The spectrum of abnormal tongue movements: Review of phenomenology, etiology, and differential diagnosis

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Recognizing and classifying abnormal tongue movements is challenging due to the range of possible movements and since it remains largely hidden during routine examination. Accurate identification of the phenomenology can point to specific diagnoses. Yet, a systematic classification of tongue movements has not been available to date.  

To address this gap, we performed a comprehensive review of the literature focusing on disorders in which abnormal tongue movements were the primary or a prominent clinical feature. Whenever available, published videos were reviewed to verify the reported phenomenology, and additional illustrative cases from the Toronto Western Hospital Movement Disorders Clinic video archive were included. We synthesized these findings into movement disorder categories including tremor, myoclonus, dystonia, chorea, myorhythmia, and unusual or difficult-to-classify phenomenologies.  Indeed, because the tongue is a “muscular hydrostat” capable of highly complex movements, traditional movement disorder classifications do not always adequately describe its abnormalities. 

Specific tongue movement phenomenologies can point to distinct underlying etiologies. The various etiological categories are classified by phenomenology in the paper. Some characteristic examples include: Myoclonus of the tongue can be seen in multiple system atrophy, while craniofacial myoclonus should raise suspicion for amantadine toxicity, particularly in patients with renal impairment. Tongue myorhythmia is an important clue to disorders such as Whipple's disease and anti-IgLON5 disease. Dystonia can occur in genetic disorders with prominent orofaciolingual involvement including X-linked dystonia parkinsonism, Lesch–Nyhan syndrome and Wilson’s disease. Tongue chorea is classically described in tardive dyskinesia but can also be seen in autoimmune encephalitis such as anti-NMDA receptor encephalitis.  

The review also emphasizes the importance of routinely examining the tongue during the neurological examination. Because the tongue is hidden, abnormal movements are often missed unless specifically assessed at rest, during protrusion, speech, and rapid lateral movements (to assess for bradykinesia). Careful examination may reveal fasciculations, bradykinesia, tremor, dystonia, or other abnormalities that provide valuable diagnostic clues. Adjacent structures including the palate, larynx, lips, peri-oral tissues, chin, and jaw should also be examined. 

One of the major findings of the review is that the terminology surrounding tongue movements is inconsistent. Colorful terms such as “trombone tongue,” “galloping tongue,” and “serpentine tongue” have been used to describe movement patterns, and in some instances the same term has been applied to different phenomenologies. We therefore advocate for future reports to focus on detailed descriptions of the observed movement and to include high-quality video documentation.  

Overall, this review provides a practical framework for recognizing, classifying, and interpreting abnormal tongue movements in clinical practice. 

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