Absence seizures are characterized on EEG by:
**Core Concept**
Absence seizures are a type of epilepsy characterized by brief, sudden lapses in consciousness, typically lasting a few seconds. They are often seen in children and adolescents and are associated with a specific abnormality on electroencephalogram (EEG).
**Why the Correct Answer is Right**
Absence seizures are characterized by a generalized 3 Hz spike-and-wave discharges on EEG. This pattern is due to the synchronous firing of neurons in the thalamus and cortex, which leads to a loss of consciousness. The 3 Hz frequency is a key distinguishing feature of absence seizures, as it is different from other types of seizures that may have different EEG patterns.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it refers to a different type of EEG pattern, which is more commonly associated with focal seizures.
**Option B:** This option is incorrect because it refers to a type of seizure that is more commonly associated with status epilepticus and is not a characteristic feature of absence seizures.
**Option C:** This option is incorrect because it refers to a type of EEG pattern that is more commonly associated with myoclonic seizures.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the 3 Hz spike-and-wave discharges on EEG are a hallmark of absence seizures, and this pattern is often used to diagnose this condition.
**Correct Answer: C. 3 Hz spike-and-wave discharges.**