AAN 2009: Weight Loss Proves Successful in Relieving Idiopathic Intracranial Hypertension

Pauline Anderson

April 30, 2009

April 30, 2009 (Seattle, Washington) — Weight loss in obese patients with idiopathic intracranial hypertension (IIH) reduces intracranial pressure (ICP), eases headaches, and improves papilledema, according to a new study.

The trial is the first to conclusively show that weight loss reduces ICP in patients with IIH, a condition characterized by pressure in the subarachnoid space, which can lead to vision loss, double vision, blackouts, and disabling headaches, said lead author Alexandra J. Sinclair, MD, from the School of Immunology, Infection, and Inflammation at the College of Medical and Dental Sciences at the University of Birmingham, in the United Kingdom.

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"We often thought that if these patients lost weight they'd get better, but this has never been shown in a prospective study before," Dr. Sinclair told Medscape Neurology & Neurosurgery.

The study was presented here as a late-breaking abstract during the American Academy of Neurology (AAN) 61st Annual Meeting.

Some Patients Cured

By the end of the study, some patients "were rendered completely symptom-free and were actually what you'd call 'cured,' " said Dr. Sinclair. "Their brain pressure had come down to where it was no longer elevated."

The results of this study might encourage physicians to get their obese patients with IIH to lose weight before turning to drugs or surgery, said Dr. Sinclair.

Restrictive Diet

With the global epidemic of obesity, IIH is becoming an increasingly frequent problem, said Dr. Sinclair, adding that it now affects 20 per 100,000 of obese women.

The study included 25 women aged 19 to 54 years with a body-mass index (BMI) of between 28.4 and 50.2 (mean BMI, 37.4) who had IIH for from 4 to 189 months.

The trial was a 2-stage crossover study. For the first phase of the study, researchers merely monitored the women for 3 months to ensure that baseline parameters did not change. Then, for 3 months, the women followed a highly restrictive diet, consisting of 3 meal-replacement drinks per day totaling 420 calories, plus water. The women received weekly nutritional information and counseling.

At baseline and after each of the 2 phases of the study, researchers weighed patients, used lumbar puncture to determine ICP, assessed optic-nerve swelling to determine visual function, and administered headache questionnaires.

As expected, there were no significant changes during the first phase, but during the second phase there were significant reductions in weight; patients lost about 15.2 kg and their BMI dropped about 5.4 points. Intracranial pressure, the primary end point of the trial, was reduced by about 8 cmH2O.

In addition, patient questionnaires showed that their headaches significantly improved; scores on the Headache Impact Test dropped by about 7 points (< .001), with a range of -28 to +10 points.

Ultrasound Scanning

Swelling of the optic nerve (papilledema) also improved as demonstrated by ultrasound scanning of the back of the eye, said Dr. Sinclair. In the past, doctors relied on assessing the swelling visually, she noted. "Before, it was usually just the physician saying 'okay, it looks a bit better,' but now we actually have some objective tests that can tell us this," she said.

There were no significant improvements on the LogMAR visual acuity score or the Humphrey visual field score, the authors note. Other symptoms, including tinnitus, diplopia, and obscurations, did significantly improve (P = .004, .008, and .025 respectively).

Although 90% of patients with IIH are obese women, it is not clear why this is the case. According to Dr. Sinclair there may be a neuroendocrine link.

Would the effect of the weight loss be less dramatic if it had occurred over a longer period of time and used a less restrictive dietary regime? According to Dr. Sinclair, the effect of weight loss on intracranial pressure was probably related to the amount of weight these women lost rather than on how they lost it. She pointed out, however, that it will be important for these women to keep the weight off to maintain these benefits.

The researchers continue to follow these women and, for the most part, they have succeeded in maintaining their weight loss, said Dr. Sinclair. One participant who did gain some weight back experienced a return of her symptoms.

Potential Blindness

When asked for comment on this research, Stephen Silberstein, MD, professor of neurology at Thomas Jefferson University, in Philadelphia, said it is an "extremely important study that will be the basis of all future studies in the treatment of idiopathic intracranial hypertension."

He added that it is very important to try to determine how to treat patients with increased intracranial pressure, as they suffer debilitating headaches and face potential total blindness. Left untreated, 25% of women with IIH will go blind permanently.

Although in the past many experts would tell their overweight patients with intracranial hypertension to lose weight, "nobody had ever in a prospective controlled scientific manner actually showed what the effects of weight loss were on papilledema, intracranial pressure, and visual acuity," said Dr. Silberstein.

So why had this not been studied before? "Neuro-ophthalmology and headache are like neglected stepchildren in neurology," said Dr. Silberstein, adding that due to a lack of funding for headache research, most treatments given to patients with headache or migraine are not evidence-based.

Weight loss for obese women with IIH is important not just to control intracranial pressure but also for overall good health, noted Dr. Silberstein.

The study was funded by the Vera Down (Neurological Diseases) 2005 and Clark and McMaster (Blinding Diseases) 2005 Awards, the British Medical Association, and the West Midlands Neuroscience Teaching and Research Fund. Dr. Sinclair is a Brain Trust Entry/Exit Scholar at the Institute of Neurology, Ipsen Research Fellow, and MRC Clinical Training Fellow, all in London, the United Kingdom. The academic unit of ophthalmology is supported by the Birmingham Eye Foundation. None of the authors report any conflict of interest. Dr. Silberstein is a member of the Medscape Neurology & Neurosurgery editorial advisory board.

American Academy of Neurology 61st Annual Meeting: Abstract LB2.002. Presented April 29, 2009.

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