Lateralized Periodic Discharges in a Patient With Dural Arteriovenous Fistula: SPECT and DWI Studies Suggest They are Ictal.

Lateralized periodic discharges (LPDs) are unilateral electroencephalography (EEG) waveforms, recurring at regular intervals. There has been a long-lasting debate about whether they represent ictal or interictal phenomena. Very few patients in the literature have been investigated with multimodal functional imaging techniques. Here, we present a 58-year-old male patient with symptomatic epilepsy who had cerebral venous sinus thrombosis in the right temporo-parietal area and dural arteriovenous fistula (dAVF) over the left fronto-parietal region. He developed acute speech disturbances and altered mental status after a generalized tonic-clonic seizure. Video-EEG monitoring (VEEGM) demonstrated LPDs over the left fronto-central area, overlapping in part with the dAVF. Diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) sequences revealed restricted diffusion compatible with cytotoxic edema, whereas single-photon emission computed tomography (SPECT) indicated hyperperfusion in the same region, leading to the conclusion that he was having possible nonconvulsive status epilepticus (NCSE). An increase in antiseizure medications led to gradual improvement in clinical status and the disappearance of LPDs.