Three women who received epidural anesthesia for gynecological surgery developed spinal arachnoiditis leading to subarachnoid cysts and cord cavitation. MRI was useful to show the subarachnoid and intramedullary cysts, as well as to monitor lesion extent and progress. Associated MRI findings were a Chiari anomaly in 1 case and a tethered cord in another. Two cases underwent surgery: 1 improved, but the other suffered progressive neurological deterioration. Although the 3rd patient had no treatment, there was spontaneous reduction in cavity size and clinical improvement. Careful handling of this procedure is urged to avoid such severe complications in young mothers.