gms | German Medical Science

64th Annual Meeting of the German Society of Neurosurgery (DGNC)

German Society of Neurosurgery (DGNC)

26 - 29 May 2013, Düsseldorf

Surgery of posterior skull base lesions in semisitting position: A prospective study evaluating the advantages and actual risks of a clinically relevant air embolism

Meeting Abstract

  • Guenther C. Feigl - Department of Neurosurgery, University of Tübingen Medical Center, Germany
  • Karlheinz Decker - Department of Anesthesiology, University of Tübingen Medical Center, Germany
  • Rainer Ritz - Department of Neurosurgery, University of Tübingen Medical Center, Germany
  • Boris Krischhek - Department of Neurosurgery, University of Tübingen Medical Center, Germany
  • Marcos Tatagiba - Department of Neurosurgery, University of Tübingen Medical Center, Germany

Deutsche Gesellschaft für Neurochirurgie. 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC). Düsseldorf, 26.-29.05.2013. Düsseldorf: German Medical Science GMS Publishing House; 2013. DocMI.09.02

doi: 10.3205/13dgnc349, urn:nbn:de:0183-13dgnc3491

Published: May 21, 2013

© 2013 Feigl et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: The semisitting position offers several advantages during surgery in the posterior cranial fossa (PCF). It reduces intracranial pressure, venous bleeding and it enhances anatomical orientation since the view to the surgical field is not obscured by pooling of blood or irrigation fluid. There is still an ongoing controversy regarding the benefits, disadvantages and risks of this positioning for patients. The aim of this prospective study was to evaluate the frequency and actual risks for patients operated on in the semisitting position to suffer clinically relevant pulmonary air embolism (PAE).

Method: In a prospective study performed between January 2008 and December 2009 200 consecutive patients with lesions in the PCF, pineal region and occipital region were included. All procedures were performed under general anesthesia and in the semisitting position. Transesophageal echocardiography (TEE) and capnometry were used intra-operatively to screen the venous system for air bubbles.

Results: A total of 200 consecutive patients were included. A patent foramen ovale (PFO) was diagnosed in 52 (26%) patients. In 91 patients (45.5%) there was no indication of an air embolism. In 109 (54.5%) patients air bubbles were visible in the TEE. Rates of PAE according to our five scale grading showed following patient distribution in patients without and with a PFO: Grade I: 57 (38.5%) / 22 (42.3%), Grade II: 11 (7.4%) / 2 (3.8%), Grade III: 8 (5.4%) / 4 (7.6%) and Grade IV: 4 (2.7%) / 1 patient (1.9%) Grade V: 0 (0%) / 0 (0%). There were no mortalities, no new or unexplained neurological deficits neither mild nor severe caused by a PAE in this study.

Conclusions: Results of this study show that under standardized anesthesiological and neurosurgical protocols patients can safely be operated in the semisitting position. Furthermore, in this