A tonic-clonic phase is characterized by strong contractions of muscles and loss of consciousness.  Epilepsy Alarm This type of seizure can be generalized or partial in onset. It is also known as a grand mal epilepsy.The duration of the tonic-clonic phase is determined by the age of the seizure onset. For example, a patient with a seizure that has a onset of less than two years has a longer tonic-clonic phase.Various studies have examined the relationship between the age of the seizure onset and the risk of epilepsy. One study found that seizures that have a onset of more than two years had a higher risk of having a recurrence.A survey showed that more than half of physicians administered benzodiazepine during a tonic-clonic seizure. A study by the First Seizure Trial Group investigated the efficacy of antiepileptic drugs in patients with a first unprovoked tonic-clonic seizure.In another study, 20 healthy controls had 100 tonic-clonic seizures simulated. They were monitored for 24 hours. The mean PRL increased 5.1-fold. Lactate levels increased 8.7-fold. Mean lactate levels returned to baseline within 2 hours.Similarly, Cav3.1-/- mice had elevated neuronal activation in the hippocampus after MES clonic seizures. These findings indicate that Cav3.1 plays a major role in mediating TTA-A2 tonic seizuricidal protection.A study of 275 tonic-clonic seizures showed that 12% of the patients had all seven phases of the GTCS. Among the seven phases, Phase 1 was defined as a simple partial seizure.