TNF and Tension-type headache: There were significantly higher levels of both Transforming growth factor (TGF)-β (SMD 0.52, 95% CI 0.18–0.86, p = 0.003) and TNF-α (SMD 0.64, 95% CI 0.33, 0.96, p = 0.0001) in patients with tension-type headache.