A cerebrospinal fluid leak (CSF leak or CSFL) is a medical condition where the cerebrospinal fluid (CSF) surrounding the brain or spinal cord leaks out of one or more holes or tears in the dura mater. A cerebrospinal fluid leak can be either cranial or spinal, and these are two different disorders. A spinal CSF leak can be caused by one or more meningeal diverticula or CSF-venous fistulas not associated with an epidural leak.
A CSF leak is classed as either non-spontaneous, caused by trauma including that arising from medical interventions, or spontaneous, sometimes in those with predisposing conditions (known as a spontaneous cerebrospinal fluid leak (sCSF leak). Traumatic causes include a lumbar puncture noted by a post-dural-puncture headache, or a fall or other accident. Spontaneous spinal CSF leaks are associated with heritable connective tissue disorders including Marfan syndrome and Ehlers–Danlos syndromes.
A loss of CSF greater than its rate of production leads to a decreased volume inside the skull known as intracranial hypotension.
Any CSF leak is most often characterized by orthostatic headaches, which worsen when standing, and improve when lying down. Other symptoms can include neck pain or stiffness, nausea, vomiting, dizziness, fatigue, and a metallic taste in the mouth. A CT myelography scan can identify the site of a cerebrospinal fluid leakage. Once identified, the leak can often be repaired by an epidural blood patch, an injection of the patient's own blood at the site of the leak, a fibrin glue injection, or surgery.
The set of symptoms associated with a sCSF leak is referred to as a spontaneous cerebrospinal fluid leak syndrome (SCSFLS). A sCSF leak is a rare condition, affecting at least one in 20,000 people and many more who go undiagnosed every year. On average, the condition develops at age 42, and women are twice as likely to be affected. Some people with a sCSF leak have a chronic leak of cerebrospinal fluid despite repeated patching attempts, leading to long-term disability due to pain and being unable to be upright, and surgery is often needed.