Aura (symptom)

An aura is a perceptual disturbance experienced by some with migraine or seizures before either the headache or seizure begins. It often manifests as the perception of a strange light, an unpleasant smell or confusing thoughts or experiences. Some people experience aura without a subsequent migraine or seizure (see silent migraine). Auras vary by individual experience, some people experience smells, lights, or hallucinations. Less known, symptoms of the eye include disturbances, where the eyes roll in the back of the head caused by photosensitive-like symptoms. A sufferer of this type of aura may experience tearfulness of the eyes and uncontrollable sensations of light and followed by reduced symptoms after approximately 20 minutes. This is the rarest type of aura.

When occurring, auras allow epileptics time to prevent injury to themselves and/or others. The time between the appearance of the aura and the migraine lasts from a few seconds up to an hour. The aura can stay with a migraine sufferer for the duration of the migraine; depending on the type of aura, this can leave the person disoriented and confused. It is not uncommon for migraine sufferers to experience more than one type of aura during the migraine. Most people who have auras have the same type of aura every time.

Auras can also be confused with sudden onset of panic, panic attacks or anxiety attacks creating difficulties in diagnosis. The differential diagnosis of patients who experience symptoms of paresthesias, derealization, dizziness, chest pain, tremors, and palpitations can be quite challenging.

Pathophysiology of auras in seizures
An epileptic aura is the consequence of the activation of functional cortex by abnormal, unilateral, and brief neuronal discharge. In addition to being a warning sign to an upcoming seizure, the nature of an aura can give insight into the localization and lateralization of the seizure or migraine.

Not everyone experiences an aura with a seizure, but the most common auras include motor, somatosensory, visual, and auditory symptoms. The activation in the brain during an aura can spread through multiple regions continuously or discontinuously, on the same side or to both sides.

Auras are particularly common in focal seizures. If the motor cortex is involved in the over excitation of neurons, motor auras can result. Likewise, somatosensory auras (such as tingling, numbness, and pain) can result if in the somatosensory cortex. When the primary somatosensory cortex is activated, more discrete parts on the opposite side of the body and the secondary somatosensory areas result in symptoms ipsilateral to the seizure focus. Visual auras can be simple or complex. Simple visual symptoms can include static, flashing, or moving lights/shapes/colors caused mostly by abnormal activity in the primary visual cortex. Complex visual auras can include people, scenes, and objects which results from stimulation of the temporo-occipital junction and is lateralized to one hemifield. Auditory auras can also be simple (ringing, buzzing) or complex (voices, music). Simple symptoms can occur from activation in the primary auditory cortex and complex symptoms from the temporo-occipital cortex at the location of the auditory association areas.

Examples
An aura sensation can include some or a combination of the following:

Visual changes

 * Bright lights and blobs
 * Zigzag lines
 * Distortions in the size or shape of objects
 * Vibrating visual field
 * Scintillating scotoma
 * Shimmering, pulsating patches, often curved
 * Tunnel vision
 * Scotoma
 * Blind or dark spots in the field of vision
 * Curtain-like effect over one eye
 * Slowly spreading spots
 * Kaleidoscope effects on visual field
 * Temporary blindness in one or both eyes
 * Heightened sensitivity to light

Auditory changes

 * Hearing voices or sounds that do not exist: true auditory hallucinations
 * Modification of voices or sounds in the environment: buzzing, tremolo, amplitude modulation or other modulations
 * Heightened sensitivity to hearing
 * Someone speaking at a level and normal tone sounds like they are shouting loudly

Other sensations

 * Strange smells (Phantosmia) or tastes (Gustatory hallucinations)
 * Heightened sensitivity to smell
 * Déjà vu or Jamais vu
 * Cephalic aura, a perception of movement of the head or inside the head
 * Abdominal aura such as an epigastric rising sensation
 * Nausea
 * A sudden feeling of anxiety, fear or foreboding
 * Numbness or tingling sensation (Paresthesia)
 * Weakness on one side of the body (Hemiparesis)
 * Feelings of being separated from or floating above one's body (Dissociation)
 * Sensation of limbs or teeth growing
 * Feeling of overheating and sudden perspiration
 * Inability to speak (Aphasia) or slurred speech
 * Confusion; forgetting how to do common tasks or comprehend spoken words