Seizures ll: Types

Focal seizures begin in a single brain region, while generalized seizures engage both sides of the brain from the onset. Focal seizures may preserve awareness, causing sensations like tingling or flashing lights, or impair awareness with blank staring. Generalized seizures always impair consciousness and include tonic-clonic, absence, myoclonic, tonic, clonic, and atonic types.

During a focal aware seizure, abnormal electrical activity occurs in one brain region while awareness is preserved. A person may experience sensory symptoms such as tingling, unusual smells, or flashing lights. These symptoms reflect the specific brain area affected and can serve as warning signs before the seizure progresses.

Focal impaired awareness seizures involve abnormal activity in one brain region with loss of consciousness. The person may stare blankly or perform repetitive movements like lip-smacking or hand-rubbing. These seizures can sometimes spread to both brain hemispheres, becoming focal to bilateral tonic-clonic seizures with stiffening and jerking.

Generalized seizures include tonic-clonic seizures with muscle stiffening and rhythmic jerking, absence seizures with sudden lapses in awareness, myoclonic seizures producing shock-like jerks, tonic seizures involving muscle stiffening, clonic seizures with rhythmic jerking, and atonic seizures causing sudden collapse. All generalized seizures impair consciousness from onset.

Atonic seizures, also called drop attacks, cause sudden loss of muscle tone leading to collapse. The person falls without warning due to complete loss of postural control. These seizures often result in injury from the sudden fall and represent one of the most dangerous generalized seizure types.

Absence seizures are brief lapses in awareness where the person suddenly stops and stares, often mistaken for daydreaming. They are generalized seizures that always impair consciousness and are particularly common in children. These seizures are typically brief but may occur multiple times daily.

Epileptic spasms, often seen in infants, involve sudden bending or extension of the body, usually occurring in clusters. Reflex seizures are triggered by specific stimuli such as flashing lights, sudden sounds, or even reading. Both types represent seizures that do not fit neatly into standard focal or generalized classifications.