Natus Fellow/Resident NCC Award - Non-invasive Vagus Nerve Stimulation Improves Glycemic Control in Neurocritical Care Patients Following Subarachnoid Hemorrhage

Introduction: Glycemic control is an independent predictor of outcome in patients following subarachnoid hemorrhage (SAH), and in neurocritical care patients regardless of admission diagnosis. We previously demonstrated intervention with transauricular vagus nerve stimulation (taVNS) during patients’ intensive care unit (ICU) stay reduces inflammatory cytokines in the blood and cerebrospinal fluid and reduces radiographic vasospasm. taVNS also has potential to improve glycemic control via increased parasympathetic tone and insulin secretion from direct activity at the pancreas.

Methods: This is a secondary analysis from the Non-invasive Auricular Vagus nerve stimulation for Subarachnoid Hemorrhage (NAVSaH) prospective, triple-blinded, randomized controlled trial. Patients with SAH were randomized to twice daily treatment with taVNS or sham stimulation during their ICU stay. Patients’ blood glucose levels, insulin administration, and diabetes history were evaluated. Continuous vital sign data were collected, and acute and aggregate changes in heart rate (HR), heart rate variability (HRV), and QTc interval were assessed.

Results: 33 SAH patients were randomized, 15 sham and 18 taVNS. Baseline age, Hunt and Hess score, and diabetes history were similar between groups. In patients with diabetes, there was a lower average blood glucose in taVNS treated patients compared with sham (189 mg/dL vs 159 mg/dL, p< 0.001), and 3.4 times fewer hyperglycemic events (glucose >180 mg/dL). For all patients regardless of diabetes history, total daily insulin dose/kg in the taVNS group was 50% lower (p=0.02). Acutely, taVNS increased HR and this elevation in HR was more pronounced in patients with a decrease of > 1 point in mRS at discharge. Over repeated treatments, taVNS increased overall HRV and parasympathetic activity 5–10 days after initial treatment.

Conclusion : Treatment with taVNS following SAH leads to increases parasympathetic tone as assessed by HRV, as well as improved glycemic control. These findings suggest intervention with taVNS may be applicable for broader ICU indications beyond SAH.