Objective: In patients with spinal muscular atrophy (SMA) type II, feeding problems and dysphagia are common, but the underlying mechanisms of these problems are not well defined. This case control study was designed to determine the underlying mechanisms of dysphagia in SMA type II.
Methods: Six children with SMA type II and 6 healthy matched controls between 6.4 and 13.4 years of age were investigated during swallowing liquid and solid food in 2 different postures using surface EMG (sEMG) of the submental muscle group (SMG) and a video fluoroscopic swallow study (VFSS).
Results: The VFSS showed postswallow residue of solid food in the vallecula and above the upper esophageal sphincter (UES), which can be responsible for indirect aspiration. Better results in swallowing were achieved in a more forward head position. These findings were supported by the sEMG measurements of the SMG during swallowing.
Conclusions: Dysphagia in spinal muscular atrophy type II is due to a neurologic dysfunction (lower motor neuron problems from the cranial nerves in the brainstem) influencing the muscle force and efficiency of movement of the tongue and the submental muscle group in combination with a biomechanical component (compensatory head posture). The results suggest an integrated treatment with an adapted posture during meals and the advice of drinking water after meals to prevent aspiration pneumonias.