Table 4.
Summary of the efficacy of the interventions.
| References | Intervention(s) | Intervention duration (sessions/weeks) | Efficacy |
|---|---|---|---|
| at-VNS vs. at-VNS (different parameters of frequency) | |||
| Cao et al. (2021), China | G1; taVNS = 20-Hz. G2; taVNS = 1 Hz continuous wave (width: ~ 0.2 ms), stimulation of 8 min Intensity ~4 mA | Unique session | ta-VNS 1 HZ was superior in terms of the number of migraine attacks and functional brain connectivity. |
| Wei et al. (2022), China | G1; electrical acupuncture with low-frequency pulse therapy instrument G2; healthy people 2 Hz, 1 mA for 8 min | Unique session | G1 (electrical acupuncture) had some influence in brain connectivity with a therapeutic role. |
| Sacca et al. (2022), USA | G1; taVNS = 1 Hz. G2; taVNS = 20 Hz 8 minutes, 4 mA, | 2 sessions | G1 (1 Hz) improves more than G2 (20 Hz) in migraine attacks. Both improved functional brain connectivity. |
| Straube et al. (2015), Germany | G1; taVNS 25 Hz, 250 μs, cycle: 30 s on, 30 s off G2; ta-VNS 1 Hz 250 μs, cycle: 30s on, 30 s off | 4 h per day over 12 weeks | G2; t-VNS at 1 Hz was safe and effective and after 12 weeks showed a reduction of migraine. |
| Real at-VNS vs. sham at-VNS therapies | |||
| Zhang et al. (2021), China | G1 ta-VNS 1 Hz with the duration of 0.2 ms. Stimulation was continuously applied for 30 min. Intensity 1.5–5 mA G2; Sham group = another location | 30 min of 12 treatment sessions in total during the 4-week treatment | G1; relieved the symptoms of headache as well as modulated the thalamocortical circuits in migraine patients |
| Luo et al. (2020), China | G1; taVNS 1 Hz, 0.2 ms. intensity below the pain threshold (vagal afferent fibers) G2; taVNS Sham. (no vagal afferent fibers) | Unique session of MRI scan, total of 6 20 min fMRI runs and 8 min ta-VNS | G1; FC Improved, left amygdala, left MFG, right SMA, left dorsolateral superior frontal gyrus, bilateral paracentral lobules, bilateral postcingulum gyrus, and right frontal superior medial gyrus. Left FC and right SMA in frequency/time in migraine in 4 weeks. |
| Zhang et al. (2021), China | G1; taVNS = (frequency: 1 Hz; width: 0.2 ms). Stimulation intensity was adjusted to approximately 1.5–3 mA) G2; Sham group = another location | Unique session of fMRI with at-VNS and sham at-VNS | G1; 1 Hz can significantly modulate activity/connectivity of brain regions and pain modulation system in migraine. |
| Electro-acupuncture (auricular branch) vs. another technique | |||
| Yang et al. (2014), China | G1; AG G2; SAG 100 Hz, for 30 min, 1,0 mA G3; MG | 30 min of unique session | Acupuncture stimulation at both sub-specific acupoints evokes central mechanism of acupuncture analgesia by neuroimaging measurement. |
| Vijayalakshmi et al. (2014), India | G1; Electro acupuncture 10-20 Hz, 0.5 mA; an output of 6-9 volts for 20 min G2; Drug therapy; flunarizine 20 mg OD and tab. paracetamol 500 mg SOS | 10 sessions for 30 days | G1 improved in QOL and MIDAS. |
VAS, visual analog scale; MSQ, Migraine Specific Quality of Life; SDS, Self-rating Depression Scale; SAS, Self-rating Anxiety Scale; NVS, transcutaneous auricular-Nerve Vagus stimulation; fMRI, functional Magnetic Resonance Image; AG, Electro-acupuncture group; SAG, Sham Acupunture Group; MG, Migraineur Wait-List control Group; WHO QOL BREF.
Levels of Evidence based on the Quality Rating Scheme for Studies and Other Evidence modified from the Oxford Centre for Evidence-Based Medicine for rating of individual studies; available online at https://www.cebm.net/2016/05/ocebm-levels-of-evidence/.RCT.
NR, Not reported; LC, locus coeruleus; rsFC, Resting state functional connectivity; SF, Significance; EA, Electro-acupuncture; PCC, MTC, Middle Temporal Cortex; SMA, supplementary motor area; MFG, middle frontal gyrus; MFC, Middle Frontal Cortex.