<I>Cerebral Microthrombosis in Symptomatic Cerebral Vasospasm</I>

Abstract

A comparative investigation of the pathogenetic factor in symptomatic cerebral vasospasm was made by quantitative histological and clinical studies in four patients who died immediately of sympto matic cerebral vasospasm (Cases 1-4) and in two who died without fatal cerebral vasospasm (Cases 5 and 6). Histological examination of the brain from Cases 1 and 2 found many white and fibrin microthrombi together with ischemic and infarctic changes in the territories of spastic arteries, which corresponded to the low-density areas (LDAs) observed on computed tomographic (CT) scans and the typical neurological symptoms. In Case 3, who had suffered severe vasospasms in bilateral ante rior cerebral and middle cerebral arteries, bilateral LDAs were observed on CT scans and multiple fibrin thrombi were seen diffusely throughout the brain. In Case 4, extensive bilateral LDAs (It > rt) were observed on CT scans, and multiple microthrombi were seen diffusely but predominantly in the left cerebral hemisphere. Only in Case 3 the possible complication of disseminated intravascular coagulation could not be ruled out. Only negligible thrombi were observed in Cases 5 and 6, whose immediate cause of death was considered to be acute hydrocephalus and aneurysmal rerupture, re spectively. Distributions of microthrombi were significantly greater in the regions clinically identified to have been ischemic or infarctic.

The Role of Arterioles and the Microcirculation in the Development of Vasospasm after Aneurysmal SAH

“…Compared to the latter two patients, the other four patients showed significantly more microthrombi of intraparenchymal small vessels in clinically ischemic regions and in areas showing cerebral infarction on CT scan. They concluded that the significant regional correlation of thrombi distribution and DCI suggests a close relationship between them [46]. This is supported by a recent autopsy study investigating 29 SAH patients by Stein et al They revealed a strong correlation between microclot burden and DCI, as patients with clinical or radiological evidence of DCI had, in the mean, significantly more microclot burdens than patients without DCI.…”

“…Patients with DCI have significantly more microthrombi in areas showing cerebral infarction than those patients who die from aneurysmal rebleed or hydrocephalus [46]. Microthrombosis also correlated with the amount of overlying free subarachnoid blood and clinical and pathological signs of ischemia [47].…”

Role of platelet function in symptomatic cerebral vasospasm following aneurysmal subarachnoid hemorrhage.

“…Internal jugular venous blood showed elevated platelet aggrega- Qinical grade according to World Federation of Neurological Surgeons scale. 13 M, male, F, female; ACoA, anterior communicating artery; ICA, internal carotid artery; ACA, anterior cerebral artery, MCA, middle cerebral artery; BA, basilar artery. bility in seven of the 13 cases on admission, but aggregability recovered to the normal range by day 4 in five of the seven.…”

“…- 13 The markedly high concentrations of /3-TG obtained in patients with unimproved ischemic symptoms suggest that thrombus formation affects the severity of ischemic symptoms and the prognosis after vasospasm. Recently, antiplatelet agents, such as a thromboxane synthetase inhibitor 19 or ticlopidine, 27 have been reported to be useful for cerebral ischemic symptoms accompanied by cerebral vasospasm.…”

To Look Beyond Vasospasm in Aneurysmal Subarachnoid Haemorrhage

“…Some authors claim that many factors determine whether infarction develops after vasospasm confirmed angiographically, including the duration and severity of ischemia, the presence and length of stenosis, and the presence of collateral pathways [151]. In some cases, however, infarction occurs immediately after SAH without detectable vasospasm in the territorial artery [152] and other effects such as microthrombus formation or spasm and dysfunction in the microcirculation may make a significant contribution [153]. …”