Seizures ll: Types

Seizures are sudden bursts of abnormal electrical discharge in the brain that interfere with normal function. They are commonly divided into three groups: focal seizures, generalized seizures, and other types that do not fit neatly into either category.

Focal Seizures

• Focal seizures begin in a single brain region. When awareness is preserved, they are called focal aware seizures and may cause sensations such as tingling, unusual smells, or flashing lights. When awareness is impaired, they are called focal impaired awareness seizures. In these cases, the person may stare blankly or perform repetitive movements, like lip-smacking or hand-rubbing. Sometimes, focal seizures spread to both hemispheres, becoming focal to bilateral tonic-clonic seizures.

Generalized Seizures

• Generalized seizures arise when abnormal electrical activity affects both hemispheres of the brain at once from the start and always impair consciousness. They appear in several distinct forms:
   
  • Tonic-clonic seizures cause body stiffening followed by rhythmic jerking, often with loss of consciousness and post-seizure confusion.
     
  • Absence seizures are brief lapses in awareness, often mistaken for daydreaming, especially in children.
     
  • Myoclonic seizures produce sudden, shock-like jerks in the arms or legs.
     
  • Tonic seizures involve sudden muscle stiffening, sometimes leading to falls.
     
  • Clonic seizures feature rhythmic jerking without a stiffening phase.
     
  • Atonic seizures, or drop attacks, cause a sudden loss of muscle tone and collapse, often leading to injury.

Other Types

• Some seizures are more complex to classify. Epileptic spasms, often seen in infants, involve sudden bending or extension of the body, usually in clusters. Reflex seizures are triggered by stimuli such as flashing lights, sudden sounds, or even reading. In some cases, seizures remain unclassified because their features do not match established patterns.