A 62-year-old hospitalized woman is evaluated for muscle weakness. The patient was admitted 2 weeks ago due to septic shock from acute pyelonephritis. She was treated in the intensive care unit with intravenous fluids, vasopressors, and broad-spectrum antibiotics. The patient was also mechanically ventilated due to respiratory failure. Her hemodynamic status and infection gradually improved, but she has had difficulty being taken off the ventilator due to respiratory muscle weakness. She is also noted to have significant extremity weakness. Physical examination shows diffuse mild atrophy of the extremity muscles. Bilateral upper and lower extremity deep tendon reflexes are decreased.