from * iDepartment of Neurosurgery , lwate Medical University * 2Department of Neurosurger } l Hachinohe Red Cross Hospital 厂 Fvo cases of porencephalic cyst after surgery for subdural empyema are reported . The first case was a 34 − year − old female who was admitted with subdural empyema . Subdural drainage and e )rternal decompression were performed . One month later , Magnetic res 〔 } nance imaging ( MRI )revealed a porencephahc cyst in left temporal lobe. She was treated with a cyst −

more »

... oneal shunt . The second case was an 8 − month − old female who presented with subdural empyema folloWing meningitis . She was treated with antibiotic therapy and placement of an Ommaya reservoir . During the surgical procedure , a small parenchymal injury on surface of the left frontal lobe was causeCl by the tip of Ommaya reservoir . Five months after surgery , MRI revealed a porencephalic cyst at the site of the left frontal 】 obe in which Omrnaya reservoir remained . Removal of Ommaya reservoir redllced the size of the poren − cephalic cyst . We discuss the mechanisms of formation and progressive growth of porencephalic cysts after surgery for sub − dural empyema . We also notice that porencephalic cysts may be caused by iatrogenic injury to the brain during sur − gery for subdural empyema .