For this reason, a SCSFL is referred to as CSF hypovolemia as opposed to CSF hypotension.Spontaneous intracranial hypotension, a subtype of CSF leak, refers to lower than normal than CSF volume due to an initially unknown or insidious cause. This differentiates it from CSF leaks of known causes such as cranial or spinal trauma, surgery or lumbar puncture or spinal anesthesia (most common cause of CSF leak). The International Classification of Headache Disorders (ICHD) Third Edition diagnostic criteria for spontaneous intracranial hypotension includes any headache attributed to low CSF pressure (low CSF opening pressure) or CSF leakage (evidence of CSF leakage on imaging). Further, the headache must have a temporal relation to the low CSF pressure or leakage and the headache cannot be better explained by another ICHD diagnosis. The final criteria is that in the rare cases of spontaneous intracranial hypotension with no headache present, the neurologic symptoms that are present must be attributable to low CSF or explained by the diagnosis of spontaneous intracranial hypotension. Signs and symptoms
The most common symptom of a CSF leak is a fast-onset, extremely painful orthostatic headache or thunderclap headache. This headache is usually made worse by standing and typically becomes prominent throughout the day, with the pain becoming less severe when lying down. Orthostatic headaches can become chronic and disabling to the point of incapacitation. Some patients with a SCSFL will develop headaches that begin in the afternoon. This is known as second-half-of-the-day headache.
The evidence of the last decade suggests however, that these leaks result from either a discogenic pathology, such as microspur, osteophyte or intra-dural disc herniation that pierces the dura like a knife, connective tissue disorder (which can often lead to discogenic pathology), or spinal drainage problems.A cerebrospinal fluid leak can be a rare complication of an anterior cervical discectomy and fusion (ACDF). One study suggested a CSF leak to follow from 0.5% of operations. Another study suggests a CSF leak to follow from 1% of operations. In most of these cases repair is successful. Discogenic causes
The most common cause of an intractable "sCSF" leak is discogenic, either from an intra-dural disc herniation, osteophyte or microspur on the disc or vertebral body. "Recent radiological and microsurgical investigations revealed that a calcified, degenerative bony microspur is often the culprit lesion in cases of intractable CSF leaks. Arising from the level of the intervertebrate disk space, these microspurs pierce the ventral dura and produce a slit-like defect a few millimeters in length. These microspurs and the associated CSF leak have to be localized exactly, and then they are amenable to surgical treatment." Connective tissue theory
Various scientists and physicians have suggested that SCSFLs may be the result of an underlying connective tissue disorder affecting the spinal dura. It may also run in families and be associated with aortic aneurysms and joint hypermobility.Up to two thirds of those affected demonstrate some type of generalized connective tissue disorder.