Tongue pressure during swallowing in adults with down syndrome and its relationship with palatal morphology.

In individuals with Down syndrome, hypotonicity of the tongue and an underdeveloped maxilla may lead to poor oral motor coordination, which adversely affects the oral phase of swallowing. This study aimed to evaluate the characteristics of pressure produced by the tongue against the hard palate during swallowing in individuals with Down syndrome. In addition, the relationship between tongue pressure and palatal morphology was examined. We studied nine adults with Down syndrome and ten healthy adults as controls. Tongue pressure while swallowing 5 mL water was recorded by a sensor sheet system with five measuring points attached to the hard palate. Palatal length, depth, width, curvature, and slope were measured by three-dimensional digital maxillary imaging. The order of onset of tongue pressure on the median line of the hard palate was the same in all participants, except for three with Down syndrome. The duration and maximal magnitude of tongue pressure on the median line in nine participants with Down syndrome were significantly shorter and lower than those of controls. In participants with Down syndrome, significant positive correlations were observed between the duration of tongue pressure at the mid-median part of the hard palate and palatal depth and width, and between the duration and maximal magnitude of tongue pressure at the posterior-median part and palatal length. These findings suggest that impaired tongue activity, poor tongue control, and constrained tongue motion due to a short and narrow palate contribute to swallowing difficulty in individuals with Down syndrome.

Morphologic characteristics of masseter muscle in cleidocranial dysplasia: a report of 3 cases.

Cleidocranial dysplasia (CCD) is a rare autosomal dominant skeletal dysplasia. In order to define the morphologic characteristics of the masseter muscle incidental to bone abnormalities, we present 3 cases of CCD with the masseter muscle thickness and maxillofacial bone abnormalities, using computed tomography (CT) and panoramic radiographs. In CCD patients (a) the masseter muscles were less thick than in age- and sex-matched control subjects, (b) the zygomatic arch was discontinuous with the hypoplastic zygomatic bone, (c) the ascending ramus of the mandible had parallel-sided borders, and (d) the coronoid process pointed upwards and/or posteriorly. We have concluded the masseter muscles are less thick than normal, alongside the maxillofacial bone abnormalities in CCD patients.