Encapsulated Acute Subdural Hematoma Mimicking Acute Epidural Hematoma on Computed Tomography

Abstract

An 87-year-old woman presented with an atypical case of acute subdural hematoma (ASDH) manifesting as disturbance of consciousness and left hemiparesis. Computed tomography revealed a high density lentiform lesion in the right convexity, which was thought to be acute epidural hematoma preoperatively. Emergent decompressive craniotomy revealed an encapsulated solid fresh clot in the subdural space and a bleeding small cortical artery under the clot. The arachnoid membrane and the brain parenchyma were intact, and no other abnormal feature such as aneurysm or arteriovenous malformation was observed. The encapsulated ASDH was removed en bloc and the patient fully recovered. Histological examination confirmed that both the outer thicker and the inner membrane were fibrinous single structures without vasculature. The red blood cells constituting the clot in the capsule maintained their cell structure. The reported pathological mechanisms of lentiform ASDH are adhesion of the arachnoid membrane and the dura mater or intracapsular bleeding from sinusoidal vessels in the outer membrane of the chronic subdural hematoma. However, in our case, the arachnoid membrane had not adhered to the dura mater and the capsule was a fibrinous single structural membrane without vasculature, which probably resulted from a previous hematoma due to initial bleeding from the cortical artery. The possible mechanism in our case was that the re-bleeding dissected and flowed into the fibrinous single structural membrane, resulting in formation of the lentiform ASDH.

Subacute Subdural Hematoma mimicking Epidural Hematoma in Infant Patient

“…Subacute SDH is a thin encapsulated collection of old blood, mostly liquefied and located at the dura-arachnoid interface. [1][2][3] We describe here an interesting case of hyperdense intracranial lesion that has never been reported previously; its lenticular form was diagnosed as an acute epidural hematoma (EDH) preoperatively, but was revealed to be an encapsulated subacute SDH intraoperatively.…”

Spontaneous Development of Encapsulated Subdural Hematoma in the Posterior Cranial Fossa after Cardiac Surgery: A Case Report

“…Formation of the fibrous capsule can be observed not only in CSHs but also sometimes in acute subdural hematomas. 19 , 20) Mechanisms underlying the formation of the subdural neomembranes have been investigated and reported. In an unresolved subdural hematoma or subdural hygroma, the dural border cells proliferate and form subdural neomembranes.…”

Acute Epidural Hematoma Mimicking an Acute Subdural Hematoma Case Report and Review of the Literature

“…Careful and correct analysis of images is more necessary because it will helps in surgical planning as extradural hematoma requiring limited exposure; however, an acute subdural hematoma needs a large exposure with duraplasty. Presence of a fracture lines in the vicinity of clot, presence of pneumocephalus in the hematoma and absence of underlying brain lesion on CT scan are features suggestive of extradural hematoma [5]. However, an uncertain diagnosis should not delay surgery as the outcome could be fatal if not.…”