Think Like a Doctor: The Baby Who Won’t Eat Solved!

April 8, 2013

On Thursday, we challenged Well readers to solve the mystery of a 3-month-old baby who stopped eating and became weak. More than 700 readers wrote in with their take on this terrifying case. More than 100 nailed the diagnosis. And I loved all the discussion!

The correct diagnosis is…

Infant botulism.

The first person with the correct answer was Michael Pelster, who solved the mystery with the help of his girlfriend, Meredith Sellers. Both are graduating from Vanderbilt Medical School this May, then heading to Northwestern in Chicago to do their residencies in dermatology (Mr. Pelster) and internal medicine (Ms. Sellers). He was not convinced that the baby had botulism because no food exposure was mentioned. She suggested that the exposure could have been environmental because bacterial “cousins” of the botulism bacteria are frequently found in the environment. Strong work!

The Diagnosis:

Botulism is a rare, potentially deadly disease of the muscles caused by a toxin made by the bacterium Clostridium botulinum. When exposed to this toxin, muscles are unable to contract and patients are paralyzed. If the paralysis involves the diaphragm, patients can suffocate without medical help.

The disease was first described in the 19th century in Germany after hundreds of people became paralyzed after eating sausage that was contaminated with the bacterium and its paralyzing toxin. The names botulinum and botulism come from the Latin word for sausage, botulus.

Although botulism was first described as a food-borne illness, only a quarter of the 100 or so cases reported in the United States each year are contracted from food. The rest come from environmental exposures. Because the dose of bacterium in soil is low, when the exposure is from the environment, the paralytic illness only develops when it is able to get a toehold in the gastrointestinal tract and then has the right set of factors that allow the bacterium to make its poison. The majority of cases worldwide are in infants. Their incompletely colonized digestive tract makes getting a spot in the gut easier for the bug.

Although raw honey is often cited as a possible source of botulinum, public awareness of the risk of honey has not reduced the number of infant botulism cases that occur each year, suggesting that honey is not a common cause of the illness. Most of the exposures likely come through contaminated soil, which is presumably where this child picked it up. Three states are known to have high levels of C. botulinum in the soil: Utah, Pennsylvania and California. Not surprisingly, they also have the highest rate of reported cases of botulism each year.

The toxin made by the bacteria causes muscle paralysis. In infants, the first symptom is usually constipation, as the muscles of the G.I. tract become paralyzed. Then the babies lose their ability to suck. Their eyelids droop, and they may drool because their ability to swallow is impaired. Weakness of the arms, legs, neck and trunk follows, and infants may stop breathing altogether if the diaphragm is affected.

Because the disease is rare, the diagnosis is often missed. In one study, half the infants ultimately diagnosed with the disease were not suspected of having it at the time of their admission to the hospital.

How the Diagnosis Was Made:

After Dr. Phinizy, the resident who saw the infant at Morgan Stanley Children’s Hospital in New York, finished examining the baby and reviewing the notes and lab results from the original hospital, he sat down to try to figure out what could be going on with this baby.

The previous doctors had already ruled out some of the most obvious causes. The tests on blood, urine and spinal fluid suggested that the illness was probably not infectious. And the CT and ultrasound of the baby’s intestines showed that there was no obstruction or displacement.

So, what was left? Could this be the first sign of some inherited disease of the muscles or nerves? The family had no history of these kinds of problems, and that made this diagnosis a little less likely. However, some of these genetic diseases are recessive and so won’t be seen until both mom and dad pass on the defective gene. Others can occur as a spontaneous mutation.

Or could this be Guillain Barre? Or an infectious encephalitis that didn’t get picked up in the spinal tap? Or botulism?

One thing Dr. Phinizy was sure of was that this baby was too sick to be taken care of in the usual pediatric ward. The gurgling sound he heard in the child’s throat suggested that the baby was not able to swallow and might allow her secretions to drip into her lungs, causing pneumonia. She really needed to be taken to the intensive care unit. So Dr. Phinizy headed up to the I.C.U. and tracked down Dr. Stanley Hum, the pediatric intensivist on call that day.

Dr. Phinizy outlined the case and carefully described his physical exam. Hearing the description of this weak, floppy baby, who suddenly became unable to nurse and barely able to move, Dr. Hum was immediately concerned. And right away, before he even saw the baby, he thought of botulism. He’d only seen one child with botulism in the past, but it was enough.

The baby would need to come up to the I.C.U for close monitoring. She would probably need to be put on a breathing machine to protect her airways from the secretions she didn’t seem able to swallow. They would send off blood and stool to look for traces of the bacteria to confirm the diagnosis. But that could take days. So even before the results of these studies came back, she would need the botulism anti-toxin, called BIG-IV, a drug that provides antibodies taken from adults who had botulism to help stop the disease’s progression.

Dr. Phinizy hurried back down and told the worried parents their diagnosis. They were amazed and terrified. Dr. Hum and his team contacted the makers of BIG-IV in California. It arrived the next day.

The baby did need to be intubated, and she ended up staying in the I.C.U. for nearly three weeks. She was finally able to go home the following week, not quite as plump as she had been but back to her usual happy, hungry self.

Old-Fashioned Skills:

In a recent study of diagnostic errors, Dr. Hardeep Singh noted that more than three-fourths of the errors occurred in the initial meeting between doctor and patient, and that most of them were a result of inadequate history gathering or an inadequate physical exam. In this case, Dr. Phinizy was able to get a detailed history from the child’s parents and from the note sent from the first hospital the baby went to. He also took the time to do a thorough physical exam. He wasn’t sure what the baby had, but his careful data collection allowed a more experienced doctor to make the diagnosis without even seeing the child.

Our high-tech diagnostic tools get all the glory in medicine. But it turns out that most often it is the old-fashioned skills – listening to the patient, examining their body – that allows us to make the right diagnosis.

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