Triple furrow tongue in myasthenia gravis

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Triple furrow tongue in a patient with AchR antibody positive, non-thymomatous, bulbar predominant MG. The furrowing resolved after treatment including thymectomy, prednisone, and mycophenolate.
The triple furrow, or trident, tongue is a rare but characteristic manifestation of MG in which a midline and two parallel longitudinal grooves appear in the tongue.(1) The unusual furrowing pattern is usually accompanied by tongue atrophy. Muscle atrophy is not typically part of MG. Tongue and facial muscle atrophy occurs more commonly in the MuSK (muscle specific tyrosine kinase) variant of the disease. MG with MuSK antibodies is a subgroup of seronegative MG characterized clinically by severe, predominantly faciobulbar weakness and the frequent occurrence of atrophy of the tongue and facial muscles.(2) It is much more common in females. MuSK antibodies are present in about 70% of patients with seronegative MG.

Tongue atrophy, as well as atrophy of other muscles, apparently occurred more often in the past before effective therapies were available and patients sometimes had severe, long-standing, poorly controlled MG. Many reports of muscle atrophy in MG date from a time before MuSK, or even AchR antibodies, were described. Disuse and functional denervation have been postulated as the explanation for the muscle atrophy.(3,4)

An MRI study showed thinning of the buccinator, orbicularis oris and orbicularis oculi muscles in MuSK-MG patients, whereas thinning of these muscles was not significant in patients with AChR-MG.(5) Tongue areas with T1W high signal were increased in MuSK-MG patients. The findings suggest that bulbar and facial muscle atrophy occur more commonly in MuSK-MG than in AChR positive patients. MuSK antibodies per se might predispose to muscle atrophy, or the often refractory nature of the condition causing more severe and longer duration disease may be a factor.

The figure shows a triple furrow tongue in a patient with seropositive MG. There is also mention in the literature of the triple furrow tongue occurring occasionally in myotonic dystrophy.

Figure courtesy of Dr. Vern Juel of Duke University.


1. Campbell WW. Clinical signs in neurology: a compendium. Philadelphia: Wolters Kluwer Health, 2016.

2. Hurst RL, Gooch CL. Muscle-Specific Receptor Tyrosine Kinase (MuSK) Myasthenia Gravis. Curr Neurol Neurosci Rep. 2016;16:61.

3. Brownell B, Oppenheimer DR, Spalding JM. Neurogenic muscle atrophy in myasthenia gravis. J Neurol Neurosurg Psychiatry. 1972;35:311-22.

4. Kurihara T. Seronegative myasthenia gravis and muscle atrophy of the tongue.Intern Med. 2005;44:536-7.

5. Farrugia ME, Robson MD, Clover L, et al. MRI and clinical studies of facial and bulbar muscle involvement in MuSK antibody-associated myasthenia gravis. Brain. 2006;129:1481-92.