An aura is a subjective physical, sensory, or emotional sensation that marks the beginning of a focal seizure. It originates from abnormal electrical activity starting in a specific brain area, and the resulting sensation depends on the function of that brain region. While often described as a warning sign, the aura itself is technically the start of the seizure, classified as a focal aware seizure. The duration of this warning is highly variable among individuals and even between different seizure types in the same person.
Typical Duration and Variability
The time an aura lasts before progressing to a more severe seizure is typically very short, often less than one minute. This brief window reflects the speed at which the abnormal electrical discharge spreads from its focal point to other brain areas. The median duration for auras that progress into a full seizure has been reported to be around 60 seconds in some studies.
The variability in duration is directly related to the seizure focus location and the brain’s anatomy. For instance, a temporal lobe seizure might cause a prolonged experiential aura, such as déjà vu, before spreading. Conversely, a discharge beginning in a motor area might progress almost instantaneously to observable movements. If the electrical activity spreads quickly across the cerebral cortex, the aura will be significantly shorter than if the activity remains localized. Auras rarely extend past one to two minutes before the seizure progresses or resolves.
The Distinction Between Aura and Prodrome
An aura and a prodrome represent distinct phases of the seizure process with very different time frames. The aura is a direct manifestation of the initial electrical discharge and is considered the first part of the seizure event itself. It is an immediate, specific warning that occurs seconds or minutes before the seizure progresses. Common aura symptoms include specific sensory changes like unusual smells, flashing lights, or sudden intense emotions.
The prodrome is a less specific set of symptoms that can occur hours or even days before a seizure. This phase is not part of the seizure itself but signals a potential seizure is brewing, often described as a general feeling of being unwell. Symptoms in this longer phase may include fatigue, headache, irritability, difficulty sleeping, or mood changes. Recognizing this distinction is vital because the prodrome provides a much wider, though less certain, window of anticipation than the immediate aura.
When the Aura Is the Seizure
In some cases, the aura does not precede a more widespread event but rather constitutes the entire seizure itself. This is classified as a focal aware seizure, formerly known as a simple partial seizure. During a focal aware seizure, the person remains fully conscious and aware of their surroundings, even while experiencing the unusual sensation of the aura. The abnormal electrical activity remains confined to a small region of the brain without spreading to cause impaired awareness or full body convulsions.
When the aura is the entire seizure, it can last longer than the typical pre-seizure warning, often up to two minutes. These events can manifest as a specific, localized sensory experience, such as a tingling sensation in one limb, a strong feeling of fear or panic, or complex hallucinations like hearing sounds or seeing formed images. Since awareness is preserved, the person can usually recall the entire event, which is why the aura is often the only symptom reported. In rare instances, a phenomenon called “aura continua” can occur, where these sensory symptoms persist for hours or even days, representing a form of focal status epilepticus.
Immediate Action Steps During the Aura
Because the aura provides only a brief window of warning, immediate action steps must be swift and focused on safety. The goal is to minimize the risk of injury should the seizure progress or cause a loss of awareness. The person should immediately move away from potential hazards, such as stairs, sharp objects, or machinery.
Getting to a safe position, usually sitting or lying down on the floor, is essential. If possible, position yourself in an open area and place something soft, like a jacket or cushion, under your head. Alerting a trusted person nearby is helpful so they can monitor and assist. Removing glasses or loosening tight clothing around the neck can prevent injury and aid breathing if the seizure progresses.