Malperfusion-associated transient monoplegia as an initial manifestation of aortic dissection.

Acute aortic dissection (AD) is a life-threatening emergency. The most common symptom of AD is chest pain, more frequently associated with Type-A AD per the Stanford classification, while Type-B AD is associated with back and abdominal pain. Conversely, monoplegia is an uncommon symptom of AD. We encountered a case of transient monoplegia caused by Stanford type-B AD. A 75-year-old man presented with acute-onset lumbar back pain with monoplegia. Lumbar radiography revealed multiple compression fractures and spinal-canal stenosis, and accordingly acute spinal-cord compression was suspected. Monoplegia subsided after a diclofenac suppository was administrated to reduce his pain. However, the patient's right lower-extremity pain and paralysis worsened at rest during the stay. Computer tomography angiography revealed Stanford type-B AD and the false lumen obstructing the right common iliac artery. Monoplegia in type-B AD can develop due to spinal-cord or lumbosacral-plexus ischemia. Malperfusion, determined by the balance of the pressure in the false and true lumens and subsequent end-organ ischemia, may produce transient or persistent symptom patterns. Emergency physicians need to suspect AD when a patient presents with monoplegia or transient symptom patterns of unknown etiology.