Temporomandibular joint dysfunction in myotonic dystrophy

THIS STUDY was suggested by the author’s experience at the University of Colorado Muscular Dystrophy Clinic where, in a short space of time, 3 patients with myotonic dystrophy complained of difficulties with their jaws. While such clinical signs of myotonic dystrophy as temporal balding, atrophy of the sternomastoids and muscles of mastication, cataracts, percussion and mechanical myotonia, and testicular atrophy have been well described in the literature, only a few authors have briefly mentioned temporomandibular joint difficulties. Nonne, in 1905,l appears to have been the first to describe a patient with myotonic dystrophy and dislocation of the temporomandibular joint. Batten and Gibb2 referred to this work and Adie and Greenfield3 mentioned 2 more cases. In their extensive monograph, Caughey and Myrianthopo~los~ mention that dislocations of the jaw may be troublesome. Calvert and associates5 recently mentioned another patient with this difficulty. In this study, 12 consecutive patients with the diagnosis of myotonic dystrophy admitted to the Medical Neurology Branch of the National Institute of Neurological Diseases and Blindness were screened for symptoms, physical signs, and radiographic evidence of temporomandibular joint dysfunction. While the series is too small to indicate the prevalence of this disorder, the frequency with which it occurred suggests that it is quite common. In addition, 2 patients with bulbar amyotrophic lateral sclerosis who also had temporomandibuIar joint difficulties are described. Unfortunately, there is some difference of opinion in the literature as to what constitutes the radiographic appearance of the normal temporomandibular joint. Most authors agree that in the closed mouth position the condyle must be in the mandibular fossa in contact with the inferior posterior surface of the articular eminence. In open mouth views, however,