gms | German Medical Science

Objective: Awake surgery plays an important role in surgery of the eloquent areas of the cortex. To achieve the objective of a fully awake patient during brain surgery different methods of anaesthesia are practiced.

Methods: To compare the advantages and the outcome of different methods of awake surgery we reviewed 11 studies and 7 case reports that were published between 1993 and 2004. Methods of narcosis induction, methods of awakening the patient during surgery, complications and outcome after surgery were taken into consideration.

Results: Awake surgery was applied to 1099 patients. Basically there are three major concepts for realization of awake surgery. In the earlier publications awake surgery is realized by an asleep-awake-asleep (SWS) concept (882 patients, 80.3%). In four of the studies the patients were intubated during the asleep-periods (134 patients, 12.2%). Other studies report a deep sedation (748 patients, 68.1%) without intubation. In four publications of which three were published 1999 and later there is only a mild sedation (MS) used even for craniotomy (217 patients, 19.7%). The SWS concept is based on a general anaesthesia or a deep sedation that is induced and maintained using propofol and is discontinued after dural incision for mapping of the cortex and removal of the tumour. In all the reviewed manuscripts there is consent that additional local anaesthesia is necessary for the skin incision. Intraoperative seizures are reported in 4.5% (133 patients analyzed, range 0-6.1%) of the patients operated in SWS-mode with intubation. In SWS-mode without intubation seizures are reported in 12.3% (748 patients analyzed, range 8-18.9%) and in MS in 6% (217 patients analyzed, range 5.5-13.3%). Intraoperative nausea and vomiting is analyzed in 8 of the studies, all of which deal with SWS surgery and is reported in 6.8% (737 patients analyzed, range 0-50%). Occurrence of new neurological deficits is reported in 7.4% (445 patients analyzed, range 4-26.7%) in SWS surgery and in 3.3% (215 patients analyzed, range 2.5-13.3%) in MS.

Conclusions: There is far more experience in SWS surgery than in MS though mild sedation as a mode for surgery in the awake patient is becoming more frequently used. There is a tendency to less postoperative neurological deficits after surgery in MS as compared to SWS surgery. Furthermore there is a tendency of more seizures during SWS surgery without intubation compared to MS mode.