Can a low-pressure headache have abnormal cerebrospinal fluid (CSF)?

From the Guidelines

Yes, low pressure headache can have abnormal cerebrospinal fluid (CSF) findings, including low CSF pressure, typically below 6 cm H2O, as well as increased protein concentration, normal glucose levels, and occasionally a mild pleocytosis. The most characteristic abnormality is low CSF pressure, which occurs because CSF is leaking faster than it can be produced, leading to reduced cushioning of the brain and traction on pain-sensitive structures 1. This causes the characteristic orthostatic headache that worsens when upright and improves when lying down.

Key Points

• The low pressure occurs because CSF is leaking faster than it can be produced, leading to reduced cushioning of the brain and traction on pain-sensitive structures.
• MRI findings often include diffuse pachymeningeal enhancement, brain sagging, and sometimes subdural fluid collections, which correlate with these CSF abnormalities.
• Treatment focuses on sealing the leak, often starting with conservative measures like bed rest, hydration, and caffeine, followed by epidural blood patches if necessary.
• It is estimated that spontaneous intracranial hypotension (SIH) occurs with an incidence of approximately 5 per 100,000 individuals annually, and the true incidence of this condition may be higher due to underdiagnosis and misdiagnosis 1.
• Clinical risk factors for the development of SIH include spinal osteophytes, weakened ectatic dura/meningeal cysts, and a history of bariatric surgery 1.

Diagnosis and Imaging

• Imaging plays a critical role in the diagnostic evaluation of intracranial hypotension, with goals of confirming the diagnosis and localizing the source of leak for targeted therapy 1.
• Intracranial imaging features suggestive of intracranial hypotension include qualitative signs such as engorgement of venous sinuses, pachymeningeal enhancement, midbrain descent, superficial siderosis, subdural hygroma or hematoma, and convex superior surface of the pituitary 1.
• Spinal imaging findings associated with SIH include direct evidence of CSF leakage via epidural fluid collections and CSF-venous fistula, as well as secondary indirect signs of CSF leakage such as dilated epidural venous plexus, subdural hygromas, and dural enhancement 1.

Treatment

• Treatment focuses on sealing the leak, often starting with conservative measures like bed rest, hydration, and caffeine, followed by epidural blood patches if necessary 1.
• In cases where symptoms persist after a negative full imaging workup, the possibility of SIH mimicking pathologies such as positional orthostatic tachycardia syndrome, cervicogenic headaches, migraines, or new daily persistent headache syndromes should be considered 1.

From the Research

Low Pressure Headache and Abnormal CSF

• Low pressure headache can be caused by alterations in cerebrospinal fluid (CSF) pressure, leading to neurologic symptoms, with the most common manifestation being headache 2.
• The headache is typically orthostatic and related to traction on pain-sensitive intracranial and meningeal structures, distention on periventricular pain-sensitive areas, and direct pressure on pain conveying cranial nerves 2, 3.
• Spontaneous intracranial hypotension (SIH) is a syndrome characterized by orthostatic headache, low CSF pressure, and unique imaging findings, including diffuse pachymeningeal enhancement and cerebellar tonsillar descent 2, 3, 4.
• CSF analysis in patients with low pressure headache may be normal or show increased protein concentration and a primarily lymphocytic pleocytosis 4.
• The pathogenetic core of low pressure headache is a decrease in CSF volume, whereas clinical, imaging, and CSF findings are variables dependent on the loss of CSF volume 4.

Imaging Findings

• Magnetic resonance imaging (MRI) of the brain with gadolinium is the first study of choice, which typically reveals diffuse pachymeningeal enhancement and frequently, cerebellar tonsillar descent and posterior fossa crowding 2, 3.
• Spinal MRI is an up and coming investigational technique, which may be helpful even in the case of a normal brain MRI 2.
• Computed tomography myelography is the diagnostic study of choice and may follow radiocisternography, which often shows absence of activity over the convexities and early appearance of activity in the renal/urinary tract 2.

Treatment

• Epidural blood patch (EBP) is the treatment of choice for low pressure headache 2, 3.
• Surgery and epidural fibrin glue injection are options for those who fail conservative therapy and/or EBP 3.
• Conservative measures are often undertaken first, but the effectiveness of these measures is not well established 2, 3.