Review of assessment and diagnosis of childhood apraxia of speech in Chinese speakers

Introduction
Childhood apraxia of speech (CAS), a type of motor speech disorder, is characterized by speech sound errors and dysprosody, which result from impaired speech motor planning and programming skills. Recently, a valid and reliable assessment tool was published (i.e., the Dynamic Evaluation of Motor Speech Skills; Strand & MaCauley, 2019). Through the use of this test, along with other available assessment tasks (e.g., syllable repetition tasks [Shriberg et al., 2009]; maximum performance tasks [Thoonen et al., 1996]), suggested protocols (e.g., Murray et al., 2015), and available clinical checklists (e.g., Strand’s 10-point checklist [Shriberg et al., 2011]), the diagnosis of CAS in English speakers can be made empirically. However, the efficacy of assessment and diagnosis of CAS in children who speak Chinese, a syllable-timed language with lexical tones, was unknown. The purpose of this study was to review the available evidence regarding assessment and diagnosis of CAS in Chinese (Mandarin and Cantonese) speakers.

Methods
This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISM – ScR) guidelines. Published articles and unpublished theses with a focus on CAS in Chinese speakers were systematically searched in seven English and five Chinese databases, supplemented by manual searching of references. Three reviewers performed a trial run of screening, data extraction, and quality assessment prior to the review process to ensure reliability for later independent work. Identified abstracts were screened using the criteria: 1) written in either English or Chinese, 2) published between January 1980 and October 2020, and 3) included at least one Chinese speaker who had been diagnosed with CAS. Data extracted from the articles included 1) participants’ ages and genders, 2) initial diagnosis/es, 3) comorbidity or co-existing conditions, 3) assessment methods, and 5) diagnostic criteria. A quantitative analysis was performed to determine the quality of the diagnoses. The studies were rated at one of four levels, including level I (reliable and valid tests or methods), level II (objective data/criteria), level III (perceptual judgment), and level IV (unclear).

Results
Five studies (two masters theses, two peer-reviewed articles, and one non-peer-reviewed article) were identified. A total of 15 children with CAS, aged from two to six years, were included. A variety of assessment tasks were identified, including standardized tests and non-standardized speech production tasks. ASHA’s three core features (ASHA, 2007) were the most common set of diagnostic criteria. Among the studies, one study was rated as IIIa (expert perceptual judgment). Three studies were rated at level IIIb (non-expert perceptual judgment) and one was rated at level IV.

Conclusion
There are neither reliable and valid tests nor evidence-based objective methods available for assessing and diagnosing Chinese speakers with CAS. The current standard of diagnosing CAS in Chinese is based on expert perceptual judgment of a set of clinical features. Future investigations should focus on language-specific clinical features, the development of possible objective measures, and the efficacy of intervention for Chinese speakers with CAS.