Acute Subdural Hematoma Secondary to Paraclinoid Internal Carotid Aneurysm with Rebleeding following Angiography

A previously healthy 36-year-old woman with no history of trauma presented with a sudden-onset severe headache, syncope, and transient left arm hemiparesis. CT demonstrated acute subdural hematoma (aSDH) Figure 1a and b. CT angiography (CTA) and digital subtraction angiography (DSA) revealed a left paraclinoid internal carotid artery (ICA) aneurysm Figure 1c and d.Figure 1: CT (a and b) shows bilateral aSDH predominantly in the frontobasal region (arrowheads). CTA and angiography (c and d) reveal a left paraclinoid ICA aneurysm. aSDH = acute subdural hematoma, CTA = CT angiography, ICA = Internal carotid arteryDuring DSA, the patient developed seizures. CT was immediately performed, revealing progression of the aSDH Figure 2a. She underwent successful coil embolization Figure 2b and c and was discharged 12 days later with complete resolution of her neurological symptoms.Figure 2: CT immediately after angiography (a) demonstrates progression of the aSDH. Post-embolization angiography (b and c) shows complete occlusion of the aneurysm (black arrow). aSDH = acute subdural hematomaPure aSDH is an uncommon presentation of ruptured intracranial aneurysms. Many hypotheses have been proposed to explain how a ruptured aneurysm can cause aSDH, depending on the aneurysm anatomy and its perianeurysmal environment.1 Some authors have suggested that adhesions may develop between the arachnoid membrane and the aneurysm wall, predisposing the aneurysm to rupture with direct blood extravasation into the subdural space.1,2 Others have postulated that the arachnoid membrane may be torn by the rapid accumulation of high-pressure blood from the ruptured aneurysm.1-3 In this case, we believe that the aneurysm interaction with the basal arachnoid membrane may explain the direct rupture into the subdural space. It is also possible that the aneurysmal bleeding point was located directly within the subdural space, which would account for the lack of acute subarachnoid hemorrhage, as previously described in the literature.2-4 Given that uncommon presentations of aneurysm rupture can delay diagnosis, clinicians must consider intracranial aneurysms as a possible cause of spontaneous aSDH to allow early treatment and avoid rebleeding. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.