Basal ganglionic infarction before mechanical thrombectomy predicts poor outcome.

BACKGROUND AND
PURPOSE: Use of mechanical thrombectomy for acute cerebrovascular occlusions is increasing. Preintervention MRI patterns may be helpful in predicting prognosis.
METHODS: We reviewed all Merci thrombectomy cases of either terminal ICA or M1 occlusions and classified them according to diffusion MRI patterns of (1) completed basal ganglia infarct (pure M1a), (2) near-completed basal ganglia infarct (incomplete M1a), and (3) relative sparing of deep MCA field (M1b). We compared the M1a and M1b patients with respect to neurological deficit on presentation, recanalization rates, hospital length of stay, and disability on discharge. We also determined whether deep MCA compromise predicted hematomal hemorrhagic transformation (HT) and whether this correlated with worse clinical outcome at discharge.
RESULTS: The M1a group had worse pre-Merci NIHSS (21 versus 14, P=0.004), worse discharge NIHSS (12 versus 4, P<0.001), longer hospital length of stay (11.5 versus 6.4 days, P=0.003), and higher rates of discharge mRS > or = 3 (OR 8.4, 95% CI 2.1 to 44.7) despite equivalent recanalization rates when compared to the M1b group. The M1a group had a higher rate of parenchymal hematomal HT (OR 6.7, 95% CI 1.02 to 183.3). Patients with such hematomal HT had higher rates of death or dependency discharge (100% versus 60%, OR=infinite).
CONCLUSIONS: Among patients with ICA and M1 occlusions, preintervention diffusion MRI evidence of advanced injury in the basal ganglia bodes worse dysfunction and disability at discharge, longer hospital stays, and higher rates of hemorrhage after intervention when compared to other diffusion patterns.