Differential Diagnosis of Apraxia of Speech in Children and Adults: A Scoping Review

Abstract

Purpose Despite having distinct etiologies, acquired apraxia of speech (AOS) and childhood apraxia of speech (CAS) share the same central diagnostic challenge (i.e., isolating markers specific to an impairment in speech motor planning/programming). The purpose of this review was to evaluate and compare the state of the evidence on approaches to differential diagnosis for AOS and CAS and to identify gaps in each literature that could provide directions for future research aimed to improve clinical diagnosis of these disorders. Method We conducted a scoping review of literature published between 1997 and 2019, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews guidelines. For both AOS and CAS, literature was charted and summarized around four main methodological approaches to diagnosis: speech symptoms, quantitative speech measures, impaired linguistic-motor processes, and neuroimaging. Results Results showed that similar methodological approaches have been used to study differential diagnosis of apraxia of speech in adults and children; however, the specific measures that have received the most research attention differ between AOS and CAS. Several promising candidate markers for AOS and CAS have been identified; however, few studies report metrics that can be used to assess their diagnostic accuracy. Conclusions Over the past two decades, there has been a proliferation of research identifying potential diagnostic markers of AOS and CAS. In order to improve clinical diagnosis of AOS and CAS, there is a need for studies testing the diagnostic accuracy of multiple candidate markers, better control over language impairment comorbidity, more inclusion of speech-disordered control groups, and an increased focus on translational work moving toward clinical implementation of promising measures.

Figure 1.

Summary of article search procedures. ALS = amyotrophic lateral sclerosis; AOS = acquired apraxia of speech; CAS = childhood apraxia of speech.

Figure 2.

Distribution of inclusion criteria reported in studies since 2007 for (a) determining childhood apraxia of speech (CAS) diagnosis and (b) determining acquired apraxia of speech (AOS) diagnosis. AMRs = alternating motion rates; DDK = diadochokinetic; EL = expressive language; RL = receptive language; SMRs = sequential motion rates.

Figure 3.

Comparison of inclusion criteria in childhood apraxia of speech (CAS) studies and apraxia of speech (AOS) studies published since 2007. Frequency of occurrence of each individual inclusion criterion is represented on the radial axis as a proportion of studies using the given criterion relative to the total number of CAS (magenta) or AOS (teal) studies. Shaded areas indicate the degree of (non)overlap between features commonly used in CAS versus AOS studies. AMR = alternating motion rate; EL = expressive language; OM = oral motor; RL = receptive language; SMR = sequential motion rate.