Definition and Overview
Autonomic symptoms such as nausea, lacrimation, nasal congestion, and facial pallor frequently accompany migraine attacks. More than 50% of migraine patients exhibit autonomic dysfunction both during and between attacks, reflecting the close relationship between migraine pathophysiology and the autonomic nervous system [1].
The trigeminovascular system, the primary pain pathway in migraine, is intimately connected to autonomic pathways through the trigeminal-autonomic reflex. This connection explains the prominent autonomic features of migraine and the overlap with trigeminal autonomic cephalalgias [2].
Cranial Autonomic Symptoms During Migraine
Cranial autonomic symptoms (CAS) occur in 27-73% of migraine attacks and include lacrimation, conjunctival injection, nasal congestion/rhinorrhea, eyelid edema, ptosis, forehead/facial sweating, and aural fullness [3].
Activation of the trigeminal-autonomic reflex via the sphenopalatine ganglion triggers parasympathetic outflow to cranial structures, producing these symptoms. CAS are more common with severe attacks and in migraine with aura.
Interictal Autonomic Dysfunction
Between attacks, migraine patients show altered autonomic function including reduced HRV (decreased parasympathetic tone), orthostatic intolerance, gastrointestinal dysmotility, and pupillary abnormalities [4].
Sympathetic nervous system alterations include cold extremities, Raynaud's phenomenon, and abnormal blood pressure responses to standing.
HRV Assessment in Migraine
HRV analysis reveals reduced overall variability (SDNN) and decreased parasympathetic markers (RMSSD, HF power) in migraine patients compared to controls. HRV changes correlate with attack frequency and may serve as a biomarker for treatment response [5].
Clinical Implications
Understanding the autonomic component of migraine has therapeutic implications. Autonomic assessment (HRV testing, tilt table test) may complement standard migraine evaluation. Treatments targeting autonomic balance, including HRV biofeedback, vagus nerve stimulation, and regular aerobic exercise, show promise as adjunctive migraine therapies.