Generalized tonic-clonic (GTC) seizures (formerly called grand mal seizures) usually are not difficult to diagnose. The loss of consciousness usually occurs simultaneously with the onset of a generalized stiffening of flexor or extensor muscles (the tonic phase). After the tonic phase, generalized jerking of the muscles (clonic activity) occurs. A GTC seizure is almost always followed by deep postictal sleep.
Some patients may have a simple partial seizure (aura) preceding the loss of consciousness. This indicates that the onset of the seizure is located in a limited area. As the seizure spreads in the cortex, the seizure develops into a GTC seizure. This type of seizure is classified as a simple partial seizure with secondary generalization.
Two types of episodes that may end with brief generalized tonic-clonic seizures should not be treated with antiepileptic drugs:
Reviewed and revised January 2004 by Gregory L. Holmes, MD, Dartmouth Medical School
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