Postoperative cerebral air embolism with delayed abnormal brain MRI findings.

Cerebral air embolism (CAE) is a rare but well-known complication resulting from invasive medical procedures; however, previous studies have not examined the postoperative longitudinal MRI changes in CAE. In particular, the likelihood that such changes may be observed after an initial delay when using magnetic resonance imaging (MRI) has not been explored. We herein report a case of CAE with no MRI abnormalities 4 h after a pulmonary vein isolation (PVI) procedure and where the first abnormality was found 22 h after the procedure. A 65-year-old man underwent PVI for paroxysmal atrial fibrillation and showed no signs of recovery from anesthesia after the procedure; thus, he was transferred to our emergency department for further examination. Neurological examination revealed conjugate eye deviation to the right and quadriplegia. Although initial computed tomography (CT) and MRI revealed no abnormalities, CAE was suspected, and a high-concentration oxygen treatment was administered. MRI performed 22 h after the procedure revealed restricted diffusion affecting the cortical areas. At the same day, he was transferred for hyperbaric‑oxygen chamber treatment. After 7 days of treatment, the patient recovered clinically and neurologically. He regained consciousness and was able to communicate. As suggested by this case, CT and MRI findings may fail to reveal CAE abnormalities initially. In such cases, as urgent treatment is necessary, it is important to consider diagnosing CAE based on the patient's history and administering a high concentration of oxygen. Finally, to reach a correct diagnosis, repeated brain MRI should be considered for patients with suspected CAE.