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Abstract
Introduction Inflammation plays an important role in mediating morbidity following subarachnoid hemorrhage (SAH), including the development of cerebral vasospasm and hospital-acquired infections. Vagus nerve stimulation (VNS) is a non-pharmacologic approach to immunomodulation, and when applied non-invasively via a transcutaneous auricular approach, is a novel and rapidly deployable mechanism for modulating the deleterious post-SAH inflammatory response.
Materials and Methods Data is reported from an ongoing prospective, triple-blinded, randomized controlled trial. Patients with SAH were randomized to twice daily transauricular VNS (taVNS) or Sham stimulation. Blood and cerebrospinal fluid (CSF) were collected every three days to quantify inflammatory markers. Serial vascular imaging studies were reviewed to grade the presence and severity of cerebral vasospasm. Clinical records were reviewed to assess for incidence and type of hospital-acquired infection. All statistics were performed with the help of Statistical Software SPSS version 28.0. Significance was set at α= 0.05 for all tests. Outcomes with binary outcomes were reported with absolute and relative frequencies, and assessed using 2x2 contingency tables and 2-sided Fisher’s Exact tests.
Results 22 patients presenting with SAH were randomized (taVNS n=10, sham n=12). No adverse events related to the intervention were encountered. The level of IL-6 in CSF was significantly different between treatment groups at day 13 (p=0.04), while the level of IL-6 in plasma was similar between treatment groups (p=0.32). The level of IL-10 was numerically lower in the treatment group at day 13 in both CSF and plasma, but did not reach significance (p=0.08 and p=0.25, respectively). Hospital acquired infections were identified in 6 patients in the sham group, and 2 patients in the taVNS group (50% vs 20%, p=0.20). In addition, two patients assigned to the sham arm were diagnosed with two separate hospital-acquired infections during their admission. Radiographic vasospasm was identified in 10 patients in the sham group, and in 5 patients in the taVNS group (83.3% vs 50%, p=0.17). Vasospasm was graded as moderate or severe in 8 patients in the sham group, and in 3 patients in the taVNS group (66.7% vs 30%, p=0.10).
Conclusion taVNS is a non-invasive, non-pharmacologic method of immunomodulation. Preliminary data from this ongoing trial supports that taVNS following SAH can mitigate the inflammatory response, and decrease rates of radiographic vasospasm and hospital-acquired infections.
Disclosures A. Huguenard: 4; C; Aurenar. G. Tan: None. G. Johnson: None. M. Adamek: None. A. Coxon: None. G. Zipfel: None. A. Vellimana: None. P. Brunner: 4; C; Aurenar. E. Leuthardt: 2; C; Acera, Alcyone, E15, Intellectual Ventures, Microbot, Monteris Medical, Neurolutions, Osteovantage, Pear Therapeutics Inc., Sante Ventures. 4; C; Aurenar, Inner Cosmos, Neurolutions, Petal Surgical, Sora Neuroscience, Face to Face Biometrics, General Sensing, Immunovalent, Kinetrix, NeruoDev, Osteovantage, Pear Therapeutics, Sora Neuroscience.