CSF Hypotension and CSF Leaks

Spontaneous intracranial hypotension (SIH) is a relatively uncommon and under-recognized disorder that is caused by a spinal CSF leak. The clinical symptoms typical for SIH syndrome are described. An orthostatic headache is the main clinical finding. This chapter reviews the brain and spine imaging findings that may be associated with this disorder, including pachymeningeal enhancement, subdural fluid collections or hemorrhage, venous sinus distension, enlargement of the pituitary gland, brain sagging, spinal epidural fluid collections, and distension of the spinal epidural venous plexus. These radiological findings may be highly characteristic, allowing the neuroradiologist to suggest the specific diagnosis. The imaging methods used for the diagnosis of SIH and detection of CSF leak sites, such as brain and spine MRI as well as CT myelography and digital subtraction myelography, are discussed. A recommended radiological protocol is also presented. When conservative therapy is unsuccessful, nontargeted epidural blood patch (EBP) is the mainstay of treatment and can be performed under imaging guidance. If patients do not respond to EBP and the leak site is subsequently identified by myelography, site-directed therapeutic options include CT-guided injection of fibrin sealant, transvenous embolization of CSF-venous fistulas, and neurosurgery. Since SIH may present with a variety of symptoms, many of which are nonspecific, it is not infrequently misdiagnosed, so it is important to consider this entity in the differential diagnosis when reporting clinical neuroradiology cases. Patients who are misdiagnosed may be exposed to the unnecessary risk of starting treatment for diseases that mimic intracranial hypotension, including aseptic meningitis or pituitary disorders; therefore, every specialist in radiology should know and properly recognize this condition.