Pneumonia preceding respiratory failure. A rare, easily misleading clinical manifestation in adult Arnold-Chiari malformation.

A 47-year-old woman was admitted for bilateral lower lobe pneumonia with respiratory distress. Two episodes of respiratory failure developed despite improvement of pneumonia after antibiotic chemotherapy. Loss of consciousness and quadriplegia accompanied the last episode of respiratory failure. Arnold-Chiari malformation type 1 was diagnosed and a suboccipital craniectomy was performed. The neuromuscular and respiratory disorders greatly improved after operation. We believe that ACM 1 should be considered when an adult develops unexpected respiratory failure after improvement of the primary pulmonary condition. This disease is potentially treatable by surgical management, and if it is misdiagnosed, will be fatal.