Interictal epileptiform discharges in calcified neurocysticercosis–associated epilepsy: An exploratory study

The objective of the study was to assess the frequency of interictal epileptiform discharges (IEDs) in calcified neurocysticercosis (NCC) and its relationship with calcification burden. Forty-nine patients with calcified NCC (low-burden, 1–2 calcifications, n = 24; high-burden, ≥15 calcifications, n = 25) and seizure history underwent prolonged (8-h) electroencephalography (EEG), interpreted by epileptologists who were blinded to patient history and calcification category. Clinical seizure outcomes were also assessed. We found that IEDs occurred in 7 of 49 participants (14.3%), with no difference between low-burden (12.5%) and high-burden (16.0%) groups (p = 1.000). All IEDs (spikes and/or sharp waves) in the high-burden group (n = 4) were high-voltage (100–150 μV), whereas those in the low-burden group (n = 3) were low or medium voltage (20–70 μV). Among the participants who had IEDs, 5 (71.4%) had seizures in the last year, compared with 14 (33.3%) in the group without IEDs detected (p = 0.093). Among 19 participants with seizures in the last year, 5 were identified as having drug-resistant epilepsy (DRE). All five cases of DRE occurred in individuals with 15 or more calcifications (5/25, 20%, vs 0/24, p = 0.023). We conclude that IEDs occur frequently in individuals with calcified NCC. Although calcification burden itself was not associated with the presence of IEDs, drug-resistant cases and high-voltage IEDs were concentrated in the high-burden group, supporting the role of calcified parasites as epileptogenic foci.