Migraine is a complex neurological disorder characterized by recurrent attacks involving debilitating symptoms like intense pain, nausea, and sensitivity to light and sound. Classification is primarily based on the frequency of these attacks, which is important for appropriate treatment.
Defining Episodic Migraines
Episodic migraine is the most common classification, defined by the frequency of headache days per month. The International Classification of Headache Disorders, 3rd edition (ICHD-3), establishes this diagnosis when a person experiences fewer than 15 headache days each month. A diagnosis requires at least five lifetime attacks that meet the full criteria for a migraine, lasting between four and 72 hours if left untreated.
These attacks must display specific characteristics, including a pulsating quality and moderate to severe pain intensity. The pain is often located on one side of the head and is aggravated by routine physical activity. Additionally, the attack must be accompanied by at least one non-headache symptom, such as nausea, vomiting, or sensitivity to light (photophobia) and sound (phonophobia).
Distinguishing Episodic from Chronic Migraines
The defining difference between episodic and chronic migraine is the number of headache days experienced over a period of time. Episodic migraine exists on one end of a spectrum, while chronic migraine is defined by having headaches on 15 or more days per month for at least three months. For a chronic diagnosis, at least eight of those monthly headache days must exhibit the full features of a migraine attack. This threshold is a key distinction for determining the most appropriate long-term management strategy.
Episodic migraine can evolve into chronic migraine. Approximately three percent of people with episodic migraine transition to the chronic form each year. This progression is associated with greater disease severity and significantly impacts quality of life. Understanding this potential encourages proactive management to maintain the lower frequency of episodic attacks.
The Four Phases of a Migraine Attack
A single migraine event typically progresses through four distinct phases, although not everyone experiences all of them. The first phase is the Prodrome, which can begin hours or days before the actual headache pain starts. Symptoms include subtle changes like increased yawning, food cravings, mood shifts, or neck stiffness. Recognizing these early warning signs allows for earlier treatment intervention.
The second phase is the Aura, which occurs in about one-third of people with migraine. Aura involves temporary, reversible neurological symptoms that usually precede the headache phase. Visual disturbances are the most common form, manifesting as flashing lights, zigzag lines, or temporary blind spots. Other aura symptoms may include sensory changes, such as numbness or a “pins-and-needles” sensation in the face or limbs, or difficulty speaking. These symptoms generally last from five to 60 minutes.
The third phase is the Attack phase, which is when the head pain is most intense. This stage is characterized by the moderate-to-severe, throbbing, or pulsating pain often on one side of the head. Nausea, vomiting, and extreme sensitivity to light and sound are common during this phase. The attack phase can be highly debilitating, lasting anywhere from four to 72 hours.
Finally, the Postdrome phase, sometimes called a “migraine hangover,” follows the resolution of the head pain. During this final stage, people often feel drained, fatigued, and experience difficulty concentrating. Other lingering symptoms can include body aches or a mild continuation of the sensitivity to light. This phase can last up to a day after the primary headache has subsided.
Diagnosis and Initial Management
The diagnosis of episodic migraine is primarily clinical, meaning there is no single blood test or imaging scan to confirm the condition. A healthcare professional relies heavily on a detailed patient history and the documentation of symptoms to match them against the established ICHD-3 criteria. A headache diary is a valuable tool in this process, helping to track the frequency, duration, intensity, and associated symptoms of each attack.
Management strategies for episodic migraine fall into two main categories: acute (or abortive) and preventive treatments. Acute treatments are taken at the onset of an attack to stop it from progressing and relieve the pain. These include over-the-counter medications like nonsteroidal anti-inflammatory drugs (NSAIDs), as well as migraine-specific prescription drugs such as triptans and CGRP antagonists.
Preventive treatments involve medications taken regularly to reduce the overall frequency and severity of attacks. These are used if attacks are frequent, severe, or significantly impacting quality of life. Classes of preventive medications include certain beta-blockers, anti-seizure medications, and CGRP monoclonal antibodies. Lifestyle adjustments, such as managing stress, maintaining a consistent sleep schedule, and avoiding known triggers, also form a large part of initial management.