Oral motor, sensory and developmental indicators in children with speech sound disorders : a clinical cohort study

<jats:p>&lt;p dir="ltr"&gt;Background &lt;/p&gt;&lt;p dir="ltr"&gt;Atypical speech sound development in children encompasses a range of conditions affecting the planning, coordination, and execution of speech movements and is among the most common developmental disorders in childhood. The umbrella term speech sound disorders (SSDs) is widely used to describe speech production difficulties that fall outside typical developmental norms and is applied across speech-language pathology settings. SSDs vary widely in severity, ranging from isolated speech sound delays to pervasive speech production impairments, and may arise from motor-based and/or phonological dysfunctions of known or unknown origin. Increasingly, SSDs are recognised as neurodevelopmental in nature, reflecting disruptions in the complex interplay of genetic, neurological, and environmental factors that support speech and language acquisition. Children with SSDs frequently present with co-occurring language difficulties, delays in fine and gross motor development, and atypical sensory processing patterns,suggesting broader neurobiological vulnerabilities affecting sensorimotor integration. The children included in the present project were referred for specialised assessment of suspected oral and speech motor difficulties. In this thesis, the term SSD is used to denote the broader clinical phenotype observed in this population, characterised by the co-occurrence of motor-based and language-based speech impairments, and is therefore adopted as an overarching diagnostic category for the thesis. &lt;/p&gt;&lt;p dir="ltr"&gt;Aim &lt;/p&gt;&lt;p dir="ltr"&gt;The overall aim of this doctoral project was to deepen the understanding of multidimensional profiles in children aged 4–9 years referred for specialised assessment of oral and speech motor difficulties. In particular, the thesis aimed to investigate how speech difficulties relate to oral motor function, sensory processing, and developmental factors. A further aim was to consider how these multidimensional challenges may influence the child’s functioning and participation in everyday contexts. &lt;/p&gt;&lt;p dir="ltr"&gt;Methodology &lt;/p&gt;&lt;p dir="ltr"&gt;The thesis comprises three observational studies based on a consecutive cohort of children aged 4–9 years referred to the Centre for Eating, Speech, and Oral motor Function (OMC) for differential diagnostic assessment. An age-matched control group was included in two of the studies. The work was conducted within established clinical pathways at the OMC, with the intention of reflecting routine clinical practise in specialised speech-language pathology care. Diagnoses were documented in the medical record using ICD-10 codes as part of routine clinical practice and reflected an overall clinical synthesis based on assessment findings and the professional judgement of experienced speech-language pathologists working at the clinic. For research purposes, individual clinical diagnoses were regrouped into four analytic subgroups: motor speech disorder (MSD+; with or without oral motor developmental delay and/or language-oriented disorder); language-oriented disorder with oral motor developmental delay (LD+ODD; no MSD); oral motor developmental delay only (ODD-only); and language-oriented disorder only (LD-only) reflecting common and clinically meaningful constellations of symptoms. These subgroupings were applied consistently across all studies based on the same clinical cohort. &lt;/p&gt;&lt;p dir="ltr"&gt;Main findings &lt;/p&gt;&lt;p dir="ltr"&gt;Across three studies, the results demonstrate that children referred for assessment of oral and speech motor difficulties frequently present with multidimensional profiles, including chewing inefficiency, differences in sensory processing patterns, and developmental risk indicators. Study I (n = 177) show reduced chewing efficiency in older children with motor speech disorders compared with typically developing peers, suggesting oral motor involvement that may form part of a broader symptom complex, especially given the frequent co-occurrence of oral motor developmental delay within SSD. Study II (n = 143) examined caregiver-reported sensory processing patterns and demonstrated that sensory modulation difficulties are common across children with SSD (including those with combined oral motor and language difficulties), with potential consequences for participation in daily activities as well as with compliance in therapy. Study III (n = 275) explored developmental and medical risk indicators, revealing complex developmental trajectories and highlighting the relevance of early language development, motor milestones, sensory characteristics, and hereditary factors, particularly among children with co-occurring diagnoses. Children with speech difficulties showed a higher prevalence and accumulation of risk indicators compared to typically developing peers, including early differences in vocal behaviour, delayed motor milestones, medical history, oral behaviours, and heredity. These findings suggest that speech difficulties often emerge in the context of multiple interacting developmental influences. &lt;/p&gt;&lt;p dir="ltr"&gt;Conclusions &lt;/p&gt;&lt;p dir="ltr"&gt;Taken together, the current findings show that speech sound difficulties in childhood commonly co-occur with differences in oral motor performance, sensory processing patterns, and early developmental trajectories. These cooccurring functional features suggest that difficulties do not arise in isolation but reflect broader developmental constellations that influence how children respond to everyday demands and intervention. Recognising and addressing this heterogeneity is therefore crucial for the development of tailored, functionally informed intervention approaches that accommodate individual profiles and support effective therapy outcomes. &lt;br&gt;&lt;br&gt;&lt;/p&gt;&lt;h3 dir="ltr"&gt;List of scientific papers&lt;/h3&gt;&lt;p dir="ltr"&gt;I. Björelius H., Tsilingaridis G., Johansson F., Trang J., Grigoriadis A., Thorman R., Terband H. (2025). Chewing efficiency in children with motor speech disorders. European Archives of Paediatric Dentistry, 1–11. &lt;a href="https://doi.org/10.1007/s40368-025-01095-6" target="_blank" rel="noreferrer"&gt;https://doi.org/10.1007/s40368-025-01095-6&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;II. Björelius H., Tükel Ş., Tsilingaridis G., Malmenholt A., Terband H. (2025). Sensory Profiles in Children with Speech Sound Disorders. Folia Phoniatrica et Logopaedica. &lt;a href="https://doi.org/10.1159/000548782" target="_blank" rel="noreferrer"&gt;https://doi.org/10.1159/000548782&lt;/a&gt;&lt;/p&gt;&lt;p dir="ltr"&gt;III. Björelius, H., Terband, H., Johansson, F., Tsilingaridis, G., &amp; Tükel, Ş. (2026). Multidomain Developmental Indicators in 4–9-Year-Old Children with Oral Motor and Speech Sound Disorders. Folia Phoniatrica et Logopaedica. &lt;a href="https://doi.org/10.1159/000551061" target="_blank" rel="noreferrer"&gt;https://doi.org/10.1159/000551061&lt;/a&gt;&lt;/p&gt;</jats:p>