Spinal cerebrospinal fluid (CSF) leak is an important and underdiagnosed cause of new onset headache that is treatable. Cerebrospinal fluid (CSF) bathes and supports the brain and spinal cord. When the connective tissue known as dura that holds CSF in around the spinal cord has a hole or tear, the result is a loss of CSF volume, known as intracranial hypotension. The most common symptom is a positional headache that is worse when upright and improved when lying down, but there are other neurologic signs and symptoms. Many patients are quite disabled by their inability to be functional while upright. Suffering for months or years before a diagnosis is common. Information provided by our partner Spinal CSF Leak Foundation.