Diane Bahr of Ages and Stages, LLC

 

Diane H. Bahr, MS, CCC-SLP, CMT, CIMI

 

Speech-language pathologists work with oral phase dysfunction for swallowing as well as concurrent speech difficulties resulting from oral-motor difficulties in the pediatric population. This sets the speech-language pathologist apart from the occupational therapist, who may also work with swallowing disorders. Morris (1985) as well as Moore and colleagues (Moore, Smith, & Ringel, 1988; Moore & Ruark, 1996; Green, Moore, Ruark, Rodda, Morvee, & VanWitzenburg, 1997; Ruark & Moore, 1997) have looked at possible relationships between the processes of eating, drinking, and speaking in children, since the same musculature is used. Many feeding, eating, drinking, and speaking difficulties seen in children result from disorders of oral muscle function and motor planning.

 

It is important to understand typical oral motor function in order to identify atypical function. Speech-language pathologists spend much time assessing, diagnosing, and treating children with atypical oral motor patterns; however, they frequently do not have the opportunity to extensively study typical oral motor patterns in children. Kramer and Eicher (1993, p.215) have expressed that “an appreciation of normal age-related feeding behavior is a prerequisite for the study of pediatric feeding disorders.” There are a number of profiles or checklists that describe typical oral phase function for eating and drinking as well as typical speech development. However, there are some other areas that need to be considered to complete the entire picture of how these processes develop. They include the understanding of infant oral reflexes, critical or sensitive learning periods, neural development, cranial nerve function, and specific muscle function. 

 

 

Understanding the role of oral reflexes is a good starting point toward the study of typical and atypical oral motor development. There are a number of infant reflexes that support feeding development; however, the role that these “reflexes play in the development of normal voluntary movement is not clearly understood” (Hillis & Bahr, 2001, p. 5). Some believe primitive reflexes develop simultaneously with complex, voluntary motor patterns instead of being the building blocks from which these skills emerge (Smith, Weber, Newton, & Denny, 1991). Therefore, the information on reflexes is best used in assessing the development of the infant. Reflexes that persist beyond the typical period of integration or those that are delayed need to be considered when they affect the feeding, eating, and drinking processes.

 

Oral reflexes allow the infant to feed prior to the neurological maturation of the motor system (Morris & Klein, 1987; Samuels & Samuels, 1991; Love & Webb, 1996; Hillis & Bahr, 2001). The rooting reflex (i.e., touch to the cheeks or lips resulting in a head turn toward the stimulus) allows the infant to locate the mother’s nipple. The infant begins to develop control over this response at approximately 1 month of age, and the response is integrated by the nervous system between 3 and 6 months of age. The suckling (i.e., front-back tongue movement when stimulus placed in mouth), swallowing, and tongue (i.e., front-back tongue movement elicited by touch to the lips or tongue) reflexes assist the infant in obtaining and managing fluid expressed from the mother’s nipple or the bottle nipple. The infant begins to develop control of the suckling response between 2 and 3 months of age. Involuntary suckling seems to be integrated by the nervous system between 6 and 12 months of age. The tongue reflex seems to be integrated by the nervous system between 12 and 18 months. The swallowing response persists throughout life, unless some type of neurological damage occurs. The infant is believed to have volitional control of swallowing at approximately 18 months of age. The gag reflex (i.e., touch to the back half of the tongue or back wall of the pharynx results in mouth opening, head-neck extension, rapid elevation of the soft palate, as well as elevation of the larynx and diaphragm) prevents nasal regurgitation of liquids and the swallowing of items that are too large. While the gag response usually persists throughout life, it can change over time depending on the individual’s oral experiences. It can be elicited at birth by touching the posterior three-fourths of the tongue (Morris & Klein, 1987). As the infant has oral experiences with fingers, mouth toys, food, and liquid the gag is usually elicited further back on the tongue and in the pharynx. The bite (i.e., moderate pressure on the gums elicits jaw closure and phasic bite response) and the transverse tongue (i.e., tongue moves toward touch or taste stimulation to the side of tongue) reflexes seem to allow the infant to experience movements that will be used in the later developing processes of biting, chewing, and tongue lateralization. The infant seems to develop volitional control over the transverse tongue response between 6 and 8 months of age. The palmomental (i.e., touch to palm results in wrinkling of mentalis muscle) and Babkin’s (i.e., mouth opens, eyes close, head moves forward when base of palm pressed) reflexes demonstrate a hand and mouth connection at a neurological level. A hand and mouth connection will again be seen in self-feeding. 

 

When a child has some type of neurological disorder, the reflexes may be hyperresponsive, hyporesponsive, persistant, or delayed. Hyperresponsive and persistent reflexes tend to be associated with upper motor neuron damage secondary to loss of inhibition from the cortex. Hyporesponsive, diminished, or delayed reflexes tend to be associated with lower motor neuron damage. These issues can be seen in children with cerebral palsy, traumatic brain injury, congenital diseases or disorders such as Batten’s disease, strokes, and other neurological disorders.   Dimished reflexes can also be seen in children who exhibit low muscle tone (e.g., children with Down syndrome, Prader-Willi syndrome, or Velocardiofacial syndrome). 

 

A number of typically developing children have difficulty nursing to obtain adequate sustenance. This is often related to jaw weakness or another frequently inherited anatomical difference. Some of these infants have low-normal muscle tone and their oral reflexes are somewhat hyporesponsive. Therefore, it is extremely important to evaluate the nursing infant’s oral reflexes and to capitalize on the presence of these reflexes to assist the infant in developing adequate nursing skills. More information on the nursing infant can be found in the next section of this article.