Friday, August 2, 2019

A Little Known Cause of Headache: Spontaneous Intracranial Hypotension




By Christie M. Malayil Lincoln, MD
Baylor College of Medicine Radiology and Neuroradiology Specialist
2019 Graduate, Texas Medical Association Leadership College

Do you experience headaches that change with your posture and have not been diagnosed?

Many people suffer from headaches for many different reasons. Unusual, periodic headaches might be caused by a relatively rare condition few people have heard of, spontaneous intracranial hypotension (SIH). SIH happens when the fluid pressure inside the skull is lower than normal. Here’s how this occurs: Our brain floats in pressurized fluid inside our skull. In SIH, that fluid pressure drops, allowing your brain to sag inside your head. More detail: A small defect develops in the dura, a thick material that covers the spinal cord and brain. The defect allows cerebrospinal fluid (CSF) – the fluid that bathes the brain and spinal cord – to seep out into the epidural space located just outside the dura. As the fluid leaks out, its pressure decreases, causing the brain to sag downward.

Cerebrospinal fluid leakage can cause a multitude of symptoms. The most common one is a headache – one that is better while lying down but worsens while standing (known as orthostatic headache).

Other symptoms can include neck stiffness or pain, visual disturbance like double vision, tinnitus (ringing or buzzing in the ears), hearing impairment, dizziness, nausea, vomiting, walking abnormally, or memory loss. In severe and rare cases, patients may fall into a coma.

Who develops SIH, and how does the small defect in the dura develop? 

SIH occurs in approximately five per 100,000 people, mainly in those 40 to 50 years of age. It affects women more frequently than men.

Many factors can trigger SIH, including trauma from motor vehicle collision, a sports-related injury, or a prior spine-related procedure. Other spontaneous causes like connective tissue disorder and calcified disc herniations, which can cause holes in the dura, can also result in SIH.

What diagnostic tests can be performed?

If your doctor suspects you have SIH, he or she might suggest one or more imaging tests to confirm the diagnosis. Brain magnetic resonance imaging (MRI) may be done to show the imaging hallmarks of a sagging brain, if there is severe SIH.

Your doctor may suggest a whole-spine MRI to determine
where the fluid leak is occurring. 
Your doctor might suggest a whole-spine MRI to try to determine where the fluid leak is occurring. Alternatively, he or she might want to conduct a dynamic computed tomography (CT) or fluoroscopic myelography or MR myelography to try to locate the area of leak, if the whole spine MRI does not reveal the location.

A nuclear medicine study called Indium-111 cisternography, which is performed over a 24 to 48 hour period, can also be conducted in cases where diagnosis is uncertain. This can be helpful in cases of slow CSF leaks.

A SIH diagnosis can lead to a significant change in quality of life, and the debilitating effects can cause the inability to even go to work. Therefore, it is very important to discuss your symptoms with your doctor.

How is it treated?
Your doctor might first recommend simple treatments including bed rest, drinking plenty of fluids, avoiding caffeine, and taking pain medication. Physicians might also recommend that a radiologist or anesthesiologist conduct a treatment involving injecting the patient’s own blood outside the dura to seal off the leak.

If these measures aren’t effective, a radiologist or anesthesiologist might perform a treatment called a targeted blood patch or fibrin glue injection. This procedure requires injecting either blood or fibrin glue outside the dura of the suspected leak to seal the hole. Surgery is also another solution.

This web site contains additional information about the condition and how to treat it.

Discussing a potential or established SIH diagnosis and treatment options with your doctor is important in coordinating the best care.

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