What are the expected EEG findings?
Choose the correct option:
A. Generalized 4- to 6-Hertz (Hz) polyspike and wave discharges with a photoconvulsive response
B. Generalized 3-Hz spike and wave discharges
C. Generalized 2.0-Hz spike and wave discharges
D. Left temporal focal epileptiform discharges
The correct answer and explanation is :
The correct answer is B. Generalized 3-Hz spike and wave discharges.
Explanation:
This EEG finding is characteristic of absence seizures, which are a type of generalized epileptic seizure. These seizures are most commonly seen in children and involve a sudden, brief loss of consciousness. The typical EEG pattern associated with absence seizures includes generalized 3-Hz spike and wave discharges.
Here’s a breakdown of the EEG findings and what they mean:
- Generalized 3-Hz spike and wave discharges (Option B):
- This is the hallmark of absence epilepsy, particularly typical absence seizures.
- The pattern consists of sharp spikes followed by slow waves at a frequency of about 3 Hertz, which are seen simultaneously in both hemispheres (generalized).
- The seizure usually involves a brief loss of awareness or staring without convulsive movements. Patients often exhibit a sudden onset and resolution of the seizure, lasting just a few seconds.
- Generalized 4- to 6-Hertz polyspike and wave discharges with a photoconvulsive response (Option A):
- This finding is more indicative of juvenile myoclonic epilepsy (JME), a generalized seizure disorder that involves myoclonic jerks (brief muscle twitches), especially in the morning. It may also present with generalized tonic-clonic seizures.
- Polyspike and wave discharges are faster in frequency (4-6 Hz), and the photoconvulsive response (induced seizures triggered by flashing lights) is also commonly seen in JME.
- This pattern is not typical for absence seizures, which have a slower frequency.
- Generalized 2.0-Hz spike and wave discharges (Option C):
- A frequency of 2.0 Hz for spike and wave discharges is not commonly associated with typical absence seizures. While it could be seen in some cases, the standard is 3 Hz. A frequency of 2 Hz is more unusual and might be seen in atypical forms of epilepsy.
- Left temporal focal epileptiform discharges (Option D):
- This finding is characteristic of focal seizures, which originate in one part of the brain (in this case, the left temporal lobe). These seizures are not generalized and would not be associated with generalized absence seizures, which involve widespread brain activity.
Thus, the 3-Hz generalized spike-and-wave discharges (Option B) are most strongly associated with typical absence seizures, which is why it is the correct answer.