Dropped Head Syndrome: A Rare Clinical Entity Due to Chlorthalidone-Induced Dyselectrolytemia

A bstract Dropped head syndrome (DHS) is an uncommon medical condition that is characterized by severe weakness of the neck extensor muscles, leading to failure in holding the head in an upright posture. This clinical entity was first systematically described by Suarez and Kelly in 1992, who emphasized that DHS represents a clinical sign rather than a specific diagnosis and requires evaluation for underlying causes. It is most frequently associated with neuromuscular junction disorders, motor neuron disease, Parkinson-plus syndromes, and inflammatory myopathies. Metabolic causes are uncommon and often overlooked. Hypokalemia is a well-recognized cause of generalized muscle weakness and paralysis; however, isolated axial muscle involvement presenting as DHS is extremely rare. We report a case of acute reversible DHS secondary to severe hypokalemia induced by chronic chlorthalidone therapy in middle-aged women with long-standing hypertension and diabetes mellitus. Laboratory evaluation revealed profound hypokalemia (1.79 mmol/L) with elevated urinary potassium excretion, suggesting renal potassium loss. No evidence of neuromuscular junction disorder, thyroid dysfunction, or motor neuron disease was found. Prompt recognition, withdrawal of chlorthalidone, and potassium replacement resulted in rapid and complete clinical recovery. Thus, this case report highlights the importance of reversible causes, such as hypokalemia should be taken into account for the acute presentation of DHS for ensuring timely management.