Case 28

Discussion:

Spontaneous Intracranial Hypotension (SIH) is a condition where patients get postural headaches characterized by an orthostatic headache, that is, one that occurs or worsens with upright posture and improve with recumbent position. It is most of the time secondary to a leak of the Cerebrospinal Fluid. The exact etiology of CSF leak remains largely unkown, but an underlying structural wekaness of the meninges is suspected. There is an association with generalized connective tissue disorder. Women are affected more commonly than men.

Typical MRI findings include: subdural fluid collections, enhancement of the pachymeninges, engorgement of venous structures, pituitary hyperemia, and “sagging” of the mid brain. CT myelography of the entire spine has been shown to be helpful in determining the location and extent of a CSF leak.

In some milder cases of SIH, the condition can resolve spontaneously. However, in  more serious cases this will require an epidural blood patch.

References:

• Bell WE, Joynt RJ, Sahs AL. Low spinal fluid pressure syndromes. Neurology. 1960;10:512-521.
• Lasater GM. Primary intracranial hypotension: the low spinal fluid pressure syndrome. Headache. 1970;10:63-66.
• Rando TA, Fishman RA. Spontaneous intracranial hypotension: report of two cases and review of the literature. Neurology. 1992;42:481-487.
• Schievink WI, Meyer FB, Atkinson JLD, et al. Spontaneous spinal cerebrospinal fluid leaks and intracranial hypotension. J Neurosurg. 1996;84:598-605.
• Wouter I. Schievink. Spontaneous Spinal Cerebrospinal Fluid Leaks and Intracranial Hypotension.  JAMA.2006;295:2286-2296.