Ischemic cerebral infarction with hemorrhagic transformation: peculiarities of perifocal tissue changes depending on the disease phase and background and concomitant pathology

Background. Hemorrhagic transformation of brain tissue with necrosis is a common complication of ischemic stroke. There are numerous discrepancies in the literature regarding the clinical classification and imaging criteria of such strokes, which undoubtedly complicates the diagnosis. A crucial aspect in the progression of ischemic stroke with hemorrhagic transformation (IS with HT) is the presence of comorbidities and background diseases such as hypertension and diabetes mellitus that affect the integrity of the neurovascular unit and the blood-brain barrier. The purpose was to study the features of pathomorphological changes in the perifocal zone of brain tissue at different phases after the onset of IS with HT in patients with background and comorbid conditions. Materials and methods. The medical histories, clinical data, comorbidities and background diseases, and autopsy material of 18 patients aged 35–82 years with IS with HT were analyzed. The material was grouped according to the classification of stages of cerebral infarction (Mena H. et al.) into three phases: 1 — acute neuronal injury (1–3 days); 2 — acute organization (4–7 days); 3 — chronic organization (> 7 days). For histological examination, brain tissue samples (1.5 × 1.5 cm) adjacent to the infarction zone were taken. They were prepared using standard methods, and the sections were stained with hematoxylin and eosin. Statistical ana­lysis of the results was performed using Statistica for Windows 6.0 software (StatSoft, USA). Results. The study of patients with IS with HT revealed the presence of both isolated and combined acute neuronal damage. In addition to acute neuronal changes, a significant number of cases showed neurons with chronic chan­ges, corpora amylacea, and areas with neuron loss (a statistically significant difference for areas with neuron loss between phase 1 and phase 2 and between phase 1 and phase 3: p1–2 < 0.05 and p1–3 < 0.05), indicating severe disturbances of cerebral blood supply. Early reactive astrogliosis and neoangiogenesis were observed in phase 1 of IS with HT, with an increase in the frequency of these signs in phases 2 and 3 of the disease (p1–2 < 0.05 and p1–3 < 0.05 for astrogliosis and p1–3 < 0.05 for angiogenesis). It was found that as a result of ischemia/reperfusion in the perifocal brain tissue, reactive inflammation developed, with a predominance of neutrophils over other elements in phase 1 (p1–3 < 0.05) and the presence of lymphocytes and macrophages throughout all phases of IS with HT. Acute damage to microcirculatory vessels in the form of transmural fibrinoid necrosis of the vessel wall was observed in some cases, while in most cases, changes were in the form of sclerosis and hyalinosis. Conclusions. The rapid fatal outcome of IS with HT in patients was influenced by the combination of hypertension and diabetes mellitus. The features of the microcirculatory system indicated comorbid conditions in the form of necrosis, arteriosclerosis, arteriolar hyalinosis. In most cases, during the acute phase of the disease, coagulative and liquefactive necrosis of neurons was observed in the perifocal zone, and despite the severity of the disease, healing processes were present.