The Operation for Cervicomedullary Gliomas in Children
Midline craniotomy: A midline suboccipital craniotomy and laminotomy is performed as needed to provide adequate exposure to the solid component of the tumor as determined by preoperative MRI, particularly with cervical extension of the mass. Extension of the suboccipital craniotomy to remove the dorsal lateral rim of the foramen magnum can aid in exposure of a bulging medulla.
Laminotomies as needed: Laminotomies of the cervical vertebrae should be kept to a minimum to reduce the chance of the subsequent development of progressive deformity.
Ultrasound can be useful: The adequacy of the exposure and localization of the tumor can be confirmed with intraoperative ultrasound before the dura is opened.
Confirm anatomy and locate arteries before entry into CNS: The medulla is often displaced rostrally, and the posterior inferior cerebellar arteries are also likely to be displaced by the tumor. Consequently, the surgical field should be studied to appreciate the location of critical structures before entry into the brainstem and/or spinal cord so as to avoid injury to important fiber tracts, nuclei, and arterial vessels.
Look for subpial tumor that can serve as entry point: Cervicomedullary tumors often have a component around the region of the obex that will be practically subpial. This should serve as an entry point to begin the resection.
Myelotomy technique: The contact laser can be used to perform the initial myelotomy and access the tumor. Alternatively, a sharp myelotomy in the midline covering the extent of the tumor may be used.
Biopsy early to determine grade of tumor: Specimens should be sent early for analysis by frozen section. Identification of a high-grade lesion is an indication to halt the surgery, as there is no proven long-term benefit to debulking of aggressive lesions.
Resection from center to periphery: Surgical resection should begin with internal debulking utilizing the ultrasonic aspirator or suction-aspiration.
Special technique for resection at periphery: Towards the perceived margins of the tumor, the contact laser may be helpful in resection. Further mapping of the walls of the resection bed can be useful to determine tumor margins.
Avoid cautery: Use of electrocautery should be avoided as the surgeon reaches the tumor margins to avoid potential injury to functional tissue.
Primary closure of dura: Primary closure of the dura in a water-tight fashion is preferred. Grafting with a dural substitute can be performed as needed.
Replace bone when possible: If possible, the bone from the craniotomy and laminotomies should be replaced using plating or sutures.
Fascial closure important: Fascial closure should be water-tight as this is the layer that prevents CSF leakage.
Drains: Surgical drains are typically not placed postoperatively unless there is concern for inadequate hemostasis during closure.