International Journal of Clinical & Medical Images

Diagnosis: Aneurysm rupture presenting as delayed ischemic stroke related to severe vasospasm

Discussion: The interpretation of this imaging is challenging. Various MRI findings help determine the etiology of stroke and patient selection for acute ischemic stroke treatment (thrombolysis) [1]. The most common mechanisms of stroke in young population are cardioembolism and patent foramen ovale, and dissection of the cervical arteries. The first cause can be suspected when patients present acute multiple territorial lesions or a single large cortical and subcortical lesion on DWI and patent foramen ovale, another source of cardioembolism, usually causes small cortical lesions in vertebro-basilar territory. The presence of hypointense signals with blooming artifacts in the arterial system on T2* sequence (susceptible vessel sign) assess the presence of intra-arterial thrombi, usually associated with cardioembolic stroke. In this unusual presentation of stroke in a young patient without any risk factor, the absence of visualization of intra-arterial thrombus on T2* sequence and of carotid artery dissection (mural hematoma) on dedicated 3D CUBE sequence and the presence of a long spasm allow to conclude that a ruptured aneurysm was responsible for stroke, related to the spasm that occurred at the 7th day of rupture contemporary of neck pain.

Seven days after the aneurysm rupture, a subarachnoid hemorrhage could not be identified on CT, nor on FLAIR and T2* MRI sequences : even if FLAIR sequence is more sensitive than CT and over a longer time period, the patient underwent MRI to late for examination at the 7th day [2]. Cerebral angiography identified a small aneurysm of the left anterior choroidal artery (Figure 5). Patients with DWI-FLAIR mismatch are likely to be within the time of adequate treatment. Endovascular treatment was performed using mechanical angioplasty and coiling. At 3-month follow-up, the patient was asymptomatic and MRA was normal (Figure 6). FHVs are imaging markers of both occlusion or narrowing when proximal to the ischemic core and of collateral system when distal. When present outside the ischemic core, they are associated with good outcome [3]. In the present case, the presence of collateral flow objective by FHV, an early treatment and the absence of risk factors contributed for the good outcome of a symptomatic vasospasm [4,5].