Why a standard contrast-enhanced MRI might be useful in intracranial internal carotid artery stenosis

Giant-cell arteritis related strokes: scoping review of mechanisms and rethinking treatment strategy?

Stroke is a rare and severe complication of giant cell arteritis (GCA). Although early diagnosis and treatment initiation are essential, the mechanism of stroke is often related to vasculitis complicated by arterial stenosis and occlusion. Its recurrence is often attributed to early steroid resistance or late GCA relapse, so immunosuppressive treatment is often reinforced. However, many questions concerning the mechanisms of stroke remain elusive, and no review to date has examined the whole data set concerning GCA-related stroke. We therefore undertook this scoping review. GCA-related stroke does not necessarily display general signs and inflammatory parameters are sometimes normal, so clinicians should observe caution. Ischemic lesions often show patterns predating watershed areas and are associated with stenosis or thrombosis of the respective arteries, which are often bilateral. Lesions predominate in the siphon in the internal carotid arteries, whereas all the vertebral arteries may be involved with a predominance in the V3-V4 segments. Ultrasonography of the cervical arteries may reveal edema of the intima (halo sign), which is highly sensitive and specific of GCA, and precedes stenosis. The brain arteries are spared although very proximal arteritis may rarely occur, if the patient has microstructural anatomical variants. Temporal artery biopsy reveals the combination of mechanisms leading to slit-like stenosis, which involves granulomatous inflammation and intimal hyperplasia. The lumen is sometimes occluded by thrombi (<15%), suggesting that embolic lesions may also occur, although imaging studies have not provided strong evidence for this. Moreover, persistence of intimal hyperplasia might explain persisting arterial stenosis, which may account for delayed stroke occurring in watershed areas. Other possible mechanisms of stroke are also discussed. Overall, GCA-related stroke mainly involves hemodynamic mechanisms. Besides early diagnosis and treatment initiation, future studies could seek to establish specific preventive or curative treatments using angioplasty or targeting intimal proliferation.

Gadolinium-enhanced MR improved motion sensitized driven equilibrium (iMSDE) for intracranial vessel imaging in giant cell arteritis

BACKGROUND

Giant cell arteritis (GCA) generally affects extracranial large and medium-sized vessels. It rarely causes intracranial vessel stenosis, presenting as cerebral infarction (CI). Consequently, accurate diagnosis of CI induced by GCA is often challenging. Improved motion-sensitized driven-equilibrium (iMSDE) is one of the advanced high-resolution magnetic resonance (MR) vessel wall imaging techniques that enables direct visualization of the vessel wall because of a strong reduction in blood flow artifacts, leading to higher quality images. Herein, we effectively used gadolinium-enhanced MR iMSDE imaging to diagnose a patient presenting with recurrent CI due to right intracranial internal carotid artery (ICA) stenosis as GCA.

CASE DESCRIPTION

A 64-year-old man with polymyalgia rheumatica for several years and who had experienced CI due to moderate intracranial ICA stenosis one year ago, presented to the emergency room with dysarthria and left hemiparesis. Diffusion-weighted MR imaging showed high signals in the right centrum ovale, and MR angiography revealed severe stenosis of the right intracranial ICA. Gadolinium-enhanced MR iMSDE imaging showed marked concentric enhancement in the vessel wall of the right stenosed ICA, which led to a definitive diagnosis of GCA via biopsy from the right superficial temporal artery. The patient's symptoms gradually improved after initiation of steroid treatment. Three months later, gadolinium-enhanced MR iMSDE imaging revealed improvement in the contrast enhancement in the vessel wall and vascular stenosis.

CONCLUSION

Gadolinium-enhanced MR iMSDE imaging is useful to diagnose and evaluate GCA with intracranial vessel involvement.

The TXA2R rs1131882, P2Y1 rs1371097 and GPIIIa rs2317676 three-loci interactions may increase the risk of carotid stenosis in patients with ischemic stroke

Background

The genetic risk factors for carotid stenosis are not fully understood. The aim of this study is to investigate the relationship between variants in platelet activation-relevant genes and carotid stenosis in patients with ischemic stroke (IS).

Methods

Eleven variants of platelet activation-relevant genes, aggregates of platelet-leukocyte, and platelet aggregation were examined in 236 IS patients with carotid stenosis and 378 patients without carotid stenosis. High-resolution B-mode ultrasound was used to assess carotid stenosis. Generalized multifactor dimensionality reduction (GMDR) methods were applied in analyzing gene-gene interactions to determine whether there was any interactive role of assessed variants in affecting risk of carotid stenosis.

Results

Platelet aggregation and aggregates of platelet-leukocyte showed higher value in patients with carotid stenosis, compared with patients without carotid stenosis. Excluding potential disturbance variables, these 11 variants were not associated with carotid stenosis. However, according to the GMDR analysis, gene-gene interactions among TXA2R rs1131882, P2Y1 rs1371097 and GPIIIa rs2317676 had a synergistic influence on carotid stenosis. The high-risk interactions between the three variants showed a relationship with higher platelet activation, and have independent associations with risk of carotid stenosis (OR = 2.72, 95% CI: 1.28–7.82, P = 0.001).

Conclusion

The interactions among rs1131882, rs1371097 and rs2317676 perhaps increase the risk of symptomatic carotid stenosis, and maybe a potential marker for carotid stenosis. In this study, the combinatorial analysis made good use in elucidating complex risk factors in the heredity of carotid stenosis.