NATURAL-HISTORY OF THE SPONTANEOUS REPERFUSION OF HUMAN CEREBRAL INFARCTS AS ASSESSED BY TC-99M HMPAO SPECT

Objective-Little is known about the effect of spontaneous reperfusion of human cerebral infarcts. Single photon emission computerised tomogr aphy (SPECT) data were analysed from a study using Tc-99(m) HMPAO (Tc- 99(m) hexamethylpropyleneamine oxime) in human cerebral infarction for the frequency of reperfusion and to see if it affected infarct size, oedema, haemorrhagic transformation, or functional outcome. Methods-Fi fty sequential cases of ischaemic stroke were studied with 124 Tc-99(m ) HMPAO SPECT at around one day, one week, and three months after stro ke along with detailed clinical and functional assessments. Results-Vi sually apparent reperfusion occurred in 14 of 50 patients (28%) with a mean delay of 5.8 days and reperfusion was seen in seven others in wh om it was identified on the basis of changes in perfusion deficit volu me. It occurred in 13 of 23 embolic events but only in three of 23 oth er events. In only two cases did spontaneous reperfusion occur early e nough to preserve tissue or function. Reperfusion did not otherwise re duce infarct size, or improve clinical or functional outcome, and was not associated with oedema but an association with haemorrhagic transf ormation was suggested. Reperfusion significantly decreased the appare nt perfusion defect as measured by SPECT one week from the ictus, but was mostly non-nutritional and transient. The mean volume of tissue pr eserved by nutritional reperfusion was 10 cm(3), but this was unequall y distributed between cases. Late washout of Tc-99(m) HMPAO from areas of hyperaemic reperfusion may be a good prognostic marker but is a ra re phenomenon and too insensitive to be of general applicability. Conc lusions-Spontaneous reperfusion after cerebral infarction occurs in 42 % of cases within the first week but is associated with clinical impro vement in only 2%. It has few adverse consequences although it may be associated with haemorrhagic transformation.