Objectives: Even 250 years after Beethoven's birth, the irrevocable cause of his hearing impairment remains unclear despite multiple publications by different professional groups. This study aimed to analyse the development of the most likely aetiologies during the last 100 years by a systematic review of the relevant medical literature.
Methods: A systematic review of medical literature in PubMed®, PubMed Central®, and Web of Science® for the period 1920-2020 was conducted. Medical publications between 1920 and 1935 were additionally searched manually by review of reference lists. Studies were eligible when a statement regarding the most likely aetiology of the hearing loss of Beethoven was the aimed objective of the publication.
Results: 48 publications were included. The following aetiologies were supposed: otosclerosis (n = 10), syphilis (n = 9), Paget's disease (n = 6), neural deafness (n = 5), immunopathy with inflammatory bowel disease, neural deafness with otosclerosis, sarcoidosis or lead intoxication (n = 2), and systemic lupus erythematosus, trauma, labyrinthitis or inner ear disease (n = 1). There is an ongoing effort with a mean publication frequency in this topic of 0.48/year. From 1920 to 1970, otolaryngologists were the group with the highest interest in this field (67%), whereas since 1971 most authors have belonged to non-otolaryngologic subspecialities (81%).
Conclusion: Over the past 100 years, otosclerosis and syphilis were predominantly supposed to be the underlying causes. The hypothesis of syphilis-although rejected for a long time-has had a remarkable revival during the past 20 years. Regarding the outcome following therapeutic intervention by cochlear implantation, the differential diagnosis of neural deafness would be relevant today.
Keywords: Aetiology; Beethoven; Cause; Deafness; Hearing loss.