Seizure Disorders

Seizure disorders, or convulsions, are the most common neurological condition of childhood. Seizures are the outwardly visible sign of an abnormal electrical discharge in the brain, which, depending on the type, are associated with various degrees of loss of consciousness and/or involuntary motor activity. Seizure disorders are usually placed in one of three broad classifications (partial, generalized, or unclassified), with more specific categories described within each classification.

Partial seizures typically involve a more limited number of nerve cells in the brain than generalized seizures and account for up to 40% of the seizures diagnosed. Partial seizure disorders are classified into three types, which refer to the degree of consciousness involved:

• 1.
  Simple partial
• 2.
  Complex partial
• 3.
  Partial with secondary generalization

Simple partial seizures typically do not impair consciousness, but they do manifest asynchronous movements that usually involve the neck, face, and/or extremities that last for 10 to 20 seconds. In contrast, complex partial seizures (with or without an aura) do involve an impairment of consciousness. Approximately 33% of children with seizures report an aura consisting of a vague, unpleasant feeling and/or undifferentiated fear. Presence of an aura usually indicates a focal onset of a seizure. Children undergoing this type of seizure often engage in automatic, uncoordinated, purposeless behaviors such as walking or running in a repetitive, nondirective fashion; rubbing objects; picking at clothing; and blank stares. Partial seizures with secondary generalization refer to seizures that spread to other parts of the brain and show a convulsion.

Generalized seizures involve larger areas of the brain than partial seizures and typically involve a loss of consciousness. They are categorized—depending on the type of body involvement exhibited during the seizure—as absence, tonic-clonic, myoclonic, or atonic. Absence seizures (previously called petit mal seizures) are seen most commonly in children. This type of seizure involves abrupt changes in consciousness characterized by a rapid cessation of motor activity and a blank, staring appearance with eyelid flickering. [Page 488]These seizures are never associated with an aura and rarely last more than 30 seconds. Historically, absence seizures have been misdiagnosed as a form of attention deficit because the children were observed to not be paying attention. In contrast, tonic-clonic seizures (previously called grand mal seizures) involve sudden loss of consciousness with convulsions that involve stiffening then jerking of the limbs. These may follow a partial seizure. Tonic seizures involve stiffening of extremities without jerking, while clonic seizures involve the jerking without the stiffening of the extremities. The rest of the specific generalized seizure disorders involve minor motor seizures. Myoclonic seizures involve brief, involuntary, rapid muscle contractions. Atonic or astatic seizures are sometimes called drop attacks because they involve abrupt loss of posture tone, which may result in falling forward. Atypical generalized seizures are those that don't fit into the typical categories. Unclassified seizures are typically initial seizures where more information is needed before a classification can be made.