Neuro-ophthalmic trial calls for enrollees

Baltimore-Optimal treatment and management of patients with idiopathic intracranial hypertension (IIH) is currently unknown.

To attempt to answer this and other questions about the pathophysiology of this neurologic disorder, researchers have begun enrolling patients for the Neuro-Ophthalmology Research Disease Investigator Consortium (NORDIC) Idiopathic Intracranial Hypertension Treatment Trial (I₂HT₂), according to Vivian Rismondo, MD.

Dr. Rismondo, director of neuro-ophthalmology at the Greater Baltimore Medical Center, explained the inclusion criteria, study design, and objectives of the NORDIC I₂HT₂ study, but began with an explanation of IIH.

IIH occurs nine times more frequently in women than in men, and 90% of patients are overweight or obese. The incidence of IIH is 1 per 100,000 patients per year.

"Patients present with headache (often daily), pulse-synchronous tinnitus, vision loss, transient visual obscurations, or horizontal diplopia," explained Dr. Rismondo, who also is assistant professor of ophthalmology, Johns Hopkins University School of Medicine, Baltimore. "There are some who have an abrupt onset of rapid deterioration of vision. Patients may also present with neck, back, or arm pain from pressure on the nerve root sheaths.

"In these patients, magnetic resonance imaging is normal, with no mass lesion to account for the headaches," she added. "Upon lumbar puncture, cerebrospinal fluid (CSF) pressure is elevated, but there are no other causes for increased intracranial pressure (ICP)."

Current diagnosis of IIH centers on the Dandy criteria, which include:

Visual loss in patients with IIH results from axoplasmic flow stasis leading to axonal ischemia at the optic disc, the spread of edema into the macula, transient hypotension, choroidal folds, and elevated peripapillary retina.

Papilledema in these patients can be quantified with the modified Frisén Papilledema Staging Scheme.

Optimal treatment unknown

Currently, there are insufficient data to develop an evidence-based management strategy for patients who have IIH, Dr. Rismondo continued.

Her primary recommendation for management of patients with visual loss that is not severe is a weight reduction of 10% and a low-sodium diet.

"Weight loss is very important," she said. "Even a 6% weight loss result is associated with a significant reduction in papilledema.

"Treatment is now based on the degree of progression of visual loss," Dr. Rismondo said. "If there is no visual loss, we recommend diet and oral acetazolamide (Diamox, Duramed Pharmaceuticals). Surgical treatment is reserved for more severe cases."