Abstracts

Rationale: Electrographic seizures are frequently observed in critically ill patients undergoing continuous EEG monitoring. Cyclic seizures have been reported in such clinical settings where frequent seizures occur at nearly regular intervals, and most commonly originate from the posterior head region. We report a unique case of unilateral independent cyclic seizures with independent frontal and posterior head region onset.

Methods: A case report.

Results: A 62-year-old male underwent right sphenoid wing meningioma resection. In the afternoon of post-op day 3, he was found to be intermittently confused and became more lethargic. Continuous EEG monitoring was started around 2 am the next day. EEG showed cyclic seizures originating independently from right frontotemporal region and right parieto-occipital region, both separately and overlapping at times, although the overlapping seizures generally started anteriorly first. On Persyst analysis, the anterior onset seizure arises from F4 and builds, spreading to the temporal chain. The Persyst array demonstrates the asymmetry relative spectrogram leading from the anterior group and the FFT spectrogram from the F4C4 and F8T8 measures as well. In the posterior onset seizure, there is clear morphological differentiation from the anterior onset seizure on the EEG, emanating from P8 with dorsal spread, and reflected in the relative spectrogram posterior asymmetry in particular. His head CT showed vasogenic edema throughout the right hemisphere. He was treated with lorazepam rescue, anti-seizure medications and dexamethasone, and the seizures were subsequently controlled. He had a normal neuro exam on the day of discharge.

Conclusions: To our knowledge, this is the first case report of cyclic seizures originating from independent foci in one hemisphere. The cyclic nature of the seizures is clearly demonstrated on the quantitative measures of Persyst 14, which is a very useful tool in analyzing cyclic seizures. A previous retrospective study indicates that most of the cyclic seizures occur in the setting of acute or progressive brain injury and typically carry a poor prognosis. Our case occurred in the setting of post-op vasogenic edema and patient recovered well with anti-seizure medications and steroids to reduce the vasogenic edema, indicating that the outcome in cyclic seizures may be case dependent. Prior observations suggested that most of the reported cyclic seizures have posterior cerebral onset. In our case, the frequency of frontal onset and posterior onset seizures was roughly the same. Additional cases will help determine if the posterior onset is truly predominant for cases of cyclic seizures, and clarify the underlying pathophysiology.

Funding: Please list any funding that was received in support of this abstract.: n/a.