Brain dysfunction following 'awake' craniotomy, brain mapping and resection of glioma

The rationale for 'awake' resective brain tumour surgery and brain mapping is that the amount of tumour removed is optimized, and risks of damage to adjacent eloquent brain minimized by intraoperative patient assessments. Both goals are generally attained, but occasionally patients may have iatrogenic postoperative deficits. Five such cases (20%) are described from a consecutive series of 25 awake craniotomies. These patient fell into three distinct clinical categories; those (n = 2) who developed sensory-motor deficits that were recognized intraoperatively; those (n = 2) who had deficits that were apparent only on postoperative testing; and one patient who developed a sudden deficit with no warning. The former four patients had deficits that recovered within weeks to months (16%), but the latter one (4%) was left with a severe focal motor disability. These cases highlight both the benefits and limitations of awake craniotomy and intraoperative assessment. Although sensory-motor deficits can be recognized early, some high-level neurological functions may not be readily assessed intraoperatively and vascular catastrophes may occur without warning. The pathophysiological basis of these iatrogenic neurological deficits, and techniques to minimize such problems are discussed.