Epilepsy, interictal EEG abnormalities and hippocampal atrophy in patients with calcified neurocysticercosis: a population study in an endemic milieu

Abstract

Objective. Calcified neurocysticercosis has been associated with hippocampal atrophy (HA). However, the pathogenesis of this association is still elusive. This study assessed the role of epilepsy or interictal EEG abnormalities in the occurrence of HA in the Atahualpa Project cohort. Methods. Atahualpa residents aged ≥20 years, identified by means of door-to-door surveys, were offered an unenhanced head CT to identify neurocysticercosis cases. Individuals with cysticercotic parenchymal brain calcifications (121/1,299; 9.3%) underwent brain MRI, scalp EEG, and neurological evaluation to assess history of epilepsy. The independent association between combined exposures (epilepsy and/or EEG abnormalities) and HA (outcome) was assessed using univariate logistic regression models and a multivariate model adjusted for age, sex, level of education, alcohol intake and characteristics of calcifications. Results. A total of 112 NCC patients were enrolled (mean age: 52.2 ± 16.9 years; 67% women); the remaining nine declined consent. A single calcification was noticed in 70% of cases. Thirty-one patients (27.7%) had HA, which was asymmetrical in 14. Calcification burden was higher among patients with HA than in their non-atrophic counterparts (p=0.012). Eighteen patients had epilepsy, abnormal EEG recordings, or both. Nine of these 18 patients (50%) had HA as opposed to 22 of 94 patients (23%) with a normal EEG and no history of epilepsy (p=0.025). This association became borderline significant based on a multivariate logistic regression model, after adjusting for all covariates (OR: 3.26; 95% CI: 0.91-11.68; p=0.070). In this model, having only one calcification was inversely associated with HA (OR: 0.32; 95% CI: 0.11-0.95; p=0.039). Significance. Epilepsy and EEG abnormalities play a minor contributory role in the development of HA in neurocysticercosis patients. The burden of infection, leading to recurrent bouts of inflammation around calcified cysticerci, is a more likely contributor to HA development in patients with neurocysticercosis.

Evaluating the Association of Calcified Neurocysticercosis and Mesial Temporal Lobe Epilepsy With Hippocampal Sclerosis in a Large Cohort of Patients With Epilepsy

“…Rathore et al ( 38 ) observed that patients with MTLE-HS and cNCC had a lower incidence of febrile seizures, older age at IPI, and more diffuse epileptiform discharges compared to patients with MTLE-HS alone, findings in line with some of our previous results ( 35 , 40 , 79 ). A possible cause-effect of NCC and MTLE-HS has also been suggested by some other authors ( 12 , 74 , 75 , 77 , 78 ).…”

“…According to this hypothesis, NCC would be a type of CNS infection that could act as an IPI leading to hippocampal damage and MTLE-HS later in life due to inflammatory mechanisms or repetitive seizures. These two mechanisms are not mutually exclusive and both could contribute to the development of HS and MTLE-HS ( 33 – 45 , 74 , 75 , 77 , 78 ). Some case reports seem to point in this direction.…”

EEG background frequency is associated with discharge outcomes in non-ICU hospitalized patients with COVID-19

“…This finding implies that of the varied effects of COVID, the shortterm outcome is most closely related to its effect on cognition. Previous studies have shown that even mild COVID infection can affect cognitive function 6 months after infection, although EEG background frequency is not sensitive to the relatively mild cognitive dysfunction at this time point (25). For those who recover from mild COVID infections, cognitive function tends to recover many months later, returning to baseline after 18 months (26).…”

Neurocysticercosis: an update on diagnosis, treatment, and prevention

“…In a prospective study of epilepsy in a village in Ecuador, there was a >1% incidence of epilepsy and 35% of cases were associated with calcified NCC [7]. Chronic epilepsy is associated with calcified NCC and control is poorer when accompanied by hippocampal atrophy on magnetic resonance imaging (MRI) [10].…”

“…However, experts generally recommend at least 2 years of ASM after the last seizure. Calcified lesions are a risk factor for recurrent seizures, particularly when associated with perilesional edema or hippocampal atrophy [9,10,30].…”