Focal Seizure | Can You Be Aware of What's Happening During a Seizure?

A focal aware seizure, formerly known as a simple partial seizure, originates in a specific, localized area of one cerebral hemisphere. The defining characteristic of this seizure type is the complete preservation of consciousness and awareness. The individual remains awake, alert, and able to recall the events that occurred during the episode. The symptoms experienced are entirely dependent on the function of the brain region where the abnormal electrical activity begins. For example, if the seizure starts in the motor cortex, symptoms may include twitching or jerking of a limb. If it originates in the occipital lobe, the primary visual processing center, the person might experience visual phenomena like flashing lights or colors. Similarly, a seizure in the temporal lobe can cause sensory experiences like strange smells or sounds, or evoke strong emotions such as sudden fear or joy. These episodes are typically brief, often lasting less than two minutes. It is critical to understand that these experiences are not imagined; they are real neurological events caused by a temporary disruption in brain function.

A focal impaired awareness seizure, previously called a complex partial seizure, also starts in a specific area of the brain but is distinguished by a change in consciousness or awareness. The individual may not lose consciousness completely—they might remain standing or appear awake—but their connection to and awareness of their environment is disrupted. They will not respond normally to questions or commands and will have no memory, or only a fragmented memory, of the event afterward. A key feature of this seizure type is the presence of "automatisms." These are involuntary, repetitive behaviors performed during the seizure. Common automatisms include lip smacking, chewing motions, fumbling with clothes, or picking at objects. The person is not in conscious control of these actions. These seizures often originate in the temporal or frontal lobes, areas of the brain involved in memory, emotion, and executive function. The duration is typically between one and three minutes, and the person may feel confused, tired, or disoriented for a period following the seizure.

The term "aura" can be misleading. In neurology, an aura is not a pre-seizure warning but is, in fact, the seizure itself. Specifically, an aura is a focal aware seizure. It represents the initial phase of abnormal electrical activity in the brain. The symptoms of the aura are the seizure's first noticeable manifestation. For some individuals, this focal aware seizure (the aura) is the entire event. For others, the electrical activity spreads to other parts of the brain, leading to a focal impaired awareness seizure or a generalized seizure where consciousness is lost and convulsions may occur. Therefore, experiencing an aura like a rising sensation in the stomach, a feeling of déjà vu, or smelling something that isn't there, is a definitive sign that a seizure has already begun. Recognizing it as such is crucial for safety and management.

While focal seizures can often occur without an identifiable trigger, certain internal and external factors can increase their likelihood in susceptible individuals. One of the most common triggers is sleep deprivation, as fatigue lowers the seizure threshold. Emotional and physical stress are also significant contributors, as they alter hormonal and neurotransmitter levels in the brain. Other potential triggers include illness or fever, hormonal changes associated with the menstrual cycle, and exposure to flashing or flickering lights (photosensitivity), although this is more common in generalized epilepsies. Missing doses of anti-seizure medication is a primary cause of breakthrough seizures. Less common triggers can include specific sounds or even complex thought processes in rare forms of reflex epilepsy. Identifying and managing personal seizure triggers is a key component of effective epilepsy care, although it must be noted that for many, seizures remain unpredictable.

The diagnosis of focal seizures is a multi-step process that begins with a thorough clinical evaluation. The most critical component is the detailed description of the event, provided by the patient and any witnesses. The neurologist will ask specific questions about what the person experienced before, during, and after the seizure to determine if awareness was maintained and to identify symptoms that point to a specific brain region. A neurological examination is performed to assess brain function. The primary diagnostic tool is the electroencephalogram (EEG), which records the brain's electrical activity. An EEG can capture abnormal spike-and-wave patterns and help pinpoint the seizure's origin. For more detailed information, long-term video-EEG monitoring may be required. Neuroimaging, particularly Magnetic Resonance Imaging (MRI), is essential. An MRI provides a detailed picture of the brain's structure, allowing clinicians to identify potential causes for the seizures, such as brain tumors, scarring from a previous injury (gliosis), or developmental abnormalities.