Clinical Implications of Basilar Artery Plaques in the Pontine Infarction with Normal Basilar Angiogram: A High-Resolution Magnetic Resonance Imaging Study

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Abstract

Background

Using high-resolution magnetic resonance imaging (HR-MRI), we investigated the impact of basilar artery plaques that were not detected by magnetic resonance angiography (MRA) on the functional outcomes of patients with acute pontine infarction.

Methods

A total of 40 patients with acute pontine infarction and normal basilar findings on MRA prospectively underwent HR-MRI for detection of basilar artery plaques. A relevant plaque was defined as one on the dorsal side of basilar artery, the same side of the ischemic lesion, and the same axial slices of the ischemic lesion. We analyzed the relationship between the relevant basilar artery plaques and the functional outcomes at 3 months.

Results

The initial National Institutes of Health Stroke Scale score (3.5 versus 2.0, P = .012), and the incidences of neurological deterioration (42.9% versus 6.3%, P = .031) and unfavorable functional outcome (71.4% versus 12.5%, P = .001) were higher in patients with relevant basilar artery plaques than in those without. On multiple regression analysis, the relevant basilar artery plaque was a significant and independent predictor of unfavorable functional outcome (odds ratio, 6.662; 95% confidence interval, 1.117-39.735; P = .037).

Conclusions

The presence of a relevant basilar artery plaque was closely related with unfavorable functional outcome in patients with acute pontine infarction even if the patients’ MRA showed normal basilar findings.

Introduction

It has been traditionally accepted that the pathological findings of small subcortical infarctions are lipohyalinosis or fibrinoid necrosis of the perforating arteries.1, 2 However, this concept is debatable because previous researchers have described that atheromatous plaque in the intracranial arteries can obstruct the orifice of the perforators, the so-called branch atheromatous disease (BAD), and subsequently cause a subcortical infarction.3, 4 Although advances in imaging methods such as magnetic resonance angiography (MRA) made it possible to detect atheromatous plaques occluding the perforating arteries, the incidence of BAD may be underestimated since atheromatous plaques that do not cause luminal narrowing cannot be identified by MRA. Therefore, the application of imaging technologies that are able to show the arterial wall is necessary to improve our understanding of the pathogenesis of subcortical infarction.

High-resolution magnetic resonance imaging (HR-MRI), a promising noninvasive tool for depicting the arterial wall characteristics,5 can be more useful than MRA for identifying and localizing the atheromatous plaque in the intracranial arteries.6, 7, 8, 9 A previous study based on HR-MRI suggested that the atheromatous plaque close to the orifice of perforating arteries could increase the risk of an unfavorable functional outcome in cases of lenticulostriate artery territory infarction.10 However, there have been limited data regarding how the presence and location of atheromatous plaque relate to functional outcomes in patients with acute pontine infarction, especially those with a normal basilar artery on MRA. Thus, using HR-MRI, we sought to detect the basilar artery plaques that were not recognized by MRA and investigated its impact on functional outcomes in patients with acute pontine infarction.

Section snippets

Patient Selection

From January 2014 to June 2016, we prospectively screened 70 patients with unilateral isolated pontine infarction, as demonstrated by diffusion-weighted image (DWI) that was performed within 48 hours of symptom onset. Of these, we enrolled the patients with a normal basilar artery on MRA. Patients were excluded if they had greater than 50% stenosis in the vertebral arteries, potential cardiac sources of embolism according to the Trial of Organization 10172 in Acute Stroke Treatment

Patient Characteristics

Among the 70 screened patients, 40 were eligible for this study. The median age was 67.5 (59.0-75.0) years, and 27 (67.5%) patients were male. The median NIHSS score was 2.0 (1.0-4.0) on admission, and neurological deterioration occurred in 9 (22.5%) patients. An unfavorable functional outcome at 3 months was observed in 15 (37.5%) patients. Basilar artery plaques were observed in 24 (60.0%) patients. Of them, 14 (58.3%) patients had relevant basilar artery plaques. Interobserver reliability

Discussion

This study demonstrated that the presence of a relevant basilar artery plaque was associated with neurological deterioration within 7 days and unfavorable functional outcome at 3 months in patients with an acute pontine infarction. On the contrary, there was no significant difference in functional outcomes between the patients with irrelevant plaques and those without basilar artery plaques. Therefore, we suggest that functional outcome may be critically affected by basilar artery plaque

Conclusions

This study suggests that basilar artery plaques, if they were located close to the orifice of perforating arteries, could be responsible for severe initial clinical symptoms, neurological deterioration accompanied by a significant increase in subacute lesion volume, and subsequent unfavorable functional outcomes. Therefore, basilar artery plaque location should be carefully assessed, even in patients with normal basilar findings on MRA.

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    Grant Support: This work was supported by Clinical Research Grant from Pusan National University Hospital 2018.

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