Final answer:
The seizure formerly known as grand mal, leading to loss of consciousness and convulsions, is the tonic-clonic seizure, one of the main types linked with epilepsy.
Step-by-step explanation:
The type of seizure once known as grand mal, which causes the individual to lose consciousness and experience rigid extensions and rhythmic contractions of extremities, is the tonic-clonic seizure. This type of seizure is characteristic of epilepsy, which is a disorder involving recurrent seizures due to abnormal electrical activity in the brain. Tonic-clonic seizures involve two phases: the tonic phase, where muscles suddenly become rigid, and the clonic phase, where there is rhythmic muscle contraction and relaxation. Epilepsy can result from various causes, including brain injury, infection, or tumor, and may be managed with anticonvulsant medications. Though there is no cure, some children may outgrow the condition by adulthood.