Primary Aldosteronism Presenting as Dropped Head Syndrome With Hypokalemic Rhabdomyolysis: A Case Report

Primary aldosteronism (PA) is a common cause of secondary hypertension and hypokalemia, but it rarely presents with neuromuscular symptoms. Although only a few cases of hypokalemia-induced rhabdomyolysis have been reported, dropped head syndrome (DHS) due to cervical axial muscle weakness has not previously been described in the context of PA.

A 65-year-old woman with a history of hypertension presented with progressive posterior neck weakness, followed by proximal limb soreness and weakness. Cervical spine disease was initially suspected, but CT imaging revealed only degenerative changes without cord compression. Laboratory tests showed severe hypokalemia (1.5 mmol/L), metabolic alkalosis, and markedly elevated creatine kinase and myoglobin levels, consistent with rhabdomyolysis. Her symptoms resolved after potassium supplementation. Endocrine workup revealed an elevated aldosterone-to-renin ratio (ARR) and a positive captopril suppression test. CT and NP-59 SPECT/CT identified a left adrenal functioning adenoma. Laparoscopic adrenalectomy confirmed an aldosterone-producing adrenal cortical adenoma. Postoperatively, the patient achieved complete biochemical remission with normalized potassium levels, improved blood pressure, and no recurrence of muscle weakness or neck symptoms.

This case highlights a rare presentation of PA as hypokalemia-induced rhabdomyolysis and DHS mimicking cervical spine pathology. In patients with unexplained focal muscle weakness and persistent hypokalemia, particularly in the setting of hypertension, PA should be considered. Clinicians should maintain a high index of suspicion and pursue comprehensive diagnostic evaluations. Early diagnosis and definitive treatment can prevent long-term complications and enable full metabolic recovery.