For a study, glioma resection in the non-dominant hemisphere, including motor centers and pathways, necessitates brain-mapping techniques to spare vital motor control sites. When suited to the therapeutic environment, there were no obvious recommendations for doing motor mapping when awake or asleep or for the optimum mapping paradigm (e.g., resting or active, high-frequency [HF] or low-frequency [LF] stimulation) that gives the best oncological and functional outcomes. This study discovered clinical, and imaging characteristics that influenced surgical approach (asleep vs. awake motor mapping) and were linked to the best functional and oncological outcomes and developed a “motor mapping score” for guiding tumor resection in this area. The researchers looked at a group of patients who had nondominant-hemisphere gliomas that were located or infiltrating within 2 cm anteriorly or posteriorly to the central sulcus, affecting the primary motor cortex, its fibers, and the praxis network, and who had motor mapping was done while asleep (HF monopolar probe) or awake (LF and HF probes). A motor mapping score was created using clinical and imaging factors. This motor mapping score was validated using a prospective group of patients.

A total of 136 patients were studied retrospectively: 69 had surgeries with sleeping (HF stimulation) motor mapping, and 66 had operations with awake (LF and HF stimulation and praxis task evaluation) motor mapping. The mapping score was designed using previous motor (strength) deficits, previous treatment (surgery/radiotherapy), tumor volume > 30 cm3, and tumor involvement with the praxis network (on MRI). Large tumor volume and participation of the praxis network support awake motor mapping; motor deficiency, current therapy, and position within or adjacent to the central sulcus favor asleep motor mapping. The motor mapping score was validated by researchers in a prospective series of 52 patients with a low rate of postoperative motor-praxis deficit (3%) and a great extent of resection (median 97%; complete resection in > 70% of patients) who underwent operations with awake motor mapping and 17 with asleep motor mapping based on the score indications. Extensive excision of tumors, including the eloquent areas for motor control, was possible, and the incidence of postoperative motor-praxis loss is low when an adequate mapping method is used. For lesions near to or involving the central sulcus and in patients with a preoperative strength loss and a history of previous therapy, sleep (HF stimulation) motor mapping is preferred. Awake mapping is preferred when a patient has no motor deficits or previous therapy and a lesion (> 30 cm3) impacting the praxis network.

 

Reference:thejns.org/view/journals/j-neurosurg/136/1/article-p16.xml