The increase of cerebrospinal fluid nitrate after SAH may attribute to the endogenous nitric oxide production in the injured brain.

Three unusual cases of sphenoethmoidal mucoceles with rare intracranial extension are reported. A 64-year-old female presented with a 7-month history of right visual disturbance. Computed tomography (CT) and magnetic resonance (MR) imaging demonstrated a huge mass in the right middle fossa. She underwent right frontotemporal craniotomy. Postoperatively, her proptosis and cranial nerve dysfunction had improved markedly. A 53-year-old female complained of headache, nausea , and dizziness. CT and MR imaging revealed a cystic mass filling the right sphenoid sinus. The cystic le sion was evacuated through the transnasal approach. She was doing well postoperatively and has been asymptomatic.A 39-year-old male complained of headache, vomiting, and right visual disturbance. CT and MR imaging demonstrated a homogeneous mass occupying the sphenoid sinus. Sphenoidotomy exposed the cyst extending superiorly into the anterior cranial fossa. He recovered from the visual disturbances and has been asymptomatic since. MR imaging provides confirmation of the diagnosis of sphenoethmoidal mucocele and is important for preoperative evaluation.

This report describes a study of brain stem blood flow (BBF) change under various grades of brain stem ischemia in a new experimental rat model. The main damage was caused by occlusion of the median and paramedian perforating arteries of the basilar artery. In this model, hyperperfusion was generally observed in cases of mild or moderate ischemia within 1 hr after recirculation and lasted for approximately 1 hr. During hyperperfusion, BBF increased to over 60 ml/100 g brain/min and was significantly greater than basal values (p <0.01). The fact that hyperperfusion was unobserved in some cases might be due to the degree of damage to the medulla oblongata. Hypoperfusion or lack of reflow phenomena was also followed by severe ischemia with remarkable hypotension. It is fairly clear from our results that the pattern of postischemic hyperperfusion is responsible for decreased oxygen availability in the brain stem and dysfunction of autoregulation. Acetazolamide reactivity was disturbed and had an inverse response during hyperperfusion. Such phenomena can be explained by paralytically dilated vessels due to ischemia. If BBF falls below a critical level, as we have seen, postischemic hyperperfusion may be induced with dysfunction of autoregulation and inverse acetazolamide reactivity due to vasoparalysis in the brain stem. brain stem ; ischemia ; recirculation ; blood flow ; rat Permanent and transient experimental ischemic models have recently been developed using various laboratory animals. Rats in particular have many advantages : a) They are relatively inexpensive even when a large number of experiments are necessary ; and b) The use of small brain ischemia models has become important as a result of the development of quantitative autoradiographic techniques for investigating cerebrovascular system function. Though there have been many supratentorial ischemic models using variety of techniques, there have been few involving the posterior fossae. This report describes a study of brain stem blood flow (BBF) change under various grades of brain stem ischemia in a

The majority of multiple meningiomas are associated with von Recklinghausen's disease, and those that are not, i.e., true multiple meningiomas, particularly with simultaneous development in the posterior fossa and spinal canal, are very rare. We recently encountered a case of true multiple me ningiomas in which the lesions were found simultaneously in the left posterior fossa and the upper thoracic spinal canal. The spinal meningioma consisted mainly of meningotheliomatous components, and that in the posterior fossa of fibroblastic components. Both tumors were surgically removed.The cause of the multiplicity in cases of true multiple meningiomas is unknown. Incidental multiplic ity is a consideration when the number of tumors is relatively small. Spinal meningiomas are often undetected in the absence of neurological symptoms. However, even if von Recklinghausen's disease is not present, and particularly when more than two meningiomas have been discovered, the patient must be carefully examined for other tumors.

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