Differential Diagnosis of Pediatric Motor Speech Disorders

Diagnosing motor speech impairments in children can be challenging. More often than not, the child may also have delayed or atypical development in other areas.¹ Sorting out the relative contribution of cognitive, linguistic, motor, and general developmental factors requires an evaluation that looks beyond speech-sound acquisition and speech-motor skills for the clinician to understand the child's speech-motor ability in the context of their overall development.

In recent years, several articles have addressed improving consistency in the assessment of childhood apraxia of speech (CAS).² Much less attention has been given to childhood dysarthria (CD), which can co-occur with childhood apraxia or occur as a unique diagnosis. Childhood dysarthria is most consistently associated with general neurologic disorders of childhood like cerebral palsy but should be considered as a possible diagnosis for any child with motor speech impairment.

A New Tool

Recently, a tool called the ProCAD was proposed to assist in making systematic observations of a child's motor speech characteristics to contribute to a more confident differential diagnosis.³ The ProCAD's goal is to support clinical diagnostic thinking regarding CAS and CD, as opposed to a "test" for assigning a diagnosis. Regardless of the battery of assessments used, clinicians making a differential diagnosis of motor speech disorder will need to consider multiple factors beyond the characteristics in this tool.

Additional Considerations for Assessment

A comprehensive "whole child" assessment will also need to take factors such as these into account:

• The interaction of language and cognition with speech and speech-motor development, which changes over time.⁴ Are the child's skills discrepant from what would be predicted based on language and developmental skills?

• The child's ability to cooperate for a motor speech examination. In the pilot study for the development of the ProCAD, several children were not classified because of their limited verbal output. This tool can point towards a "suspected" diagnosis, but it is wise to collect sufficient behavioral data before assigning a definite diagnosis.

• The overlap between CAS and CD. There may be children who exhibit characteristics of both disorders. Identifying the features that affect intelligibility the most at a given time may help to guide treatment while a determination is made regarding a diagnosis of CAS, CD, or both.

• How the subsystems of respiration, phonation, resonance, prosody, and articulation are affected. The ProCAD may highlight needs in subsystems that can be addressed separately or concurrently to maximize the efficiency of intervention and promote optimal therapy outcomes.

• The need for further evaluation of children who don't clearly meet the criteria for a specific diagnosis or multiple diagnoses. This may be due to age or ability to cooperate fully with assessment tasks intended to elicit target behaviors, or to the severity of speech impairment, where diagnostic therapy may be indicated to make additional behavioral observations over time.

Assessment for childhood motor speech disorders has typically involved procedures to rule in or rule out a diagnosis of CAS. A comprehensive assessment for motor speech needs to consider the whole child. The possibility of childhood dysarthria should be included to assure an accurate diagnosis and determination of the most appropriate treatment techniques for a given child.

For more information on childhood motor speech disorders, I offer courses on the treatment of CAS, as well as reading and speech impairment.