Spontaneous Convexity Subarachnoid Hemorrhage:Clinical And Radiological Features,Etiologies,and Outcome

Backgroud:Convexity subarachnoid hemorrhage is a rare subtype of nonaneurysmal subarachnoid bleeding with diverse etiologies.It is characterized by haemorrhage localized to one or a few cortical sulci at the convexity of the brain without spread into the sylvian fissure,the interhemispheric fissure,the basal cisterns or the ventricles.It shares many clinical features and neuroradiological characteristics that differ from those of classical aneurysmal SAH.Several diseases have been described as the potential causes of spontaneous cSAH,such as dural/cortical venous thrombosis(CVT),cerebral amyloid angiopathy(CAA),stenosis or occlusion in the internal carotid artery system,moyamoya disease and syndrome,vasculitides,reversible cerebral vasoconstriction syndrome(RCVS),posterior reversible encephalopathy syndrome(PRES),infective endocarditis,cavernoma,arterial dissection,vascular malformations,and so on.Objective:This study was to describe the clinical presentations,radiological features and outcome and discuss the etiologies of cSAH,thus to improve the understanding of cSAH.Metheds:This study collected 1459 SAH patients who were admitted in Qilu hospital of Shandong University during 2013.03-2017.10.Aneurysms are not found in 152 patients,including 25 cSAH patients.We retrospectively analyzed the demographics,medical history,clinical manifestations,imaging patterns,outcome and etiologies of the 25 cSAH patients.Result:1.General features:Among 25 cSAH patients,14(56%)were male while 11(44.0%)were females.Patients ranged from 17 to 82 years old,the median age was 60 years old.12(48.0%)patients were younger than 60 years old,while 13(52.0%)patients were>60 years.6 patients(24.0%)were taking antithrombotics,including 5 patients taking antiplatelets and 1 patient taking anticoagulant due to thrombus of lower extremity veins.A 44-year-old woman took oral contraceptives due to endometriosis.2 women endured delivery within 1 month.2.Clinical presentation:The commonest symptom was headache(n=13,52.0%),following by transient focal neurological symptoms(TFNS)(n=12,48.0%).Headache(9/12)was the commonest symptom among those<60 years old,while TNFS(8/13)was the commonest symptom among those>60 years old.Other symptoms included persistent ischemic symptoms(n=6,24.0%),seizures(n=2,8.0%),dizziness(n=8,32.0%),confusion(n=2,8.0%),nausea/emesis(n=7,28%).There were 6(24.0%)cases presenting nuchal rigidity in this study.Sports,tired and shitting may induce cSAH.3.Serologic test:Blood sample analysis showed thrombocytopenia in 1 patient(PLT 4×109/L),high blood sugar in 4 patients,hyperlipidemia in 8 patients,hyperhomocysteinemia in 9 patients.4.Imaging:All 25 patients had undergone plain CT,acute cSAH was found in 24 patients.17 patients had undergone MRI,and acute cSAH was found on all MRIs performed.The bleeding was mainly around central sulcus,unilateral in most cases.13 patients had undergone SWI,including 5 patients with cortex micro bleeding.cSAH was characterized by the hypointensity in the Convexity Subarachnoid in SWI.Acute infarction showing on DWI co-existed with cSAH in 2 patients.22 cSAH patients had undergone cerebrovascular imaging,including 20 patients undergone DSA,9 patients undergone MRA,4 patients undergone CTA,7 patients undergone MRV.Cerebrovascular imaging revealed stenosis or occlusion of the internal carotid artery system in 6 patients,cerebral venous system thrombosis(CVST)in 4 patients,moyamoya disease in 4 patients,dissecting in 1 patient.5.Etiologies:The cause of cSAH were identified in 21 patients.The most common cause was stenosis or occlusion of MCA/ICA(6/25),following by cerebral amyloid angiopathy(CAA)(4/25),moyamoya disease(4/25),and CVST(4/25).Among those<60 years old,the commonest etiologies were moyamoya disease(3/12)and stenosis or occlusion of MCA/ICA(3/12);while among those>60 years old,the commonest etiology was CAA.6.Outcome:One patient died during the hospitalization.One patient whose initial symptom was transient unilateral weakness followed by repeating tonic-clonic seizures developed persistent unilateral weakness at discharge.Other 23 patients had a favorable outcome.The mean follow-up duration was 24.3±16.8 months.There was no recurrent cSAH,acute ischemic infarction and acute ICH in at the last follow up.Conclusions:cSAH is an important subtype of nonaneurysmal SAH with special clinical presentations,imaging patterns,diverse etiologies,and favorable outcome.Among those<60 years old,the commonest clinical presentation was non-specific headache and the commonest etiologies were moyamoya disease and stenosis or occlusion of MCA/ICA.Among those>60 years old,the commonest clinical presentation was TFNS,and the commonest etiology was CAA.