Echinococcosis is caused by tapeworms of the genus Echinococcus, common parasites of dogs and cats, who are the definitive hosts; humans can be intermediate hosts. The disease is endemic in countries around the Mediterranean: Greece, Turkey, and Lebanon have the highest prevalences.162

The small adult worms live in the definitive host’s gut and discharge eggs into feces. If inadvertently ingested by a human, the eggs hatch in the human’s gut, enabling the organism to penetrate the human’s gut wall and spread hematogenously. Once located in a final tissue site, the organism forms a slowly enlarging cyst, a hydatid.

When in the CNS, cysts usually locate in brain parenchyma. Clinical manifestations are secondary to this mass lesion, raised intracranial pressure, or both. They may include:162

  • headache
  • nausea
  • papilledema
  • focal deficits
  • partial seizures
  • generalized seizures


Although rare, CNS echinococcosis should be included in the differential diagnosis of any patient with a CNS mass lesion who has lived in an endemic area. Diagnosis is made by neuroimaging, which usually reveals a single, large spherical cystic lesion. There is usually no ring enhancement or associated edema.173


Although praziquantel has activity against these organisms, the primary treatment of CNS hydatids is surgical.173 Antiepileptic management is a crucial adjunctive treatment.162

Adapted from: Goldstein MA and Harden CL. Infectious states. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;83-133. 
With permission from Elsevier (