Introduction and validation of a phenotypic classification of neurogenic dysphagia based on flexible endoscopic evaluation of swallowing (FEES).
A systematic literature review was conducted, searching MEDLINE from inception to May 2020 for FEES findings in neurologic diseases of interest. Based on a retrospective analysis of FEES videos in neurologic diseases and considering the results from the review, a classification of neurogenic dysphagia was developed distinguishing different phenotypes. The classification was validated using 1,012 randomly selected FEES videos of patients with various neurologic disorders. Chi-square tests were used to compare the distribution of dysphagia phenotypes between the underlying neurologic disorders.
A total of 159 articles were identified, of which 59 were included in the qualitative synthesis. Seven dysphagia phenotypes were identified: (1) "premature bolus spillage" and (2) "delayed swallowing reflex" occurred mainly in stroke, (3) "predominance of residue in the valleculae" was most common in Parkinson disease, (4) "predominance of residue in the piriform sinus" occurred only in myositis, motoneuron disease, and brainstem stroke, (5) "pharyngolaryngeal movement disorder" was found in atypical Parkinsonian syndromes and stroke, (6) "fatigable swallowing weakness" was common in myasthenia gravis, and (7) "complex disorder" with a heterogeneous dysphagia pattern was the leading mechanism in amyotrophic lateral sclerosis. The interrater reliability showed a strong agreement (kappa = 0.84).
Neurogenic dysphagia is not a symptom, but a multietiologic syndrome with different phenotypic patterns depending on the underlying disease. Dysphagia phenotypes can facilitate differential diagnosis in patients with dysphagia of unclear etiology.