The marionette technique for treatment of isolated fourth ventricle: technical note.

Isolated fourth ventricle is not uncommon in complex posthemorrhagic or postinfectious hydrocephalus. When the condition is symptomatic, the current surgical treatment is endoscopic aqueductoplasty, followed by endoscope-assisted placement of a catheter in the fourth ventricle. The authors suggest a very simple method of steering the tip of standard ventricular catheters by using materials commonly available in all operating rooms. The main advantage of this method is that it permits less invasive transaqueductal drainage of trapped fourth ventricles, especially in cases of narrow third ventricle, because the scope and catheter are introduced in sequence and not in a double-barreled fashion. Two illustrative cases are reported.