Evaluation of Brainstem Dysfunction in Primary Headache Using the Blink Reflex
Analysis of the blink reflex (BR) is a simple noninvasive method to evaluate the nociceptive brainstem pathways which are implicated in the pathogenesis of primary headaches. In the study, 75 patients of primary headaches were evaluated with the BR in the interictal period. There were 51 patients of migraine (Group I), 16 patients of tension‑type headache (Group II), 8 patients of cluster headache (Group III), and 70 were control patients (Group IV) at a tertiary care referral center. All were subjected to a thorough clinical examination and were then evaluated with the BR. Significantly prolonged R2i and R2c were found in all study groups as compared to controls. An intergroup comparison with the controls revealed significantly prolonged R2i and R2c in the migraine and TTH group but not in the cluster headache group. Thus, abnormalities in the BR were found even in the headache‑free periods in patients with primary headaches, thus implicating persistent sensitization of central brainstem nociceptive pathways. The nonsignificance in cluster headache could be due to small sample size.