Development of sucking behavior in infants with Down's syndrome

The aim of this study was to gain a better understanding of the development of sucking behavior in infants with Down's syndrome. The sucking behavior of 14 infants with Down's syndrome was consecutively studied at 1, 4, 8 and 12 mo of age. They were free from complications that may cause sucking difficulty. The sucking pressure, expression pressure, frequency and duration were measured. In addition, an ultrasound study during sucking was performed in sagittal planes. Although levels of the sucking pressure and duration were in the normal range, significant development occurred with time. Ultrasonographic images showed deficiency in the smooth peristaltic tongue movement.

The sucking deficiency in Down's syndrome may result from not only hypotonicity of the perioral muscles, lips and masticatory muscles, but also deficiency in the smooth tongue movement. This approach using the sucking pressure waveform and ultrasonography can help in the examination of the development of sucking behavior, intraoral movement and therapeutic effects.