Serial changes in focal hyperemia associated with hypertensive putaminal hemorrhage

Blood pressure management in acute intracerebral hemorrhage

Primary intracerebral hemorrhage (ICH) results from spontaneous rupture of an intracranial vessel and is associated with high rates of early mortality and long-term morbidity. No surgical or medical intervention has been demonstrated to improve outcome. Acute blood pressure elevation is seen in the majority of patients with ICH and is correlated with poor outcome. Potential, but unproven, mechanisms for this association include facilitation of hematoma expansion as well as perihematomal edema growth. Conversely, the perihematomal region has also been hypothesized to have ischemic properties. Therefore, management of blood pressure in the acute phase lends itself to two competing rationales and the optimal target blood pressure remains unknown. A number of parenchymal and blood-flow imaging techniques have been utilized to improve our understanding of blood flow and metabolism in acute ICH. These studies generally indicate that ischemia is not a major pathophysiological mechanism of secondary injury in ICH. Ultimately, randomized, controlled trials, which are underway, will be required to definitively determine the safety and efficacy of acute blood pressure reduction. It appears most likely that earlier and more aggressive treatment of acute blood pressure will be recommended in the future.

Cerebral blood flow changes associated with intracerebral hemorrhage

Recent advances have furthered our understanding of changes in CBF after ICH. Recent evidence from experimental and clinical studies has not supported the role of CBF changes in the pathogenesis of neuronal injury. A better understanding of these changes in ICH has modified the basis for formulating treatment strategies and developing innovative therapies.

Reversible ischemia around intracerebral hemorrhage: a single-photon emission computerized tomography study

OBJECT

A zone of perilesional ischemia has been demonstrated around intracerebral hemorrhage (ICH) in numerous experimental models and in human studies. There is potential for perfusion recovery in the zone of perilesional oligemia around ICH. The authors sought to demonstrate, quantify, and study the chronological evolution of perilesional ischemic change in ICH in humans by measuring cerebral blood flow.

METHODS

Eleven patients with spontaneous supratentorial ICH underwent two technetium-99m hexamethylpropyleneamine oxime single-photon emission computerized tomography (SPECT) scanning, one in the acute stage (within days of ictus) and the other in the late stage (6-9 months postictus). All patients in this study were treated nonsurgically. Methods of SPECT data analysis based on count differences in regions of interest can be difficult to apply to images with large space-occupying lesions such as ICH, because of the distortion of intracranial anatomy, midline shift, and alterations in the three-dimensional (3D) characteristics of the lesion over time (that is, absorption of the hematoma on the later studies). The authors used the following method: the late and early images were registered and aligned to a common 3D orientation and were normalized to maximal counts. The late images were then compared voxel by voxel with the early ones. The region-growing algorithm was used to discern the difference between the two images, outlining voxels in the perihematoma region, with a signal improvement of at least 15% on the late image. Discrete brain regions around the hematoma with at least a 15% improvement in radiotracer uptake (and hence perfusion) in the late images were observed in all cases. The mean volume of brain with a greater than 15% improvement in perfusion between the two studies was 34.8 cm3 (range 7.2-71.3 cm3). These volumes represent regions of the brain that were poorly perfused in the initial studies. This may represent a zone of reversible perilesional oligemia (penumbra) in ICH in humans.

CONCLUSIONS

This is the first study in which it is documented that some of the perilesional hypoperfused tissue around human ICH regains its perfusion in the long term, leading the authors to suggest that there may be a penumbra in human ICH. Medical or surgical therapeutic interventions could increase the volume of perilesional brain that recovers after the initial insult. The results of this study therefore support the concept that intervention in ICH has the potential to reduce the ultimate neurological deficit and improve outcome.

Changes in cerebral hemodynamics following encephalo-duro-arterio-synangiosis (EDAS) in young patients with moyamoya disease

To evaluate the effect of encephalo-duro-arterio-synangiosis, (EDAS), we obtained follow-up angiograms and measured regional cerebral blood flow in 21 young patients with Moyamoya disease. Carotid fork stenosis continued to progress after EDAS, although angiography demonstrated a marked increase in the number of middle cerebral artery branches via implanted arteries. Preoperative cortical blood flow was lower than normal. The post-EDAS increases in hemispheric and cortical flow were significant in patients with transient ischemic attacks, but not in patients with infarction. The increase in cortical flow at the site of EDAS was first noted 2 weeks after EDAS.