Semi-sitting Position in Neurosurgery: A Review

Specialists rarely perform neurosurgical procedures on patients in the semi-sitting position. This is due to several factors, most importantly, the perception of risks associated with this position and lack of practice in some services. Nevertheless, the benefit of this position is still the subject of controversy both in neurosurgery and neuroanesthesia. Our objective is to report on the benefits associated to its use for posterior fossa diseases and dorsal cervical spine procedures, through cases in the literature. We survey and analyze state-of -the art works that mention the semi-sitting position, based on searches in Pubmed, Scielo, Science Direct, and Lilacs. We found 46 original articles on the subject that we included in the review. This review demonstrates that the advantages for access in this position include gravitational drainage of venous blood and cerebrospinal fluid, easier surgical access to midline structures, as well as reduced cerebellar edema, surgery time and blood loss. This technique also allows ventilation with low pressure, less impairment of diaphragmatic motion, and better access to the tracheal tube. There are, however, some disadvantages, among which the most serious is paradoxical arterial embolism. We describe early detection methods of complications and discuss situations that can factor in to the choice of position. In summary, a semi-sitting position is safe and effective in neurosurgical posterior fossa and the upper cervical spine, provided there is a joint effort between neurosurgeons and anesthesiologists in selecting patients and complying with the technical standards favorable to this technique.