Epilepsy is the second most frequent neurological condition (after migraine), and affects about 1 out of every 100-200 people in the general population (approximately 300,000 Canadians). Epilepsy is often more common in low resource countries where certain causes of epilepsy (e.g., brain infections) are common. Studies indicate that we all face an 8-10% lifetime risk of one seizure and a 3% chance of epilepsy.
Everyone is at risk of having a seizure. For example, very low blood sugars could trigger a seizure in a person. This kind of seizure is provoked and is unlikely to recur, if blood sugars are controlled. If a first seizure is unprovoked, however, studies suggest that there is a 30-50% chance that a second seizure will occur. If a second, unprovoked seizure occurs, there is a 70-80% chance that another one will occur. Because of these chances, a diagnosis of epilepsy (a tendency for recurrent seizures) is made after a second, unprovoked seizure.
Practically speaking, epilepsy is defined as the occurrence of at least 2 unprovoked seizures. Under exceptional circumstances, epilepsy can be diagnosed with a single seizure when EEG or brain imaging tests suggest that there may already be a risk of further seizures equal to that of having 2 unprovoked seizures (e.g., past history of severe traumatic brain injury, past history of severe large stroke, brain tumor, etc.).
A significant number of persons with epilepsy develop physical and psychosocial problems and are also diagnosed with psychiatric and behavioural problems. Epilepsy can therefore pose a significant burden on the person, their family/caregivers and society. Persons with epilepsy may require counseling to address their psychosocial and psychiatric issues, may have a 2-3 fold increase in premature death and are 2-3 times more likely to be unemployed compared to the general population. About 70% of epilepsy-related long-term health-care costs are due to so called indirect costs such as repeated sick leaves, unemployment, lack or loss of productivity, early retirement. Development of drug resistant (non-treatment responsive) epilepsy incurs the greatest health care costs.
Duration and timing of a seizure
Seizures usually last on average 30-45 seconds, but rarely can be shorter or longer.
Any seizure lasting longer than 5 minutes is suspicious of status epilepticus, defined as either a prolonged seizure or a series of subsequent seizures without regaining function. Status epilepticus with generalized tonic-clonic seizures (“grand mal status”) is a life-threatening condition that must be urgently treated.
If seizures occur repeatedly within a few hours with preserved function in the interval, this is named a series of seizures (or repetitive seizures).