title: A rare case of tension pneumocephalus after head trauma.
abstract: OBJECTIVE
  We present a rare case of tension pneumocephalus (TP) after head trauma not involving mask ventilation but based on pathological respiration pattern, kussmaul breathing. TP is rare condition and exceptionally rare when positive airway pressure has not been applied. In this particular case, the vacuum and one-valve intracranial effects causing pneumocephalon were instead accentuated by a pathological pattern of respiration due to severe ketoacidosis - a condition not previously reported in the literature.
  
  
  METHODS
  This is a case report showing a rare cause of pneumocephalon caused by patients own respiration. We retrospectively reviewed the patients' journal to find the cause of his severe pneumocephalon. The patient has not been ventilated and the only cause of TP in this case seems to be his own rapid and pathological breathing caused by ketoacidosis.
  
  
  CONCLUSIONS
  In the presented case, pathologic deep and rapid respiration exerted additional pressure on the dural fistula allowing ambient air at a pressure above ICP to drive itself into the intracranial space. The loss of CSF from skull base fractures created a void space and relative negative pressure, allowing air to bubble in and fill the void.
authors.affiliation: Department of Neurosurgery, Aarhus University Hospital, Noerrebrogade 44, DK-8000 Aarhus C, Denmark. Electronic address: shibje@rm.dk.
authors.forename: Shima
authors.initials: S
authors.lastname: Bjerrum
authors.affiliation: Department of Neurosurgery, Aarhus University Hospital, Denmark. Electronic address: rikros@rm.dk.
authors.forename: Frederikke
authors.initials: F
authors.lastname: Rosendal
keywords: Kussmaul breathing; Metabolic acidosis; Tension pneumocephalus