Over a decade ago, a then 15 year old girl began experiencing unexplained episodes of loss of consciousness. There are many possible causes of such episodes, including simple fainting and seizure disorders. What was most remarkable about these episodes was the trigger: the patient lost consciousness or felt faint every time she ate a sandwich!

As described earlier this month in the medical journal The Lancet, the patient had a very extensive workup over many years:

 She had been subjected to many investigations, many more than once. Blood tests—including a full blood count, a standard biochemistry screen, thyroid function tests, a pituitary hormone profile, an autoantibody screen (including, to screen for coeliac disease, antibodies to the endomysium, and IgA antibodies to reticulin), an ESR, a short synacthen test, an oral glucose tolerance test, and concentrations of glucose (after an overnight fast), C-reactive protein and immunoglobulins; chest radiography; standard and 24 h electrocardiograms (ECGs); and 24 h ambulatory blood pressure recordings had all given unremarkable results. In November, 2007, an electroencephalogram (EEG) had shown no evidence of epilepsy.

In the interim, she was referred for psychiatric evaluation, as often happens when doctors do not understand the cause of a patient’s illness. During the following years, the young woman experienced many similar episodes, some precipitated by drinking carbonated beverages.

Because she was so young, and because a 24 hour electrocardiogram was normal, her doctors thought that her heart was not involved. However, when she was referred to new cardiologists for yet another evaluation, they decided to try monitoring her for a week. She wore a portable ECG device that kept a continuous record of her heart function. At the end of the week, she reported several episodes of lightheadedness when eating. Examination of the monitor strip revealed a surprising finding. Every time she ate a sandwich, her heart stopped! That certainly explained why she fainted. Why, though, did her heart stop whenever she ate a sandwich?

The patient was diagnosed with a very rare syndrome known as swallow syncope (fainting when swallowing). Swallow syncope happens when “wires” get crossed. Both heart rate and swallowing are controlled by the vagus nerve. It’s called the vagus (wandering) nerve because it is the longest nerve of its kind. It exits the brain and extends through the neck, into the chest, and down into the abdomen, throwing off branches along the way.

The vagus nerve carries both signal to control heart rate and sensations that come from the throat and esophagus that are used to regulate swallowing. In people with swallow syncope, the signals sent from the esophagus indicating a large piece of food get “crossed” with  signals to the heart. These errant signals actually cause the heart to stop for several seconds.

Not surprisingly, when no blood is flowing to the brain, the patient faints. In this young woman, the episodes had resolved spontaneously, but there was always the possibility that an episode would last long enough to lead to her death. Therefore, she received a pacemaker.

You can see the results in the Lancet illustration shown above. In the top tracing, the patient’s heart stops when she swallows a bite of her sandwich. In the bottom tracing, the patient has a pacemaker, and when her heart stops, her pacemaker kicks in.

The patient was thrilled upon learning the diagnosis. It confirmed what she had insisted all along. Her symptoms were real, and not “all in her head” as some doctors had told her. Now she can eat anything she wants. She promptly gained almost 10 pounds. She jokingly chided her doctor that he hadn’t warned her that she would gain weight as a result, but she is not really concerned. First the first time in more than a decade, she has reached a normal weight, and more importantly, can have a normal life.