The interictal symptom burden in vestibular migraine-a condition in need of recognition

Vestibular migraine (VM) by current definition is an episodic vestibular disorder, yet many patients experience vestibular symptoms that persist beyond discrete attacks and extend into the interictal phase. Symptoms like head-motion intolerance, visually induced dizziness, positional vertigo, and increased susceptibility to motion sickness form an interictal symptom profile, which is often accompanied by migraine-associated sensory hypersensitivities. Clinical, psychophysical, vestibular laboratory, and ocular motor findings indicate altered central vestibular sensory and oculomotor networks, rather than a primary peripheral vestibular disorder. Longitudinal data indicate that interictal vestibular symptoms and ocular motor abnormalities are common and may increase over time, even when attack frequency decreases. These observations support a spectrum-based view of VM, in which episodic attacks and persistent interictal symptoms represent different clinical expressions within the same disorder. This narrative review summarizes current evidence on persistent interictal manifestations of VM and discusses implications for diagnosis and clinical decision-making in patients with episodic and chronic vestibular migraine phenotypes, using an operational definition of chronic vestibular migraine based on symptom frequency, for which preliminary diagnostic criteria are proposed.