Dropped head syndrome: a rare adverse drug reaction identified in the FDA adverse event reporting system and review of case reports in the literature.

Background: Dropped head syndrome (DHS) is a relatively rare disease, and its potential relationship with drug exposure has been postulated but is poorly understood.

Research Design And Methods: This retrospective study evaluated the adverse event reports of DHS in the FDA adverse event reporting system （FAERS) between 1 January 2004, to 31 March 2021. Empirical Bayes Geometric Means (EBGM) and the lower 95% one-sided CI of EBGM were calculated to identify disproportionate reporting of DHS associated with drugs. In addition, published case reports were identified in the PubMed, Embase and Cochrane Library up to 5 August 2021.

Results: There were 193 reports of DHS in the FAERS, in which nervous system agents were most frequently reported, followed by antineoplastic and immunomodulating agents. Pramipexole, ropinirole, levodopa, pregabalin, rotigotine, cisplatin, imatinib and botulinum toxin showed disproportionality signal based each on more than 5 cases. Ten published DHS case reports were identified in the literature.

Conclusion: Our study provides a more explicit profile on the occurrences and characteristics of DHS associated with drugs by analyzing the FAERS data and indicates that exposure of certain drug showed disproportionality signal with the increased DHS risk, which suggests the importance of further clinical and observational investigations.