A 55-year-old man is evaluated in the intensive care unit for acute neurological deterioration. Five days ago, he was admitted to the hospital with severe confusion and a serum sodium level of 105 mEq/L. His medical history is significant for chronic alcohol use disorder and severe malnutrition. Upon his initial admission, he was treated with hypertonic saline, and his serum sodium was rapidly corrected to 125 mEq/L within the first 24 hours. Following this correction, his mental status improved significantly, and he was able to converse and eat normally. However, yesterday he began to develop progressive slurred speech and difficulty swallowing. This morning, the nursing staff noted that he is entirely unable to move his arms or legs. His wife states he seems “trapped” in his own body, as he can only communicate by blinking and moving his eyes vertically. He is afebrile. His blood pressure is 130/80 mmHg with a heart rate of 88 bpm and a respiratory rate of 16 breaths per minute.