Does the Mount Fuji Sign always signify ‘tension’ pneumocephalus? An exception and a reappraisal

Pneumocephalus is expected after any craniotomy and usually resolves without any sequelae. However if the air entering the cranial cavity gets entrapped, it can lead to tension pneumocephalus and can have disastrous consequences. It is of utmost clinical importance to differentiate a tension pneumocephalus from a non-tension pneumocephalus as the latter does not usually require decompressive surgery. CT scan is considered the gold standard and diagnostic modality of choice for the diagnosis of pneumocephalus in the post-operative period. The Peaking sign and Mount Fuji sign are proposed as fairly specific for tension pneumocephalus, the latter being the most specific and an important sign to differentiate it from non-tension pneumocephalus. We present a case of a 20 year old male whose post-operative CT brain showed the typical Mount Fuji sign suggestive of tension pneumocephalus but was managed conservatively without any decompressive surgery.