Posted on Mar 04, 2022
Characterized by severe and often debilitating positional headaches, intracranial hypotension is a condition in which the cerebrospinal fluid (CSF) pressure inside the cranium and the spine are lower than normal. Almost always, intracranial hypotension occurs when there is a CSF leak in the spine.
While some CSF leaks are easier to catch - particularly those caused by spinal procedures such as lumbar puncture, myelography, and surgery - leaks that happen spontaneously for unknown reasons can be sometimes difficult to diagnose. Many patients who seek care are told they have migraines and are prescribed treatments that offer no relief. Others who are evaluated for a CSF leak may be imaged incorrectly, resulting in missed or delayed diagnosis.
To better understand how patients can navigate such a challenging diagnosis, we spoke with Academic Neuroradiologist and Spine Interventionist, Dr. Majid Khan. An integral member of the Jefferson Headache Center, one of the nation’s top referral centers for spontaneous CSF leak treatment, Dr. Khan walks us through the steps of proper evaluation and discusses the types of imaging tests patients should request to prevent misdiagnosis.
DocPanel is committed to making sure every patient receives excellent care. If you believe you or a loved one may have a CSF leak and would like an expert second opinion on your medical imaging from Dr. Khan or one of our other fellowship-trained subspecialty radiologists, you can learn more here.
[DocPanel] What is the difference between intracranial hypotension and spontaneous intracranial hypotension (SIH)? Why is the latter so often overlooked and misdiagnosed?
An overwhelming majority of patients with spinal CSF leaks will experience positional headaches due to low CSF pressure. When they stand up, the headache gets worse. And when they lay down, the headache gets better. This type of headache, also called orthostatic headache, is perhaps the most important symptom to be noted as a potential indication of intracranial hypotension caused by a CSF leak.
Iatrogenic intracranial hypotension occurs in patients with a history of proceeding spinal procedure, most commonly lumbar puncture, myelogram, and intradural drain placements. This type of CSF leak is called an iatrogenic leak, meaning it was caused by instrumentation. Spontaneous intracranial hypotension, on the other hand, is diagnosed when a CSF leak happens without any underlying cause or a proceeding event. This makes it, at times, challenging to diagnose.
Patients who get SIH are often healthy individuals who, suddenly, start to get a headache, with a positional component, that becomes relentless over time. In the early phase, these headaches get better very quickly when the patient lays down, often within just a few minutes. But as the diagnosis becomes more chronic, say, for example, if the patient has had these headaches for six months to a year, they will start noticing that they need to lay down for a longer period of time in order to experience relief from the headache. For those suffering from SIH, their life can come to a complete standstill. It’s such a tragedy because, with effective treatment, symptoms can clear up in as little as 72 hours.
For those suffering from SIH, their life can come to a complete standstill. It’s such a tragedy because, with effective treatment, symptoms can clear up in as little as 72 hours.
Spontaneous CSF leak is, sadly, the most misdiagnosed and underdiagnosed condition that I presently see. The main reason stems from a general lack of physician familiarity with this condition, as well as misconceptions about how it is diagnosed. At the Jefferson Headache Center, we see patients from all over the country who have been dealing with undiagnosed symptoms despite ongoing attempts to seek care.
[DocPanel] Can you walk us through what the diagnostic process looks like? At what point should investigation begin for spontaneous intracranial hypotension and CSF leak? Where are the mistakes being made in the evaluation process?
If a patient presents with positional headache, has found no relief with standard headache treatments, and has no prior history of spine intervention - then there is clinical reason to suspect spontaneous intracranial hypotension. At that point, evaluation for possible CSF leak should begin. A brain MRI with and without contrast is usually the first test, as it can sometimes pick up signs of intracranial hypotension. If the brain MRI shows signs of SIH, or if there is high clinical suspicion of a leak, a full spine MRI with and without contrast, should also be ordered as a non-invasive screening tool.
But for proper evaluation, the spinal MRI exams should be performed using a CSF leak protocol. If the right protocol is not deployed, a subtle leak may be missed, leading to missed or delayed diagnosis.
But for proper evaluation, the spinal MRI exams should be performed using a CSF leak protocol. In other words, the MRI must include specific sequences that are used to demonstrate CSF leak, making it easy to diagnose. If MRI with this specific CSF leak protocol is not deployed, a subtle leak may be missed, and, even sometimes, with an accurately performed MRI, some of the leaks cannot be diagnosed. Unfortunately, there are imaging centers, hospitals, outpatient centers, and private practices around the world that are all using regular degenerative spine MRI protocols to look for CSF leaks.
Based on a patients' clinical symptomology and the screening MRI results, CT myelograms are performed next to help diagnose/confirm a leak and pinpoint the exact level of leak in the spine. But, again, a CSF leak myelogram requires a different technique and protocol. It is different from the routine spinal myelogram performed at most hospitals throughout the country. With CSF leak CT myelography, a lumbar puncture is performed under CT. CSF pressure is measured, contrast dye is injected into the spinal canal via a small needle, and the entire spine is imaged quickly after doing certain maneuvers to mix the contrast throughout the spine. This helps to identify the site of the leak so that targeted treatment can be performed. There are different types of CSF leak myelograms that are used to target the different sources of leak.
Once the leak is confirmed and accurately located, a blood patch procedure is usually an effective treatment. The patient's blood is injected into the epidural space, and the blood clots that form stop the leak. Fibrin glue is also used with blood in such cases. In some cases, a patient may need multiple patches over a period of time.
[DocPanel] Are there any types of CSF leaks or specific locations that are particularly difficult to visualize on imaging?
About 70-80% of the time, patients have what is called a diverticula leak. These leaks are typically detected with CSF leak protocol MRIs and myelograms. The other 20-30% of leaks are ventral leaks and spinal CSF venous fistula, both of which can be difficult to diagnose and need dynamic myelographic techniques.
Ventral leaks are caused by a bone spur that acts as an ice pick and pokes a hole in the dura. These leaks are so frequently missed because they can only be visualized with specialized myelographic imaging techniques. Once identified, surgery needs to be performed to shave off the spur and the dura can be patched at the same time.
These leaks are so frequently missed because they can only be visualized with specialized myelographic imaging techniques. Once identified, surgery can be performed to shave off the spur and the dura can be patched.
A CSF leak due to a venous fistula occurs when the CSF in the spinal canal drains into the venous system through an abnormal connection, called a fistula, and happens around the exiting nerve in the foramen. These are the most difficult leaks to catch and even get missed with our specialized myelograms, requiring an even more specialized protocol to look, specifically, for this fast leak. Once identified, surgery and endovascular treatment can repair the leak and venous fistula.
[DocPanel] What advice do you have for patients with symptoms of spontaneous intracranial hypotension who suspect they may have an undiagnosed leak? How can they ensure they are evaluated correctly?
My first piece of advice would be to make sure your treating physician and the radiologist who reads your imaging both have experience with CSF leaks. Few experts in the country are skilled at finding and repairing spontaneous spinal CSF leaks, so you want to be sure you are at such a center. A lot of patients who are referred to me have had symptoms for months to years and have hopped from hospital to hospital seeking help. But, unfortunately, they have either not been evaluated properly, or are misdiagnosed with other types of headaches.
If you suspect you may have a spontaneous CSF leak but are unsure of whether your MRI was performed with the correct protocol, a second opinion from a radiologist with CSF leak expertise is an excellent way to make sure you are being evaluated properly.
If you suspect you may have a spontaneous CSF leak because of positional headache but are unsure of whether your MRI was performed with the correct protocol, a second opinion from a radiologist with CSF leak expertise is an excellent way to make sure you are being evaluated properly. The radiologist can let you know if your scan used the correct technique. If it did not, they can offer guidance for follow-up imaging.
[DocPanel] For those who have been diagnosed with a CSF leak, is there anything they should be aware of before getting treatment?
Even if a CSF leak is detected with a routine MRI, specialized myelographic techniques are still needed to accurately localize the site of the leak to direct treatment. For example, if an MRI shows a leak going all the way from the cervical to the lumbar region of the spine, it doesn't mean that the patient is leaking from every site. My advice would be to go to a center that specializes in spinal CSF treatment. There are only a few centers like this in the whole country - but the expertise is crucial.
Fortunately, awareness of SIH and spontaneous CSF leak is growing. Thanks to research and education from institutions like the Spinal CSF Leak Foundation, more physicians are gaining expertise in the area prompting headache centers across the country to lead initiatives for incorporating CSF leak programs in their facilities. Patient-centric groups are also thriving, offering support and guidance to anyone who believes they may have a CSF leak. While misdiagnosis remains common today, these resources offer a lot of hope for patients that can give them timely relief from this diagnosis and turn the statistics around.
Dr. Majid Khan is an Interventional Neuroradiologist at Johns Hopkins, an Associate Professor of Radiology at Thomas Jefferson University Hospitals, and a Radiologist at DocPanel. He is also Director of Non-Vascular Spine Intervention at Johns Hopkins University hospitals. Dr. Khan graduated from the University of Kashmir, India in 1993. He completed his residency in radiology at the Nassau University Medical Center at Stony Brooks University and then completed his fellowship in Neuroradiology at Johns Hopkins University. Dr. Majid enjoys teaching and is especially interested in advanced head & neck and spine tumor imaging, with extensive experience in CSK leak diagnosis and spine tumor ablations.