Cerebral blood flow and magnetic resonance imaging in locked-in syndrome.

The cerebral blood flow (CBF) of a patient suffering from locked-in syndrome (LiS) was examined before and after the onset using 99mTc-hexamethylpropyleneamine oxime single-photon emission computed tomography (SPECT) and the intravenous 133Xe injection method. The mean CBF during the locked-in state was 32.2 ml/100 g/min, a 42% reduction from the asymptomatic stage. SPECT showed profound reductions of perfusion in the bilateral cerebral cortices, subcortical regions and in the cerebellum, with a less marked reduction in the frontal cortices. On Day 49, the patient showed some minimal voluntary return with a moderate increase in mean CBF of 40.2 ml/100 g/min. The relative CBF values in the cerebral cortices and subcortical regions were restored, but the bilateral cerebellar hypoperfusion remained unchanged. SPECT and CBF are useful for a better characterization of the brain pathophysiology in LiS.