Neurogenic Dysphagia: A Systematic Review and Proposal of a Classification System

Objective:Introduction and validation of a phenotypic classification of neurogenic dysphagia based on flexible endoscopic evaluation of swallowing (FEES).Methods:A systematic literature review was conducted, searching MEDLINE from inception to 05/2020 for FEES findings in neurological diseases of interest. Based on a retrospective analysis of FEES-videos in neurological diseases and considering the results from the review, a classification of neurogenic dysphagia was developed distinguishing different phenotypes. The classification was validated using 1012 randomly selected FEES-videos of patients with various neurological disorders. Chi-square-tests were used to compare the distribution of dysphagia phenotypes between the underlying neurological disorders.Results: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 patients, (3) “predominance of residue in the valleculae” was most common in Parkinson's disease, (4) “predominance of residue in the piriform sinus” occurred only in myositis, motoneuron disease and brainstem stroke patients, (5) “pharyngolaryngeal movement disorder” was found in atypical Parkinsonian syndromes and stroke patients, (6) “fatigable swallowing weakness” was common in patients with myasthenia gravis, and (7) “complex disorder” with a heterogeneous dysphagia pattern was the leading mechanism in amyotrophic later sclerosis. The interrater reliability showed a strong agreement (kappa = 0.84).Conclusion:Neurogenic dysphagia is not a mere symptom, but a multi-etiological syndrome with different phenotypic patterns depending on the underlying disease. Dysphagia phenotypes can facilitate differential diagnosis in patients with dysphagia of unclear etiology.