Detection of experimental and clinical brain edema using an electrical impedance method

Abstract

✓ To clarify the development of brain edema, the electrical impedance of white matter was measured with intracerebral implanted electrodes in cold-induced edema in the cat and in cases of edema after major intracranial surgery. Impedance measurements were made at 50 kc using a tetrapolar electrode method with a pair of concentric platinum electrodes. The impedance of the brain gradually decreased 25% after several hours of cold application. The amount of increase of sulfate space of brain showed a good correlation with decrease of impedance. In four postoperative cases of brain tumor, a 7.5% to 25% decrease of impedance was observed within several hours of surgery. A severe case of brain edema, in which the prognosis was poor, showed marked intracranial pressure and 25% decrease of impedance.