Effects of brain oedema in the measurement of ischaemic brain damage in focal cerebral infarction.

Abstract

In a model of focal cerebral ischaemia, enlargement of ischaemic tissue by ischaemic brain oedema is one of the major problems in the measurement of infarction volume. To minimize an error of this overestimation, several methods have been proposed. However, there has been no attempt to compare these methods to elucidate their eligibility in the measurement of ischaemic area. The authors used three different morphometric analyses in the measurement of infarction volume to assess the antiischaemic affects of a competitive NMDA antagonist, D-CPPene in MCA occlusion model of the rat: a direct measurement, the Swanson's method, and a measurement using a diagram. Post-occlusion treatment of D-CPPene (4.5 mg/kg, i.v. +3 mg/kg/h, i.v.) produced reduction of infarction volume to about 40% compared to the control (P < 0.05). The volume of infarction determined by the direct measurement was much larger than that by Swanson's or diagram method (P < 0.05), about 70% larger in the control and by two times in the treated. However, there was no significant difference in the measured volume between the Swanson's and diagram methods. The protection rate, which was calculated as % = (infarct volume of the control--that of the treated/infarct volume of the control) x 100%, was larger in the Swanson's and diagram methods than in the direct measurement. In conclusion, it is confirmed that the direct measurement at the peak time of ischaemic brain oedema brings about not only an overestimation of infarction volume but lower protection rate also, compared to the methods designed to minimize the overestimation. Our results also demonstrate the diagram method is useful in reducing overestimation of infarct volume that may be caused by ischaemic brain oedema, though this method was not designed for the purpose of avoiding oedema at first.