Is the swelling in brain edema isotropic or anisotropic?
A study was conducted to examine whether swelling of the brain due to vasogenic-type and cytotoxic-type edema is isotropic or anisotropic. Vasogenic edema was induced by cryogenic injury in cats, and coronal sections of the brain were examined at 4-5 h after injury. The swelling of the edematous white matter longitudinal to and transverse to the subcortical neuronal fibers was 2.3% and 91.1%, respectively. Ischemic edema was examined using cortical tissue specimens of cat brain subjected to either middle cerebral artery occlusion for 3 h or immersion in saline after decapitation for 3 h. The swelling parallel to the left-right axis, caudo-rostral axis and antero-posterior axis was 9.6%, 10.1% and 8.5%, respectively. Neuroglial cell swelling was prominent in the ischemic cortex. Thus swelling of the white matter in vasogenic-type edema was anisotropic, whereas that of gray matter in cytotoxic-type (ischemic) edema was isotropic. This observed difference in the biomechanical properties of brain tissue should be taken into account when the etiology of edema-mediated tissue injury, such as herniation, secondary bleeding or ischemia is investigated.
Kuroiwa
T
T
Department of Neuropathology, Tokyo Medical and Dental University, Japan.
Ueki
M
M
Chen
Q
Q
Ichinose
S
S
Okeda
R
R
D000818:Animals; D016880:Anisotropy; D001812:Blood-Brain Barrier / Q000502:physiology*; D001921:Brain / Q000473:pathology; D001929:Brain Edema / Q000473:pathology*; D001930:Brain Injuries / Q000473:pathology*; D002415:Cats; D002470:Cell Survival / Q000502:physiology*; D002544:Cerebral Infarction / Q000473:pathology*; D005615:Freezing; D008854:Microscopy, Electron; D009412:Nerve Fibers / Q000473:pathology; D014882:Water-Electrolyte Balance / Q000502:physiology