Please refer to specific syndromes and etiologies in which this seizure type occurs for specific information. As a general rule, EEG abnormality may be enhanced in sleep deprivation states and in sleep. For some patients, EEG abnormality and ictal events may be precipitated by sensory stimulation e.g. movement or touch of a body part.
EEG abnormalities (spike-and-wave or sharp slow waves) may be seen in a posterior distribution in lateral parietal lobe brain abnormalities. The EEG may be normal in structural brain abnormalities affecting mesial parietal areas.
Surface ictal EEG in parietal lobe seizures can be unhelpful, the ictal EEG may be normal in up to 80% of seizures, or there may be lateralized slow activity. Central parietal rhythmic spike or spike-and-wave is occasionally seen. The EEG patterns may instead reflect the seizure spread, which may be to the temporal or frontal lobes or bilaterally. Seizures arising in mesial parietal areas are often associated with secondary bilateral synchrony.