Examining teeth with a stethoscope

I was examining a patient with Parkinson's disease.

His left hand knocked rhythmically against the exam table at four beats per second, until he sat on it in frustration. His writing sample showed tiny Farsi script. When I extended his forearms, the movement was stiff and jerky, with classic cogwheel rigidity. 

As I rapped on his patellar tendon with my reflex hammer, he interrupted me. "I would be obliged if you would examine my teeth with your scope," he entreated through the interpreter. He hadn't complained of dental pain, and I gestured questioningly at the otoscope. He shook his head and pointed to my stethoscope. I handed it to him. He put the bell over his cheek and I slipped the ends into my ears.

I stood there, the stethoscope pressed against the grey stubble of his jaw, listening. And I was amazed to hear a loud, rapid, relentless drumming. His teeth were chattering. It sounded like the racing heart of a wild rabbit, jackhammering in a little ribcage. Though I had noticed a tremor in his chin earlier, the rattling of his teeth was inaudible to the naked ear.

I finally removed the stethoscope from my ears, and looked at his silent, quivering jaw.

"You learned something!" announced the interpreter. She's watched me use my stethoscope hundreds of times, for a dozen purposes, but this was a new one.

"Did your doctor in Iran listen to your teeth?" I asked the patient.

"Yes." He looked at me owlishly and blinked once, slowly. But even through the Parkinson's mask, I could tell he was pleased.