Migraine is much more than just a headache.

It’s a common neurological disease that affects about 39 million people in the United States.

Migraine can be classified as episodic or chronic. If you have 14 or fewer headache days per month, you have what’s called episodic migraine, or migraine episodes.

But if you experience more than 15 headaches per month, you likely have chronic migraine. It’s important to treat a migraine so that it doesn’t go from episodic to chronic.

The symptoms of migraine can be debilitating, often lasting from hours to days. These may include:

  • moderate to severe head pain
  • nausea or vomiting
  • sensitivity to light or sound
  • pain that gets worse with physical activity

Some people might have migraine with an aura. This is a visual or sensory disturbance that appears before a migraine episode. It can also cause vision loss or blurred vision.

One type of aura is called “fortification illusion” because the shapes you see resemble the walls of a castle.

This article will explore migraine fortification illusions, including symptoms, other types of migraine auras, and what to expect from a migraine episode.

The best known visual aura is referred to as a migraine fortification spectra. This can manifest in many different ways.

“Fortification illusion specifically refers to a visual hallucination where geometric lines arrange themselves in something that many say looks like a castle fortification,” says physical therapist Jason Schuster.

It usually begins at the center of your field of vision and then moves outward. “The geometric lines typically continue to shift and move and various colors may accompany them,” Schuster says.

Some people may even experience partial loss of vision, which is referred to as a “scotoma.” Fortification illusions are sometimes referred to as scintillating scotoma.

Most migraine fortification illusions symptoms last for fewer than 30 minutes, followed by an intense headache that can last 4 to 6 hours. Some may not experience a headache at all.

“People can sometimes experience migraine fortification illusions without headaches, but with other visual or illusion symptoms,” explains Leva Kubiliute, a wellness psychologist at oliolusso.com.

Not all auras are visual. Some may also experience a temporary sequence of sensory and auditory disturbances.

This may include:

  • Sensory aura. You may experience a feeling of tingling or numbness; for example, a feeling of pins and needles that travels up your arm before turning numb.
  • Aphasia. Aphasia affects speech. You may have difficulty putting words together or processing written words.
  • Auditory or dysphasic aura. This includes hearing voices, although auditory hallucinations are extremely rare with auras. Auras indicate how the brain nerve cells are arranged — not hearing or seeing things that our mind makes up.

There are typically four migraine episode stages, though not all four always occur.

1. Prodrome

This stage is also known as the “preheadache” or “premonitory stage.” It can last several hours or even days.

Symptoms can include:

  • irritability
  • depressed mood
  • cravings for specific foods
  • thirst
  • trouble concentrating
  • hyperactivity
  • neck pain or stiffness
  • tiredness, with lots of yawning

2. Aura

About 20 percent of people will get a migraine with aura. It typically occurs about 10 to 30 minutes before a headache and only lasts less than 60 minutes before the headache sets in.

Visual disturbances are the most common symptom of aura. This includes seeing zigzag patterns, flashing sparks, and bright dots or lines.

Some people also experience other disturbances, such as:

  • speech issues
  • numbness or tingling in the face or limbs
  • muscle weakness
  • temporary blindness
  • feeling dizzy or off balance

3. Headache

This is the “attack” stage of a migraine. It’s when the throbbing pain in the head or neck can last from a few hours to a few days.

While symptoms vary by individual, they most commonly include:

  • sensitivity to light, sounds, and smells
  • nausea, vomiting, or both
  • lightheadedness or dizziness
  • difficulty sleeping
  • mood changes

4. Postdrome

Postdrome, also known as the migraine hangover stage, occurs when your headache stops. After the attack stage, you may feel very drained.

This stage can last 24 to 48 hours, although not everyone will experience it.

Common symptoms may include:

  • fatigue
  • brain fog
  • sluggishness
  • confusion
  • dehydration
  • depressed mood
  • euphoric mood

When you’ve never had a migraine episode with aura before, it can be scary to suddenly go through the symptoms.

That’s why you should visit a doctor if you experience any of the following:

  • You have several headaches that last for hours or days.
  • Your headaches are affecting your daily life, such as work, school, and home life.
  • Your headaches are accompanied by a stiff neck.
  • Your headaches appeared when you used to be headache-free, or there is a significant change in how the headache feels.
  • You’re having an especially bad episode.
Medical emergency

The symptoms of a severe migraine often mimic symptoms of serious conditions, such as a stroke or seizure. Call emergency services or go to the nearest emergency room if you experience any of the following:

  • headache that comes on suddenly and severely
  • headache that occurs with other symptoms, such as confusion, loss of consciousness, or convulsions
  • headache that happens after a head injury
  • numbness on one side of your body

A fortification illusion aura is one common type of aura experienced during a migraine episode. It’s so named because the images you see resemble castle walls.

If you experience migraine episodes often, or start having them suddenly, you should contact a doctor.