Periodic Drop Thumb, Hypokalemia and Adrenal Adenoma

OBJECTIVE: To report an unusual involvement of focal distal muscles but not proximal muscles in a patient with hypokalemic periodic paralysis (hypoPP). CLINICAL PRESENTATION AND INTERVENTION: A middle-aged woman presented with episodic weakness of the bilateral thumbs lasting for 2 years. Hypokalemia and a left adrenal mass were subsequently found. Her weakness subsided after surgical removal of the adrenal mass, which was pathologically proven to be an adrenal adenoma. CONCLUSION: The findings for this patient should alert physicians to consider focal distal motor paresis due to hypoPP. A preexisting occult trauma may predispose to paralysis at an atypical location in secondary hypoPP.