This is a condition of low cerebrospinal fluid (CSF) pressure resulting in a particular type of headaches and many other symptoms.

What is CSF?

CSF is a clear fluid within the cavities of the brain and all around it, in a way providing a buffer between the brain and the skull bones. It is produced slowly inside the cavities of brain, comes out through some openings in the base of the brain, travels upwards and downwards in the spine, and is absorbed in the venous sinuses on top of the brain. The cavity containing this fluid extends from brain down to the whole length of the spine, which is called intrathecal cavity. Normally, CSF is a clear fluid like water, but has small amount of protein, glucose, and a few cells. Normal CSF pressure is about 7-20 cm (or 70-200 mm) of H2O. This pressure is usually checked by performing a lumbar puncture. Checking its pressure and its lab analysis provides very useful information to diagnose multiple conditions, such as bacterial meningitis, in which case, the pressure, the cells and protein levels may be high, and glucose level low. High CSF pressure can typically cause continuous headache, but a low CSF pressure can also result in a particular type of headache.

 

What may be the cause of low CSF pressure?

Its main cause is a leak in the system. The cavity containing CSF is a closed and sealed cavity, surrounded by tissues whose pressure in many places is lower than CSF. In case of an injury in this system, CSF may continue to leak resulting in a low CSF pressure state. A CSF pressure of 6 mm or less is considered abnormally low. A common cause of a leak is an epidural procedure performed during childbirth or a surgical procedure, or a diagnostic lumbar puncture. In most cases though, the leak is quickly healed in a matter of hours to a few days. In some patients, this correction does not happen, or does not happen quick enough resulting in low fluid pressure in the system. Some other causes include a physical injury, like an auto-accident, or merely a strong cough or a sneeze.   

 

What are the symptoms of low CSF pressure?

Its most typical symptom is a headache that occurs when the patient is standing or sitting, while disappearing or significantly better when supine or in a flat position. It is sometimes called an orthostatic headache. Other symptoms appearing with the headache are photophobia, nausea, vomiting, dizziness, vertigo, tinnitus, hearing impairment, neck stiffness, blurred vision, and unsteadiness. Some patients may also feel fogginess of mind, and rarely double vision. It is important to note that in chronic cases, patient may not have a classical orthostatic pattern of headache. At the same time, not every patient with orthostatic headache has low CSF pressure.

 

How is the low CSF pressure diagnosed?

CSF pressure is checked by performing a lumbar puncture. As the procedure of lumbar puncture may itself result in low CSF pressure state, one should be careful selecting the right patient. Usually, an MRI is already before a lumbar puncture. If not, it should be done before the procedure. It can reveal certain findings suggesting low CSF pressure, though it cannot confirm or provide the exact pressure. MRI findings suggestive of low CSF pressure are diffuse abnormal signal in meninges, a distended venous sinus, or a prominent pituitary gland. Of note, meningeal signal abnormality is not unique to this condition. These MRI signs are noted in acute cases of low CSF pressure, more than chronic, and may not be present in every case.

In most cases, it is not particularly important to check the pressure, as the history can be strongly suggestive of this condition. For example, a patient developing an orthostatic headache right after a lumbar puncture, or an epidural injection, may not need another procedure to check the pressure, as the diagnosis is reasonably straight-forward. A lumbar puncture is a consideration in cases where there is no clear history of a triggering procedure or a reason having orthostatic headache.

 

What may be the complications of low CSF pressure?

Other than headaches and related symptoms, it may rarely cause more complex problems, including subdural hematoma, venous sinus thrombosis, brain herniation, cranial nerve palsies, Parkinson like state, alteration of consciousness or even COMA.

 

Who is at risk of developing the low CSF state?

Female gender, younger age and low body weight are common indicators of higher risk. There are some health conditions resulting in higher risk, such as dolichostenomelia (disproportionally long limbs), Ehlers-Danlos syndrome, and Marfan syndrome. In most patients, there is no obvious genetic abnormality.

 

How is a CSF leak detected?

As stated above, in a straightforward case, like after a lumbar puncture or an epidural, a test to find a CSF leak is not warranted as it is already known. In other cases, the first order of business is to determine if there is evidence of low CSF pressure. This is determined by doing a lumbar puncture, but one should be careful with this test as, either due to technical difficulties or due to inexperience, it may not provide the right information, and may make patient’s condition worse.

If CSF pressure is confirmed low, or strongly suspected to be low, a test to find the source of CSF leak can be considered. Following tests can be used:

A: CT Myelography: On one hand it is an excellent test for this purpose, the so-called “gold-standard,” but only if done right by expert hands. It can easily miss finding a leak if not done right. It requires a lumbar puncture to inject a radioactive dye in the CSF chamber, and the whole spine CT imaging to trace its flow. Ultrafast CT technique is more useful as the dye may leak very quickly and the leak may not be detected. On the other hand, in some patients the leak may be very small and may take time to reveal itself. The risks involved with this procedure include further worsening of low CSF pressure, and exposure to significant radiation. 

B: Spinal MRI: A special MRI technique (heavily T2 weighted MRI) is probably as useful as CT myelography to detect a leak.

C: Spinal MRI with contrast or spinal MRI myelography: It is another useful technique but requires injection of MRI contrast into CSF space, whose significance or impact is not clearly known.

D: Digital subtraction myelography: It requires injecting a dye in the CSF space, tilting the table and taking x-ray picture of the spine.  

 

What is the treatment for low CSF pressure?

There is no definitive medical treatment. Some medicines may help. More effective are caffeine and steroids. Complete bedrest for a few days with meds can be tried. If that does not work, specific treatment for the leak is needed. In most cases, as the source of leak is straightforward, caused by a lumbar puncture or an epidural injection, it is easily localized and done. The procedure used to seal this type of leak is called an epidural blood patch. In this procedure, a few cc of patient’s own blood is used to patch the potential hole created by the needle. For the patient, this procedure seems like having another lumbar puncture or an epidural, but it is done by an expert used to doing such procedures. In most cases, it is an anesthesiologist. If diagnosed correctly, the response is right away with resolution of orthostatic headaches and other associated symptoms.

In other cases, where the leak is not located in the lower part of the back, or not caused by lumbar puncture or an epidural injection, a surgical procedure is used to seal the leak. This is done by a neurosurgeon.

 

Where can I get more information about the low CSF pressure headache?

American Academy of Neurology