Background/Objectives: Transcutaneous auricular vagus nerve stimulation (TaVNS) is a non-invasive method of electrical stimulation used to autonomic neuromodulation. Position and form of the electrodes are important for the effectiveness of autonomic modulation. This study was aimed to investigate the effect of TaVNS in-ear and behind-ear on autonomic variables. Methods: A total of 76 healthy participants (male: 40, female: 36) were randomized into four groups as in-ear TaVNS, behind-ear TaVNS, in-ear sham, and behind-ear sham. The TaVNS protocol included bilateral auricular stimulation for 20 min, 25 hertz frequency, a pulse width of 250 μs, and a suprathreshold current (0.13–50 mA). Heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), and heart rate variability (HRV) were measured baseline and after stimulation. The parameters RMSSD (root mean square of consecutive differences between normal heartbeats), LF power (low-frequency), and HF power (high-frequency) were assessed in the HRV analysis. Results: HR decreased in the in-ear TaVNS after intervention (p < 0.05), but did not change in behind-ear TaVNS and sham groups compared to baseline (p > 0.05). SBP and DBP decreased and RMSSD increased in the in-ear and behind-ear TaVNS groups (p < 0.05), but did not change in sham groups compared to baseline (p > 0.05). There was no significant difference in LF and HF power after TaVNS compared to baseline in all groups (p > 0.05). SBP was lower and RMSSD was higher in-ear TaVNS than behind-ear TaVNS after intervention (p < 0.05). Conclusions: In-ear TaVNS appears to be more effective than behind-ear TaVNS in modulating SBP and RMSSD, but this needs to be studied in larger populations.

Evaluation of the Sympathetic Skin Response to the Dry Needling Treatment in Female Myofascial Pain Syndrome Patients

The autonomic nervous system and its dysfunction are associated with many diseases. For a healthy individual, it is essential that the sympathetic and parasympathetic systems are balanced and functioning at a high capacity. Psychiatric disorders often exhibit disruptions in the activity of the vagus nerve, which can lead to autonomic dysfunction. People with psychiatric disorders, including panic disorder, depression, bipolar disorder, schizophrenia, post-traumatic stress disorder, anxiety disorders, and substance addiction, often show reduced heart rate variability. Heart rate variability is a reliable marker for assessing autonomic functions, and decreased heart rate variability in individuals with psychiatric disorders can lead to an increased risk of sudden cardiac death. Autonomic dysfunction is observed in psychiatric disorders, and it occurs during the course of the illness, not necessarily at its onset. Autonomic dysfunction accelerates the progression of the disease. Therefore, controlling autonomic functions is crucial. This can help reduce disease symptoms and decrease the morbidity and mortality caused by autonomic dysfunction."

Objectives: This study aims to investigate the effects of transcutaneous auricular vagus nerve stimulation (taVNS) on visual memory performance and fatigue in healthy individuals. Patients and methods: Between April 10, 2022 and May 25, 2022, a total of 60 physical therapy and rehabilitation students (27 males, 33 females; mean age: 20.6±1.6 years; range, 18 to 24 years) were included in the study. The individuals were divided into two groups as the experimental group (n=30) and the control group (n=30). The experimental group received taVNS, mobile device supported games, and low-medium intensity aerobic exercises, while the control group received mobile device supported games and aerobic exercises. The personal information form was applied to all participants. The level of fatigue was measured using a computer-based evaluation and Fatigue Severity Scale (FSS) to analyze the visual memory performance. Results: All parameters used to evaluate visual memory performance showed a significant difference, while the FSS scores showed no significant difference (p>0.05). Only one sub-parameter in the control group was significantly different, while none of the other sub-parameters or FSS scores were significantly different (p>0.05). There was a significant difference between the two groups in terms of two of the visual memory sub-parameters, although no significant difference was found for the results of one parameter and the FSS (p>0.05). Conclusion: Our study results show that taVNS can produce positive effects on visual memory performance, although it does not apparently affect fatigue.