With the goal to minimize the risk of sequelae in brainstem and spinal cord surgery, methods of intraoperative mapping using direct electrical stimulations were developed in the last decade. However, the current was delivered with a monopolar stimulator with risk of a spreading, or using a bipolar probe or silicone strip with 5 mm of precision. To improve the accuracy and easiness of the mapping, the authors describe in this work a new device with the following characteristics: bipolar probe without current diffusion; reduction of the space tips to 2 mm; building of a bent handle, improving the field of view and ergonomics under the microscope. This device has been used successfully in 6 consecutive patients, 4 harboring a brainstem lesion and 2 with a spinal cord tumor. This new device allows the surgeon to perform repetitive intraoperative brainstem and spinal cord electrical mapping under the microscope in a very simple, quick and accurate way all along the resection. Improvement of such a mapping first minimizes the risk of sequelae, second optimizes the quality of resection, and third may also give a prognostic value concerning the changes of postsurgical recovery in case of a preoperative deficit.