Methods of assessment
The literature review has so far demonstrated that there is limited information about the development of oral motor function during infancy and early
childhood. Not surprisingly then, very few methods of assessing oral and/or pharyngeal function in infancy and early childhood exist and none is
Methods are available for assessing dysphagia in adults with acquired neurological disorders or structural problems (Dworkin and Culatta 1980, Price et al 1987, Enderby 1983, Logemann 1983). Administration of such assessments to children would at best provide limited information and
perhaps worse, misleading or incorrect information. Such assessments were developed for the mature oral motor system; abnormal performance on a particular test may represent a deficit in an adult but age appropriate performance in an infant or young child.
The early development of sucking and swallowing in young infants has been well documented (Adran et al 1958, Doty and Bosma 1956, Bosma 1957, W eber et al 1986, Wolff 1968) and a number of studies have suggested that early feeding behaviour is a sensitive indicator of central nervous system integrity in neonates (Kron et al 1966, Brazleton 1970, Dreier et al 1979, Hill and Voipe 1981, Casaer et al 1982). In order to provide an objective method of rating the acquisition of these skills. Leaf and Gisel (1986) developed an observation method for analysing sucking and Braun and Palmer (1985) developed the Neonatal Oral Motor Assessment Scale (NOMAS); however both are only applicable to the neonatal population. Other researchers
(W eathers et al 1974, Kron et al 1963, Selley et al 1990, Vice et al 1991) have developed a variety of techniques and used innovative equipment to assist in the evaluation of early sucking and swallowing behaviour during infancy but are not practical tools which can be used in a clinical setting.
Although methods for assessing children's oral motor functioning do exist (Vuipe 1969, Campbell 1979, Sleight and Niman 1984, Morris 1982, Stratton 1981, Shepperd 1987, Kenny et al 1989, Gisel and Patrick 1989), they all have limitations. In general, the early literature is descriptive, discussing the development of oral motor skills and highlighting areas to be included in an evaluation; 'feeding checklists' have been developed primarily for use with disabled children, such as those with CP (Ogg 1975, Lewis 1982).
The Pre-speech Assessment Scale (PSAS) developed by Morris (1982b) is the most comprehensive scale developed to date. The PSAS examines control of oral secretions, eating, pre-speech vocal behaviours, and early speech development in developmentally disabled infants and children. The PSAS norms on which the scale is based are extremely limited; Morris (1982) studied the development of feeding patterns in 6 normal children at intervals of 3 months from 12 to 24mths. Furthermore, the scale suffers from the serious limitation that judgements about what are 'normal' and 'abnormal' behaviours at specific ages are based on norms that are derived from an inadequate sample. The reliability data, calculated upon percentage of
agreement among therapists, ignores the extent of agreement by chance and is therefore inadequate (Berk 1979).
Kenny et al (1989) developed a multidisciplinary profile for use with dependent feeders which they demonstrated was of good reliability. The profile is divided into 6 sections: physical/neurological, oral-facial structure,
oral-facial sensory inputs, oral-facial motor function, ventilation/phonation and functional feeding assessment. It is designed to be administered by a range of different health professionals, in a variety of settings and takes approximately 45 minutes to administer. The profile was designed for developmentally disabled children and pilot tested on 8 such subjects who were dependent feeders. Kenny et al (1989) considered dependent feeders to be the most functionally disabled individuals and those most likely to be considered for nonoral feeding methods. No details are given as to how the individual items were selected for inclusion in the profile and no normative data presented.
Stratton's (1981) 'Evaluation of Oral Function in Feeding' measures a limited number of skills, was not standardised on normal children and has been shown to have marginally acceptable reliability (Ottenbacher et al 1985). Sheppard (1987) developed a model for the Pre-school Oral Motor Examination, to be used by clinicians working with children with CP and various other populations of at-risk infants. There are 8 sections to the examination which include the history, peripheral speech-mechanism examination, oral reflexes, oral postural control, control of oral secretions, eating, voluntary, nonverbal behaviours and vocal behaviours. No details are given regarding normative data or reliability.
Gisel and Patrick (1988) developed a scale of 14 abnormal oral-motor behaviours and compared the performance of children with CP with weight- aged matched controls. Two textures of food were used, purée and solids.
Although the authors used a comparison group of normal children for some measures, no normative data or measures of inter-rater reliability were provided. Vulpe's (1969) Developmental Feeding Assessment Scale scores children's abilities in different domains of eating but does not lend itself to the quantification of specific oral motor behaviours.
In summary the paediatric oral motor assessments currently available have a number of limitations;
■ First, they were developed primarily for use with a neurologically impaired population and therefore cannot easily be applied to infants with an intact neurological system or with relatively minor degrees of dysfunction. Recent research has shown that oral-motor dysfunction in infancy is not limited to those with neurological disorders (Mathisen et al 1989, Mathisen et al 1992, Sonies 1990).
■ Second, they do not assess oral motor behaviours in a standardised manner using a variety of food textures; texture has been shown to be an important factor affecting the oral motor performance of infants and young children.
■ Third, norms have not been established on the developmentally appropriate oral motor skills of neurologically intact subjects during infancy and early childhood.
■ Finally, there is no known instrument with reported reliability that has been validated both on a sample of normally developing infants and applied to different clinical groups (Ottenbacher et al 1985, Kenny et al
1991, Berk and DeGangi 1979).
Therefore, there is an urgent need for the development of a valid and reliable measure of oral motor functioning in children. Such an instrument should fulfill a number of basic criteria which include;
■ be applicable to a relatively wide age range of young children, ■ incorporate the rating of exposure to a range of food textures, ■ have established norms standardised on children with normally
developing oral motor skills,
■ be a reliable instrument capable of being administered by a variety of therapists
■ be applicable to a variety of clinical groups including children with gross oral motor deficits occurring as a result of neurological dysfunction and to children with more subtle deficits where the aetiology is less clear.
Because the ingestion of food and liquid is such a complex process a
thorough evaluation will ensure that a variety of assessment tools should be used to examine the 4 stages of eating and drinking.
Chapter 3
Sum m ary and aim o f the study
The review of the literature indicated an almost wholly descriptive approach to oral motor development and dysfunction in infants and young children. There is considerable morbidity and mortality secondary to dysphagia. Despite this no satisfactory method with established reliability and validity exists for evaluating one of the most crucial stages of feeding.
The main aim of this study was to develop an instrument capable of objectively rating oral motor function in children aged between 6 and 24 months.