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Masticatory muscle function in patients with spinal muscular atrophy
M W Granger1, P H Buschang, G S Throckmorton
1Department of Orthodontics, Baylor College of Dentistry, Texas A&M University System, Dallas, USA.
Summary
Spinal muscular atrophy (SMA) significantly weakens chewing muscles, reducing bite force and jaw movement range. Patients with SMA experience faster muscle fatigue and less efficient chewing compared to healthy individuals.
Area of Science:
- Neurology
- Biomedical Engineering
- Physical Therapy
Background:
- Spinal muscular atrophy (SMA) is a genetic disorder affecting motor neurons.
- Masticatory function is crucial for nutrition and quality of life.
Purpose of the Study:
- To investigate the impact of spinal muscular atrophy (SMA) on masticatory muscle strength and mandibular range of motion.
- To compare functional parameters between individuals with SMA and healthy controls.
Main Methods:
- Evaluated maximum bite force, electromyography (EMG) activity, mandibular range of motion, and masticatory muscle endurance.
- Compared 15 subjects with SMA to age- and sex-matched controls.
Main Results:
- Maximum bite force was halved in the SMA group compared to controls.
- EMG activity was similar, but the relationship between EMG and bite force was steeper in SMA patients, indicating reduced muscle efficiency.
- Mandibular opening and protrusion were reduced by approximately 50% in the SMA group.
- Masticatory muscle fatigue time was reduced by 30% in individuals with SMA.
Conclusions:
- Masticatory muscles are weakened and less efficient in individuals with spinal muscular atrophy.
- Patients with SMA exhibit significantly reduced mandibular range of motion and faster muscle fatigue.
- These findings highlight the orofacial functional deficits associated with SMA, impacting chewing and potentially nutrition.