Why Children with Down Syndrome Have Poor Tongue Control
Children with Down syndrome have poor tongue control primarily due to generalized hypotonia (low muscle tone) affecting the orofacial muscles, including the tongue, perioral muscles, lips, and chewing muscles, which results in characteristic features like tongue protrusion, open mouth posture, and impaired oral motor function. 1, 2
Primary Mechanism: Hypotonia
The fundamental problem is muscular hypotonia, which is one of the most dramatic signs of Down syndrome and affects multiple body systems 2. Specifically affecting the oral region:
- Hypotonic tongue musculature leads to reduced strength and control, with studies demonstrating significantly lower anterior and posterior tongue strength in children with Down syndrome compared to typical peers 3
- Perioral muscle weakness affects the lips and surrounding facial muscles, contributing to decreased lip strength and endurance 4, 3
- Chewing muscle hypotonia impairs mastication and overall oral motor coordination 2
Anatomical and Functional Consequences
The hypotonia creates a cascade of functional problems:
- Tongue prolapse and protrusion: The tongue rests exposed on the everted lower lip due to insufficient muscle tone to maintain normal position 2, 4
- Persistently open mouth: Inability to maintain mouth closure results from weak lip and perioral muscles 2, 4
- Relative macroglossia: While the tongue may appear large, this is often relative to the narrow nasopharynx and shortened palate characteristic of Down syndrome 1
- Impaired oral phase of swallowing: Most children with Down syndrome lack sufficient tongue strength to complete the oral phase of swallowing effectively 3
Additional Contributing Factors
Beyond hypotonia alone, several anatomical features compound the problem:
- Midfacial and mandibular hypoplasia creates a smaller oral cavity, making tongue positioning more difficult 1
- Narrow nasopharynx and shortened palate further restrict the space available for normal tongue positioning 1
- Cranial nerve abnormalities may contribute to motor control deficits beyond simple muscle weakness 1
Clinical Impact on Function
The poor tongue control has significant downstream effects:
- Speech impairment: Hypotonia affects articulation, resonance, and overall speech intelligibility 1, 2
- Feeding difficulties: Impaired sucking, chewing, and swallowing are common 2, 4
- Drooling: Inability to manage oral secretions results from combined tongue and lip weakness 4
- Mouth breathing: The persistently open mouth leads to dehydration of oral tissues, increased bacterial colonization, and premature dental destruction 2
- Sleep-disordered breathing: Hypotonia of the tongue can cause complete or partial airway obstruction during sleep, leading to obstructive apnea and sleep bruxism 1, 5
Management Approach
Immediate referral to early intervention services is essential, with specific focus on oral motor therapy 6:
- Speech and language evaluation including assessment of oral-motor functioning should be initiated early, beginning at 6-18 months 6
- Orofacial regulation therapy using methods such as Castillo-Morales therapy has shown significant positive results in improving tongue position, lip tonicity, mouth closure, and drooling 2, 4
- Physical and occupational therapy should address overall hypotonia and motor development 6
Critical Pitfall to Avoid
Do not delay early intervention services while awaiting complete diagnostic workup—therapy must begin immediately 6. One case report highlighted how well-intentioned hypotonia therapy using sweets to induce oral muscular function inadvertently contributed to severe dental caries requiring extraction of all primary teeth, emphasizing the need for interdisciplinary coordination 7.