Tension pneumocephalus following external ventricular drain insertion.

We report a rare case of the development of tension pneumocephalus after the placement of an external ventricular drain in a 4-year-old child with gross hydrocephalus and residual posterior fossa tumor. The child had developed hydrocephalus in the postoperative period after being operated for the posterior fossa tumor. The tension pneumocephalus resulted in delayed recovery in the child. The possible mechanism of the cause of pneumocephalus is discussed.