Hypokalemic Periodic Paralysis: A Case Report of Acute Flaccid Quadriparesis Mimicking Guillain-Barré Syndrome.

Hypokalemic periodic paralysis (HPP) is an uncommon but reversible cause of acute flaccid paralysis. It can clinically resemble neurological emergencies such as Guillain-Barré syndrome (GBS), leading to potential misdiagnosis and delays in appropriate treatment. We report a 30-year-old man who presented with sudden-onset quadriparesis following an acute febrile illness with gastrointestinal symptoms characterized by fever, myalgia, arthralgia, and vomiting. Initial neurological assessment demonstrated proximal and distal weakness without sensory involvement. Laboratory tests revealed severe hypokalemia (2.2 mmol/L), mild hypomagnesemia, hypophosphatemia, and markedly elevated CRP and procalcitonin. An MRI of the brain and spine was unremarkable. Although GBS was considered, rapid improvement in muscle strength following intravenous (IV) and oral potassium supplementation supported the diagnosis of hypokalemic periodic paralysis. The patient made a full recovery with the correction of electrolytes. This case emphasizes the importance of early electrolyte evaluation in acute flaccid paralysis and highlights the need to distinguish hypokalemic paralysis from GBS, as timely potassium replacement leads to rapid and complete recovery.