Medical Mystery: His face hurt at every meal

A 56-year-old  man who had suffered from severe pain on both sides of his face ever since he was a teenager was referred to the oral medicine faculty of the University of Pennsylvania School of Dental Medicine and University Health System.

He said that his symptoms started every time he took the first bite of a meal, but subsided as he continued to chew. The pain flared again at his next meal. The patient was previously evaluated for this complaint by several health-care providers, who thought his symptoms were consistent with temporomandibular disorder (TMD), an overall term for pain and dysfunction associated with the jaw joint, the chewing muscles, or both.

This man was no stranger to pain, with a variety of chronic problems in his mid and lower spine. He also suffered from high blood pressure, high cholesterol, peripheral artery disease – a painful condition in which blood flow to the legs is reduced — and depression. It's not surprising that he took numerous medicines, including a statin, a vasodilator to help with blood flow, a medicine to reduce stomach acid and aspirin. His surgical history included spinal fusion, femoral-tibia bypass graft, and a colonoscopy.

Detailed examination of his cranial nerves, temporomandibular joints and the muscles involved in chewing showed that all were normal. His facial pain was replicated by giving him a lemon-flavored glycerine swab to stimulate his salivary glands.

At this point, we had a strong hunch of what the problem was, but just to be certain, we sent him for an MRI to be certain he didn't have a tumor somewhere in his neck.

The MRI showed no evidence of a tumor, leading us to conclude that our patient had a rare condition known as first bite syndrome. As the name implies, the pain is sharpest with the first bite of a meal, and subsides as the patient continues to chew.

Characterized by pain in the parotid gland region – on either side of the mouth and in front of both ears — FBS is a recognized complication of certain types of head and neck surgery. Or, as with our patient, it also can be of unknown origin. It can mimic other types of painful conditions affecting the head and neck, which makes diagnosing and treating FBS extremely challenging. Treatments may include medications, acupuncture, botulinum toxin A injections (better known as Botox, the wrinkle reducer), radiotherapy, or some combination of these.

For our patient, we tried an anti-seizure medicine, oxcarbazepine, for a month, in addition to the gabapentin he already was taking for back pain. But the new medicine didn't help, so botulinum toxin A injections near the parotid glands were tried next. Within a week, our patient reported that his symptoms had improved, and after further injections, he found he didn't need to come back for more treatment.

Eric T. Stoopler, D.M.D., and Thomas P. Sollecito, D.M.D. are associate professors of oral medicine at the University of Pennsylvania School of Dental Medicine and attending physicians at the University of Pennsylvania Health System. This article is based on a case previously published in the Journal of Oral and Maxillofacial Surgery.