Participants

Ten children with ascertained idiopathic childhood apraxia of speech were selected for the current study from a larger sample referred to Stella Maris Scientific Institute for a suspected motor speech disorder. The diagnosis of childhood apraxia of speech was carried out by a multidisciplinary team in accordance with the 3 American Speech-Language-Hearing Association consensus criteria (ASHA, 2007)¹ and with any combination of at least 5 of the 10 Strand speech features detectable across 3 contexts that varied in difficulty^19-21 (see Supplementary Table S1 for a description of the individual profiles). The 3 ASHA consensus criteria are as follows: (1) inconsistent errors on consonants and vowels during repeated productions of syllables or words, (2) lengthened and disrupted coarticulatory transitions between sounds and syllables, and (3) inappropriate prosody in the realization of lexical or phrasal stress. The Strand’s 10-point checklist of speech features includes difficulty achieving initial articulatory configurations or transitionary movement gestures, syllable segregation, lexical stress errors or equal stress, vowel or consonant errors including distorted substitutions, groping (articulatory searching prior to phonating), intrusive schwa, voicing errors, slow rate, slow diadochokinetic rate, and increased difficulty with multisyllabic words. The identification of the diagnostic features was based on formal testing and on perceptual analysis of video-recorded speech samples by 2 independent observers (AC, BF). As part of the clinical diagnostic protocol, all children underwent a comprehensive neurologic, genetic, behavioral, and metabolic assessment, as well as conventional brain MRI with spectroscopy, which included the study of a white matter and a gray matter volume for each subject.

Additional inclusion criteria were the presence of nonverbal IQ within the normal range at standardized tests of intelligence (WPPSI-III or the WISC-IV performance scales depending on the child’s age) and normal structural brain MRI and magnetic resonance spectroscopy at 1.5-tesla (T) GE Scanner. Exclusion criteria were the presence of orofacial structural abnormalities, known pathologies of neurologic, neurometabolic, and genetic etiologies; audiological deficits; epilepsy; or behavioral and social-relational disorders (ie, autism spectrum disorder).

The final sample included 10 subjects (9 male and 1 female), all right-handed and monolingual Italian speakers, with a mean age of 6.3±1.4 years. Five children were assigned to PROMPT treatment (PROMPT-t) and 5 to a treatment protocol that targeted language and nonspeech oral movements (LNSOM-t). The mean age of the PROMPT-t group was 5.9 (SD 1.35) at enrolment, whereas the mean age of the LNSOM-t was 6.5 (SD 1.1). The 2 groups did not differ significantly in age at baseline (P > .2).