Motor mapping-guided resection of a brainstem recurrent pilocytic astrocytoma.

Brainstem tumors are bounded by a compact topography of eloquent tracts, cranial nerves, and nuclei. Reliable intraoperative neuromonitoring aids microneurosurgical technique to optimize safe resection. The authors present a case of motor mapping-guided resection of a recurrent brainstem pilocytic astrocytoma. They demonstrate reliable and continuous responses from the corticospinal tract at the level of the midbrain to the pons with dynamic subcortical motor mapping using a monopolar stimulating suction. Contralateral limb and ipsilateral face muscles can be simultaneously detected and tumor resected until a threshold of less than 1 mA, corresponding to 1 mm or less from the corticospinal tracts. The video can be found here: https://stream.cadmore.media/r10.3171/2024.10.FOCVID24110.