The current state of the art of primary motor mapping for tumor resection: A focused survey

Introduction: Cortical and subcortical motor mapping has advanced the notion of maximal safe resection of intra-axial brain tumours, thereby preserving neurological functions as well as improving survival. Despite being an age-old and established neurosurgical procedure across the world, the strategy and techniques involved in motor mapping have a gamut of variation due to a lack of defined standard protocols.Methods: We disseminated a structured survey among focused group of neurosurgeons with established practices involving brain mapping. It consisted of 40 questions, split into five sections assessing the practice description, general approach for motor mapping, preference for asleep versus awake mapping, operative techniques and approach to representative tumor cases. Practice-patterns during primary motor mapping for brain tumours were analysed from responses of 51 neurosurgeons.Results: 60.8 % felt that any lesion even near (without infiltration) was suffice to define involvement of the cortical/subcortical motor pathways. 82.4 % felt that motor mapping was necessary for brain tumours involving motor pathways, irrespective of the tumor histology or patient age. 90.2 % opined that tumor location was the predominant factor affecting their choice between awake or asleep mapping. 31.4 % believed that all cases should be performed awake unless patient-related medical, psychological, or anaesthetic contraindications exist, whereas 45.1 % felt that all cases should be performed asleep unless language mapping is required. MRI, DTI -based tractography and intra-operative fluorescence were the most commonly employed surgical adjuncts.Conclusions: The data from this survey may serve as a preliminary foundation for a more standardized approach to patient selection and the approach to motor mapping for brain tumors.

Automated summary

Cortical and subcortical motor mapping has become an important technique for maximal safe resection of intra-axial brain tumors. However, there is a lack of standardized protocols for motor mapping due to variation in strategies and techniques. In this survey of 51 neurosurgeons, preliminary data was obtained on patient selection and the approach to motor mapping for brain tumors.