Aura

An aura is the perceptual disturbance experienced by some migraine sufferers before a migraine headache, and the telltale sensation experienced by some people with epilepsy before a seizure. It often manifests as the perception of a strange light, an unpleasant smell or confusing thoughts or experiences.

When occurring, auras allow epileptics time to prevent injury to themselves. The time between the appearance of the aura and the migraine lasts from a few seconds up to an hour. 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.

An aura sensation can include some or a combination of the following:
- Visual Changes.
- Bright lights.
- Zigzag lines.
- Distortions in the size or shape of objects.
- 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
- Total temporary monocular (in one eye) blindness (in retinal migraine)
- 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.
- Strange smells (Phantosmia).
- Feelings of numbness or tingling on one side of the face or body.
- Feeling separated from one's body.
- Feeling as if the limbs are moving independently from the body.
- Feeling as if one has to eat or go to the bathroom.
- Anxiety or fear.
- Nausea.
- Weakness, unsteadiness.
- Saliva collecting in the mouth.
- Being unable to understand or comprehend spoken words during and after the aura.
- Being unable to speak properly, despite the brain grasping what the person is trying to verbalize. (Aphasia)

The specific type of sensation associated with an aura can potentially be used in an attempt to localize the focus of a seizure.
Auras share similar symptoms with strokes, but onset is more gradual with auras. Auras can last from several seconds to several minutes and can sometimes end with feelings of extreme tiredness, weakness, heart palpitation, sweating and warmth throughout one's body.
From the Greek meaning ‘breath’, the word aura is mostly used in the metaphorical sense of someone having simply ‘an aura’ about him or, more vividly, one of ‘wisdom’, ‘saintliness’, or ‘evil’. However, for those suffering migraine or epilepsy, an aura is no longer simply a metaphor relating to their perception of a person in the external world but now a disagreeable perceptual experience heralding an impending attack of their sick headache or convulsion (grand mal). In the case of migraine the aura is most commonly visual. The images do not relate to previous visual experience but can take the form of scintillating, wavy patterns of bright, silvery light that superimpose on the current visual image — but in contrast to the latter they persist when the eyes are closed.
In epilepsy the simplest form of aura may be an ill-defined feeling of uncertainty or nausea preceding a convulsion. This may be an expression of changes in the cardiovascular and digestive systems induced by the autonomic nervous system as an early aspect of the epileptiform activity within the brain. Undoubtedly the most remarkable ‘aura’ occurs in the particular type known as ‘temporal lobe epilepsy’. At its simplest the aura may take the form of a familiar odour, or more commonly a disagreeable or even disgusting one. At its most complex the aura can be a perceptually complete image of a person with no counterpart in the external world. Such an image is to be distinguished from one summoned voluntarily in the mind's eye, or from an illusion due to the brain's interpretation of conflicting visual stimuli from the external world. Instead, that of the aura is a remarkable product of the uncontrollable discharge of neurones associated with an epileptiform focus in the temporal lobe(s) of the brain, demonstrable in the recording of the electrical activity of the brain, and, when the severity of the condition demands, abolished by surgical removal of the offending lobe.

By— Tom Sears