[Spontaneous intracranial hypotension due to a broken dorsal perineural cyst]

It is now recognized that most, if not all, cases of spontaneous intracraneal hypotension result from spontaneous cerebrospinal fluid (CSF) leaks. The exact cause of spontaneous leak often remains unclear. However, two factors are typically considered: trivial trauma and weakness of the dural sac.

A 61-year-old woman came with a one week history of orthostatic headache. The neurologic examination and funduscopy were normal. Brain contrast- enhanced magnetic resonance imaging (MRI) showed subdural fluid collections and diffuse pachymeningeal enhancement. Cervical-dorsal-lumbar MRI showed a dilated spinal venous plexus throughout the canal. Computed tomography (CT) myelography demonstrated perineural cysts at the level of D7, D8, D9 and D10. The right D10 cysts was broken with extravasation of contrast medium into the extradural space. Three months later, after rest and hydration, the patient was asymptomatic. The brain and dorsal MRI, four months later were normal.

Spontaneous CSF leaks from broken perineural cysts has been exceptionally demonstrated. CT myelography should be employed to detect the involved site.