Spontaneous Intracranial Hypotension: 10 Myths and Misperceptions
This 2018 publication by the team of neuroradiologists in the Department of Radiology at Duke University Medical Center reviews the body of literature on spontaneous intracranial hypotension and outlines common myths and misperceptions. The abstract is below, followed by a summary of the 10 myths outlined in the paper. This summary is written with permission from the authors, two of whom kindly sit on our medical advisory board.
Spontaneous Intracranial Hypotension: 10 Myths and Misperceptions
Peter G. Kranz, MD; Linda Gray, MD; Timothy J. Amrhein, MD
Headache 2018. First published: 24 May 2018. https://doi.org/10.1111/head.13328
Abstract
Objective
To discuss common myths and misperceptions about spontaneous intracranial hypotension (SIH), focusing on common issues related to diagnosis and treatment, and to review the evidence that contradicts and clarifies these myths.
Background
Recognition of SIH has increased in recent years. With increasing recognition, however, has come an increased demand for management by neurologists and headache specialists, some of whom have little prior experience with the condition. This dearth of practical experience, and lack of awareness of recent investigations into SIH, produces heterogeneity in diagnostic and treatment pathways, driven in part by outdated, confusing, or unsubstantiated conceptions of the condition. We sought to address this heterogeneity by identifying 10 myths and misperceptions that we frequently encounter when receiving referrals for suspected or confirmed SIH, and to review the literature addressing these topics.
Methods
Ten topics relevant to diagnosis and treatment SIH were generated by the authors. A search for studies addressing SIH was conducted using PubMed and EMBASE, limited to English language only, peer reviewed publications from inception to 2018. Individual case reports were excluded. The resulting studies were reviewed for relevance to the topics in question.
Results
The search generated 557 studies addressing SIH; 75 case reports were excluded. Fifty‐four studies were considered to be of high relevance to the topics addressed, and were included in the data synthesis. The topics are presented in the form of a narrative review.
Conclusions
The understanding of SIH has evolved over the recent decades, leading to improvements in knowledge about the pathophysiology of the condition, diagnostic strategies, and expanded treatments. Awareness of these changes, and dispelling outdated misconceptions about SIH, is critical to providing appropriate care for patients and guiding future investigations going forward.
Here is a list of the 10 myths.
Please see the full text publication for more details.
Myth 1: Spontaneous intracranial hypotension (SIH) is defined by low CSF pressure.
Several studies have confirmed that normal opening CSF pressure by lumbar puncture measurement is common so cannot be used to rule out the disorder.
Myth 2: SIH is always characterized by orthostatic headache / orthostatic headache is always SIH.
While the headache is most often worse after minutes to hours of assuming upright posture, and improved with lying flat, this is not universally the case, and this positional aspect often diminishes with time. In addition, not all positional headaches are due to SIH.
Orthostatic headache may be related to postural orthostatic tachycardia syndrome (POTS). Complicating this is the fact that both POTS and SIH may coexist in the same patient. Other causes of headache that worsens with upright posture include cervicogenic (related to problems in the neck) headache or craniocervical instability.
Myth 3: A negative brain MRI excludes SIH.
While gadolinium-enhanced brain MRI is a very important test in all suspected SIH cases, and findings are easily recalled by the SEEPS mnemonic, normal MRI is not unusual and does not rule out the disorder. Learn more about SEEPS findings HERE.
Myth 4: Patients with dural enhancement should be worked up for meningitis.
Dural enhancement on contrast-enhanced MRI is a specific finding in SIH and should not be confused with meningitis or malignancy.
Myth 5: Chiari I is a feature of SIH.
Brain sag may be apparent on brain MRI in SIH patients. When the cerebellar tonsils are low-lying, this can be confused with Chiari I, which is a congenital abnormality. In the case of SIH, other evidence of brain sag will be present and therefore can be distinguished on imaging from Chiari I.
Myth 6: All spinal CSF leaks are caused by Tarlov cysts / spinal diverticula.
There are several types of spontaneous spinal CSF leaks. While some leaks are associated with spinal diverticula, bone spurs related to calcified discs also cause spinal CSF leaks. CSF-venous fistula is another type of leak in which there is an abnormal communication between the CSF fluid space and a vein just outside the dura that hold CSF in around the spinal cord. Tarlov cysts in the sacral region are infrequently associated with spontaneous spinal CSF leaks. Learn more about the types of leaks HERE.
Myth 7: Spinal imaging rarely reveals a leak in SIH.
While spinal imaging may be normal in up to half of patients, in centers with more experience, many leaks can be localized, often with additional imaging, which helps to direct treatment.
Myth 8: Skull base leaks cause intracranial hypotension.
Spontaneous CSF leaks in the skull base, or cranial CSF leaks are not associated with intracranial hypotension. If a patient has an orthostatic headache and SIH is suspected, a search for a cranial leak would not normally be necessary. [NOTE: A study in 2021 did demonstrate a case where a patient with a cranial leak experienced intracranial hypotension.]
Myth 9: Epidural blood patch immediately cures SIH.
While an epidural blood patch tends to offer an immediate response with a high cure rate for a post-dural puncture headache, response may not be as immediate or as durable with a spontaneous spinal CSF leak.
Myth 10: The job is done after the epidural patch.
While a fraction of patients do very well with a single epidural blood patch, in practice, more than one procedure may be needed for many patients. Furthermore, follow-up management is needed. Rebound intracranial hypertension, or elevated CSF pressure, is not uncommon after epidural patching or surgical repairs, and may require medication or other intervention
As you can see, the understanding and care of patients with spontaneous intracranial hypotension is evolving. We look forward to learning more from this team of experts and others in the field.