Journal of neurosurgery
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Journal of neurosurgery · Jul 2011
Gain-of-function polymorphisms of cystathionine β-synthase and delayed cerebral ischemia following aneurysmal subarachnoid hemorrhage.
Cystathionine β-synthase (CBS) is an enzyme that metabolizes homocysteine to form H(2)S in the brain. Hydrogen sulfide functions as a vasodilator as well as a regulator of neuronal ion channels and multiple intracellular signaling pathways. Given the myriad effects of H(2)S, the authors hypothesized that patients possessing gain-of-function polymorphisms of the CBS gene will experience a decreased incidence of delayed cerebral ischemia (DCI) following aneurysmal subarachnoid hemorrhage (aSAH). ⋯ Polymorphisms of the CBS gene that impart gain-of-function may be associated with a reduced risk of DCI after aSAH, independent of serum homocysteine. Signaling through H(2)S may mediate protection from DCI following aSAH through a mechanism that does not involve macrovascular vasodilation.
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Journal of neurosurgery · Jul 2011
Transient bilateral brainstem dysfunction caused by topical administration of papaverine.
Papaverine has been associated with transient cranial nerve dysfunction after topical application during craniotomy. The authors report similar dysfunction after the use of papaverine affected brainstem structures. Two patients undergoing craniotomy for clipping of an aneurysm experienced bilateral depression of cortical somatosensory evoked potentials to both median and tibial nerve stimulation after administration of papaverine. ⋯ Topical papaverine use may be associated with direct effects on brainstem structures. The transient nature of those changes suggests that aggressive intervention may not be needed. Maneuvers to limit the spread of papaverine to basal cisterns should be considered.
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Journal of neurosurgery · Jul 2011
Ventricle wall movements and cerebrospinal fluid flow in hydrocephalus.
The dynamics of fluid flow in normal pressure hydrocephalus (NPH) are poorly understood. Normally, CSF flows out of the brain through the ventricles. However, ventricular enlargement during NPH may be caused by CSF backflow into the brain through the ventricles. A previous study showed this reversal of flow; in the present study, the authors provide additional clinical data obtained in patients with NPH and supplement these data with computer simulations to better understand the CSF flow and ventricular wall displacement and emphasize its clinical implications. ⋯ The authors' MR imaging-based measurements of the CSF flow direction and lateral ventricle volume size change and the results of computer modeling of fluid dynamics lead them to conclude that the directional pattern and magnitude of CSF flow in patients with NPH may be an indication of the disease state. This has practical implications for shunt design and understanding the mechanisms that produce hydrocephalus.
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Journal of neurosurgery · Jul 2011
Relation between brain interstitial and systemic glucose concentrations after subarachnoid hemorrhage.
The aim in the present investigation was to study the relation between brain interstitial and systemic blood glucose concentrations during the acute phase after subarachnoid hemorrhage (SAH). The authors also evaluated the effects of insulin administration on local brain energy metabolism. ⋯ After SAH, there was a positive correlation between plasma and MD glucose concentrations with a high degree of individual variation. A gradual decline in MD glucose and the MD/plasma glucose ratio and an increase in MD pyruvate and MD lactate concentrations during the 1st week after SAH suggest a transition to a hyperglycolytic state with increased cerebral glucose consumption. The administration of insulin was related to a lowering of MD glucose and MD pyruvate, often to low levels even though plasma glucose values remained above 6 mmol/L. After SAH, the administration of insulin could impede the glucose supply of the brain.
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Journal of neurosurgery · Jul 2011
Lateral supracerebellar transtentorial approach for petroclival meningiomas: operative technique and outcome.
The retrosigmoid intradural suprameatal approach with the patient in a semisitting position is an effective alternative to transpetrosal approaches for the treatment of petroclival meningiomas. The authors have made a simple modification to the retrosigmoid intradural suprameatal approach by using the lateral oblique position and preferentially dividing the tentorium with limited drilling of the suprameatal bone, which is termed the "lateral supracerebellar transtentorial approach." ⋯ The lateral supracerebellar transtentorial approach provides the simplest and safest access to the petroclival region. It offers an advantageous approach to petroclival meningiomas exclusively located in the posterior fossa with minimal extension into the Meckel cave and middle fossa.