Transcutaneous auricular vagus nerve stimulation induces stabilizing modifications in large-scale functional brain networks: towards understanding the effects of taVNS in subjects with epilepsy.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a novel non-invasive brain stimulation technique considered as a potential supplementary treatment option for subjects with refractory epilepsy. Its exact mechanism of action is not yet fully understood. We developed an examination schedule to probe for immediate taVNS-induced modifications of large-scale epileptic brain networks and accompanying changes of cognition and behaviour. In this prospective trial, we applied short-term (1 h) taVNS to 14 subjects with epilepsy during a continuous 3-h EEG recording which was embedded in two standardized neuropsychological assessments. From these EEG, we derived evolving epileptic brain networks and tracked important topological, robustness, and stability properties of networks over time. In the majority of investigated subjects, taVNS induced measurable and persisting modifications in network properties that point to a more resilient epileptic brain network without negatively impacting cognition, behaviour, or mood. The stimulation was well tolerated and the usability of the device was rated good. Short-term taVNS has a topology-modifying, robustness- and stability-enhancing immediate effect on large-scale epileptic brain networks. It has no detrimental effects on cognition and behaviour. Translation into clinical practice requires further studies to detail knowledge about the exact mechanisms by which taVNS prevents or inhibits seizures.

Audiologic changes after pinna augmentation.

No studies to date have objectively assessed whether pinna morphology affects sound intensity detected within the external auditory canal (EAC). Commonly performed procedures on the EAC are carried out for acquired and congenital pathology, together with correction of ear deformities. Our aim was to use an experimental model to identify whether a relationship exists between pinna shape and its subsequent effect on the hearing subject. An anatomically accurate and life-size model made of rubber composite was used for this study. Serial sections (small wedge, defect open; small wedge, defect closed; large wedge, defect open; large wedge, defect closed [equivalent to a protruding ear]; and pinnectomy) were undertaken, and the sound intensity changes assessed at the junction between the EAC and middle ear (tympanic membrane position) using an AURICAL Plus (Otometrics; Taastrup, Denmark) sound processor. A statistically significant loss was demonstrated for wedge-excised models, which was greatest at 180° azimuth. This loss was significantly reduced when the wedge defects were closed. A statistically significant improvement was demonstrated in the protruding ("bat") ear model compared with the normal ear at 0° azimuth. In this model, gain in sound intensity is adversely affected by pinna wedge resection. Because this change may be increased in those with protruding ears, this factor is important to consider for all cosmetic and noncosmetic operations to the pinna, and it supports the notion that the pinna is not a simple funnel.

[Effect of electroacupuncture stimulation of auricular concha region at different time-points on behavior changes in depression rats].

UNLABELLED: OBJECTIVE To observe the effect of electroacupuncture (EA) stimulation of auricular concha region (ACR) on behavior changes of depression rats. METHODS: A total of 80 male Wistar rats were randomized into depression model (model, n = 6), EA-ACR (n = 12), preventive EA-ACR (Pre-EA-ACR, n = 11) and EA-ear-tip (n = 12) groups. Depression model was established by chronic unpredictable mild stress for 21 days and isolated breeding. Open-field test and sucrose solution intake preference test were conducted to assess changes of the rats' behavior activities before modeling and on day 22, 36 and 50 after starting model. For rats of the pre-EA-ACR group, EA (2 Hz, 1 mA) was applied to the bilateral auricular concha area for 20 min, once daily for 14 days, beginning from the 8th day on after starting model preparation till the end of the modeling, and for rats of the EA-ACR and EA-ear-tip groups, EA was given to the bilateral ACR and ear-tips respectively, beginning after modeling, once daily for 14 days. RESULTS: In comparison with pre-modeling, the percentages of sucrose solution consumption in rats of the model group decreased gradually from day 22 to 50 (P > 0.05). Compared with the model group,the percentage of sucrose solution consumption in the EA-ACR group was increased significantly on day 50 (P < 0.05), suggesting an inhibitory effect of EA on the reduction of sucrose intake preference at this time-point. No significant differences were found between the pre-EA-ACR and the model groups and between the EA-ear-tip and model groups as well as between the EA-ACR and model groups at most time-points (P > 0.05). Open-field test showed that in comparison with pre-modeling in the same one group, the total scores, crossing and rearing scores on day 22 were decreased considerably in the model and EA-ear-tip groups (P < 0.05, P < 0.01), rather than in the pre-EA-ACR and EA-ARC groups (P > 0.05), suggesting a suppressing effect of pre-EA-ACR and EA-ACR on depression behavior. Compared to day 22 in the same one group, the total scores, crossing and rearing scores on day 36 and 50 in the pre-EA-ACR and EA-ear-tip groups were decreased significantly (P < 0.05, P < 0.01). CONCLUSION: EA of auricular concha region can restrain the development of depression behavioral status in depression rats, which is superior to that of EA of ear-tip.

[Effects of transcutaneous electrostimulation of auricular concha at different stimulating frequencies and duration on acute seizures in epilepsy rats].

OBJECTIVE: To observe the inhibitory effect of auricular concha transcutaneous electrostimulation (ACTES) of different frequencies and duration on acute seizures in epilepsy rats so as to select a better stimulating parameter for relieving epilepsy. METHODS: According to the stimulation duration of ACTES, 44 Sprague-Dawley rats were randomized into: 30 s, 5 min, 10 min, and 30 min groups. Epilepsy model was duplicated by intraperitoneal injection of PTZ (pentylenetetrazol, 50 mg/kg). Cerebral field potentials delivered from the fixed 4 recording electrodes array (A-P: -3 -6, L: 4 - 6, H: 1. 5) and reference electrode (a fixed screw) touching the cerebral dura surface were recorded using a data acquisition system (Cerebus 5.0 system). Transcutaneous electrostimulation (1 mA, duration 500 micro(s)) of frequency 2 Hz, 20 Hz and 100 Hz was applied to auricular concha by using an electric stimulator. The anti-epileptic effects of ACTES were evaluated by using the duration and rate of seizure suppression. RESULTS: (1) The anti-epileptic effect of 20 Hz -ACTES was markedly longer than those of 2 Hz and 100 Hz in the duration of seizure suppression (P < 0.05). (2) After 2 Hz-ACTES, the anti-epileptic effects (duration and inhibitory rate) in 30 s-stimulation group were markedly longer than those of the 5 min-, 10 min- and 30 min-stimulation groups (P < 0.01, P < 0.05). (3) After 100 Hz-ACTES, the anti-epileptic effects (duration and rate of seizure suppression) in the 30 min-stimulation group were markedly longer than those in the 30 s-, 5 min- and 10 min-stimulation group (P < 0.01, P < 0.05). CONCLUSION: ACTES at 20 Hz can effectively lessen epileptic seizures, and under fixed stimulating frequencies of 2 Hz and 100 Hz, the anti-epileptic effects of 30 s ACTES and 30 min-ACTES are obviously better in epilepsy rats.