Prodrome

Prodrome refers to early signs and symptoms that precede the onset of a disease or the acute phase of an attack. Prodromal phases are described in a variety of conditions, including primary headaches, infections, neurodegenerative diseases, and psychiatric disorders. The symptoms are usually nonspecific and may occur hours to days before more characteristic features emerge.

Etiologies vary by condition; for migraines, common prodromal symptoms include mood changes, fatigue, yawning, and changes in appetite or craving. Some patients also report neck stiffness or heightened sensitivity to light and sound, but these features can overlap with the later ictal phase. In infectious illnesses, prodromes commonly include malaise, low-grade fever, headache, myalgia, and irritability.

In Parkinson's disease and some other neurodegenerative disorders, a prodromal phase may precede the classic motor symptoms by years and may include reduced sense of smell (hyposmia), constipation, REM sleep behavior disorder, and subtle cognitive or mood changes.

Prodrome is distinct from an aura, particularly in migraine. An aura consists of definite focal neurological symptoms such as visual disturbances or sensory changes that directly herald an attack, whereas the prodrome is often nonspecific and not limited to a single neurological system.

Recognition of prodromal signs can aid in early management or prevention, such as initiating migraine treatment sooner or monitoring for disease onset. However, prodromal symptoms are not reliably diagnostic on their own and can be highly variable across individuals and conditions.