Cerebral hydatid disease (neurohydatidosis) is caused by Echinococcus granulosus or less commonly E. alveolaris or E. multilocularis. The larval stage is the cause of hydatid disease in humans 1.
Cerebral hydatid disease is a rare parasitic infestation and accounts for 1-2 % of all cystic echinococcosis. Hydatid disease is endemic in the Mediterranean region, the Middle East, Africa, eastern part of Turkey, Australia and parts of South America 2.
Symptoms and signs include:
- focal neurological deficits
- increased intracranial pressure
- papilloedema and loss of vision
- altered mental status
- seizures (rare)
The infection is acquired via contaminated food with eggs of the tapeworm. The oncospheres released from the eggs in the bowel enters the portal circulation. Hence the liver is most commonly affected, followed by the lung. Other organs may be infected as bones, genitourinary system, bowel and even subcutaneous tissues.
Intracranial hydatid disease is very rare. Most of cerebral hydatid cysts are located in supratentorial structures in the vascular territory of middle cerebral artery 1.
Intracranial hydatid cysts can be classified into:
primary hydatid cysts
- occur as direct invasion of larva that managed and filtered via liver and lung to the brain
- usually solitary but may be multiple
- is fertile
secondary hydatid cysts
- occur as a result of rupture of primary cysts in others organs then reaching by embolization to the brain
- usually multiple
- do not have brood capsule or scolices
Described features include:
- well-defined circumscribed spherical non-enhancing intra-axial cystic lesion
- lies in the territory of the middle cerebral artery.
- cyst fluid is isointense with CSF in all pulse sequences
- no calcification or and typically no surrounding oedema
- presence of perilesional edema usually indicates complication as rupture or secondary infection
Treatment and prognosis
Management is surgical, with removal of the entire cyst without rupture using Dowling’s maneuver (instilling warm saline between the cyst wall and the brain) 5. In some cases where it is felt that removing the cyst intact (without cyst rupture during surgery) is unlikely to succeed, the cyst can be removed after puncture and aspiration of its contents.
Serology and histopathology of the excised cyst will confirm the diagnosis of neurohydatidosis.
Rupture of the cyst can result in recurrence in the subarachnoid space, both intracranially and of the spine 6.
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- 5. Ulutas M, Cinar K, Secer M. Removal of large hydatid cysts with balloon-assisted modification of Dowling's method: technical report. Acta Neurochir (Wien). 2015;157 (7): 1221-4. doi:10.1007/s00701-015-2449-x - Free text at pubmed - Pubmed citation
- 6. Izci Y, Tüzün Y, Seçer HI et-al. Cerebral hydatid cysts: technique and pitfalls of surgical management. Neurosurg Focus. 2008;24 (6): E15. doi:10.3171/FOC/2008/24/6/E15 - Pubmed citation