Carotid Occlusion May Not Be Associated With High Risk For Stroke

Yang et al published on JAMA Neurology their retrospective analysis of patients who presented at two atherosclerosis clinics in Ontario with asymptomatic carotid artery stenoses that were followed for 20-years with carotid duplex scans.

Among the 3681 patients who had annual carotid ultrasound examinations, 316 (8.6%) were asymptomatic before an occlusion that occurred during observation period.

Of the new occlusions, 254 of 316 [80.4%] occurred before 2002, when medical therapy was less intensive; the frequency decreased by quartile of years (P < .001, χ2 test). Only 1 patient (0.3%) had a stroke at the time of the occlusion, and only 3 patients (0.9%) had an ipsilateral stroke during follow-up (all before 2005).

In Kaplan-Meier survival analyses, neither severity of stenosis nor contralateral occlusion predicted the risk of ipsilateral stroke or transient ischemic attack, death from stroke, or death from unknown cause at a mean follow-up of 2.56 years. In Cox proportional hazards regression analyses, only age (P = .02), sex (P = .01), and carotid plaque burden (P = .006) significantly predicted risk of those events.

The authors concluded that the risk of progression to carotid occlusion is well below the risk of carotid stenting or endarterectomy and has decreased markedly with more intensive medical therapy. Preventing carotid occlusion is not  a valid indication for intervention to prevent occlusion as the circle of Willis offers substantial protection.

JAMA Neurol. 2015.1843

Combined MRS and DWI could Predict Stroke's Outcome

Parsons etal in their article that appeared in Neurology¹ report on the prognostic value of the biochemical changes seen with proton MR spectroscopy (MRS) in patients with ischemic stroke.

Nineteen patients had 36 1H MRS studies, 13 of the patients acutely (mean, 11.1 hours), 10 patients sub-acutely (mean, 3.9 days), and 13 patients at outcome (mean, 82 days). Single-voxel, long-echo, timepoint-resolved spectroscopy was used to obtain lactate, n-acetylaspartate (NAA), choline, and creatine levels from the infarct core. Diffusion-weighted imaging (DWI) was used to identify regions of ischemia for 1H MRS voxel localization.  Outcome measures were final infarct volume and clinical assessment scales (Canadian Neurological Scale, Barthel Index, and Rankin Scale).

Acute lactate/choline ratio correlated more strongly with clinical outcome scores and final infarct size than acute DWI lesion volume or acute NAA/choline ratio. Combination of acute lactate/choline ratio and DWI lesion volume improved prediction of all outcome scores. The predictive effect of acute lactate/choline ratio was independent of acute DWI lesion volume (p < 0.001). In subacute and chronic infarction, both lactate/choline and NAA/choline ratios continued to correlate with outcome (p < 0.05). At the chronic stage, persistent lactate/choline ratio elevation strongly correlated with outcome measures (r = 0.71 to 0.87).

The authors concluded that lactate/choline ratio measured in the acute infarct core by 1H MRS improves the prediction of stroke outcome and provides prognostic information complementary to DWI.

1. Parsons M, Barber P, Yang G, Darby et al: Combined (1)H MR spectroscopy and diffusion-weighted MRI improves the prediction of stroke outcome. Neurology. 2000 Aug 22;55 (4):498-505