Bariatric Surgery Linked to Intracranial Hypotension

Pauline Anderson

October 22, 2014

Bariatric surgery may increase the risk for spontaneous intracranial hypotension, a new study suggests.

Cerebrospinal fluid leaks are the main cause of spontaneous intracranial hypotension, with patients presenting with a unique type of headache. "The hallmark of a spinal fluid leak is a headache that is much worse when you're up and about and relieved when you lay down," said lead study author Wouter Schievink, MD, professor, neurosurgery, Cedar Sinai Medical Center, Los Angeles, California.

Although the typical patient with spontaneous intracranial hypotension is thin, physicians may want to probe patients undergoing bariatric surgery a little further in light of the new results, said Dr. Schievink.

"If you have patients who have undergone bariatric surgery and they get a new kind of headache, at least ask about any sort of positional features of the headache."

Their results are published online October 22 in Neurology.

Tall and Lanky

Dr. Schievink has been treating patients with spontaneous leaks in the spine since the early 1990s. "I was always struck by the fact that they were tall and lanky," he said. "Then I started seeing patients who were not like that, and it seemed that quite a few had undergone bariatric surgery. I didn't know if it was a coincidence or not."

He and his colleagues decided to investigate further. In this new study, they reviewed the medical records of 338 consecutive patients (205 women and 133 men; mean age, 43.8 years) who were evaluated for spontaneous intracranial hypotension from January 1, 2001, to December 3, 2010.

Almost all these patients presented with "a uniquely different headache" that was much better when they lay down and much worse when they were upright. "Oftentimes, they had neck pain or their hearing was off; some felt like they were underwater or there was a sort of echoing," said Dr. Schievink.

In rarer cases, patients can get double vision and even become comatose, he added.

Researchers abstracted demographic and clinical data from computerized medical records and obtained further details of bariatric surgery from the patients.

Of these patients, 11 (3.3%) had undergone bariatric surgery before onset of intracranial hypotension. Bariatric surgery techniques included Roux-en-Y gastric bypass and gastric banding.

The mean age at the time of this surgery was 40.8 years and their mean age at the time of onset of spontaneous intracranial hypotension was 45.6 years.

The mean weight at the time of the bariatric surgery was 130 kg (287 lb). The mean weight loss from surgery to onset of spontaneous intracranial hypotension was 52.5 kg (116 lb), although the authors noted that this weight loss was quite variable.

Aneurysm Controls

As a control group, the investigators used 245 patients with an unruptured intracranial aneurysm (150 women and 95 men) with a mean age of 52.1 years who were evaluated during the same time frame. Of these patients, 2 (0.8%) had undergone bariatric surgery (P = .02 for intracranial hypotension patients vs the control group).

The number of patients who had both a spinal leak and bariatric surgery was too small to determine whether the type of surgery had any impact on the association, noted Dr Schievink.

Although the mechanism by which bariatric surgery may promote intracranial hypotension remains to be determined, two main factors may play a role, he speculates.

The first is a mechanical issue. A relationship between body weight and high spinal fluid pressure has already been established. "With weight loss, the pressure goes away," explained Dr Schievink. "Patients who have been obese probably are at a little bit higher risk to begin with because of the pressure and when they lose that weight, it might open up a leak."

This explanation seems to be supported by the fact that epidural blood patches, which all patients received, appeared to alleviate the problem in many patients, and five patients ultimately had surgical repair of the leak. In nine patients symptoms completely resolved with these strategies.

Another explanation could be the frequent postoperative complication of a deficiency in micronutrients, such as vitamins A and D. Bariatric surgery may interfere with maintaining the integrity of the dura, leading to nutrient malabsorption. Among next steps, Dr Schievink would like to develop an animal model to investigate whether different nutrients influence the dura.

He emphasized that while bariatric surgery, which is one of the fastest-growing surgical procedures, may increase risks for spontaneous intracranial hypotension, it decreases risks for other health problems, such as diabetes and metabolic syndrome.

A possible limitation of the study was that patients and controls were not all that well matched for age, with the controls being about 8 years older. Another limitation was that the study was referral-based, with patients requiring surgical leak repair over-represented.

Faster Diagnosis

Commenting on the study for Medscape Medical News, headache specialist William Young, MD, professor, neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, and a member of the American Academy of Neurology (AAN), said it may be useful in making a faster and more precise diagnosis in patients presenting with this unique kind of headache.

As it stands, headaches due to spontaneous intracranial hypotension are notoriously difficult to diagnose, partly because they're so rare. "You would think that of all the headaches, the one caused by pressure around the brain would be the simplest one, and yet it isn't," said Dr Young. "These cases are very confusing and they have confused us for decades."

Once a diagnosis is made, the first step is to give the patient a blood patch, he said. "If one or two blood patches don't stop the problem, then it's a very meticulous tricky evaluation to find the particular spot where the spinal fluid is leaking. Once you find that spot, then you apply blood or (fibrin) glue, or the surgeon opens up the patient, finds the leak and sews it shut."

In some cases, a leak is never found. "If you can't find a leak, then the question becomes, is there a tiny leak you can't see or is there another type of headache that causes the same symptoms," said Dr Young.

The authors have disclosed no relevant financial relationships.

Neurology. Published online October 22, 2014. Abstract

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