In this article, the author reviews new concepts in spontaneous spinal CSF leak. She discusses the role of CSF volume depletion and addresses the substantial variability in the clinical aspects, imaging findings, and CSF abnormalities related to this disorder. Preexisting dural defects, likely related to disorders of the connective tissue matrix, are sometimes seen and contribute to the often complex anatomy of these spontaneous leaks. These “spontaneous” defects present therapeutic challenges far beyond the expected management of post-lumbar puncture or even post-epidural catheterization CSF leaks. An update with special emphasis on recent theories on orthostatic headache pathogenesis and advances of the imaging techniques to localize CSF leaks and treatment options is provided. The author also briefly discusses posttraumatic CSF leak.
• Spontaneous spinal CSF leak is characterized by an orthostatic headache often accompanied by neck stiffness, tinnitus, hypacusia, photophobia, or nausea. However, leaks can also present with a “second-half-of-the-day” headache and, rarely, no headache.
• The spinal location of spontaneous spinal CSF leak is important. Its pathophysiology is thought to be linked to reduced spinal dural compliance, resulting in a downward shift of the hydrostatic indifferent point and intracranial hypotension.
• The 2 main imaging tools used to localize spinal CSF leaks are fat suppressed heavily T2-weighted magnetic resonance myelography and computed tomographic (CT) myelography.
• The treatment of choice is an autologous epidural blood patch, preferably delivered at the level of the spinal CSF leak. Fibrin sealant injection and surgical repair are reserved for intractable cases.
Historical note and terminology
The history of how spontaneous spinal CSF leaks have been described over the years reflects clinical controversy regarding the underlying pathophysiology of this disorder.
Schaltenbrand, a German neurologist, introduced the term “aliquorrhea,” meaning “lacking” or “absence of” to describe a disorder associated with low, unobtainable, or even negative CSF pressures. He noted that clinically, the disorder was marked by orthostatic headache and other features (105). This description provided the first understanding of what is now known as spontaneous spinal CSF leak.
From the 1960s to the 1990s, with the advent of radionuclide cisternography (44; 64), conventional myelography, and MRI, CSF leaks and CSF dynamics could finally be studied (103; 53; 43; 93). Imaging findings, such as venous sinus engorgement, evoked the Monroe-Kellie doctrine, suggesting that changes in these structures occurred to compensate for lack of CSF in the brain space. For this reason, in the late 1990s, spontaneous spinal CSF leak was called “CSF hypovolemia” or “CSF volume depletion” (80). However, patients were also noted to have low CSF pressure, and a competing term “spontaneous intracranial hypotension” emerged (25; 77). No data has ultimately supported the theory of low volume or even consistently low CSF pressure. Even the concept of the Monroe-Kellie doctrine, or the constancy of brain volume, has been challenged; a study revealed that there was a decrease in brain tissue volume in patients with spontaneous intracranial hypotension (149).
Therefore, the current preferred descriptive term is “spontaneous spinal CSF leak” (108). This term captures the importance of the CSF leak being spontaneous, or occurring with minimal or no clear precipitant. The word “spontaneous” is important because patients with spontaneous leaks can have a very different prognosis and workup than patients with iatrogenic and traumatic CSF leaks. The term also specifies that the CSF leak should be from a spinal source. This term is important because the majority of people with leaks from the cranium, ie, skull-based leaks, rarely, if ever, develop symptoms or brain imaging findings consistent with spontaneous spinal CSF leak (108; 118).