We report the case of a 76-year-old man who received a spinal anaesthesia for inguinal hernia repair surgery. A cranial CT scan which was performed because the patient complained of postoperative headache and hemiparesis showed an important pneumocephalus. Because postoperative questioning revealed that the patient had a chronic and neglected rhinorrhea, we hypothesise that this pneumocephalus was secondary to an old unknown osteodural leak with intracranial air entry secondary to the spinal anaesthesia-releated decrease in CSF pressure.