A 72-year-old man presented with a 1-year history of throat discomfort. He noticed involuntary trembling of the tongue as well as worsening of the volume and quality of his voice. The trembling was notably worse with his mouth closed and at rest, and it was partially relieved by speaking. He had a medical history of hypertension and ventricular extrasystole. His family history was unremarkable.
Clinical assessment showed rhythmic tongue bobbing on mouth opening. Other neurological findings included a masklike face, bradykinesia, limb rigidity, and a short-stepped gait. However, the patient was unaware of these symptoms because they were mild. The odor-stick identification test revealed abnormal olfaction. There was no noted constipation, rapid eye movement sleep disorder, hallucinations, or cognitive dysfunction. The brain magnetic resonance imaging results were essentially normal with no noted ischemic changes or brainstem atrophy. There was symmetrical uptake reduction, predominantly in the dorsal putamen on dopamine transporter single-photon emission computerized tomography. The clinical findings were suggestive of Parkinson disease (PD). To clarify the characteristics of tongue movement and its potential association with PD, ultrasonography was performed under 4 conditions: mouth closed, tongue extended, teeth clenched, and vocalization. An 8-MHz linear transducer was placed in the transverse plane of the upper anterior neck and directed to the lingual muscle. The B-mode image showed continuous rhythmic lingual muscle movement at rest with the mouth closed. The M-mode image identified the frequency of this movement for 5 Hz (Figure; Video). These findings corresponded with a parkinsonian resting tremor. On tongue protrusion and teeth clenching, the tongue tremor was interrupted, and it restarted at the same frequency with a latency of 3 to 4 seconds. This supported a diagnosis of a parkinsonian reemergent tremor. The tongue tremor paused during vocalization (Video).
Hirose M, Kitagawa T, Suenaga T. Visualization of Parkinsonian Tongue Tremor on Ultrasonography. JAMA Neurol. 2022;79(10):1081–1082. doi:10.1001/jamaneurol.2022.2390
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