• medication-overuse headache;
  • chronic migraine;
  • migraine;
  • leukocyte;
  • lymphocyte;
  • psychiatric co-morbidity

(Headache 2011;51:1228-1238)

Objective.— To evaluate the number of immune cells in the peripheral blood of medication-overuse headache (MOH), chronic migraine (CM), and migraine without aura (MWA) patients, as well as from controls.

Background.— Migraine has been linked to immunologic disturbances, but the role of the immune system in chronic forms of headache that evolve from migraine has not been studied. Psychiatric co-morbidity has been related to both headache chronification and immunologic alterations.

Methods.— This cross-sectional study comprised 68 subjects divided in 4 groups: MOH, CM, MWA, control. Subjects were gender-matched, had no physical co-morbidity, and were taking only acetaminophen. Clinical and psychological data were recorded in a standardized protocol. Samples of peripheral blood for hematological analysis were obtained in the morning during the ictal (MOH, CM, and MWA groups) and interictal periods (MWA group), as well from control group.

Results.— A higher lymphocyte count was measured in MOH patients relative to the MWA patients (mean ± standard deviation: 2448.7/mm3 ± 775.8 vs 1859.7/mm3 ± 564.7; P = .027). The numbers of blood lymphocytes for CM and control subjects were 2086.1/mm3 ± 540.5 and 1961.7/mm3 ± 385.6, respectively. Multiple linear regression analysis demonstrated that only MOH and MWA groups remained associated with lymphocyte count (B = 540.7; CI 95%: 55.2-1026.1; P = .03; R2 = 19.2%). Analysis for linearity of variables in the spectrum control/MWA/CM/MOH resulted positive for body mass index (from 23.5 ± 3.25 in controls to 26.5 ± 4.49 in MOH patients; P = .034), scores on Beck Depression Inventory (from 3.29 ± 3.05 to 14.65 ± 11.21; P < 0.001) and Hamilton Anxiety Scale (from 4.29 ± 3.93 to 23.24 ± 11.01; P < 0.001), hemoglobin (from 13.7 ± 0.79 to 14.6 ± 1.31; P = .022), and lymphocyte count (from 1961.7 ± 385.6 to 2448.7 ± 775.8; P = .01), but negative for CD8+ T lymphocytes (from 34.0 ± 8.82 to 30.0 ± 6.64; P = .046).

Conclusions.— A higher lymphocyte count in the MOH group relative to the MWA group may indicate a chronic inflammatory state. Several clinical and laboratorial characteristics have a range along a spectrum extending from healthy subjects to patients suffering from chronic forms of migraine.