Post-shunting corpus callosal signal change and review of the literature.

MRI signal changes in the corpus callosum can be seen in 8.3% of patients following shunt insertion for obstructive hydrocephalus. Several causes have been hypothesised, including mechanical compression, decompression associated oedema and ischaemia, and overshunting. We present a case of a patient with a pineal tumour of intermediate differentiation (WHO grade III), which had caused long-term obstructive hydrocephalus due to compression of the tectal plate and cerebral aqueduct. Following insertion of a shunt, prominent changes in the corpus callosum became evident on CT and MRI characterised by oedema and swelling, particularly affecting the dorsal surface of the corpus callosum. This pattern of signal change, although dramatic, should not be mistaken for other pathologies.