Audiological implications in vestibular schwannoma patients undergoing gamma knife surgery

Brig (Dr) Maneet Gill; Dr Saurabh Anand Dubey; Surg CDRE (Dr) Arti Sarin; Brig (Dr) AV Ramesh

Volume : IX, Issue : V, May - 2019

Audiological implications in vestibular schwannoma patients undergoing gamma knife surgery

Brig Dr Maneet Gill, Dr Saurabh Anand Dubey, Surg Cdre Dr Arti Sarin, Brig Dr Av Ramesh

Abstract :

AIM:The aim of the study was to evaluate the changes in heå in vestibular schwannoma patients undergoing Gamma Knife Surgery (GKS) in the first six months following the procedure. Material and Methods:The study was a prospective clinical study done at Army Hospital (R&R), Delhi Cantt., done between March 2012 to March 2014. It had 26 patient included in the study who were evaluated with pre–GKS Contrast MRI (CEMRI), pure tone audiogram (PTA) and post–GKS evaluation with PTA at 3 months and 6 months and a CEMRI ain at the end of 6 months. Patient underwent GKS on Leksell Gamma Knife 4C unit installed at our institute. Results:Tumors with dimensions more than 2.4 cm had a definite deterioration in heå levels. The critical tumor volume above which significant changes in heå occurred came out to be 6.2 cc. Our study showed that a cochlear dose of 5.5 Gy was the critical dose above which significant changes in heå occurred during the first six months. Conclusions:The radiation changes after GKS usually start to occur after 2 to 3 months of the procedure and about 3–5 year is required for the final changes to occur. Dose of irradiation to cochlea, size & volume of tumor affects audiological outcome in short term. Shielding of the cochlea by blocking the collimator with plugs, is a useful method of altering the dosimetry, thus affecting outcome.