RecruitingDevice studyTumor Treating Fields for the Treatment of Brainstem GliomasThis clinical trial tests the safety and side effects of tumor treating fields in treating patients with gliomas located in the brainstem. Optune is a wearable, portable, treatment that creates low-intensity, wave-like electric fields called tumor treating fields (TTFields), which interfere with cancer cell division. TTFields may prevent growth or decrease size of gliomas in patients