TONIC SEIZURE

A generalized tonic seizure involves bilaterally increased tone of the limbs typically lasting 3 seconds to minutes. They often occur out of sleep, can occur in a series through the night, and can vary in the intensity of tonic stiffening. Mild tonic seizures may show little limb stiffening and may only manifest as eye opening/widening. The individual is unaware during these events. At the beginning of a tonic seizure with more intense stiffening, the individual may make an expiratory sound or grunt. Stronger, more prolonged tonic seizures may include vibratory movement which may be confused with clonic jerking. Tonic seizures often occur in individuals with intellectual impairment.

CAUTION Although asymmetry, such as head and eye deviation, can occur in a generalized tonic seizure, if consistent focal features are seen from seizure to seizure consider a focal to bilateral tonic-clonic seizure or a focal bilateral motor seizure.

NOTE Tonic seizures are one type of seizure that can result in a "drop attack", other causes of drop attacks include myoclonic (especially in younger children), atonic and myoclonic-atonic seizures.