Cerebral venous sinus thrombosis (CVST) is a rare disorder with multiple known risk factors. Sometimes a rare and unusual cause is found. We describe a patient in whom fatal CVST occurred following a lumbar puncture with post lumbar puncture headache. A nineteen-year-old man was treated with high dose corticosteroids (methylprednisolone) and underwent a lumbar puncture after demyelating lesions were seen on cerebral magnetic resonance imaging. He developed post lumbar puncture headache and after four days generalised seizures. A computed tomography scan showed CVST with diffuse swelling of the brain and no contrast enhancement of the straight sinus, superior sagittal sinus and transverse sinus. Despite thrombosuction and placement of a stent, bilateral decompression craniotomy, deep sedation and hypertonic saline the patient died two days after the diagnosis of CVST. The cause of the CVST was probably due to cerebrospinal fluid leakage after lumbar puncture in combination with high dose corticosteroids (methylprednisolone). Intracranial hypotension after a lumbar puncture may cause intracranial veins to dilate, causing reduced blood flow, stasis and subsequent CVST. High dose intravenous corticosteroids may cause a hypercoagulable state and therefore might contribute to CVST. Up to date information of the different treatment options of CVST is given. We would like to emphasize that CVST could occur after a lumbar puncture in combination with high dose corticosteroids. © 2012, Nederlandse Vereniging voor Intensive Care.