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Spontaneous intracranial hypotension may present with nonorthostatic headache, normal test findings

JAMA Neurology
Reuters Health - 05/01/2021 - A systematic review and meta-analysis of spontaneous intracranial hypotension (SIH) revealed that the commonly misdiagnosed disorder should not be excluded in patients with nonorthostatic headache, normal neuroimaging findings, or normal lumbar puncture opening pressure.

"This disorder is highly disabling, as sufferers struggle to remain upright without developing severe symptoms and therefore have poor quality of life," Dr. Manjit Singh Matharu of UCL Queen Square Institute of Neurology in London told Reuters Health by email. "Despite being a common and debilitating disease, it is currently highly underrecognized."

His team embarked on the study to raise awareness of the disorder and highlight knowledge gaps, he said. Take-home messages for clinicians include the following, according to Dr. Matharu:

- Most SIH patients have an orthostatic or positional headache, but "a small minority" do not;

- Brain imaging, especially with a contrast agent, can identify approximately 90% of cases;

- Spinal scans "often fail to identify the site of the CSF leak but nonetheless play an important role in treating sufferers";

- Lumbar punctures to measure the CSF pressure "are often normal and therefore not particularly useful"; and

- "Blood patches, which involve injecting blood into the spinal region to seal the CSF leak, are effective especially if the volume of blood injected is high (>20mL)."

Specific findings, published in JAMA Neurology, were gleaned from the team's systematic review and meta-analysis of 144 articles that included a mean of 53 patients with SIH. The most common reported symptoms were orthostatic headache (92%), nausea (54%), and neck pain/stiffness (43%).

Brain magnetic resonance imaging was the most sensitive diagnostic tool; diffuse pachymeningeal enhancement was seen in 73% of patients; findings were normal in 19%.

Spinal neuroimaging identified extradural cerebrospinal fluid in 48% to 76% of patients; digital subtraction myelography and magnetic resonance myelography with intrathecal gadolinium had high sensitivity in pinpointing the exact leak site.

Lumbar puncture opening pressures were low in 32% of patients, normal (60-200 mmH2O) in 3%, and high in 67%.

Twenty-eight percent of patients responded to conservative treatment, and a single epidural blood patch was effective in 64%. Large epidural blood patches (>20 mL) had better success rates than small epidural patches (77% and 66%, respectively).

The National Hospital for Neurology and Neurosurgery has gathered a group of UK experts who are currently working on national guidelines for management of SIH, Dr. Matharu noted.

Dr. Jared Pomeroy, Medical Director, Spectrum Health Headache Center in Grand Rapids, Michigan agreed in an email to Reuters Health that SIH is an "underrecognized" cause of headache.

"Clinicians should be on the lookout for this problem in patients who have continuous, otherwise unexplained head pain, as failure to diagnose it can lead to longstanding pain, disability and inappropriate therapies," he said. "The findings and discussion in this article represent a comprehensive synthesis of the existing information on this disorder. Patients will benefit as this disabling, but treatable, syndrome gains more attention."

Dr. Robert Kaniecki, Director of the UPMC Headache Center and an associate professor of Neurology at the University of Pittsburgh School of Medicine, also commented by email, "This is a very important systematic review and meta-analysis. I have been practicing headache medicine for over 28 years and agree completely with the findings aside from one exception - I was surprised to see, and my experience differs from, some studies which show identification of spinal leaks through imaging in upwards of 80% of cases. In my experience, the precise site of CSF leak is much more difficult to ascertain - it is perhaps closer to 50%."

He also pointed out the importance of, among other findings, "showing that 19% have normal brain MRIs, which encourages clinicians to continue pursuing the diagnosis when clinically suspicious for SIH even where MRI normal; establishing the lack of utility of CSF pressure measurements, since only 2/3 had an expected low pressure, while 1/3 had normal/high pressures; and the data showing that about a quarter of patients improve with conservative management, which are helpful to educate patients on their treatment options."

SOURCE: https://bit.ly/2LoGmPK JAMA Neurology, online January 4, 2021.

By Marilynn Larkin


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