Neurological research
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Neurological research · Sep 2002
Comparative StudyInfluence of inspired oxygen on glucose-lactate dynamics after subdural hematoma in the rat.
The mechanisms causing brain damage after acute subdural hematoma (SDH) are poorly understood. A decrease in cerebral blood flow develops immediately after the hematoma forms, thus reducing cerebral oxygenation. This in turn may activate mitochondrial failure and tissue damage leading to ionic imbalance and possibly to cellular breakdown. ⋯ We hypothesize that increased neural tissue oxygen tension, in presence of reduced regional CBF, and possibly compromised mitochondrial function, after acute SDH results in upregulation of rate-limiting enzyme systems responsible for both glycolytic and aerobic metabolism. Similar changes have been seen in severe human head injury, and suggest that a simple therapeutic measure, such as early ventilation with 100% O2, may improve cerebral energy metabolism, early after SDH. Further studies to measure the generation of adenosine triphosphate (ATP) are needed to validate the hypothesis.
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Neurological research · Jul 2002
Callosal anomalies in patients with spinal dysraphism: correlation of clinical and neuroimaging features with hemispheric abnormalities.
Dysgenesis of the corpus callosum can occur in association with spinal dysraphic lesions. Clinical and neuroimaging features were reviewed in 23 patients (12 male, 11 female; mean age 11.3 years) with caudal spinal dysraphism (myeloschisis in eight, meningomyelocele in 10, and lumbosacral lipoma in five) to characterize types and degrees of callosal and other cerebral anomalies. T1- and T2-weighted magnetic resonance images were obtained, and the total midsagittal cross-sectional area of the corpus callosum was determined. ⋯ All callosal anomalies were accompanied by hemispheric ones. This supports a disordered developmental relationship between the corpus callosum and the hemispheres as a cause. Spinal dysraphism can no longer be considered a single developmental abnormality, given the frequent association of other defects.
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Neurological research · Jun 2002
Review Comparative StudyPros, cons, and current indications of open craniotomy versus gamma knife in the treatment of arteriovenous malformations and the role of endovascular embolization.
The successful treatment of an intracranial arteriovenous malformation poses both technical and conceptual problems to the neurosurgeon. Treatment decisions are made in light of current understanding of the natural history of these lesions. It is important to understand the pros, cons and current indication of open craniotomy vs. gamma knife in the treatment of arteriovenous malformations and the role of endovascular embolization. ⋯ Although recent advances in technology and medical management have allowed previously inoperable arteriovenous malformations to be surgically excised, there is still a small group of arteriovenous malformations that cannot be excised safely due to their size and location. Stereotactic radiosurgery is clearly an important adjunct in the multimodality treatment approach for large arteriovenous malformations. Endovascular embolization can potentially increase safety and efficacy in the treatment of arteriovenous malformations when applied to selective cases with well-defined treatment goals.
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Neurological research · Apr 2002
The anatomy of the circle of Willis as a predictive factor for intra-operative cerebral ischemia (shunt need) during carotid endarterectomy.
The collateral flow to the cerebral hemisphere after carotid cross clamping during carotid endarterectomy is mainly through the circle of Willis, and the circle is incomplete in the majority of cases. A correlation between the status of the circle of Willis and the necessity of shunting was evaluated in 67 carotid endarterectomies with pre-operative four-vessel cerebral angiogram. All carotid endarterectomies were performed with selective shunting, based on the change of consciousness and motor function after carotid test clamping under regional anesthesia. ⋯ Twelve patients had neither anterior nor posterior communicating artery, and 10 (83.3%) showed signs of cerebral ischemia necessitating shunting. Mandatory shunt was significantly higher in patients with absence of collaterals (p = 0.00). The rate of intraoperative cerebral ischemia was significantly higher in patients with poor collateral circulation defined by the anatomy of the circle of Willis.
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Neurological research · Apr 2002
Adequate cerebral perfusion pressure during rewarming to prevent ischemic deterioration after therapeutic hypothermia.
Ischemic deterioration during rewarming is one of the most notable clinical complications after successful therapeutic cerebral hypothermia, but the mechanism is not completely understood. Hypothermia may cause vasoconstriction and relative ischemia, especially with insufficient cerebral perfusion pressure (CPP). Various parameters were evaluated to determine the critical CPP threshold to avoid ischemia during rewarming. ⋯ Extracellular glutamate significantly increased during the rewarming period only in the CPP= 40 mmHg group. CPP less than 60 mmHg during rewarming causes secondary ischemic insult, which might indicate continuation of cerebral vasoconstriction in hypothermia. CPP higher than 90 mmHg is required to avoid the potential risk of relative ischemia after hypothermia.