Swallowing markers in spinal and bulbar muscular atrophy

Abstract

Objective: We examined the characteristics of dysphagia in spinal and bulbar muscular atrophy, a hereditary neuromuscular disease causing weakness of limb, facial, and oropharyngeal muscles via a videofluoroscopic swallowing study, and investigated the plausibility of using these outcome measures for quantitative analysis.

Methods: A videofluoroscopic swallowing study was performed on 111 consecutive patients with genetically confirmed spinal and bulbar muscular atrophy and 53 age- and sex-matched healthy controls. Swallowing of 3-mL liquid barium was analyzed by the Logemann's Videofluorographic Examination of Swallowing worksheet.

Results: Of more than 40 radiographic findings, the most pertinent abnormal findings in patients with spinal and bulbar muscular atrophy, included vallecular residue after swallow (residue just behind the tongue base), nasal penetration, and insufficient tongue movement (P < 0.001 for each) compared with healthy controls. Quantitative analyses showed that pharyngeal residue after initial swallowing, oral residue after initial swallowing, multiple swallowing sessions, and the penetration-aspiration scale were significantly worse in these patients (P ≤ 0.005 for each) than in controls. In patients with spinal and bulbar muscular atrophy, laryngeal penetration was observed more frequently in those without subjective dysphagia.

Interpretation: Dysphagia of spinal and bulbar muscular atrophy was characterized by impaired tongue movement in the oral phase and nasal penetration followed by pharyngeal residues, which resulted in multiple swallowing sessions and laryngeal penetration. Although major limitations of reproducibility and radiation exposure still exist with videofluoroscopy, pharyngeal residue after initial swallowing and the penetration-aspiration scale might serve as potential outcome measures in clinical studies.

Figure 1

Results of qualitative analyses. (A) We compared the qualitative radiographic findings of SBMA patients with those of the control group. Qualitative videofluoroscopic swallowing study (VFSS) findings found significantly more frequently in the SBMA group than the control group are shown in bold. More than 80% of SBMA patients had vallecular residue after swallowing (residue just behind the tongue base); approximately 50% of patients had residue (stasis) in both pyriform sinuses (residue in both sides of the laryngeal orifice), and piecemeal deglutition (multiple swallowing sessions). Ten of the 14 findings that differentiate SBMA patients from the control group were pharyngeal phase findings. Solid bars denote SBMA patients (N = 111). Open bars denote control participants (N = 53). *Statistically significant difference between SBMA and control groups; chi‐square test. Red asterisks indicate pharyngeal phase findings. (B) For the SBMA‐related qualitative radiographic findings, we also compared their occurrences in patients with and without subjective dysphagia. Significant differences between these two groups are shown in bold. Half of the findings that differentiate the with (solid bars; N = 53) and without (open bars; N = 58) subjective dysphagia groups were oral‐phase findings. *Statistically significant difference between the with and without subjective dysphagia groups; chi‐square test. Red asterisks indicate oral‐phase findings.

Figure 2

Putative scheme of dysphagia in SBMA patients. Dysphagia in SBMA stems from tongue atrophy and incomplete velar elevation, both of which cause dysfunctional tongue movement. Tongue movement dysfunction leads to oral and pharyngeal residues, both of which eventually result in multiple swallowing sessions (piecemeal deglutition) and laryngeal penetration. Incomplete velar elevation/tongue atrophy also lead to nasal penetration, inevitably causing reduced tongue movement to compensate and low pharyngeal pressure, which leads to pharyngeal residue (residue in the vallecula and pyriform sinuses), and finally laryngeal penetration.