Posterior Spinal Artery Infarction With Unilateral Lumbar Spinal Cord Lesion: A Challenge in Early Diagnosis

A 71‐year‐old woman presented with acute muscle weakness and paresthesia in her left lower limb with the preceding back pain and impaired deep sensation. Although initial brain and spinal MRI were normal, follow‐up spinal MRI confirmed the left‐sided posterior lesion at T10 to T12 vertebral level, leading to the diagnosis of posterior spinal artery (PSA) infarction. PSA infarction with unilateral lumbar spinal cord lesion is rare and can mimic cerebral stroke. Clinicians should check for back pain and deep sensation in cases with symptoms of acute unilateral lower limb on suspicion of PSA infarction, even when initial MRI is normal.