Crystal, a 22-year-old wearing heavy makeup, sat in the emergency room with her eyes closed, massaging her temples. She complained of a severe headache. "It's more than I can stand," she said in a stage whisper. "It's been a nightmare."
"And no one can find out what's wrong," added her mother, raising her eyebrows. "They act like it's all in her head."
"Who's she seen so far?" I asked.
"She's seen her own doctor twice, and she's been to the ER at another hospital." Her mother flicked her hand dismissively. "They're all a bunch of quacks."
I nodded. "I'm not sure I'll make a diagnosis, but I'll do my best." I felt like a Boy Scout reciting a pledge. "Does light hurt your eyes?" I asked. Sensitivity to light is associated with migraines as well as infection or inflammation in the brain.
Crystal squinted at me. "Not really."
"Does your neck feel stiff?" That, too, can be a sign of infection or inflammation of the meninges, the membranes covering the brain and the spinal cord.
"Not really," she said, lifting her right shoulder in a shrug.
"Does anything make it worse?"
"Putting on my shoes."
"Does wearing shoes make it worse?"
|Although intracranial hypertension occurs in just 1 in 100,000 among the general population, one study found an incidence of 19 per 100,000 among women 20 percent or more over their ideal weight. This condition is eight times as common among obese women as it is in obese men.|
"Not wearing them." Crystal frowned. "Putting them on. And taking them off."
"OK." I made a note on the chart.
"You think I'm crazy too," Crystal said.
I checked her vital signs; everything was normal. I began to examine her eyes, leaning in close and peering through her pupil as if it were a keyhole. I clicked the ophthalmoscope, bringing the rich vascular lining of Crystal's retina into focus.
The retina functions as a screen; images are projected onto it when light passes through the pupil and lens of the eye. This sensory information passes into the brain via the optic nerve. At the head of the optic nerve, where all the nerves from the retina come together, is a small, creamy circle called the optic disc. Normally, the edges of the optic disc are crisp, clearly defined against the rich red background of the retina. Not in Crystal's case. Feathery white streaks radiated from the edges of her optic disc. The streaks are a sign that the disc is swollen. I checked the other eye. That disc was swollen too. The rest of her physical exam was normal.
"I'll be right back," I said to Crystal and her mother. I was a young resident doctor in training, and I needed to consult with the attending physician. When I showed him Crystal's chart and described her symptoms, he said, "Well, she's got increased intracranial pressure for some reason." He looked up from the chart. "Is she chubby?"
"Well, yeah." I shrugged. "Why?"
"What are the causes of headaches we really care about?" We meant emergency room doctors.
"Well, there are migraines, tension headaches, meningitis, subarachnoid hemorrhage . . ." I trailed off.
"Meningitis, subarachnoid hemorrhage, glaucoma, temporal arteritis." The attending physician counted on his fingers as he spoke. "All of which can cause significant morbidity and mortality if missed. But there's one more." He paused to give me a chance to come up with the answer. "You're a star when you figure it out."
"Close. I was thinking about pseudotumor cerebri." He signed the chart and handed it to me. "Get a CT scan, then do a lumbar puncture to get a reading on the cerebrospinal fluid's pressure."
While Crystal was getting her CT scan, I read up on pseudotumor cerebri, or intracranial hypertension. Cerebrospinal fluid is a clear, colorless liquid that buffers the brain and keeps it from banging against the inside of the skull. The choroid plexus, a network of blood vessels that lines areas of the brain called ventricles, makes cerebrospinal fluid by filtering blood. Specialized cells in the choroid plexus permit water, ions, and small molecules to pass out of the blood vessels and into the ventricles. The liquid flows out of the ventricles, bathes the spinal cord, and then flows back to the brain, where it is reabsorbed into the bloodstream. While it circulates, the fluid also travels around the cranial nerves, including the optic nerves. If the pressure of the cerebrospinal fluid increases, it can put pressure on the optic discs. The swelling makes the borders of the optic disc look blurry. If left untreated, the increased pressure can interrupt blood flow to the retina.
Any narrowing in the channel through which the cerebrospinal fluid flows can make the pressure climb. For example, if a clot forms in one of the blood vessels of the filtering network, the fluid can't be reabsorbed, and the pressure rises. Brain tumors, ruptured blood vessels in the brain, meningitis, and malformations in the brain's circulatory system are some other causes of increased intracranial pressure. If no cause can be found, we call the ailment pseudotumor cerebri and chalk it up to an imbalance between the production and absorption of cerebrospinal fluid. Because the condition usually affects women, researchers suspect hormonal changes may play a role.
The typical patient with pseudotumor cerebri is female, obese, and between the ages of 20 and 40. For most patients, the symptoms include a headache and swollen optic discs. They can also have nausea and vomiting, visual disturbances, double vision, ringing in the ears, and vertigo. Leaning over to tie your shoe increases the pressure, making the headache worse.
Although pseudotumor cerebri sometimes disappears in a few weeks or months, it usually doesn't. Cases that don't clear up on their own can be treated with a number of approaches. Weight loss is the most effective. Reducing fluid retention through diuretics is another. If the headaches are extremely painful, a surgical procedure can shunt the cerebrospinal fluid to the blood system or abdominal cavity. In rare cases when the patient's vision is at risk, the optic-nerve sheath is cut open to relieve pressure and preserve sight.
The CT scan of Crystal's head was normal. I explained to Crystal and her mother how cerebrospinal fluid is made and reabsorbed. I went on to say that we could confirm the diagnosis by performing a spinal tap. This procedure involves extracting cerebrospinal fluid from the spinal column. They agreed to the procedure.
I draped a sterile gown across Crystal, numbed her lower back, and slipped the needle in until I felt a subtle pop in my fingers. The pop resulted from the needle passing through the dura mater, the tough, fibrous membrane surrounding the brain and spinal cord. I pulled the stylet from the center of the needle, and clear liquid dripped out like water. I then connected the manometer, a long, thin plastic tube with black marks at every half centimeter. Crystal's cerebrospinal fluid rose higher and higher. At 30 centimeters, it stopped rising and began to bob up and down with Crystal's respirations, a sign that it had reached its true level. Normal pressures range from 7 cm to 20 cm. I collected samples in each of the four plastic tubes that come with the kit, then rechecked the pressure. It had come down to 26 cm. I drained a little more fluid and rechecked the pressure again: 21.
A subsequent check of cell counts, as well as the amount of glucose and protein in the cerebrospinal fluid, turned up nothing out of the ordinary. "All the test results are normal," I told Crystal and her mother. "So it's pseudotumor cerebri." I recommended that Crystal see a neurologist who could monitor her condition.
"I knew something was wrong," her mother said. "I knew it. Thank you."
The swollen optic discs were what had allowed me to make the diagnosis, and they no doubt had looked fine when the other doctors had seen Crystal. But the explanation seemed cumbersome, and I was feeling a small flush of pride in my success. So I just said, "You're welcome."
To learn more about pseudotumor cerebri, visit the Web site of the National Institute of Neurological Disorders and Stroke: www.ninds.nih.gov/health_and_medical/disorders/pseudotumorcerebri_doc.htm