Speech input processing in children born with cleft palate: A systematic literature review with narrative synthesis

Background: Speech development requires intact and adequately functioning oral anatomy and cognitive 'speech processing' skills. There is evidence that speech input processing skills are associated with speech output problems in children not born with a cleft. Children born with cleft palate +/- lip (CP +/- L) are at high risk of developing disordered speech output. Less is known about their speech input processing skills and whether they are associated with cleft-related speech sound disorder (SSD). Aims: (1) To collate and evaluate studies reporting evidence regarding the speech input processing skills of children born with cleft palate in comparison with data from typically developing children or other comparison groups; and (2) to identify any available evidence regarding relationships between speech input processing skills and speech output in children born with CP +/- L. Methods & Procedures: Potentially relevant studies published up to November 2019 were identified from the following databases: Medline via Ovid, Embase via Ovid, Cinahl via Ebscohost, PsycInfo via Ebscohost, BNI via ProQuest, AMED via Ovid, Cochrane Library and Scopus. Inclusion criteria were: peer-reviewed articles published in scientific journals, any design, published in English, participants born with a CP +/- L aged up to age 18 years who completed speech input processing assessments compared with normative data and/or a control or other comparison group. Critical Appraisal Skills Programme (CASP) checklists were used to quality appraise included studies. Outcomes & Results: Six studies were retained in the final review. There is some evidence that children born with CP +/- L perform less well than non-cleft controls on some speech input processing tasks and that specific input processing skills may be related to errors in the children's speech. Heterogeneity in relation to study groups and assessments used, as well as small sample sizes, limits generalization of findings. Conclusion & Implications: There is limited evidence regarding the speech input processing skills of children born with CP +/- L. There are indications that children born with CP+/L may have difficulty in some aspects of speech input processing in comparison with children not born with a cleft, and that difficulties with some speech input processing tasks may be specific to errors in children's speech output. Further research is required to develop our understanding of these skills in this population and any associations with speech output.