Susceptibility-weighted Imaging Research On The Perivascular And Perineural Hematomal Extension In Intracerebral Hemorrhage

Background:Some animal experiments have shown that "perivascular and perineural extension" was found in the tissues surrounding the hematoma in cerebral hemorrhage,which was very similar to the" piping phenomenon" on dam.As we know,"piping" is the common risk of water conservancy,in the case of high water level in flood season,the water flows downstream along the river bank soil driven by the water pressure and further resulting in seepage.As far as cerebral hemorrhage patients are concerned,perivascular and perineural extension is phenomenon that hematoma leaks into surrounding tissues through the Virchow-Robin spaces(VRS)and the spaces around the nerve fibers(perineurium).However,the mechanism underlying the phenomenon is still not fully understood,possibly due to the distant effect of hematoma,lymphostatic cerebral edema,hematoma absorption,secondary subarachnoid hemorrhage and secondary intraventricular hemorrhage.Magnetic susceptibility-weighted imaging(SWI)is considered as highly sensitive to micro hemorrhage in the brain,therefore,it is better suitable for clinical study on "perivascular and perineural extension" in the patients with cerebral hemorrhage and further understanding hematoma distribution in these brains.Objective:To investigate imaging characteristics of "perivascular and perineural extension" in cerebral hematoma in the of patients with cerebral hemorrhage,and provide basic evidence for clinical diagnosis and treatment.Methods:41 hospitalized patients with cerebral hemorrhage were enrolled in this study.They were recruited from Guangdong Second Provincial General Hospital between January 2014 and May 2017.After admission,besides detection of regular parameters,head CT scan was immediately performed,following with SWI scan in order to observe the distribution of "perivascular and perineural extension" in the different brain section.In some patients,cranial magnetic resonances were re-performed in 90 days after the onset,mainly observing the changes of SWI sequence,cerebral hematoma,brain tissues and vein structures.Through analysis of the imaging changes,interruption of vein on hemorrhagic foci was ruled out in the initial SWI detection and the distribution of "perivascular and perineural extension"in the brain tissue was characterized.Results:1.It was observed that blood disseminated into adjacent tissues after the formation of cerebral hematoma,due to the space occupying effect with the higher pressure than surrounding tissues.Low intensity signaling with scattered radiation and spot-like distribution was found around the hematoma.In 2-3 days after the onset,edema zone was presented clearly in the surrounding tissues in SWI sequences,but gradually subsided.In most cases,the hematoma and the low intensity signaling in its surrounding tissues were progressively absorbed and disappeared.As a control,no abnormality was found in SWI sequence in health volunteer.2.In all 41 cases was seen the bleeding "perivascular and perineural extension" in SWI,which mainly distributed along VRS or nerve fiber surrounding spaces."perivascular and perineural extension" with Finger-like distribution among nerve fibers was mostly found in basal ganglia,thalamus.Irregular hematoma in basal ganglia in 4 cases,insula lobe in 3 cases was found surrounded by finger-like distributing "perivascular and perineural extension".3.Repeated SWI scan in 90 days after onset in some patients showed that most "perivascular and perineural extension" has been disappeared or only a few scattered residues existed.4 cases with bigger hematoma had significant edema around the hematoma in the early phase,and distribution of"perivascular and perineural extension" was more extensive and exited in 90 d re-check with low intensity signaling in all hematomas,but the volume was obviously reduced,considering due to deposit of hemosiderin.4.The range of low intensity signaling in hematoma in SWI sequence in 90 d re-check had increased only in 1 case,with broadern peripheral vessel,possibly resulting from hematoma contents were deposited in peripheral cerebral tissues in the process of the VRS absorption.Conclusions:1."Perivascular and perineural extension" widely exists in the surrounding tissues of hematoma in the patients with cerebral hemorrhage,mainly distributing along the space among VRS or nerve fibers.In most patients,hematoma and its surrounding tissues foci are absorbed and diminished gradually.2."perivascular and perineural extension" is the main way for absorption of hematoma.3.SWI is highly sensitive to intracranial micro hemorrhage,and clearly displays the distribution of "perivascular and perineural extension" in cerebral hemorrhage.