Early Metabolic Alteration Predicts Outcome With Middle Cerebral Artery Occlusion Treated by Mechanical Thrombectomy

Predicting clinical outcome based on either the postprocedural recanalization score (modified treatment in cerebral infarction) or the initial National Institute of Health Stroke Scale (NIHSS) clinical score performed immediately after the acute phase remains controversial. The gold standard to predict clinical outcome is the NIHSS score with diffusion weighted imaging. However, magnetic resonance spectroscopy could provide useful metabolic informations. Our study aimed to determine early metabolic factors predictive of long-term clinical outcome after acute ischemic stroke in patients with middle cerebral artery occlusion successfully treated by mechanical thrombectomy.

Patients with proximal middle cerebral artery occlusion, an NIHSS score greater than 6 and successfully treated by mechanical thrombectomy with or without intravenous therapy were included. All patients underwent within 24 hours after mechanical thrombectomy, brain magnetic resonance imaging examination with multivoxel proton-phosphorus-magnetic resonance spectroscopy. Functional disability at 90 days with reference to pre-stroke activities was categorized using the modified Rankin scale. Metabolite ratios were measured and confronted to modified Rankin scale.

A total of 49 patients were included with initial mean NIHSS of 15.19±5.48. Time delay between: onset-thrombectomy was 6.77 hours±3.22, thrombectomy-magnetic resonance imaging was 29.83 hours±15.01. Results in the lesion compared with the contralateral area show an increase of Lac/Cr (0.88 versus 0.21; P<10^-10) and a decrease of PhosphoMonoEster/PhosphoDiEster (0.80 versus 0.83; P=0.00165). Lac/Cr in the lesion was significantly higher in the poor outcome group than in the favorable outcome group (1.03±0.41 and 0.75±0.42; P=0.01). Our model built with NIHSS+proton-magnetic resonance spectroscopy compared with the gold standard model (NIHSS+diffusion weighted imaging) is better (85.29% versus 77.55%) to predict clinical outcome.

Our study shows that early Lac/Cr alteration visible 24 hours after stroke is a strong predictor of 90 days clinical outcome for middle cerebral artery occlusion patients successfully treated by mechanical thrombectomy. Our NIHSS+proton-magnetic resonance spectroscopy model is the first to predict patients' long-term functional outcome with an accuracy of 85.3%, superior to existing models including diffusion weighted imaging.