The Source for Neurovascular News and Education

April 19, 2019

 

More research on targeted white-matter protection strategies is warranted, one expert says.

 

Large vessel occlusion (LVO) strokes are more likely to result in poor clinical outcomes when the white matter of the brain is damaged, a new study has found.

In patients who experience large vessel occlusions, “computed tomography (CT)- or magnetic resonance imaging (MRI)-based measurements of tissue perfusion have been developed to discriminate cores of already infarcted tissue from a critically ischemic surrounding penumbra, which is still viable and potentially salvageable but predicted to progress to irreversible infarction in case of persisting vessel occlusion,” Justus F. Kleine, Dr Med (Technical University Munich, Germany), and colleagues write in the October 2017 issue of Stroke.

These studies, however, typically fail to differentiate between grey and white matter.

“Experimental evidence shows that the fate of ischemic tissue depends on both time and hypoperfusion: with more severe hypoperfusion, penumbra progresses to infarction more rapidly. In LVO stroke, [white matter] may thus remain viable for longer than [gray matter], which implies that recanalizing therapies could sometimes have tissue-selective effects,” the researchers explain.

To determine whether rapid recanalization that spares the white matter would translate into better clinical outcomes, Kleine et al examined the infarct patterns and clinical outcomes of 322 patients with acute middle cerebral artery occlusions who underwent mechanical thrombectomy.

Overall, white matter was implicated in the infarcts of 63.4% of the 322 patients. After controlling for potential confounders such as final infarct volume, lack of white-matter involvement was independently linked with good neurological outcome (improvement in NIHSS score) and good midterm functional outcome (90-day mRS ≤ 2).

 

Without vs With White-Matter Involvement

 

Adjusted OR (95% CI)

P Value

Improvement in NIHSS Score

3.00 (1.19-7.61)

0.020

90-Day mRS ≤ 2

8.62 (2.41-30.83)

0.001

 

In addition, only 2.6% of patients who had infarcts without white-matter involvement exhibited neurological worsening, compared with 20.5% of patients with white-matter involvement (P < 0.001). None of the patients without white-matter involvement experienced malignant swelling, compared to 12.8% of those who had it (P < 0.001). This swelling contributed to greater mortality among patients whose infarcts included white matter (2.5% vs 10.3%, P = 0.014).

 

Implications for Future Research

Commenting on the study for NVX via email, Geoffrey Alan Donnan, MD (University of Melbourne, Australia), noted that it has long been known that white matter is more resistant than grey matter to ischemia.

“Animal model studies and our clinical studies showed this,” he explained. “What is new [here] is that this occurs in endovascular therapy and that preservation of the [white matter] is associated with better neurological recovery, prevention of malignant swelling, and reduced mortality.”

While the findings do not have immediate implications for patient care, continued Donnan, they do help pave a path for future research. Given that preservation of white matter appears to be critical for generating excellent outcomes, targeted white-matter protection strategies should be investigated.

The authors agree, writing, that their study has “important implications for neuroprotective strategies and perfusion imaging-based patient selection, and provides a rationale for treating selected patients in extended time windows.”

 


Source:

Kleine JF, Kaesmacher M, Wiestler B, Kaesmacher J. Tissue-selective salvage of the white matter by successful endovascular stroke therapy. Stroke. 2017;Epub ahead of print.

 

Disclosures:

Kleine and Donnan report no relevant conflicts of interest.