Intracranial Hypotension

What is intracranial hypotension?

Intracranial hypotension is a condition whereby there is abnormally low pressure or volume within the brain cavity. This condition is caused by the leaking of the fluid surrounding your brain and spinal cord (cerebrospinal fluid), which can be spontaneous (for no apparent reason), or caused by direct trauma to the spinal dura (connective tissue in the spine).

This condition is diagnosed more often in females than males, with the peak age of diagnosis at 40 years old [1].  Spontaneous intracranial hypotension is an extremely rare condition, with an occurrence rate of 5 cases per 100,000 per year [1].

How will having intracranial hypotension affect me?

The symptoms of intracranial hypotension have the potential to affect you on a daily basis, and greatly affect your activities each day, as they might be constant and experienced throughout the day. This is especially if the main symptom, headache, is more severe.

What does having intracranial hypotension feel like?

The most recognisable and main symptom of intracranial hypotension is a headache that feels like a squeezing at the back of your head, which is relieved when you’re lying down and gets worse when you stand up. Your headache might also feel like aching behind your ears or at the base of your skull, and in some cases might even extend down your back.

Other symptoms of this condition include vertigo and imbalance, nausea and vomiting, and neck pain and stiffness. You might also have sensitivity to light and sound, double vision and occasional difficulty with concentration. These symptoms are relatively common across many conditions and so intracranial hypotension can easily be misdiagnosed as something else. So, if you are experiencing symptoms, it is best to book a consultation with your doctor, and you might eventually need to be referred to a neurologist for further examination.

What are the causes of intracranial hypotension?

Besides spontaneous intracranial hypotension, this condition may also develop if you’ve previously undergone medical procedures like lumbar procedures, epidural injections, over-drainage of cerebrospinal fluid shunts, or spinal surgery.

Traumatic physical injuries like automobile or sporting accidents can also cause intracranial hypotension. It can also happen suddenly as a result of physical exertion, such as swinging a golf club. Cases like these have identifiable causes and are easier to diagnose by doctors, as compared to spontaneous intracranial hypotension, which often faces delays in diagnosis.

How is intracranial hypotension diagnosed?

To confirm a diagnosis of intracranial hypotension, your doctor might refer to your medical history, family medical history, and analyse the symptoms you are experiencing. You might also be referred to a neurologist, to carry out a neurological exam. In this exam, your senses, reflexes, balance and mental status will be tested.

A spinal tap or lumbar procedure might be performed, to extract a sample of your cerebrospinal fluid for testing, or measure the pressure of this fluid.

CT scans or myelography may be done to examine the large veins that carry the blood from the vein. MRI scans may also be done to create X-ray images of your head and brain and check for any abnormalities. Radionuclide cisternography might also be conducted, whereby a radionuclide is injected into your cerebrospinal fluid, to determine if there is abnormal flow.

What are the conditions related to intracranial hypotension?

People who have connective tissue disorders or Chiari malformation are at a greater risk of developing intracranial hypotension. 

If you have weakness in your spinal dura (the outer layer of connective tissue surrounding your brain and spinal cord), it is more likely to tear, causing a leak that would result in intracranial hypotension. If you happen to have any genetic disorders such as Ehlers-Danlos syndrome, Marfan syndrome and autosomal dominant polycystic kidney disease could also heighten your risk of cerebrospinal fluid leaks.

How is intracranial hypotension treated?

Although this condition might sound serious and diagnosis might seem scary at first, don’t worry, because it can be successfully managed and sometimes even treated with non-surgical treatments. In fact, there is a chance that your condition could resolve on its own, with sufficient rest and fluid intake, caffeine/theophylline and salt intake and steroid therapy.

If the site of the spinal cerebrospinal fluid leak can be identified, the most common treatment is epidural patching with blood or fibrin sealant. A blood patch is when blood is taken from a vein in your arm and injected into the spinal canal, in the space outside the spinal dura. This procedure might be performed by a neuroradiologist.

Surgery is sometimes needed to manually repair the spinal dura, but this procedure relies on imaging localisation of the cerebrospinal fluid leak.

These procedures can offer relief to your symptoms, but also carry the risk of some surgical complications. If you suspect that you have intracranial hypertension, book an appointment with your doctor to run some tests and find out more.

References

  1. Deline, C., & I. Schievink, W. (n.d.). Spontaneous Intracranial Hypotension. NORD (National Organization for Rare Disorders). https://rarediseases.org/rare-diseases/spontaneous-intracranial-hypotension/
  2. Intracranial Hypotension. (n.d.). Barrow Neurological Institute. Retrieved December 3, 2020, from https://www.barrowneuro.org/centers-programs/migraine-and-headache-disorders/what-we-treat/intracranial-hypotension/
  3. Intracranial Hypotension – UCLA Neurosurgery, Los Angeles, CA. (n.d.). UCLA Health. https://www.uclahealth.org/neurosurgery/intracranial-hypotension
  4. National Headache Foundation. (2017). Dr. Martin interviews patient about intracranial hypotension [YouTube Video]. In YouTube. https://www.youtube.com/watch?v=UJuQ2MpX-pc
  5. Rahman, M., Bidari, S. S., Quisling, R. G., & Friedman, W. A. (2011). Spontaneous Intracranial Hypotension: Dilemmas in Diagnosis. Neurosurgery, 69(1), 4–14. https://doi.org/10.1227/neu.0b013e3182134399
  6. Robblee, J., A. Secora, K., M. Alhilali, L., & L. Kneivel, K. (2020, May). Spontaneous Intracranial Hypotension. Barrow Neurological Institute. http://v2.practicalneurology.com/pdfs/PN0520_CF_SIH.pdf
  7. What is Spontaneous Intracranial Hypotension? | Spine Surgery MN. (2016, January 14). Dr. Stefano Sinicropi, M.D. https://sinicropispine.com/what-is-spontaneous-intracranial-hypotension/