The type of seizure that affects both sides of the brain is called a generalized seizure. These seizures begin with widespread electrical activity involving both hemispheres of the brain simultaneously and usually cause symptoms that affect both sides of the body. Generalized seizures often involve a loss of consciousness or awareness and can include muscle stiffening, jerking movements, or staring spells. There are several main types of generalized seizures:
- Generalized tonic-clonic seizures (formerly called grand mal seizures) cause the body to stiffen (tonic phase) and then convulse or shake (clonic phase).
- Absence seizures (formerly petit mal seizures) cause brief staring spells without convulsions.
- Myoclonic seizures involve brief, shock-like jerking movements, often on both sides of the body.
In contrast, focal seizures (formerly called partial seizures) begin in just one part of the brain, usually affecting one side of the body. Sometimes focal seizures can spread to both sides and become "focal to bilateral tonic- clonic seizures," also called secondary generalized seizures.
Thus, seizures that inherently affect both sides of the brain from the start are generalized seizures.
