Spinal cord astrocytomas: presentation, management and outcome.

Abstract

Intramedullary spinal cord astrocytomas are uncommon tumors. They are the most common spinal cord tumor in children and in adults are second only to ependymomas in frequency of occurrence. Low-grade histology predominates with high-grade lesions comprising only ten to fifteen percent of pediatric tumors and a slightly higher proportion in adults. Presenting symptoms typically evolve over months to years with regional back pain the most commonly reported initial complaint. Malignant tumors produce rapid neurological deterioration. MRI is the diagnostic modality of choice: spinal cord astrocytomas are iso- to slightly hypointense on T1, hyperintense on T2 and commonly have associated cysts. They enhance less intensely and are more eccentric than ependymomas. The goals of surgical intervention are to obtain a tissue diagnosis and resect as much tumor as possible without adversely affecting neurological function. Astrocytomas are infiltrating neoplasms and total resection is not generally possible. Somatosensory and motor evoked potential monitoring are routinely used but it is unclear if they improve outcomes. The operating microscope and bipolar cautery are essential surgical tools; the ultrasound and ultrasonic surgical aspirator are useful surgical adjuncts. Laminectomy is performed on adults while laminoplasty is favored for pediatric patients. Outcome for low-grade astrocytomas is less favorable than that of ependymomas with regard to both recurrence and function though many have prolonged survival. There is no correlation of extent of resection and recurrence. Outcome for high-grade tumors is extremely poor; tumor progression is relentless; median survival is thirteen months in children and six months in adults.