Introduction: The positioning for neurosurgical procedures is of paramount importance and especially so for approaches to the posterior fossa. The sitting position, while advocated frequently by many surgeons, is still difficult to use, especially in a safety first medical culture. We aim to show, in this non-inferiority study, that use of the sitting position is safe, adding no supplementary risks, when compared to other positions.

Methods: We retrospectively reviewed all the posterior fossa surgeries performed between January 2008 and December 2013 (n=966). All first time surgeries in the sitting position (n=359) were included and compared to similar patients operated in horizontal positions. Parameters analyzed were those pertaining to patient safety and complication rates: venous air embolism, operative blood loss, intraoperative hypotension, surgery and anesthesia duration, hospital and ICU length of stay. Subgroup analysis was performed on Chiari malformation patients since it was considered a model of posterior fossa approach and a standardized surgery in our institution, indifferent to patient positioning.

Results: Mean patient age was 53.0±16,7 with a 51.9% women. Main patient pathologies included cerebellar tumors (n=203, 55.5% sitting), brain stem tumors (n=48, 89.5%sitting), posterior fossa meningiomas (n=99, 60% sitting), vestibular schwanommas (n=55, 32.7% sitting) and Chiari malformation (n=120, 51.5% sitting). No significant differences were noted in any of the groups for: venous air embolism (46% vs. 33%), overall skin-to-skin surgery duration (203 minutes vs. 213 minutes, p=0.86) hospital length of stay (14 vs. 15 days p=0.93) and postoperative surgical complications. The only noted significant difference was on the total blood loss (156 vs. 271 p<0.05) in favor of the sitting position.

Conclusions: These data show that the use of the sitting position does not increase the surgical risk and operative complication rates therefore its use should not be prohibited. Specific – neurologic – outcome data is necessary to recommend its use

Patient Care: the sitting position compared to the prone or lateral positions for surgery of posterior cranial fossa provides a potential safe procedure with no significant additional operative risks.

Learning Objectives: There are potential benefits and risks of both the sitting and prone/lateral positions without supporting a significantly increased morbidity or mortality associated with either position.

References: 1. Black, S., et al. (1988). "Outcome following posterior fossa craniectomy in patients in the sitting or horizontal positions." Anesthesiology69(1): 49-56. 2.Rath, G. P., et al. (2007). "Complications related to positioning in posterior fossa craniectomy." J Clin Neurosci14(6): 520-525. 3. Ganslandt, O., et al. (2013). "The sitting position in neurosurgery: indications, complications and results. a single institution experience of 600 cases." Acta Neurochir (Wien)155(10): 1887-1893.