3D pseudocontinuous arterial spin-labeling perfusion imaging detected crossed cerebellar diaschisis in acute, subacute and chronic intracerebral hemorrhage

Longitudinal, Quantitative, Multimodal MRI Evaluation of Patients With Intracerebral Hemorrhage Over the First Year

In most patients with intracerebral hemorrhage (ICH), the hematoma and perihematomal area decrease over the subsequent months but patients continue to exhibit neurological impairments. In this serial imaging study, we characterized microstructural and neurophysiological changes in the ICH-affected brain tissues and collected the National Institute of Health Stroke Scale (NIHSS) and modified Rankin Score (mRS), two clinical stroke scale scores. Twelve ICH patients were serially imaged on a 3T MRI at 1, 3, and 12 months (M) after injury. The hematoma and perihematomal volume masks were created and segmented using FLAIR imaging at 1 month which were applied to compute the susceptibilities (χ), fractional anisotropy (FA), mean diffusivity (MD), and cerebral blood flow (CBF) in the same tissues over time and in the matching contralesional tissues. At 3 M, there was a significant (p < 0.001) reduction in hematoma and perihematomal volumes. At 1 M, the χ, FA, and CBF were decreased in the perihematomal tissues as compared to the contralateral side, whereas MD increased. In the hematomal tissues, the χ increased whereas FA, MD, and CBF decreased as compared to the contralesional area at 1 M. Temporally, CBF in the hematoma and perihematomal tissues remained significantly (p < 0.05) lower compared with the contralesional areas whereas MD in the hematoma and χ in the perihematomal area increased. The NIHSS and mRS significantly correlated with hematoma and perihematomal volume but not with microstructural integrity. Our serial imaging studies provide new information on the long-term changes within the brain after ICH and our findings may have clinical significance that warrants future studies.

Splenial Restricted Diffusion as MRI Correlate of Diaschisis in a Blind Infant With Unilateral Posterior Cerebral Artery Stroke

ABSTRACT

A 3-month-old male infant appeared on multiple clinical examinations to have acutely developed bilateral retrogeniculate blindness. Electroencephalography showed focal status epilepticus confined to the left posterior cerebral hemisphere. MRI demonstrated restricted diffusion in the domain of the left posterior cerebral artery consistent with acute stroke. Notably, the restricted diffusion extended across the midline in the splenium of the corpus callosum. This splenial sign may be the imaging correlate of cerebral diaschisis, a well-described phenomenon in which patients with new brain lesions develop acutely impaired neurologic function in related but nonlesioned brain regions. Diaschisis has been posited as the explanation for the temporary bilateral blindness in adult patients suffering from unilateral occipital infarctions.

PET Imaging of Crossed Cerebellar Diaschisis after Long-Term Cerebral Ischemia in Rats

Crossed cerebellar diaschisis (CCD) is a decrease of regional blood flow and metabolism in the cerebellar hemisphere contralateral to the injured brain hemisphere as a common consequence of stroke. Despite CCD has been detected in patients with stroke using neuroimaging modalities, the evaluation of this phenomenon in rodent models of cerebral ischemia has been scarcely evaluated so far. Here, we report the in vivo evaluation of CCD after long-term cerebral ischemia in rats using positron emission tomography (PET) imaging with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG). Imaging studies were combined with neurological evaluation to assess functional recovery. In the ischemic territory, imaging studies showed a significant decrease in glucose metabolism followed by a progressive recovery later on. Conversely, the cerebellum showed a contralateral hypometabolism from days 7 to 14 after reperfusion. Neurological behavior showed major impaired outcome at day 1 after ischemia followed by a significant recovery of the sensorimotor function from days 7 to 28 after experimental stroke. Taken together, these results suggest that the degree of CCD after cerebral ischemia might be predictive of neurological recovery.