Differential Diagnosis of Childhood Apraxia of Speech Compared to Other Speech Sound Disorders: A Systematic Review

Purpose: The aim of this study was to determine the discriminative features that might contribute to differentiation of childhood apraxia of speech (CAS) from other speech sound disorders (SSDs). Method: A comprehensive literature search was conducted for articles or doctoral dissertations that included >= 1 child with CAS and >= 1 child with SSD. Of 2,071 publications screened, 53 met the criteria. Articles were assessed for (a) study design and risk of bias; (b) participant characteristics and confidence in diagnosis; and (c) discriminative perceptual, acoustic, or kinematic measures. A criterion was used to identify promising studies: American Academy of Neurology study design (Class Ilk), replicable participant descriptions and adequate confidence in diagnosis (>= 3), and >= 1 discriminative and reliable measure. Results: Over 75% of studies were retrospective, case- control designs and/or assessed English-speaking children. Many studies did not fully describe study design and quality. No studies met the Class I (highest) quality rating according to American Academy of Neurology guidelines. CAS was mostly compared to speech delay/phonological disorder. Only six studies had diagnostic confidence ratings of 1 (best). Twenty-six studies reported discriminative perceptual measures, 14 reported discriminative acoustic markers, and four reported discriminative kinematic markers. Measures were diverse, and only two studies directly replicated previous findings. Overall, seven studies met the quality criteria, and another eight nearly met the study criteria to warrant further investigation. Conclusions: There are no studies of the highest diagnostic quality. There are 15 studies that can contribute to further diagnostic efforts discriminating CAS from other SSDs. Future research should utilize careful diagnostic design, support replication, and adhere to standard reporting guidelines.