Symptoms & Warning Signs: What to Expect During an Attack

While a typical migraine is often defined by head pain, a hemiplegic migraine (HM) is defined by its aura—a set of temporary neurological changes that happen before or during the headache ^[1]. Understanding the sequence of these symptoms can help you feel more in control when an attack begins.

The Sequence of an Attack

Unlike a standard migraine, an HM attack can be a “slow-motion” event that unfolds over several hours or even days ^[2][3].

1. The Aura Phase (5–60 Minutes): Most attacks begin with a “wave” of symptoms that build gradually ^[4]. You might notice visual changes (like flashing lights or blind spots), followed by numbness or tingling in the face or arm ^[1][5].
2. The Motor Phase: This is the defining feature of HM. You will experience hemiparesis—weakness on one side of the body ^[1]. This weakness often spreads over 5 to 60 minutes and can affect the face, arm, and leg ^[4].
3. Language and Speech: Many people experience aphasia (difficulty finding words) or slurred speech during this phase ^[3][6].
4. The Headache Phase: The headache can start during the weakness or after it begins to fade ^[1]. Crucially, the headache can be very mild or completely absent. The severe motor aura is the true defining feature, so do not doubt your diagnosis just because the head pain is minimal.

Duration: Hours vs. Days

In a typical migraine, the aura almost always lasts less than 60 minutes. In HM, the motor weakness is much more persistent ^[2]. While it is fully reversible, it frequently lasts for several hours, and in some cases, days or even weeks ^[2][7].

Additionally, you may experience a “migraine hangover” (postdrome) once the weakness resolves. Cognitive fatigue, brain fog, and exhaustion can linger for days, which is a normal part of the recovery timeline.

Red Flags: When to Seek Emergency Care

Your first few attacks will likely be treated as a medical emergency ^[8] (see Treatment & ER Protocols for creating an action plan). The following “red flag” symptoms indicate a severe attack that requires immediate medical evaluation:

• Encephalopathy: Severe confusion, disorientation, or “brain fog” that makes it hard to recognize people or follow simple instructions ^[9][10].
• Fever: A significant rise in body temperature during the attack ^[9].
• Seizures: Involuntary shaking or loss of awareness ^[11].
• Altered Consciousness: Extreme sleepiness that makes the person difficult to wake up, or, in very rare cases, a complete loss of consciousness (coma) ^[9].

Genetics and Severity

Research shows that these severe “red flag” symptoms are more common in people with specific genetic mutations, particularly the ATP1A2 (FHM2) gene ^[9][11] (learn more in Biology, Genetics, and Diagnosis). Understanding your specific genetic type can help your medical team predict how your attacks might behave and what complications to watch for.

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