Articles: brain-injuries.
-
Journal of neurotrauma · Aug 1998
Effects of moderate, central fluid percussion traumatic brain injury on nitric oxide synthase activity in rats.
Experimental traumatic brain injury (TBI) damages cerebral vascular endothelium and reduces cerebral blood flow (CBF). The nitric oxide synthase (NOS) substrate, L-arginine, prevents CBF reductions after TBI, but the mechanism is not known. This study examined the possibility that post-traumatic hypoperfusion is due to reductions in the substrate sensitivity of NOS which are overcome by L-arginine. ⋯ Total cortical soluble NOS activity in TBI-treated rats was not significantly different from either untreated or sham groups when 0.45 microM or 1.5 microM L-arginine was added. Also, there were no differences in cell-dependent NOS activity among the three groups stimulated by 300 microM N-methyl-D-aspartate, 50 mM K+, or 10 microM ionomycin. These data suggest that TBI reduces CBF by a mechanism other than altering the substrate specificity or activation of nNOS.
-
Journal of neurotrauma · Aug 1998
Endothelial-mediated dilations following severe controlled cortical impact injury in the rat middle cerebral artery.
The mechanisms associated with dysfunction of the cerebral vasculature following head trauma have not yet been fully elucidated. In an attempt to shed more light on the matter, we investigated the endothelial-mediated dilations in the rat middle cerebral artery (MCA) following severe traumatic brain injury (TBI). Rats were subjected to severe controlled cortical impact injury (CCI; 5 m/s, 130 ms duration, 3 mm deformation) over the right parietal cortex. ⋯ The constriction to L-NAME was significantly reduced in TBI MCAs compared to sham vessels. Dilations to SNAP, an NO donor, were not altered by TBI indicating that the mechanisms of dilation involving NO in the vascular smooth muscle were not affected. Unlike other pathological conditions which often diminish endothelial-mediated responses, severe TBI enhanced the sensitivity to 2MeSATP without altering the maximum response.
-
In recent years, new devices for epidural pressure (EDP) measurement have been developed, with claims of improved accuracy. However, there have been no new data from simultaneous pressure measurements to reverse the skepticism regarding this technique. ⋯ The reliability of EDP measurement has not improved, compared with 10 years ago. Using this technique, one must be aware of the possibility of overestimating intracranial pressure by more than 10 mm Hg and the possibility of significant drifting of EDP over time, which argues against the use of this method even for trend analysis.
-
To examine the effects of age on outcome in persons with traumatic brain injury. ⋯ Older adults clearly show less complete recovery 1 year after brain injury than younger adults, either because they have reduced reserves with which to tolerate brain injury or because their physiologic status creates a more destructive injury. Glasgow Coma Scale alone may underestimate the severity of brain injury in the aged as well as its associated consequences. Caution is advised in generalizing findings based principally on younger individuals to older adults with traumatic brain injuries.
-
Journal of neurosurgery · Aug 1998
Selection of severely head injured patients for mild hypothermia therapy.
The authors have analyzed the efficacy of inducing mild hypothermia (34 degrees C) in 62 severely head injured patients to control fulminant intracranial hypertension. ⋯ The authors conclude that mild hypothermia is effective for preventing ICP elevation in patients without diffuse brain swelling in whom ICP remains higher than 20 mm Hg but less than 40 mm Hg after conventional therapies.