Nummular headache (NH) is currently considered a form of peripheral neuralgia originating from the terminal branch in epicranial tissue but its etiopathogenesis is still unknown. Since autoimmune disorders often involve the trigeminosensory nerve to provoke craniofacial pain, we hypothesize that autoimmunity aberration may play a role with regard to NH.
We examined the antibodies to antinuclear factor, ds-DNA, extracted nuclear antigens, rheumatoid factor, as well as antiphospholipid antibodies, in 23 primary NH patients.
Among them were 16 patients (69.6%) found as having at least one abnormal autoimmune index, namely, antibodies to antinuclear factor in 8 patients, SSA/La in 6 patients, rheumatoid factor in 4 patients, SSB/Ro in 2 patients, and ds-DNA in 1 patient. An abnormal increase of blood anti-beta2-glycoprotein I antibody was noted in 4 patients and lupus anticoagulant in 1 patient, whereas HLA-B27 seropositivity was detected in 1 patient. Except for 2 patients positive for antinuclear factor without other associated features, 15 patients (65%) were finally diagnosed as having Sjogren/sicca syndrome, rheumatoid arthritis or antiphospholipid antibody syndrome.
A high prevalence of abnormal autoimmune indices and disorders is present in primary NH patients, suggesting a probable relationship between autoimmunity aberration and epicranial neuralgia in NH.