Abstracts

Rationale: Neurocysticercosis (NC) is assumed to represent the most frequent cause of epilepsy in developing countries. This concept has recently been challenged. Active epilepsy, especially refractory epilepsy, appears to be uncommon in NC. Recent studies have suggested an association between NC and Mesial Temporal Sclerosis (MTS). The finding of occasional inactive NC lesions on CT may represent an incidental finding in people with epilepsy. Although a few case reports have shown emergence of MTS after resolution of active NC lesions, a causal relationship cannot be established. We investigated the association of inactive NC lesions in adult patients with MTS associated epilepsy and in patients with Idiopathic Generalized Epilepsy (IGE). Methods: We randomly selected adult patients followed at the Epilepsy outpatient clinic in our institution with the diagnoses of MTS and IGE, based on clinical, EEG and MRI findings. Patients with dual pathology and patients who had undergone epilepsy surgery were not included. Patients were interviewed by the author, who collected demographic, epilepsy features and treatment, as well as epidemiologic data related to cysticercosis. After signing an informed consent form, all patients underwent a head CT that was read by a neuroradiologist blinded to clinical, EEG and MRI data. Presence of calcified lesions suggestive of inactive neurocysticercosis was noted. CT results were then matched to epilepsy syndrome (IGE and MTS). Prevalence of inactive NC lesions in the MTS group was compared with the IGE group (Fisher exact test). We also compared the collected data between the groups, as well as in the NC-positive and NC-negative MTS cases (using Yates corrected χ-square, Fisher exact, t-student and Mann-Whitney tests; p<0.05). Results: We studied 46 patients (13 with IGE and 33 with MTS). Groups were comparable in terms of gender and NC epidemiology. Patients in the MTS group had more seizures in the preceding three months, received more antiepileptic drugs, were older, had a lower average age of onset of epilepsy, longer epilepsy duration, and lower socioeconomic status and educational levels. Calcified lesions were found significantly more frequently in the MTS group than in the IGE group (MTS 11/33 vs. IGE 0/13; p=0.029). NC-positive and -negative cases did not differ in age, gender, education, socioeconomic status, age of epilepsy onset, number of antiepileptic drugs, previous contact with pigs and history of having lived in rural areas. Epilepsy duration was longer in NC-positive patients. Conclusions: We found an association of calcified lesions suggestive of inactive cysticercosis in the MTS group compared with IGE. Epilepsy features, socioeconomic and educational status were not influenced by the presence of calcified lesions in the MTS group. Other differences between MTS and IGE groups could be explained by expected differences between the two epilepsy syndromes. Although we cannot establish a causal role between cysticercosis and calcified lesions in MTS, this association should be further clarified.