Posterior reversible encephalopathy syndrome following uneventful clipping of an unruptured intracranial aneurysm: A case report

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) is characterized mainly by occipital and parietal lobe involvement, which can be reversible within a few days. Herein, we report a rare case of PRES that developed after craniotomy for an unruptured intracranial aneurysm (UIA). CASE SUMMARY: A 59-year-old man underwent clipping surgery for the treatment of UIA arising from the left middle cerebral artery. Clipping surgery was performed uneventfully, and he regained consciousness quickly immediately after the surgery. At the 4th hour after surgery, he developed a disorder of consciousness and aphasia. Magnetic resonance imaging revealed cortical and subcortical T2/FLAIR hyperintensities in the parietal, occipital, and frontal lobes ipsilaterally, without restricted diffusion, consistent with unilateral PRES. With conservative treatment, his symptoms and radiological findings almost completely disappeared within weeks. In our case, the important causative factor of PRES was suspected to be a sudden increase in cerebral perfusion pressure associated with temporary M1 occlusion. CONCLUSION: Our unique case highlights that, to our knowledge, this is the second report of PRES developing after craniotomy for the treatment of UIA. Surgeons must keep PRES in mind as one of the causes of perioperative neurological abnormality following clipping of an UIA.