Editor in Chief
IMSCTs are rare tumors in children, accounting for 4% of the tumors arising in their nervous systems. They typically are benign and produce an extremely slow, insidious evolution of symptoms that depend on the location of the tumor. It is not uncommon for families to recognize the duration of symptoms only after the tumor has been discovered and they are asked to reflect upon aspects of their child’s motor development. The time span of this evolution is months to years. Untreated, IMSCTs will cause a steady but slow loss in motor function below the level of the tumor, and pain will become an important feature. Loss of sensation only develops late, and deterioration in bowel and bladder function is rare unless the tumor is in the conus of the spinal cord.
Astrocytomas account for 40% of IMSCTs and gangliogliomas 35%. Ependymomas account for only 10-15% of IMSCTs in children and the remanding 5-10% are hemangioblastomas and other unusual primary tumors of the CNS. Astrocytomas and gangliogliomas are eccentrically located in the spinal cord while ependymomas are central and symmetric in location, a distinction that allows for their reliable differentiation on MRI. Astrocytomas are smaller than gangliogliomas, spanning on average 4 spinal segments while the length of gangliogliomas is, on average, 8 spinal segments. Hemangioblastomas are vividly enhancing on MRI when small and heterogeneous when bigger with 50% having cysts.
The preferred treatment of IMSCTs in children is surgical resection with a 80+% resection resulting in a 70% 5-year event-free survival. This event-free survival associated with surgical resection equals that seen in children whose IMSCT has been treated with radiation, but the surgical group avoids the ill effects of radiation on the growing skeletal system. The safety of surgical resection has been improved significantly with the introduction of intra-operative neurophysiological monitoring of the nervous system’s motor pathways and, in particular, the D-waves potentials of the upper motor neurons passing through the area of the tumor. Currently, the overall rate of post-operative complications is 8.9% and these complications are much more common in individuals with advanced debilitation from the tumor as opposed to the rate of complications seen in patients with minimal neurological deficits created by the tumor.
- Timing of surgery: Treatment is better tolerated when a patient is minimally affected functionally.
- Amount of resection: Radical resection is better tolerated than a biopsy.
- Management of recurrence: The risks of reoperation for tumor recurrence or progression are the same as those of a first time operation and occur with a similar frequency.