Presentation
Recurrent attacks of dizziness for three months.
Patient Data
There is a well-defined, posterior fossa, extradural, cystic lesion with mild wall enhancement. The cyst is isointense to CSF in all pulse sequences. There is extracranial soft tissue extension with enhancing internal septation, and no perifocal edema.
Posterior fossa extra-axial, multiseptated, hypodense, cystic lesion with multilocular lytic bony changes involving the adjacent occipital bone and small extra osseous calcified components.
The patient underwent surgical resection and the histopathological evaluation confirmed a hydatid cyst.
Case Discussion
Three forms of intracranial CNS hydatid disease occur, intracerebral, cranial extradural, and a combined form. Cranial epidural hydatid disease is extremely rare as the physiologic flow of blood to the brain is mainly through the internal carotid system, and therefore the likelihood of the larvae traveling through the external carotid system is very low.
Cerebral manifestations of hydatid cysts are seven times more common in children than in adults.
Cerebral hydatid cysts are usually located supratentorial in the middle cerebral arterial territory. However, cranial epidural hydatid cysts seem to tend to occur around the midline. It has been hypothesized that this may be due to the existence of a rich venous vascularization in the midline. In our patient, the hydatid cyst was in the epidural space in the posterior fossa, away from the midline, and with septa and calcification.
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