Cerebral sparganosis is a rare parasitic infection of the brain by the second-stage larva of Spirometra mansoni, most commonly encountered in Southeast Asia, China and South America.
Infection occurs from drinking contaminated water, ingesting poorly cooked or raw snake or frog meat, or using raw snake or frog meat as a poultice in an open wound 1. As such no specific age or gender predilection is identified 1.
Although radiographic features are variable, the fact that the worms are long (up to 25 cm in length) results in fairly striking imaging appearances, with the tunnel through the brain and worm itself coiled within the brain seen as tubular or comma shaped enhancing regions 1. If the worm dies then eventual gliosis and negative mass effect is seen 1.
A number of signs have been described 1:
- tunnel sign: as the worms move through the brain they leave behind a fluid filled tunnel which may have enhancing margins
- migration sign: on consecutive scans, the location of the worm may change, with development of a tunnel between the two regions
- worm-body sign: the actual worm can also be visualized in some cases
Treatment and prognosis
Treatment primarily involves praziquantel, but is not always effective and surgery in these cases is required 1.