Microsurgery of tumours of the frontal white matter

High-resolution 1H NMR spectroscopy studies of extracts of human cerebral neoplasms

High-resolution 1H NMR spectroscopy has been used to measure the concentrations of metabolites (alanine, N-acetylaspartate, gamma-aminobutyric acid, glutamate, glutamine, aspartate, taurine, glycine, succinate, creatine, cholines, inositol, and glucose) in perchloric acid extracts of human epileptic cortex and brain tumors. All tissue was obtained by surgical biopsy, excised before thermal coagulation, and immediately frozen in liquid nitrogen. Lower levels of N-acetylaspartate and gamma-aminobutyric acid and a shift in the glutamate/glutamine ratio toward glutamine in the tumors reflect neuronal loss. Abnormal glucose metabolism (aerobic glycolysis) in the tumors gives decreased levels of succinate, glutamate, aspartate, glutamine, and creatine and generally increased concentrations of glycine and alanine. Differences in metabolite concentrations that may be of use in differential tumor diagnosis include lower creatine and inositol in meningiomas than in astrocytomas. Lower taurine differentiates benign from malignant astrocytomas. Malignant astrocytomas and metastatic tumors are more regionally heterogeneous than meningiomas or benign astrocytomas. Mannitol, administered perioperatively to all patients from whom tissue was obtained, was observed only in the spectra of extracts of tissue from tumors which enhanced on computerized tomographic imaging.

Value of serial stereotactic biopsies and impedance monitoring in the treatment of deep brain tumours

Thirty-five patients with deep brain tumours have been submitted to transtumoral stereotactic impedance monitoring and serial biopsy. The direct examination of the biopsy samples confirmed the presumptive clinical and neuroradiological diagnosis in 25 patients, but in 10 patients the histological diagnosis differed from the presumptive one. In this second group the treatment was changed as a result of the histological findings. Stereotactic biopsy avoided the risks of "blind" management. The technique, the indications and the diagnostic advantages of stereotactic biopsy are reported with two illustrative cases.