Brain sag as a cause of postoperative neurological deterioration following anterior cranial fossa floor repair for post traumatic cerebrospinal fluid rhinorrhoea.

A patient with posttraumatic CSF rhinorrhoea underwent a transcranial anterior skull base repair, with a lumbar drain being inserted at induction of anaesthesia. Postoperative neurological deterioration occurred due to brain sag. Following treatment, there was significant recovery albeit in a slow and steady fashion. Patients with brain sag as a result of lumbar drain insertion can make a good recovery, despite an initial presentation with signs of severe brainstem compression, which could easily be misinterpreted as having a poor prognosis. Absence of an initial dramatic response to treatment does not necessarily imply poor outcome in the long term.