Undulating Tongue and Wilson's Disease

We read with interest the letter to the editor reported by Agarwal et al.1 describing the case of a 10‐year‐old child diagnosed with Wilson's disease revealed by an isolated involuntary movement of the tongue, exclusively at protrusion, with a striatal abnormality at brain MRI. Our case2 is closely similar to it, regarding the movement's semiology and neuroimaging. However, phenomenology remains difficult to describe. The tongue was animated by slow, sinuous, writhing movements qualified as “undulating.” An improvement was noted 3 months following copper chelation. One of the particular features of our case was its rapid onset in a few days, which is rare, but well documented in the literature.

Dozens of involuntary (rarely isolated) lingual movements were reported in the course of Wilson's disease.1, 2 This raises two points to be discussed: the location and the phenomenology of this movement disorder.

Buccolingual and laryngeal involvement is, by far, the most common, initial, neurological manifestation of Wilson's disease.3 In a somatotopic matter,4 the tongue is well represented in the corticobulbar motor pathway, which could explain its frequent involvement. However, it is unusual for it to be isolated given that it is probably clinically insignificant or subtle and often “submerged” by other bulbar manifestations, such as dysarthria, dysphagia, drooling, and the sardonic smile, indicating an already spread lesion.

The phenomenology of this involuntary movement is difficult to classify in a known category. However, it seems to be dystonic, given its slow, sometimes sustained character, worsening by movements. Its elective appearance at tongue protrusion in Agarwal et al.'s observation supports this hypothesis. This ripple‐like appearance is probably linked to the complex function and anatomy of this organ, containing 17 muscles.

In Agarwal et al.'s observation,1 unlike ours, no improvement was observed following 4 months’ anticopper treatment. Later recoveries are common, and it is possibly the case in this observation. Indeed, in our case, lingual movements resolved after 3 months, and it took 12 months to improve the dysarthria. The same findings were reported by Nagappa et al.5

We are convinced that lingual dyskinesias are a frequent and early manifestation in the course of Wilson's disease. However, an isolated involuntary tongue movement is generally paucisymptomatic, and its progression toward laryngeal involvement with a clinically significant dysarthria remains the frequently revealing complaint. So, we totally agree with Agarwal et al. that this involuntary movement could represent a clue for an early diagnosis of such a treatable disease. However, we believe that the oral cavity is “the window” that clinicians should probably consider opening, especially in the présence of subtle bulbar symptoms. “If you can't see through the window, might as well open it.”

Disclosures

Ethical Compliance Statement: IRB approval and informed patient consent was not necessary for this work. I confirm that I have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Funding Sources and Conflicts of Interest: The author reports no sources of funding and no conflicts of interest.

Financial Disclosures for previous 12 months: The author declares that there are no disclosures to report.