Neurosurgical management of adult diffuse low grade gliomas in Canada: a multi-center survey

Adult diffuse low-grade gliomas are slow growing, World Health Organization grade II lesions with insidious onset and ultimate anaplastic transformation. The timing of surgery remains controversial with polarized practices continuing to govern patient management. As a result, the management of these patients is variable. The goal of this questionnaire was to evaluate practice patterns in Canada. An online invitation for a questionnaire including diagnostic, preoperative, perioperative, and postoperative parameters and three cases with magnetic resonance imaging data with questions to various treatment options in these patients was sent to practicing neurosurgeons and trainees. Survey was sent to 356 email addresses with 87 (24.7%) responses collected. The range of years of practice was less than 10 years 36% (n = 23), 11-20 years 28% (n = 18), over 21 years 37% (n = 24). Twenty-two neurosurgery students of various years of training completed the survey. 94% (n = 47) of surgeons and trainees (n = 20) believe that we do not know the "right treatment". 90% of surgeons do not obtain formal preoperative neurocognitive assessments. 21% (n = 13) of surgeons and 23% of trainees (n = 5) perform a biopsy upon first presentation. A gross total resection was believed to increase progression free survival (surgeons: 75%, n = 46; trainees: 95%, n = 21) and to increase overall survival (surgeons: 64%, n = 39, trainees: 68%, n = 15). Intraoperative MRI was only used by 8% of surgeons. Awake craniotomy was the procedure of choice for eloquent tumors by 80% (n = 48) of surgeons and 100% of trainees. Of those surgeons who perform awake craniotomy 93% perform cortical stimulation and 38% performed subcortical stimulation. Using the aid of three hypothetical cases with progressive complexities in tumor eloquence there was a trend for younger surgeons to operate earlier, and use awake craniotomy to obtain greater extent of resection with the aid of cortical stimulation when compared to senior surgeons who still more often preferred a "wait-and-see" approach. Despite the limitations of an online survey study, it has offered insights into the variability in surgeon practice patterns in Canada and the need for a consensus on the workup and surgical management of this disease.