Abstract
Purpose: Acute subdural hematoma (ASDH) due to ruptured intracranial aneurysm, but without subarachnoid hemorrhage (SAH) or intracerebral hemorrhage (ICH), is extremely rare. We report a case of pure ASDH caused by intracranial aneurysm rupture and review the literature.
Case: A 41-year-old woman visited our hospital with complaints of severe headache. Magnetic resonance imaging and magnetic resonance angiogram (MRA) demonstrated an extensive ASDH (without SAH or ICH) at the bilateral convexity, tentorium, interhemispheric fissure, anterior fossa, middle fossa, posterior fossa, and clivus as well as from the foramen magnum to the spinal canal. The left internal carotid-posterior communicating artery (IC-PC) aneurysm was enlarged to 9 mm in diameter approximately. We diagnosed as pure ASDH due to the ruptured left IC-PC aneurysm, and treated it emergently.
Treatment: We performed coil embolization with a balloon-assisted technique, and treated the aneurysm twice because of coil compaction, and finally obtained complete occlusion. The patient recovered without any neurological deficits.
Discussion: Intracranial aneurysm rupture usually present as an SAH or ICH. ASDH is identified in 0.5%-7.9% of patients with ruptured intracranial aneurysms. Pure ASDH without SAH or ICH caused by intracranial aneurysm rupture is extremely rare, and only 50 such cases have been reported. Of the 51 cases (including our present case), the most frequent site of aneurysm in 26 cases (51.0%) was the IC-PC. The location of the ASDH was convexity in 29 cases (56.9%), and convexity + tentorium in 11 cases (21.6%). Good outcomes were reported in 35 cases (68.6%). Several mechanisms have been proposed to explain the occurrence of subdural hematoma after aneurysm rupture. (1) Minor bleeding from an aneurysm may cause adhesion to the arachnoid membrane, and the final rupture occurs directly into the subdural space. (2) Hemorrhage under high pressure may lacerate the arachnoid membrane and bleed into the subdural space. (3) Intracerebral bleeding may rupture through the cortex and lacerate the arachnoid membrane. The bleeding mechanism in our patient might be (1).
Conclusion: We treated a rare case of a ruptured intracranial aneurysm, demonstrated a pure ASDH. MRA, CT angiography and digital subtraction angiography should be performed to detect vascular abnormalities in patients who present with a pure ASDH without a history of trauma.
