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Seizures are the most common clinical manifestation of cerebral cysticercosis and occur in the presence of viable, dying, and calcified or noncalcified dead cysts. How calcified cysts provoke seizures is not known but recent observations demonstrated edema around some calcified lesions at the time of seizure activity and disappearance during periods when seizures were not occurring. Edema associated with foci in idiopathic epilepsy is highly unusual so that this observation suggests that the mechanism(s) associated with calcified cysts is unique. Documenting and understanding this phenomenon is important for a number of reasons. First, although by definition these lesions are inactive, e.g., not living larvae and do not require anti- parasitic treatment, they are frequently mistaken for active lesions and patients undergo unnecessary treatment. Second, a likely reason for perilesional edema is intermittent antigen release and subsequent host immune response resulting in inflammation and edema. If proven, then the treatment for this would not only involve suppression of seizure activity with anti- seizure medication, but also the use of anti-inflammatory medications such as corticosteroids.
During the past year we determined that the FLAIR technique of MRI is the most sensitive measure of edema among the MRI imaging techniques studied and therefore this will be used to determine the presence or absence of edema. Five patients with neurocysticercosis with only calcified lesions were prospectively studied. We identified 3 patients residing in the Washington D.C. region, 2 of whom acquired cysticercosis in endemic countries and a third with a single lesion and positive serology never resided in an endemic region. One patient has had one episode associated with a single lesion and a second has had two episodes within 4 months involving 2 separate calcified lesions while the third Within has had 3 episodes around a single lesion which only transiently responds to corticosteorid. In addition 2 patients from Peru have also been studied, one with three foci (two silent and the other anatomically correlated with her symptoms) and another with a single focus. The ease of identifying these patients indicates that the phenomenon is likely to be relatively common. A study was approved to begin a prospective study in Peru of patients with only calcified lesions to determine the frequency and symptoms a