Spontaneous intracranial hypotension is a condition in which the fluid pressure or volume inside the skull is lower than normal due to a spinal cerebrospinal fluid (CSF) leak--a hole, tear, or defect in the tissue that surrounds the spinal cord. Leaks can occur due to medical procedure, injury, or many other known or unknown causes.
The overall prevalence of spinal CSF leaks is unknown due to widespread misdiagnosis and lack of awareness but it can occur at any age or sex (though more common in females and in middle age). Diagnostic technique and interpretation are specialized.