Introduction: Resection or even biopsy of an intra-axial mass lesion in close relationship to eloquent cortex carries a major risk of neurological deficit. We review the safety and effectiveness of craniotomy under local anaesthesia and monitored conscious sedation for resection of mass lesions involving eloquent cortex. Materials and Methods: We performed a 3-year retrospective review of patients who underwent awake craniotomy under local anaesthesia at the National Neuroscience Institute, Singapore. All patients had tumours in close proximity to eloquent cortex, including speech areas in the dominant hemisphere as well as primary sensory and motor cortex in either hemisphere. Brain mapping was performed by direct cortical stimulation using the Ojemann stimulator to identify a safe corridor for surgical approach to the tumour. Intraoperative physiological monitoring was carried out by assesment of speech, motor and sensory functions during the process of surgical resection. All resections were evaluated and verified by postoperative imaging and reviewed by an independent assessor. Postoperative complications and neurological deficits, as well as extent of tumour resection, were evaluated. Results: A total of 20 patients underwent stereotactic resection over a period of 3 years from July 2003 to August 2006. There were 7 male patients and 13 female patients, with a mean age of 39.8 years. The average length of stay was 5.5 days. There were no major anaesthetic complications and no perioperative deaths. Postoperative neurological deficits were seen in 6 patients (30%) and this was permanent in only 1 patient (5%). The degree of cytoreduction achieved was greater than 90% in 58% of patients and a further 21% had greater than 80% cytoreduction. Conclusion: Tumour surgery with conscious sedation in combination with frameless computer stereotactic guidance is a safe technique that allows maximal resection of lesions in close relationship to eloquent cortex and has a low risk of neurological deficit.
The aims of surgical management in the resection of brain tumours are to obtain an accurate histological diagnosis, achieve maximal resection with minimal morbidity, relieve intracranial hypertension and improve neurological symptoms. Mass lesions in close proximity to eloquent cortex represent a significant surgical challenge and the surgeon has to balance the theoretical benefits of an aggressive resection with the anticipated postoperative neurologic morbidity. Preoperative MRI imaging with contrast and functional MRIs, together with intraoperative computerised stereotactic guidance, are commonly used to aid in maximal resection of tumours without encroaching into eloquent brain tissue. However, in tumours within or adjacent to eloquent brain, anatomical localisation alone is insufficient. Precise localisation of areas responsible for critical neurological functions are necessary to avoid postoperative neurological deficits.
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