Idiopathic myositis, or inflammatory myopathies, are autoimmune diseases manifested by different symptoms depending on their type (dermatomyositis, inclusion myositis, etc.). All of them may be accompanied by dysphagia, which is sometimes the only symptom of myositis or its inaugural symptom. Swallowing disorders are also part of the classification criteria for myositis published in 2017.
However, publications on the subject are sometimes contradictory with, for example, a prevalence ranging from 0 to 100% depending on the studies. To clarify the picture, a German team (Münster) carried out a review (234 studies included) and a prevalence meta-analysis (116 studies, on 10,382 patients) to conclude that:
- the overall prevalence of dysphagia in myositis reaches 36%, and even 56% in sporadic inclusion myositis. It is significantly higher than the average in patients with cancer associated with myositis or who produce anti-NXP2 autoantibodies;
- this dysphagia results from inflammatory damage to the muscles of swallowing, comparable to that of the peripheral striated muscles;
- swallowing difficulties can lead to serious complications (significant weight loss, inhalation pneumonia) and therefore to an increase in mortality, hence the need to look for dysphagia in any patient with inflammatory myopathy, preferably using additional examinations (videofluoroscopy, endoscopy, etc.) which are more sensitive than clinical tests;
- the treatments reported to be beneficial are immunomodulators, treatment of associated cancer if necessary, surgery (myotomy of the cricopharyngeal muscle), dilation and botulinum toxin injections.