When a 48-year-old patient with remnants of a brain tumor came to the ED complaining of a headache, Abdul-Kareem Ahmed, a neurosurgery resident at the University of Maryland Medical Center, was confident he knew how to treat the source of the patient's pain. But weeks later, Ahmed would find out that sometimes the best course of action is to "listen to our patients" instead of acting on your own assumptions, he writes in the Washington Post.

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'Something was wrong'

Ahmed writes that ten years prior to the patient's ED visit, his team had removed most of a benign tumor growing in the man's cerebellum. However, the remnants of the tumor prevented cerebrospinal fluid, which is usually absorbed by the veins, from escaping. This caused a buildup of the fluid in the brain, a condition called hydrocephalus.

The doctors placed a shunt in the patient's brain to funnel the excess fluid to the patient's abdomen, where the fluid could be absorbed. But at the ED about one decade later, "something was wrong, and I thought it was revealed on his new head CT," Ahmed writes. "His ventricles were very large, suggesting high pressure."

However, when the patient and his wife described his symptoms—a "bad headache" when he sat up, occasional vomiting, difficulty with memory and balance, and tending to feel better when lying down—they described a low-pressure headache, rather than the high-pressure indicated by the patient's CT scans, Ahmed writes.

Nonetheless, Ahmed and his attending physician concluded that the man probably needed more fluid drainage and decided to adjust the valve for his shunt to drain more cerebrospinal fluid. When that didn't work as expected—and when follow-up CT scans showed the patient's ventricles were still getting larger, suggesting high pressure—Ahmed and his team, in consultation with the patient and his wife, assumed the shunt must not be working properly and decided to replace it.

However, while the man temporarily improved after doctors replaced the shunt, he "looked worse than ever" at his follow-up appointment, Ahmed writes. The man could only mumble and could no longer look after himself—and his headaches had returned.

Ahmed and his team decided to perform a nuclear imaging study to evaluate the problem. When they injected dye into the patient's shunt, they found the fluid was not draining. "This could mean only two things," Ahmed writes: "Either his shunt wasn't working or the pressure in his head was too low to allow fluid to drain."

According to Ahmed, most neurosurgeons would, when taking into account the patient's enlarged ventricles, assume the stunt wasn't working. But Ahmed and his team already knew this was not the case. They started to wonder, if the man was having low-pressure headaches, "could he have low-pressure hydrocephalus?"

With low-pressure hydrocephalus, patients' ventricles enlarge "mysteriously," according to Ahmed. "No one knows why," Ahmed writes, "but one theory is the brain loses its elasticity and collapses, causing low pressure."

The condition is extraordinarily rare, with medical literature reporting just 80 cases. And when it does occur, it tends to afflict patients who had brain aneurysm ruptures or tumors, Ahmed writes. He notes that there isn't a "definitive" treatment for the condition, but afflicted patients who receive no intervention can experience life-long headaches, memory loss, and gait instability.

Ultimately, Ahmed and his team, in consultation with the patient and his wife, opted to try a treatment outlined in a 1994 study that two surgeons used to successfully treat hydrocephalus in 12 patients. The treatment involved installing a temporary, external ventricular drain—a rubber tube that drains fluid from the ventricles in the brain to a collection system at the patient's bedside.

A successful procedure

For the procedure, Ahmed directed a catheter through the man's brain and to the collection system. Pressure was low, but eventually some clear fluid dripped out into the system. "With an external ventricular drain set below his head, we were applying negative pressure to his ventricles, pulling fluid to encourage drainage," Ahmed writes.

The next day, the man appeared to be doing much better. According to his wife, he was able to bathe himself and even tell jokes.

A CT scan showed that the man's ventricles had shrunk and "he was himself again," Ahmed writes. But the doctors needed to find a way to wean the man off the temporary drain and replace the old valve with a low-pressure one.

Three weeks later, the man's ventricles were still small, and the team performed the surgery. And just a few days after that, the man "was ready to go home," Ahmed writes. "He was walking laps around the unit, eating well, and enjoying his visitors." Best of all, his ventricles were still small.

A 'unicorn' diagnosis

The experience reminded Ahmed of a saying often taught in medical school: "When you hear hoofbeats, think of horses not zebras." When presented with this patient's symptoms, Ahmed took the saying to heart and assumed the man's valve wasn't working—but in this case, Ahmed later realized that the hoofbeats "belonged to a unicorn, a rare condition with no clear explanation and no consensus treatment."

Ahmed writes that while doctors "should practice medicine based on evidence from controlled clinical trials, in many circumstances, particularly with rare diseases, we must rely on intuition and clinical suspicion, what's known as the art of medicine."

And in many cases, that comes down to listening to your patients, Ahmed writes. "In his words, he had low-pressure headaches," according to Ahmed. "Even though his imaging didn't match his symptoms, he was right. If we listen to our patients and if our systems support an art that can at times be blurry and indistinct, we might heal the peculiar and puzzling. Months later, our patient is himself, headache-free" (Ahmed, Washington Post, 8/2).