gms | German Medical Science

Objective: Awake craniotomy is a safe, language-concerning neurosurgical technique. In order to monitor the brain function during operation, after the extubation patients are continuously evaluated neurologically. However, not every patient awakes at the same time after extubation. This makes neurological testing difficult and compromises the safety of the operation. It is therefore desirable to be able to predict whether and when patients are fully awake and neurologically observable during awake craniotomy. Therefore, the aim of this work is to determine the optimal time frame for cortical mapping after the waking of the patient.

Methods: In this study we have chosen the moment of extubation as a time reference point (t=0). After waking up, patient reaction time was documented every 5-10 minutes for the whole duration of the waking-phase. These intraoperative parameters were entered into the "Reaction Time Sampler" app, which our team has programmed, together with other relevant data and events, such as preoperative baseline reaction times, the timestamp of the beginning of the waking phase and intraoperative epileptic seizures. All data were analyzed using the IBM SPSS Statistics 24.0 software package (IBM Corp., Armonk, NY).

Results: In total there were 26 patients included into this study. Mean baseline reaction time was 441ms (SD ± 151.9) and was significantly shorter than mean intraoperative reaction time which was 856ms (SD ± 442.9), p<.001 (Figure 1 [Fig. 1]). The longest intraoperative reaction times (mean = 944ms) were observed during the first ten minutes of the waking-phase, the shortest (mean = 709ms) during the minutes 11 to 50. However, the difference between all the intraoperative ten minute time-spans was not statistically significant (Figure 2 [Fig. 2]).

Conclusion: In current literature there are no documented attempts to define the optimal time frame for cortical mapping. According to our data, the patients are significantly slower and therefore suboptimal awake during the waking-phase of the operation. Although, there was no significant improvement of reaction time during the operation, it appears to be reasonable to postpone the cortical mapping until after the 10th minute of the waking-phase.