Which of the following best describes an EEG finding that shows a series of spikes followed by waves?

• A. Spike-and-wave discharges
• B. Polyspike activity
• C. Sharp waves
• D. Continuous beta activity

Answer: (A)

The term "spike-and-wave discharges" refers specifically to a distinctive pattern seen on an electroencephalogram (EEG), characterized by a series of spikes (sudden, sharp deflections in the EEG signal) followed by slower waves. This combination typically signifies a specific type of brain activity often associated with certain neurological conditions, most notably generalized epilepsy.

The spikes indicate a rapid depolarization of neuronal populations, while the waves represent a recovery phase of neuronal activity. This alternating pattern is a critical hallmark in diagnosing various types of seizure disorders and reflects the synchrony of neuronal firing.

In contrast, polyspike activity shows multiple spikes occurring in succession but doesn’t necessarily follow with the waves characteristic of the spike-and-wave configuration. Sharp waves are brief, transient events that do not have the same rhythmic pattern as spike-and-wave discharges. Continuous beta activity indicates a different EEG phenomenon associated with alertness and does not involve spikes or the wave component related to seizure patterns.

Therefore, the choice regarding spike-and-wave discharges accurately captures the essence of the EEG findings in question.