171 patients with intramedullary spinal cord tumors were operated on, of which 25 patients (15%), mostly children, developed symptomatic hydrocephalus. Twenty patients (12%) had malignant tumors, with 13 of the 20 cases (63%) complicated by increased intracranial pressure and ventriculomegaly. Of the remaining 151 patients with benign tumors (89%), only 12 (8%) developed symptomatic hydrocephalus. In an effort to understand the relationship between hydrocephalus and intramedullary spinal cord tumor, the authors analyze the level and histology of the neoplasm, as well as its association with spinal cysts. A review of the neurosurgical literature reveals that 34 similar cases of hydrocephalus associated with intramedullary spinal cord tumors have been reported to date. The authors note that the presence of hydrocephalus in patients with malignant intramedullary astrocytomas is associated with a shorter rate of survival than in those patients with high-grade lesions but without hydrocephalus, apparently due to rapid tumor progression. The ventriculomegaly seen with benign spinal cord gliomas has no statistically significant effect upon longterm prognosis.

Trephination is the oldest known surgical technique. Peru has been recognized as a major source of ancient trephined skulls, many of which date back 2300 years. This presentation reviews from a neurosurgical perspective many of the archaeological studies performed on these skulls. Comparative osteology has shown that almost 70% of patients survived the procedure. The various instruments, hemostatic agents, anesthetics, surgical techniques, and cranioplasties used are reconstructed from the anthropological literature. The possible reasons for the use of trephination are discussed. Analysis of the data leads to the conclusion that, despite their rudimentary knowledge of disease, the ancient Incas must have had some knowledge of anatomy and proper surgical procedure.

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