Causes and Symptoms of a Migraine Aura

Visual, speech, and sensory disturbances commonly seen

Man with headache
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In a little more than 30 percent of cases, a migraine will be preceded by a neurological disturbance known as an aura. Auras primarily involve the vision but can also include sensory, speech, and even motor impairment. They typically start anywhere from a few minutes to an hour before migraine pain occurs, developing gradually rather than all at once.

Auras can also occur during a migraine headache itself and, in some cases, without any pain at all (a condition known as a migraine equivalent).

Typically speaking, aura symptoms will last from five to 60 minutes and fully resolve on their own with no physiological damage of any sort.

Visual Symptoms of a Migraine Aura

People experiencing a migraine aura will often notice a bright spot or a small loss of vision (scotoma) in their central field of vision. That visual anomaly will then gradually expand and move into the person’s peripheral vision. It is during this stage that a person can experience other optical disturbances, including:

  • flashing or shimmering lights
  • visual hallucinations such as zigzag lines or shifting, kaleidoscopic shapes
  • light sensitivity (photophobia)
  • blurred vision
  • eye pain

Neurological Symptoms of a Migraine Aura

Neurological symptoms can also occur during a migraine aura, either on their own or in association with visual symptoms. It will often start with the tingling of a limb or on one side of the face.

The sensation will then usually migrate to other parts of the body — like from the right shoulder to the right forearm — but almost exclusively on one side of the body, not both.

(This is because most nerves are peripheral, meaning that service either the right or left side of the body.) As the sensation migrates, it leaves behind a numbness that eventually dissipates.

Speech or language difficulties are also known to occur, either on their own or in association with visual and/or sensory disturbance.

In rarer cases, the temporary loss of motor control can occur, although this is more commonly seen in a hemiplegic migraine rather than during a migraine aura.

Diagnosing a Migraine Aura

Doctors will most typically make a diagnosis based on a person's medical history and review of symptoms. Other tests, such the POUND mnemonic (which aims to pinpoint the type of symptoms) and the ID questionnaire (which aims to determine the severity of symptoms), can be helpful in confirming a migraine diagnosis.

An informed clinician will also aim to distinguish the aura symptoms from other serious neurological conditions such as a stroke or seizure. If there are any doubts as to the cause, a magnetic resonance imaging (MRI) scan of the brain would likely be ordered.

Spotting the Early Warning Signs of a Migraine

In about 30 percent of cases, a migraine will be preceded by what we call premonitory symptoms (think "premonition"). These are not facets of a migraine aura but rather an early warning sign of an approaching migraine.  

Premonitory symptoms tend to occur a day or two before a migraine and can often be quite subtle.  The most common features include:

  • fatigue
  • irritability
  • loss of appetite
  • food cravings
  • nausea
  • vomiting
  • chills
  • increased urination
  • increased sweating
  • facial swelling

While these symptoms are largely nonspecific, a combination of symptom may provide us enough warning so that we can avoid the triggers that worsen an attack. In some cases, it may even allow us to head off an attack entirely.

Source

  • International Headache Society. "The International Classification of Headache Disorders (3rd Edition.)" Cephalalgia. 2013; 33(9):629-808.

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