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Out of Breath-Paralysis of the diaphragm

... New York Times:

A 74-year-old mechanic  became strangely short of breath whenever he worked under cars. I also asked for the test that revealed the diagnosis. While a remarkable number of you figured out the diagnosis, it wasn’t until late last night that I finally got an answer that included both the right diagnosis and the right test.

The correct diagnosis was…

Paralysis of the diaphragm.

And the test the doctor performed to get the answer: He asked the patient to do in the office what triggered the symptoms at work. Just watching him breathe as he lay on his back, it became clear what was causing this shortness of breath.

The first person to offer the correct diagnosis was Victor Rebelo Procaci, a medical student from Brazil in his last year of training. He tells me that he looked up articles on orthopnea, the medical term for having to be in an upright position in order to breathe easily. When he read about paralysis of the diaphragm, he recognized the description.

However, late last night, FutureDr from Virginia wrote in with both the correct diagnosis and the test. We have contacted FutureDr but haven’t heard back yet; we’ll update you when we do.

The Diagnosis

The diaphragm is a dome-shaped muscle located below the lungs, behind the lower rib cage. It divides the chest space from the abdominal space.

With inspiration, the diaphragm typically constricts. This action flattens the dome, creating negative space in the chest cavity and stretching the lungs downward. The now enlarged lungs suck in air. Exhalation is mostly passive. The diaphragm relaxes back into its normal dome configuration and the elastic tissues of the lungs push out the air as they resume their smaller size and shape.

From watching the man breathe it was clear that his diaphragm muscle wasn’t working properly. The muscle is powered by the phrenic nerve. When that nerve is injured or destroyed, the muscle will be paralyzed and flaccid.

Shortness of Breath

The diaphragm muscle is made up of two parts — a right and left half — that come together in the middle. Each is innervated by a separate branch of the phrenic nerve. Loss of function is often limited to just one side but can involve both. From looking at the man breathe it was not clear to the doctor who saw the patient whether one half or both halves were involved.

Because this man’s diaphragm was impaired, he was forced to use the muscles in his rib cage (the intercostals) and in his neck (the scalene and sternocleidomastoid) to create the negative pressure in the chest cavity so that the lungs could expand and draw in air. That negative pressure pulls the now flaccid diaphragm upward into the chest and with it comes the stomach and viscera – which causes the abdominal pain. The movement of these organs into the chest crowds the lungs and makes it difficult for them to expand, causing the patient to feel short of breath. This occurs when lying down because when upright, gravity holds the organs of the gastrointestinal tract down.

Squatting also forces stomach and intestines upward by increasing the pressure in the abdomen, pushing the stomach and other visceral organs into the chest.

A Variety of Underlying Causes

Paralysis of the diaphragm is an unusual cause of shortness of breath, though many experts suspect that it is underdiagnosed.

Nearly a third of those who develop this kind of paralysis have lung cancer; in these cases the tumor destroys the nerve that makes the diaphragm move. In this patient’s case, the chest X-ray showed no evidence of any type of lung disease.

Less common causes include heart surgery and diseases of the nerves and muscles such as Lou Gehrig’s disease, but this patient had neither. A pinched nerve can do it as well, and although this man did have some degenerative disease of the spine, he did not report any back or neck pain.

In this case, as in many cases, the cause of the paralysis was never discovered. Many people who have paralysis of the diaphragm do well. Symptoms typically improve as patients find ways to work around the deficit and avoid the sense of breathlessness. In many, some measure of strength returns. Occasionally full strength is restored.

How the Diagnosis Was Made

A young resident in her second year of training was the first to see the patient. She examined him but still had no idea what was going on. So she brought in Dr. Stephen Workman, an internist on the faculty of Dalhousie University in Halifax, Nova Scotia, to see if he could figure it out.

The doctor watched the patient carefully as he told his story. Just sitting there his breath was easy, normal, the doctor noted. He didn’t get short of breath just talking. Now, Dr. Workman said, after the patient finished, show me what you do that makes you feel bad.

Dr. Workman watched as the man walked comfortably to the exam table and easily hoisted himself up. He lay down, flat on his back. He could feel the pressure in his stomach and it was a little harder to breathe, he told Dr. Workman and the resident. But not too bad. Then he lifted his arms straight in front of him, as if working on the bottom of a car. It starts to get pretty bad here, the patient reported.

But this is the worst, he said as he lifted his head and shoulders off the table, moving himself closer to the imaginary car. That’s all I can do, he gasped, collapsing down then quickly sitting up.

What Dr. Workman noticed was that with each breath, the man’s belly moved in a way that seemed wrong. We are much better at noticing something that is other than what we are used to seeing, something different or wrong, than we are at figuring out exactly what is wrong.

Can you just lie down for a minute more?, Dr. Workman asked the man. Watching him breathe, Dr. Workman realized what looked wrong. Normally when breathing in, the stomach is pushed outward as the diaphragm pushes downward, displacing small and large intestines. When this man took a breath his stomach flattened. His diaphragm not only wasn’t pushing down, it was being pushed up. The muscle clearly wasn’t working properly.

Dr. Workman put his hand on the man’s abdomen, just below the rib cage. Take a deep breath and try to push my hand away, he told him. As the patient took his deep breath, the doctor’s hand was pulled up toward his rib cage. Without a working diaphragm, the negative pressure in the chest that pulled in the air was also pulling the stomach and intestines upward, crowding the lungs.

Follow-Up Testing

Dr. Workman had the patient breath in and out through a spirometer, a machine designed to measure the movement of air as it passes through the lungs. The machine quantified what Dr. Workman had already observed: that the man’s ability to take in air was much weaker than normal. His exhalation was weak but still in the normal range.

There are other tests that Dr. Workman might have ordered to quantify the extent of the muscle loss. A sniff test, in which the patient is asked to inhale while being monitored by fluoroscopy, a type of moving X-ray, might have shown how much movement – if any – the patient had left in his diaphragm.

Dr. Workman felt these tests were unnecessary because they wouldn’t change the treatment. Once he was certain that the patient did not have any of the diseases known to cause this type of paralysis, he reassured the patient that his problem would not get any worse and might get better and sent him back to his regular doctor.

How the Patient Fared

The patient has done well since his diagnosis. He decided to close down his garage. He figured that daily exposure to the dirt and other crud he routinely encountered on the bottom of cars was probably not helping. And he does feel better.

He stays busy. He always has. If ever there’s something that needs doing, he told me, he’s the first one to volunteer to do it. And that hasn’t changed. If he’s doing something and ends up in some funny position that bothers him, he just changes his stance and keeps on going.

This diagnosis actually solved another mystery for the patient. He has been an active member of a theater group associated with his church for many years. He loves acting. But for the past year or so, the director kept telling him he was too soft spoken. No one could hear his lines. He’s optimistic that he can figure out a workaround for this, too. Nothing’s keeping him off the stage. 

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