Interictal Burden of Migraine: A Narrative Review

Migraine is a chronic neurological disorder associated with substantial disability and societal costs. Traditionally, research and clinical care have focused on the ictal phase, characterized by headache and accompanying symptoms. However, growing evidence suggests that a considerable portion of migraine-related disability occurs between attacks, known as the interictal burden (IIB). IIB encompasses a wide spectrum of cognitive, emotional, sensory, and functional impairments that persist during headache-free periods, including fatigue, allodynia, photophobia, cognitive dysfunction, anticipatory anxiety, and social withdrawal. These symptoms can markedly reduce quality of life, work productivity, and family functioning, even in individuals with infrequent attacks. In a descriptive survey of 506 migraine respondents, 67% experienced severe IIB. The effects of IIB extend beyond patients themselves, contributing to presenteeism in the workplace and imposing emotional and logistical strain within families. Several instruments, including the Migraine Interictal Burden Scale (MIBS-4), Migraine-Specific Quality of Life Questionnaire (MSQ v2.1), Headache Impact Test (HIT-6), and Migraine Disability Assessment (MIDAS), have been employed to assess different dimensions of IIB. Nonetheless, no single comprehensive and standardized tool fully captures the multidimensional nature of IIB. Recognizing and addressing IIB is essential for delivering holistic, patient-centered migraine care. Future research should focus on developing validated assessment instruments and incorporating IIB measures into clinical trials and routine practice to better understand and alleviate the hidden burden of migraine.