Prominent lateral palatine ridges: development clinical significance

Prominent lateral palatine ridges due to thick submucosal tissues have been noted by us in a variety of dysmorphic conditions. Such ridges have been seen in infants with neurologic disorders associated with hypotonia (ie the Prader-Willi and Down syndromes) as well as hypertonia (ie the Menkes, Smith-Lemli-Opitz and trisomy 18 syndromes). These ridges have also been noted in children with structural anomalies such as an unusually narrow palate (ie Apert syndrome) or a small or displaced tongue (ie Moebius or Robin anomaly). In normal fetuses this structure is quite prominent, but it is less readily apparent in term infants. A survey of the normal postterm populations suggests that this structure usually becomes progressively flattened out, reaching an adult configuration during infancy. These observations lead us to hypothesize that these ridges are normal in the developing fetus. As the tongue becomes well developed and functional it plays a role in molding this prominence. In disorders where there is a deficit of tongue thrust, on the basis of functional or structural abnormalities, these ridges may be unusually prominent. Accordingly, prominent lateral palatine ridges are one clue to a long-standing deficit of neurologic function or structural anomaly in early life.