This is the case of a real patient treated at a Boston-area hospital. After reading the description of the case, I invite you to submit a comment guessing the cause of the patient's symptoms. The answer will be posted Friday.
"Nah, I was never a big game hunter," Mr. M tells me. "Sure, when I was a kid I used to go shooting a lot. Mostly birds, pheasants, quail. On rare occasions, deer."
Mr. M is 74 and has lived just outside of Boston his whole life. He's a retired machinist, who worked with nylon, Teflon, and silicon. A delightful conversationalist, he tells me that other than having high blood pressure, he's been healthy. It's only in the past couple years that he's noticed strange symptoms that haven't gone away.
"So I've done my little bit of hunting," he explains. "But now I just shoot clay." For the past 28 years, Mr. M has enjoyed various gun sports, shooting as many as 20,000 rounds per year, preparing his own bullets, and usually firing at clay disks that burst open the moment the bullet makes contact. "Whenever I shoot, I'm always careful to wear ear protection. But I don't think it's been working."
Mr. M has noticed his hearing has profoundly worsened in both ears over the last two years. His wife often has to say things twice. He didn't think much of it, and figured it was part of normal aging. After all, he's had some trouble with his memory and digestion too. "I started drinking prune juice, which helps a little bit," he admits.
But what's troubled him most is that he started to have unusual sensations in his feet. "Three years ago, my feet started becoming very, very cold," he says. "I went to see a podiatrist, who recommended a [calcium-channel blocker] called nifedipine." At first, the medicine worked. But a few months later, the soles of both his feet began tingling. The sensation creeped up the side of his leg and he noticed painful, aching cramps. "I started to have some trouble walking," he says.
He went to see his primary care physician, who performed a careful physical examination. Almost immediately, his doctor noticed Mr. M was slapping his feet when he walked, a finding called "foot drop," which reflects weakness of the muscles or nerves of the lower leg. (Watch video below for an example of left-sided foot drop.)
During foot drop, the ankles and toes have difficulty moving upward, such that the forefoot drops during walking, as seen in this patient?s left foot. You can notice that the patient raises his left leg up while he walks to prevent the forefoot from dragging. Mr. M developed foot drop on both sides. Usually, this reflects a systemic disease process, rather than individual nerve injury. (Video courtesy of Larry Mellick, Medical College of Georgia)
Mr. M also had trouble feeling vibrations and light touch on his feet and ankles. His primary care physician ordered several blood tests, all of which came back normal.
Hemoglobin A1c 6.0 (normal 4.5-5.9)
Vitamin B12 596 (normal 200-900)
Hematocrit 43.6 (normal 42-54%)
Before Mr. M left the office, his primary care physician, on a hunch, added on one more blood test. A few days later, this test came back positive, and his doctor immediately called the patient, and then reported the finding to the Department of Public Health.
What did Mr. M's blood test reveal?
Click on the "Comment on this story" link below to post your guess and your reasoning. I'll post the answers on Friday.
The author is solely responsible for the content.