mmHg within 3 min of standing [During active stand, cerebral oxygenation (TSI) will be estimated using NIRS-based analysis software. TSI analysis will be undertaken using the PortaLite OxySoft© NIRS device (PortaLite, Artinis Medical Systems B.V., Elst, The Netherlands) and the light emitting diode will be placed on clean skin on the right forehead, devoid of moisture or oil, and secured with a black headband. TSI readings are transferred via Bluetooth in real-time and will give an approximation of tissue oxygenation during rest, active stand, and all cognitive assessments.Following assessment, participants will be given contact details of the principal investigator and study coordinator at the hospital who they can contact if they have concerns, or any new symptoms arise. Any adverse events will be diarised during the intervention and closely monitored until resolution. Data of participants who discontinue or deviate from the study protocol will be retained for intention to treat analysis.