Let me begin by noting that my clinical and research experience convinces me that the core problem in this disorder is appropriately described by the diagnostic term childhood apraxia of speech. The controversy, as I see it, is that there currently are no research findings that provide unequivocal support for the core problem or its diagnostic label. To answer those who take issue with this diagnostic classification, with its important implications for prognosis and treatment planning, a compelling study or program of research would have to provide at least one of three types of evidence.
The most convincing research evidence for the validity of childhood apraxia of speech as a diagnostic classification would be a clear biological finding. Although researchers have many leads to follow, the relatively small research literature on childhood apraxia to date has failed to identify a biological locus or processing correlate of the disorder. Unlike acquired apraxia in adults, in which neurological loci and neurolinguistic processing correlates are readily documented, there are no studies indicating that children with this suspected disorder share a common neurological challenge. Worldwide, research using molecular genetics and imaging techniques has only recently begun.
A less convincing, but still useful source of evidence would be a set of behavioral assessment findings that discriminate children with this disorder from children with severe phonological disorder or with dysarthria. Currently, each clinician and researcher must rely on a weighted checklist that yields individual profiles believed to be consistent with the disorder. Note the circularity here: a biological correlate of childhood apraxia will eventually be needed to determine which behavioral assessment findings are the markers for the disorder.
The third type of research finding providing support for this diagnostic classification would be tied to treatment outcomes for children with suspected childhood apraxia. As in other areas of medicine, a treatment regimen documented to be both necessary and sufficient to normalize a disorder provides some measure of support for the validity of a diagnostic category-particularly to the degree that the treatment differs significantly from treatments used with one or more other disorders that closely resemble the target disorder. Such findings from controlled treatment studies can often be the only way to begin to understand the processes that eventually define the disorder.
(Dr. Shriberg is Professor of Communication Disorders at the University of Wisconsin – Madison. Additionally, he is co-director of The Phonology Clinic and principal investigator on the Phonology Project at the Waisman Center. He is also a member of the CASANA Advisory Committee. Dr. Shriberg’s principal research interests focus on the nature and origin of childhood speech disorders, including studies to identify diagnostic markers for clinical subtypes and studies to develop subtype-specific treatment technologies, one such disorder being childhood apraxia of speech. Dr. Shriberg is the chairperson of the ASHA AdHoc Committee on Childhood Apraxia of Speech.)