5 different types of seizures
Seizures happen when the electrical system of the brain malfunctions. There are many different types of seizures, although people may experience just one type. Or they may experience different types. The kind of seizure a person has depends on which part and how much of the brain is affected by the electrical disturbance.
Generalized seizures affect both cerebral hemispheres (sides of the brain) from the beginning of the seizure. They produce loss of consciousness, either briefly or for a longer period of time, and are sub-categorized into several major types: generalized tonic clonic; tonic; myoclonic; absence, and atonic.
In partial seizures the electrical disturbance is limited to a specific area of one side of the brain. Partial seizures are the most common type of seizure experienced by people with epilepsy. Virtually any movement, sensory or emotional symptom can occur as part of a partial seizure, including complex visual or auditory hallucinations.
About three percent of people with epilepsy have photosensitive seizures. This means that exposure to flashing lights at certain intensities or to certain visual patterns can trigger seizures. Many people are unaware that they are sensitive to flickering lights or to certain kinds of patterns until they have a seizure. This type of seizure is more common in children and adolescents.
Non-epileptic seizures are episodic, paroxysmal events not related to abnormal electrical activity in the brain - they're actually physiological. They have characteristics which differ from true seizures in important points, including repeatedly normal EEG readings between seizures; lack of any response to therapeutic levels of anti-epileptic drugs, and violent thrashing of all four limbs during an episode.
Gelastic seizures are called the “laughing seizure” because they may look like bouts of uncontrolled laughter or giggling. However, the laughter-like sounds are often forced and combined with a facial contraction similar to a smile or smirk. In some children, the vocalization has a crying quality and the facial contraction resembles a grimace. These crying seizures are called dacrystic seizures.