Cerebral sparganosis: analysis of 34 cases with emphasis on CT features.

Cerebral sparganosis is a rare parasitic CNS disease, producing chronic active granulomatous inflammation. We retrospectively reviewed the clinical data, CT scans and histopathologic specimens in 34 patients with cerebral sparganosis. The majority of the patients (89%) were rural inhabitants; 75% had a history of ingestion of frogs and/or snakes. The major presenting symptoms were seizure (84%), hemiparesis (59%) and headache (56%) of chronic course. On CT scans, the disease most frequently involved the cerebral hemispheres, particularly frontoparietal lobes, with occasional extension to the external and internal capsules and basal ganglia. The cerebellum was rarely involved. Bilateral involvement was seen in 26%. The main CT findings consisted of white matter hypodensity with adjacent ventricular dilatation (88%), irregular or nodular enhancing lesion (88%), and small punctate calcifications (76%). In combination, the CT triad above appears to be specific for this disease, and was noted in 62% of cases. Of 16 follow-up CT scans, 5 (38%) showed a change in the location of the enhancing nodule. With a single CT scan, it does not appear to be possible to determine whether the worm is alive or dead, information important for deciding whether to intervene surgically. Change in the location of the enhancing nodule and/or worsening of the other CT findings on sequential CT scans would suggest that the worm is alive and that the patient is a candidate for surgery.