On the neurology ward, a 7-year old male, called Stefan, is brought by his mother. His mother is worried because he has several episodes every day where he loses consciousness for a few seconds. His teacher also complains that she often catches him daydreaming during the lesson. Next to Stefan, there’s a 17-year old male, called Jacob, who seems sluggish and tired. His friends brought him because he suddenly started “shaking and jerking” and he lost consciousness for about two minutes. His medical history is otherwise insignificant. Now, there’s also an 11-year old female, called Megan, who also seems lethargic. Her father is very upset because he witnessed an episode of twitching of her left foot that lasted a few minutes. Megan was unconscious and has no memory of the event. Finally, there’s a 19-year old female, called Joanna, that has had repetitive episodes of sudden and rapid jerking movements with loss of consciousness for the past few months. They usually occur when she wakes up in the morning and especially during periods of sleep deprivation.
Okay, so all of them had a seizure episode. A seizure is a paroxysmal motor, sensory or autonomic event that occurs due to abnormal, excessive and synchronous electrical discharges from neurons in the brain. Seizures usually last less than 5 minutes. If it lasts more than 5 minutes, it’s called status epilepticus. Epilepsy is a chronic disease of the brain that predisposes an individual to having recurrent unprovoked seizures; that is seizures without a clear triggering cause. Epilepsy is typically diagnosed when an individual has two or more unprovoked seizures separated by at least twenty-four hours.
Okay, now seizures are broadly classified into two types, generalized and focal seizures. Generalized seizures arise from both cerebral hemispheres at the same time, while focal seizures arise from specific areas in one cerebral hemisphere. However, focal seizures can spread to both cerebral hemispheres, causing a generalized seizure. When this happens, it’s appropriately called secondary generalization of a focal seizure.