02 Nov Case Studies Issue: High Pressure Situation
By Elizabeth Loder, M.D., F.A.C.P.
Director, Headache and Pain Management Programs
Spaulding Rehablitation Hospital, Boston, MA
A 32-year-old woman was referred by her primary care doctor to a headache clinic. She reported a history of “normal headaches” until four months before her appointment. At that time she began to have mild, generalized headaches that she described as “achy” and which became more frequent and intense. In fact, over the last two months, she has had a constant headache. No one in her family has a history of headache problems, although the occasional blurry vision that she has experienced since the headaches began makes her wonder if her problem is migraine with aura, a condition she learned about on an online headache information site. A CT scan of her head showed no abnormalities.
The headache specialist who evaluated this patient was concerned by the rapid progression of her headache syndrome, and wanted to know if the patient had a history of rapid weight gain, was on any medications for other conditions, or had any other unusual symptoms. When the patient noted that she was on tetracycline as treatment for acne, and occasionally heard “whooshing sounds” in both ears, the doctor examined her eyes with an ophthalmoscope, and then recommended a lumbar puncture (spinal tap) to help diagnose her condition. The doctor also noted that the patient was overweight.
This case is a typical presentation of a condition called idiopathic intracranial hypertension (IIH), sometimes known as “pseudotumor cerebri” because its symptoms and signs can mimic those seen with brain tumors. This headache disorder is produced by elevated pressure of the cerebrospinal fluid, and is best diagnosed by directly measuring spinal fluid pressure with a lumbar puncture. The reason elevated pressures develop in the absence of a tumor or other structural causes is not well understood. The disorder can develop for no obvious reason, or can be associated with elevated weight or the use of certain medications, among them tetracycline. In this patient’s case, lumbar puncture showed a clearly elevated cerebrospinal fluid pressure. The patient was advised to discontinue tetracycline and was started on the diuretic medication acetazolamide, which reduces spinal fluid formation. She was also advised to lose weight. IIH is the most common cause of elevated cerebrospinal fluid pressure. For unknown reasons, it is more common in women during childbearing years, especially those who are overweight. Headache is the most common symptom, present in 90% of cases. Specific criteria are required to make a diagnosis of IIH, to avoid missing other serious causes of increased pressure. These criteria include 1) signs and symptoms of increased intracranial pressure; 2) absence of examination findings that suggest a specific neurologic problem; 3) no deformity, obstruction or displacement of the ventricular system and normal test results except for elevated intracranial pressure on lumbar puncture; 4) normal level of alertness; and 5) no other cause of increased cerebrospinal fluid pressure.
In this case the doctor suspected the diagnosis of IIH because of several features in the history and because of the finding of papilledema (swelling of the optic disc). The “whooshing noises” and occasional visual disturbances reported by the patient are common in IIH and are clues to the diagnosis.
The headache of IIH can resemble that of almost any other headache disorder. It can be similar to migraine, with severe, throbbing pain and nausea or sensitivity to light. In 14% of cases, the headache is daily and chronic, with few clues to the diagnosis. For this reason, unsuspected IIH is quite common in patients who seek help in specialized headache centers.
It is important to make a diagnosis of IIH because timely treatment may decrease the occurrence of visual loss, one of the most serious outcomes of the disorder. Five to ten percent of untreated patients develop blindness. Once IIH is diagnosed, patients should be referred to an ophthalmologist for visual function testing. The potentially serious complications of IIH help explain why this is a high pressure situation in more ways than one.