Diagnosis and management of hydatid cyst of the central nervous system: Part 1: General considerations and hydatid disease of the brain

Hippocrates, Galen, Avicenna, and Jurjani first reported on human affliction by hydatidosis. The complete life cycle of Echinococcus includes several carnivores, but humans are infected incidentally and usually in childhood by ingestion of the ova. When an embryo of Echinococcus granulosus lodges in the brain, a solitary cyst develops. Hydatid cyst is a slow-growing lesion that does not invade the brain; it produces symptoms when the increasing size of the cyst exerts local pressure. The late appearance of focal neurologic deficits follows a long history of epileptic attacks, and symptoms compatible with increased intracranial pressure are the common clinical presentation. Serobiologic tests are not confirmatory for preoperative diagnosis, but radiologic examinations have a high degree of accuracy. In both computed tomography and magnetic resonance imaging, a spherical but occasionally ovoid cyst with clearly defined borders is visible. The cyst content is of the same density as cerebrospinal fluid on computed tomography and on T1 and T2 relaxations in magnetic resonance imaging. Usually, there is no identifiable rim in either computed tomography or magnetic resonance imaging, even after contrast injection. Surgical removal of the intact and unruptured cyst is advised in all cases. If the cyst ruptures during removal, local irrigation with 1% formalin, 0.5% silver nitrate, or hypertonic saline solutions can prevent local recurrence of the cysts. Long-term administration of oral parasiticidal agents such as mebendazole or albendazole may be effective in controlling recurrences in case of rupture of the cyst. In these two articles, the authors present their large and long-term experience in the diagnosis and management of hydatidosis of the central nervous system and orbit.