gms | German Medical Science

Objective: Operating patients in local anaesthesia enables intraoperative language mapping and assessment of motor function and is an established procedure to find safe access to a tumor. However, craniotomies for mapping procedures are generally large to provide full exposure of eloquent cortex. Surgical procedures may be long if extensive mapping is performed. We evaluated the benefits and limitations of much smaller craniotomies, tailored with intraoperative computer-assisted image guidance and exposing only the tumor and very limited adjacent cortex.

Methods: A series of 25 patients with gliomas in or near eloquent cortex underwent awake craniotomy. Craniotomies were centered over the tumor as assessed with image guidance. After dural incision, tumor location and the adjacent anatomical structures (areas) were identified by comparing visual and navigation data. After a short mapping procedure (on average 7 (3–12) areas were stimulated intraoperatively), continuous intraoperative speech and motor function monitoring was performed during tumor resection.

Results: No intraoperative seizures or complications were observed. Mean operating time was 3 hours (1.5–6 hours). Only one patient was not compliant during the procedure. Postoperative bleeding complications requiring revision were observed in 3 patients, who all recovered to their preoperative functional level. Two patients with no preoperative deficit had mild postoperative dysphasia which resolved within 3 months. Four patients who presented with mild motor aphasia preoperatively had severe aphasia postoperatively, which resolved to the preoperative level in 2 patients. Only one patient with normal language function preoperatively suffered from mild permanent aphasia. One patient showed right arm and hand paresis postoperatively. No other new postoperative focal neurological deficits and no other complications occurred. Overall permanent morbidity observed >3 months postoperatively was 12%. The extent of tumor resection as determined on early-postoperative MRI was 100% in 11 patients (44%), >80% in 11 (44%) and 50–80% in 3 patients (12%). Histological examination revealed 2 WHO °I Tumors, 9 °II, 7 °III, 5 °IV and 2 secondary °IV lesions.

Conclusions: In our experience, awake craniotomy for surgical treatment of gliomas located in eloquent areas can safely and efficiently be performed using much smaller craniotomies without the need to expose large areas of eloquent cortex for direct cortical stimulation mapping.