Ruptured Mycotic Cerebral Aneurysm Secondary to Disseminated Nocardiosis

Abstract

We report a case of a ruptured mycotic cerebral aneurysm caused by Nocardia infection. A 22-year-old immunocompromised woman with adult-onset Still's disease developed a subarachnoid hemorrhage (SAH). Digital subtraction angiography revealed a small aneurysm at the M2-3 bifurcation of the right middle cerebral artery. Cardiac ultrasonography showed vegetation at the posterior cardiac wall, suspecting infective endocarditis (IE). Gram-positive filamentous bacteria were observed in the necrotic tissue surrounding the aneurysm obtained during trapping surgery. Long-term blood culture showed that the cause of her cerebral mycotic aneurysm was nocardiosis. A mycotic ruptured cerebral aneurysm is an important cause of SAH in immunocompromised patients. Early diagnosis of IE, detection of gram-positive rods by Gram staining, and long-term culture to identify the bacteria is crucial in diagnosing nocardiosis.

Keywords: Immunosuppressed host; nocardiosis; ruptured mycotic cerebral aneurysm.

Figure 1

Head computed tomography scan at the onset of subarachnoid hemorrhage demonstrates diffuse subarachnoid hemorrhage with intracranial hematoma

Figure 2

Digital subtraction angiography at the onset of subarachnoid hemorrhage demonstrates a small aneurysm at the right M2-3 bifurcation (red arrow). (a) Anteroposterior view, (b) Lateral view, (c) 3D Rotational Angiography

Figure 3

Clinical and pathological findings of aneurysm (a) The aneurysm filled with pus, which leaked out from the point of destruction of the aneurysm wall (*). The aneurysm wall appears white and turbid with irregularities (b) Pathological analysis demonstrates an internal elastic lamina (arrow head), intravascular lumen (*), expanded media (**), destruction of internal elastic lamina (arrow), and persisting outer membrane (double arrows) (c and d) Gram-positive filamentous bacteria detected in the necrosis surrounding the aneurysm