19 May Case Studies in Headache: Intercranial Hypertension
By Anne H. Calhoun, M.D.
Partner and co-founder of the Carolina Headache Institute, Chapel Hill, North Carolina
For the last year, Janice has had frequent headaches with nausea and vomiting. The headaches vary throughout the day, from mild to severe and from steady to throbbing. They are worse with lifting heavy objects or coughing. Janice often hears her pulse “whooshing” in her right ear and has begun noticing double vision and even some visual dimming for a few seconds after bending over. She is 37 years old and weighs 192 pounds.
This uncommon disorder, which affects about 1 in 100,000 individuals, is known by a variety of descriptive names. One is pseudotumor cerebri, Latin for “false brain tumor.” Another is benign intracranial hypertension, indicating that it isn’t life-threatening. Today, however, most would agree that a disorder with a capacity to cause blindness is hardly benign, so the preferred name is idiopathic intracranial hypertension, or IIH, which means that, for unknown reasons, there is increased pressure inside the skull.
Symptoms of IIH include headache, nausea, vomiting, visual problems and pulsating sounds within the head. Although IIH is not associated with increased mortality, it may cause progressive and permanent visual loss.
Women are up to eight times more likely to develop IIH than men, and obesity is the strongest predisposition for the disorder. Women who are more than 20% above their ideal weight are 19 times more likely to develop IIH. Interestingly, the same measure of obesity in men only conveys a five-fold higher risk.
“Idiopathic” means that the cause is unknown, so IIH can only be diagnosed in the absence of identified causes, such as a tumor. Diagnostic evaluation for IIH usually includes computed tomography (CT) or magnetic resonance imaging (MRI). If the problem is IIH, these tests will fail to show a mass or other cause of the symptoms. An MR venogram (radiograph of the veins) should exclude the possibility of any barriers to blood flow in the veins or cerebral venous sinus thrombosis (a rare form of stroke). A lumbar puncture characteristically demonstrates increased cerebrospinal fluid pressure and may provide pain relief with the removal of cerebrospinal fluid.
Factors that can produce the increased intracranial pressure associated with IIH include uncommon reactions to a number of medications including high-dose vitamin A derivatives (often used to treat acne), tetracycline antibiotics (such as minocycline), steroids or hormonal contraceptives. Non drug-related causes include obstructive sleep apnea, systemic lupus erythematosis, chronic kidney disease and hypothyroidism or excessive replacement of thyroid hormone.
When IIH is confirmed, close follow-up with repeated eye exams is needed to monitor any changes in vision. Weight loss may lead to improvement, while drugs such as acetazolamide may be used to reduce cerebrospinal fluid buildup and relieve pressure.
Surgery is normally offered only when medical therapy is unsuccessful, with two procedures most commonly employed: (1) shunts (placing a plastic tube to drain cerebrospinal fluid) and (2) optic nerve sheath decompression and fenestration (making an incision in the lining of the optic nerve behind the eye). The later procedure is primarily recommended for individuals who have limited headache symptoms, but significant threat to vision, or in those in whom a shunt was unsuccessful. In cases of severe obesity, gastric bypass surgery has also been associated with marked improvement in IIH symptoms. All of these procedures have attendant risks and complications, however, and all may eventually fail to control the symptoms.
For most patients, IIH will go into spontaneous remission or resolve with treatment. However, for some, it may continue chronically and in about half the cases that achieve remission, symptoms will recur.
With strong motivation, diet and exercise, Janice lost 13 pounds. This weight loss—along with aggressive medical therapy—led to a good clinical response. Her vision remains stable with no IIH-associated visual loss, but Janice understands the need for long-term follow-up to ensure that her symptoms do not return.