Focal Seizure
A focal seizure starts in a specific, localised region of the brain rather than spreading across both hemispheres at once. Because the affected region varies from person to person, the experience can look very different: one person may notice rhythmic twitching in one hand while remaining fully conscious; another may stare blankly and be unaware of what is happening around them for a minute or two.
Key points
- Seizures are classed as aware, with consciousness intact, or impaired-awareness, involving automatic movements such as picking at clothing.
- An aware focal seizure can bring an odd smell or taste, a rising feeling in the stomach, or jerking confined to one limb.
- Phenytoin, an older anticonvulsant, calms overactive brain cell firing, though its narrow therapeutic range means blood levels need regular checks.
How a focal seizure presents
Focal seizures are grouped by whether awareness is preserved. In a focal aware seizure the person stays conscious and may feel a strange smell, taste, rising sensation in the stomach, or jerking in one limb. In a focal impaired-awareness seizure consciousness is reduced and the person may pick at clothing, make chewing movements, or wander without purpose. Either type can occasionally spread to involve both sides of the brain, becoming a generalised tonic-clonic seizure.
Managing focal seizures
Long-term control usually involves an anticonvulsant medicine. Phenytoin is one of the older agents in the neurology toolkit; it works by stabilising electrically excitable membranes in the brain and slowing the abnormal firing that drives a focal seizure. Blood levels need periodic monitoring because the therapeutic range is narrow.
Seek urgent medical attention if a seizure lasts longer than five minutes, if seizures cluster without recovery between them, or if a first-ever seizure occurs.