358 - Occipitomastoid Suture V-spread Increases Vagal Tone and Decreases Sympathetic Activity as Quantified by Heart Rate Variability Metrics

Objectives:
To test the hypothesis that occipitomastoid suture v-spread, an osteopathic manipulative treatment (OMT), improves vagal tone measured via heart rate variability (HRV) in medical students. HRV is a measure of the change in heart rate over time and describes the cardiovascular system’s ability to adapt to intrinsic and extrinsic stresses via autonomic regulation of the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS). Low HRV has been associated with stress, pain and chronic diseases, whereas elevated HRV is linked with optimal health and reduced mortality risk.

Design:
Participants were evaluated for somatic dysfunction at the occipitomastoid suture bilaterally by one of two osteopathic physicians trained and board certified in neuromuscular medicine and osteopathic manipulative medicine. Occipitomastoid suture v-spread was performed in a standardized manner as treatment for the somatic dysfunction. Main outcome measures included vagal tone quantified via HRV variables including: root mean square of successive differences (RMSSD), percentage of successive normal sinus RR intervals more than 50 ms (pNN50), high frequency (HF), Parasympathetic Index (PNSI), and Sympathetic Index (SNSI). These variables were chosen based on recommendations published in the literature.

Results: Participants receiving occipitomastoid suture v-spread had significantly elevated mean (95% confidence interval) RMSSD 4.07% (0.30%, 7.84%, p< 0.05, n=30), pNN50 25.36% (6.14%, 44.58%, p< 0.01, n=30), and PNSI 38.97% (10.06%, 67.89%, p< 0.01, n=29). PNSI values contained an outlier that was removed using 0.01 significance level. Mean SNSI demonstrated a significantly decreased mean -58.24% (-101.33%, -15.16%, p< 0.01, n=30). HF measurements were not significant with an elevated mean difference 23.62% (4.40%, 42.85%, p=0.103, n=30).

Conclusions:
The results suggest that occipitomastoid suture v-spread may increase vagal tone, decrease sympathetic activity, and improve somatic dysfunction. More research is needed to determine whether autonomic activity might be a suitable target for the treatment of somatic dysfunctions.