Medically Managed Dropped Head Syndrome: Outcomes in Isolated Neck Extensor Myopathy and Primary...

Objective We herein report our experience with medically treated patients presenting with dropped head syndrome (DHS) due to isolated neck extensor myopathy (INEM) or primary hyperparathyroidism (PHPT)-related myopathy, focusing on the treatment response and the correlation between muscle pathology and INEM outcomes. Methods This single-center retrospective observational study reviewed 20 consecutive patients who presented with DHS as their primary complaint between March 2021 and June 2025. Sixteen patients were included in this study: 13 with INEM who received immunotherapy as the primary medical treatment and 3 with PHPT-related myopathy who received oral evocalcet. The severity of DHS and treatment response were graded semi-quantitatively. Muscle biopsy findings were analyzed in one patient with INEM. We conducted a literature review of biopsy-proven INEM cases. Results INEM was the most common cause of DHS (13/20). Patients with INEM with a shorter disease duration experienced dramatic improvement, whereas those with a longer disease duration showed only partial improvement. Relapse occurred in six patients with INEM. All three patients with PHPT-related myopathy achieved complete remission of DHS with oral evocalcet. Although our single biopsy case showed no pathological inflammation and responded well to immunotherapy, a literature review revealed that inflammatory infiltrates were present in 38% of the 56 INEM cases and correlated with a significantly better immunotherapy response. Conclusion INEM is the predominant etiology of DHS at initial presentation, and immunotherapy is an effective management strategy, especially with early intervention. PHPT-related myopathy represents another important etiology of DHS, with a favorable response to medical therapy with evocalcet.