Dropped Head Syndrome Unmasking Myotonic Dystrophy Type 1 in a Patient with Parkinson's Disease: A Case Report and a Case‐Based Review

Ethical Compliance Statement: Informed patient consent was regularly obtained for video usage. Both oral and written consent was obtained. The approval of an institutional review board was not required. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. Funding Sources and Conflicts of Interest: No specific funding was received for this work. The authors declare that there are no conflicts of interest relevant to this work. Financial Disclosures for the Previous 12 Months: The authors declare that there are no additional disclosures to report. The data that support the findings of this study are available from the corresponding author upon reasonable request. TABLE S1. Clinical, neurophysiological, neuroimaging and therapeutic features of reported cases of myotonic dystrophy and concurrent parkinsonian syndrome (ref. 1–10) and of reported cases of myotonic dystrophy presenting with dropped head syndrome (ref 11,12). AAO, age at onset; DM, myotonic dystrophy; DHS, dropped head syndrome; EMG, electromyography; PET, positron emission tomography; SPECT, single-photon emission computed tomography; DAT, dopamine transporter; MSA-P, multiple system atrophy, parkinsonian variant. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.