Spontaneous intracranial hypotension (SIH) was described nearly 70 years ago, and for years it was essentially equated with post dural puncture headaches (PDPH). The interest in this entity substantially increased after the magnetic resonance imaging (MRI) abnormalities of this disorder were recognized in the early 1990s, and consequently many more patients were diagnosed than before and a far broader clinical spectrum of this disorder began to become apparent. It also came to be recognized that the overwhelming majority if not all cases of SIH result from spontaneous cerebrospinal (CSF) leaks and that the independent pathogenic parameter is loss of CSF volume.

As experience with spontaneous CSF leaks is increasing, it is becoming more apparent that often, although not always, this entity can not be equated with PDPH. This is particularly noteworthy with regard to treatment outcome. Conservative estimates point to a persistent symptomatic relief in nearly three-quarters of patients with post puncture headaches, where the response to a second epidural blood patch is even higher. The figures are even more impressive if only patients with post diagnostic lumbar puncture headaches are considered. This can be contrasted with nearly one-third good response to each epidural blood patch in spontaneous CSF leaks and somewhat better response in highly selected cases.