Evolution of Subarachnoid Hemorrhage Extension in Lobar Hemorrhage in the Early Chronic Phase and the Impact on Cerebral Amyloid Angiopathy Criteria

BackgroundSubarachnoid hemorrhage extension (SAHE) in acute lobar hemorrhage (LH) is frequent. Little is known about the short- and medium-term radiological evolution of SAHE. Our aim was to study this evolution by magnetic resonance imaging (MRI).MethodsWe performed an observational study and analyzed retrospectively MRIs of patients with LH with possible/probable/definite cerebral amyloid angiopathy (CAA), and compared initial MRI performed between 3 hours and 21 days after symptom onset with follow-up MRI performed between 2 and 12 months after initial MRI.ResultsTwenty patients were analyzed. Initial MRI showed 11 of 20 patients (55%) with SAHE. Follow-up MRI showed, compared with initial MRI, an increase of 77% (45% versus 80%) of patients with chronic intrasulcal hemorrhage, an increase of 36% (22% versus 30%) of the number of lobes with chronic intrasulcal hemorrhage, and an increase of 37% (1.75 versus 2.4) of lobes with chronic intrasulcal hemorrhage seen per patient. All new chronic intrasulcal hemorrhages involved the brain lobe with initial LH except 1 lobe in 1 patient. Three patients switched from possible to probable CAA according to the modified Boston criteria after follow-up MRI due to chronic intrasulcal hemorrhage in the lobe involved by LH. In 6 patients, follow-up MRI showed more diffuse chronic intrasulcal hemorrhage than pre-existing combined SAHE and chronic intrasulcal hemorrhage in the LH lobe, or showed presence of chronic intrasulcal hemorrhage in the absence of initial SAHE and/or chronic intrasulcal hemorrhage in the LH lobe.ConclusionIn LH patients, presence of SAHE on initial MRI changes the modified Boston CAA criteria on follow-up MRI in a portion of patients. On follow-up MRI, SAHE/chronic intrasulcal hemorrhage extension or chronic intrasulcal hemorrhage appearance in the LH lobe is relatively frequent.