Abstract 18: Association of Peri-Infarct N-Acetyl Aspartate with Recovery from Stroke
Introduction: Recovery from stroke has been correlated with specific anatomical lesions in the brain, however much of the variability in recovery remains unexplained. Recent research has indicated that the peri-infarct tissue plays a crucial role in recovery. We hypothesised that N-acetyl aspartate (NAA) can serve as a marker of neural integrity in the structurally intact peri-infarct region following stroke, with the potential to predict recovery. The objective of our study was to measure NAA in a longitudinal MR spectroscopy study in stroke patients, and to correlate these findings with functional outcome.
Methods: Six patients (age 53±10 y) with a non-lacunar ischemic stroke in the left middle cerebral artery territory underwent MR spectroscopy on a 3.0 T MRI scanner. Patients were scanned at 3 and 15 weeks after stroke onset. Proton spectra were acquired from the structurally intact peri-infarct thalamus, the contralesional thalamus, and the anterior cingulate cortex (ACC) using a point resolved spectroscopy sequence with an echo time of 30 ms. NAA concentrations were calculated with LCModel. Clinical assessment included the Fugl-Meyer (FM) scale for the motor performance of the right arm and the NIHSS. Seven healthy controls (age 53±7 y) were also recruited.
Results: At baseline, NAA was significantly lower in the patients in the structurally intact ipsilesional thalamus (9.0±2.1 vs 11.3±1.2, p=0.030), but not in the other 2 voxels. Baseline NAA was also significantly lower in the ipsilesional thalamus than in the ACC (9.0±2.1 vs 12.7±1.2, p=0.016) in the patients, but not in the controls. NAA decreased significantly between the 2 visits (9.0±2.1 vs 7.2±1.7, p=0.021) in the patients in the ipsilesional thalamus, but not in the other 2 voxels. The patients demonstrated significant clinical improvement during the course of follow up (median 15-point gain on the FM scale, p=0.042; and a 7-point decline on the NIHSS, p=0.026). NAA in the ipsilateral thalamus at baseline significantly correlated with the final FM (rs=0.81, p=0.025) and NIHSS scores (rs=-0.84, p=0.018).
Conclusions: Stroke disturbs neuronal integrity in the structurally intact peri-infarct tissue. Despite clinical improvement, neural damage in the peri-infarct area appears to progress during the first 3-4 months following a non-lacunar ischemic stroke. This decreased neuronal integrity is associated with impaired recovery and may therefore represent a therapeutic target. Peri-infarct NAA is a potential biomarker not only for the prediction of recovery, but also for the monitoring of therapeutic interventions.
- © 2012 by American Heart Association, Inc.