If intracranial hypertension and papilledema are left untreated or fail to respond to the measures outlined below, there is danger of permanent visual loss from compressive damage to the optic nerve fibers and compression of the central retinal veins. Corbett and associates, who described a group of 57 patients followed for 5 to 41 years, found severe visual impairment in 14, and Wall and George, using refined perimetric methods, reported an even higher incidence of visual loss. Moreover, children with pseudotumor share the same visual risks as adults (Lessell and Rosman). Sometimes, vision is lost abruptly, either without warning or following one or more episodes of monocular or binocular visual obscurations.
Treatment of Pseudotumor Cerebri
This has proven difficult and a variety of methods have been proposed. The main concern, as alluded to earlier, is the prevention of visual loss but headache may become disabling enough to require special attention. Most patients with idiopathic intracranial hypertension will be found initially to have no, or minor visual changes aside from the papilledema; the headache and lumbar puncture pressure then guide treatment. Besides symptomatic relief of headaches, the progression of visual loss is the main concern. At least one-fourth of patients have recovered within 6 months after treatment by repeated lumbar punctures and drainage of sufficient CSF to maintain the pressure at normal or near-normal levels (<200 mm H2O). The lumbar punctures have been performed daily or on alternate days at first, and then at longer intervals, according to the level of pressure. While cumbersome and sometimes impractical, evidently, this is sometimes sufficient to restore the balance between CSF formation and absorption for at least several months. At the same time, weight loss has been encouraged and the best results have been reported when weight reduction was successful (see further on regarding weight loss).
This approach has been considered the first step in treatment for patients who are not losing visual acuity rapidly. Large doses of acetazolamide in the range of 1 to 5 g/d, are required and the expected side effects of paresthesias and nauseas may not be tolerated. Sustained use of the drug has a risk of kidney stones. Oral hyperosmotic agents—such as glycerol (15 to 60 mg four to six times daily), or furosemide 20 to 80 mg bid—to reduce CSF formation all have their advocates, but they generally have only a short-term impact on vision and headaches.
This is always advised if the patient is markedly overweight but is difficult to accomplish. In two pathologically obese patients, we have resorted to bariatric surgical approaches, which had a beneficial effect on the pseudotumor but left the patient for a time with the gastrointestinal disturbances that commonly complicate these procedures. Sugerman and associates (1999) studied 24 obese women with pseudotumor who had operations and found the results to be satisfactory over several years. Two of our patients developed a sensory polyneuropathy after surgery. The use of bariatric procedures is currently undergoing reevaluation for obesity in general, but in the circumstances of pseudotumor with visual loss, it is a reasonable alternative. The effect of weight loss in less overweight individuals is uncertain.
In patients whose headaches are unresponsive to the usual therapeutic measures—mainly acetazolamide and weight reduction—a treatment method that may have considerable temporary success is a lumbar–peritoneal shunt. Only a few of our patients have undergone this surgical procedure. It has been relatively safe and effective, but because of a tendency for the shunt to become obstructed or to be dislodged in obese patients, sometimes causing back or sciatic pain, the procedure has less appeal than in the past. Burgett et al, who treated 30 patients in this manner, reported success in reducing headache in almost all and in improving vision in 70 percent. Despite its shortcomings, this procedure may be preferable to the optic nerve fenestration described below. We have not had to resort to cranial subtemporal decompression, a procedure that was formerly used when vision was threatened.