Endoscopic fenestration of the 3rd ventricular floor in aqueductal stenosis.

Six endoscopic fenestrations of the 3rd ventricular floor have been performed in patients with stenosis (SAS) of the aqueduct of Sylvius in our institute during the last two years. The endoscopic intraventricular landmarks were the Monro's foramen followed by the mamillary bodies. The fenestration instrument was a monopolar coagulation wire, the dilatation instrument was a balloon catheter. The patients included two newborns and four adults. The two newborns developed a recurrent hydrocephalus after 2 months. The four adults remained well after the operation. The only complication was edema (SIADH syndrome) in one case for 24 hours. Flow sensitised phase MRI showed a mirroring in the prestenotic CSF pulsation curve preoperatively. This, in combination with an increased intraventricular pulsation, is a sign of reduced capacity of the subarachnoid space at the cerebral surface. The postoperative patency of the fenestration with diminished intraventricular pulsation can be demonstrated with ECG retrogated phase MRI. There was a slow and incomplete decrease of the preoperative enlarged ventricular size. This operative method is a low-risk, minimal invasive alternative method to shunt implantation in adults with SAS.