location-related. What happens during a partial seizure depends upon the exact site and pattern of discharge of abnormal nerve cells. Temporal lobe seizures are of this type.

The abnormal discharge may spread through the connections linking the two halves of the brain, or, by affecting poorly identified central collections of cells, initiate a generalized seizure discharge, in which case the seizure is said to be a partial seizure with secondary generalization (to a convulsive seizure—grand mal). These are also known as tonic-clonic seizures).

The second main class of seizure. In this class of seizure, central collections of nerve cells are in some way abnormal in their behaviour—even though they may appear to be perfectly normal under the microscope. Because of their central position, and the direction and power of their transmissions, a seizure discharge generated within them spreads more or less simultaneously to all parts of the brain. Such a seizure is generalized at onset. Typical absences (often known as petit mal), and some grand mal seizures, are of this type.

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