TNF and viral encephalitis: TNF-α in migraine group [5.60 (4.23) pg/mL], in encephalitis with headache group [5.02 (5.03) pg/mL], and in pneumonia without headache group [2.66 (2.97) pg/mL] showed that there were significant differences in the overall distribution of TNF-α levels among the three groups (H = 28.08, p < 0.0001).