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Maximal mouth opening in infants and toddlers with spinal muscular atrophy: a prospective controlled study
Jana Zang1,2, Deike Weiss3, Charlotte Dumitrascu4
1Department of Voice, Speech and Hearing Disorders, University Dysphagia Center, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. j.zang@uke.de.
Insights
Maximum mouth opening (MMO) is reduced in children with spinal muscular atrophy (SMA). This study established a reliable method to measure MMO in infants and toddlers with SMA, finding significantly wider mouth opening in healthy controls.
Area of Science:
- Neurology
- Pediatrics
- Genetics
Background:
- Spinal muscular atrophy (SMA) often impairs bulbar function, impacting quality of life.
- Reduced maximum mouth opening (MMO) is suspected in children with SMA due to bulbar dysfunction.
- No published MMO values exist for SMA children under 24 months.
Purpose of the Study:
- To present a novel method for measuring MMO in infants and toddlers with SMA.
- To compare MMO values in children with SMA to healthy controls.
- To establish normative MMO data for early-diagnosed SMA.
Main Methods:
- Prospective recruitment of children with SMA (0-24 months) on disease-modifying therapy and age-matched healthy controls.
- MMO measurement using a cardboard scale and a custom-designed instrument.
- Assessment of inter-rater and instrument reliability (ICC > 0.986).
Main Results:
- 115 children included (24 SMA, 91 controls).
- Excellent inter-rater and instrument reliability confirmed.
- MMO significantly increased with age, with healthy controls exhibiting wider mouth opening (p < .001).
Conclusions:
- MMO measurement is reliable and feasible in young children with SMA.
- MMO provides valuable insights into cranial nerve involvement in early SMA.
- This data can inform the assessment of disease-modifying therapies in SMA.
Background:
Bulbar function is frequently impaired in patients with spinal muscular atrophy (SMA). Although extremely important for the patient's quality of life, it is difficult to address therapeutically. Due to bulbar dysfunction, maximum mouth opening (MMO) is suspected to be reduced in children with SMA. However, no published MMO values exist for SMA children younger than 24 months. This study presents a novel approach to measuring MMO in infants and toddlers with SMA and compares it with healthy controls.
Methods:
Children with SMA (0-24 months) who received disease-modifying therapy at a single neuropediatric center and similarly aged healthy children were prospectively recruited. MMO was measured using a cardboard scale and a custom-designed instrument.
Results:
A total of 115 children were included (SMA = 24, healthy controls = 91). Inter-rater reliability between two examiners was excellent (ICC = 0.987, 95% CI 0.959 to 0.995), as was the reliability between the cardboard scale and the custom-designed instrument (ICC = 0.986, 95% CI 0.968 to 0.994). A mixed linear model showed a significant increase of MMO with age, and a significantly wider mouth opening in healthy controls (p < .001).
Conclusion:
For future research, MMO can provide valuable information about the involvement of cranial nerves, particularly in the context of disease-modifying therapies, even at a very early age.
