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Abstract
Objective: In a cross-sectional study, we aimed to determine (1) the effect of spinal muscular atrophy (SMA) type 2 and 3 on mandibular function reflected as masticatory performance, mandibular range of motion, and bite force and (2) the predictors of mandibular dysfunction.
Methods: Sixty patients with SMA type 2 and 3 (mean age 32.3 years, SD 17.4 years) and 60 age-matched controls filled out questionnaires about impairments of mandibular function. All participants underwent detailed clinical examination to document the mandibular range of motion including maximal mouth opening, bite force, and masticatory function.
Results: All mandibular movements, including mouth opening, lateral range of motion, and protrusion of the mandible, were reduced in patients with SMA type 2 and 3 compared to healthy controls (p < 0.001). Maximal bite force was 19% lower in patients than controls, and more in patients with SMA type 2 than type 3. The strongest predictive factor was SMA type for impairment of mandibular range of motion (R2 = 0.82) and weakness of neck muscles for bite force (R2 = 0.47).
Conclusions: Reduced mandibular mobility and bite force are common complications in SMA. SMA type and neck muscle strength are important correlates of these complications. We provide further evidence for clinically relevant bulbar involvement in patients with SMA.
GLOSSARY
- aMMO=
- active maximum mouth opening;
- HFMSE=
- Hammersmith Functional Motor Scale Expanded;
- MFIQ=
- Mandibular Functional Impairment Questionnaire;
- MLPA=
- multiplex ligation-dependent probe amplification;
- MRC=
- Medical Research Council;
- MVBF=
- maximum voluntary bite force;
- OC=
- occlusal contacts;
- ROM=
- range of motion;
- SMA=
- spinal muscular atrophy;
- TMJ=
- temporomandibular joint;
- VAS=
- Visual Analogue Scale
Footnotes
↵* These authors contributed equally to this work.
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
- Received March 6, 2015.
- Accepted in final form October 13, 2015.
- © 2016 American Academy of Neurology
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