Artikel
Favourable hearing preservation rates in small acoustic neuroma surgery and variations due to different grading systems
Ausgezeichneter Hörerhalt bei der Resektion kleiner Akustikusneurinome und Variationen des Hörerhalts bei Anwendung unterschiedlicher Gradierungssysteme
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Veröffentlicht: | 26. Juni 2020 |
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Gliederung
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Objective: Acoustic neuroma (AN) surgery is routinely performed on patients with various tumor sizes inappropriate for wait & scan or radiosurgery. Preoperatively, grading systems are applied for estimation of postoperative hearing preservation (HP) rates.
Methods: A retrospective single-centre analysis of 138 retrosigmoid operated ANs between 2014 to 2017 was performed. Patients gender was well balanced, mean tumor size was 20.4 mm (+/- 7.6 mm SD) with complete fundus infiltration in 67.4%.The overall resection rate was 93.5 %, with a low surgical complication rate of 3.6%. Tumors were classified preoperatively on T1 contrast and T2 axial MRI scans using the 3- tier Erlangen Grading System dependent on size (10.1% Grade 1 < 12mm, 65.2% Grade 2 between 12 and 25mm, 24.6% Grade 3 > 25mm) or the anatomically based 4- tier Koos Grading System (2.9% Grade 1, 40.6% Grade 2, 31.2% Grade 3 and 25.4% Grade 4).
Results: Preoperative serviceable hearing was found in 70.3% of patients and was significantly correlated to tumor size (p=0.001). An average mean postoperative serviceable HP rate of 38.6% was achieved (83.3% for tumors <12 mm, 38.5% for tumors between 12 and 25mm and 5.3% for tumors larger than 25mm according to the Erlangen Grading system). On the contrary, applying the Koos Grading System preoperatively instead, postoperative serviceable HP rates were 100% for Koos Grade 1 (meatal), 35.6% for Koos Grade 2 (cisternal), 23.1% for Koos Grade 3 (cisternal with brain stem contact) and 21.7% for Koos Grade 4 tumors (brain stem compression). Additionally, we found a trend to better HP rates in left sided tumors or when the fundus was tumor free. The rate of normal or nearly normal postoperative facial function in the total cohort was 75.3% (House and Brackmann (HB) Grade 1/2). Grade 3 paresis was found in 4.3% and severe facial deficits were apparent in 5.1% of patients (HB Grade 4).
Conclusion: This study showed that 1. performing surgery on small tumors can achieve excellenthearing preservation rates and that 2. the application of different grading systems has significant influence on the reporting of postoperative HP.