磁敏感加权成像在中枢神经系统疾病中的应用研究

磁敏感加权成像(SWI)是一种利用不同组织间的磁敏感度的差异产生影像对比的磁共振成像方法,它不同于以往的质子密度、T1WI、T2WI成像技术及磁共振血管成像等方法,对静脉结构、血液代谢产物及铁质沉积非常敏感[1].     

A central nervous system action of nitric oxide in blood pressure regulation.

We had reported that the systemic administration of N omega-methyl-L-arginine (L-NMA), a specific inhibitor of nitric oxide (NO) synthesis from L-arginine (ARG), raises arterial blood pressure (BP) while paradoxically enhancing central sympathetic outflow. Cervical spinal cord transection abolishes the increase in sympathetic outflow and attenuates the pressor effect of L-NMA. Thus, in addition to lowering BP by direct vasorelaxation, NO may also act in the central nervous system to reduce vascular sympathetic tone. To test this hypothesis we have injected L-NMA directly into the central nervous system in anesthetized rats. Intracisternally (i.c.), L-NMA elicited a small pressor response accompanied by a marked increase in sympathetic renal nerve activity (RNA). In contrast, the inactive stereoisomer N omega-methyl-D-arginine had neither pressor nor neural effects. The increases in RNA and BP elicited by i.c. L-NMA were abolished by spinal cord transection at C1 to C2 and by the i.v. administration of ARG. When administered i.c., ARG also abolished the increase in RNA elicited by i.v. L-NMA and significantly attenuated the pressor response. Thus, our findings indicate that L-NMA acts centrally by an ARG-reversible mechanism in the anesthetized rat to stimulate sympathetic nerve activity. Inasmuch as centrally synthesized NO has been postulated to play a second messenger and/or neurotransmitter role, our findings suggest that one such function would be the central regulation of sympathetic outflow and hence, BP.     

经颅低强度聚焦超声在中枢神经调控中的研究进展

神经调控技术为神经回路功能障碍所致疾病的治疗提供了新的思路,经颅低强度聚焦超声作为一项新的技术,与经颅磁刺激和经颅电刺激相比,其穿透能力更强,且可聚焦于毫米级区域,实现更为精准的神经调控。本文以特发性震颤、帕金森病、阿尔茨海默病及抑郁症为例,对近年来经颅低强度聚焦超声在中枢神经调控中的研究进展进行综述。     

Isolated central nervous system histoplasmosis

A solitary localized Histoplasma infection of the central nervous system, a "histoplasmoma," may mimic a neoplastic brain tumor clinically and radiographically and should be considered in a differential diagnosis of localized central nervous system mass lesions.     

Primary central nervous system lymphoma

Primary central nervous system lymphomas constitute less than 2% of primary brain tumors. Although their cause is unknown, they are in some way related to immunosuppression. The typical patient is a middle-aged man who displays the syndrome of a subacute mass lesion. These tumors most commonly occur as a single, bulky mass in the hemispheric white matter or the deep gray matter, but multiple tumors occur in approximately a fourth of the patients. The findings on computed tomography are distinctive and nearly pathognomonic. The majority of these tumors are B-cell lymphomas with aggressive histologic changes. Surgical intervention should be reserved for tissue diagnosis because surgical removal does not seem to influence the outcome. Conventional therapy consists of whole-brain irradiation with or without chemotherapy. The prognosis for patients with such tumors is grim, the median duration of survival being less than 2 years with conventional therapy and the 5-year survival being less than 5%.     

Infections of central nervous system shunts

Approximately 1 out of every 10 ventricular shunts for hydrocephalus will become infected. This represents a three- to fivefold increase in infection rate compared with other neurosurgical procedures. Most often, the infection results from colonization of the shunt device by normally nonpathogenic skin flora at the time of surgery. Properties of the foreign body itself may contribute to this increased risk of infection, and most infections are clinically apparent within the first 6 months following surgery. Meticulous surgical technique remains one of the most important variables in reducing shunt infection while the role of prophylactic antibiotics is still unclear. When a shunt infection is suspected, percutaneous needle aspiration of the shunt reservoir is most always diagnostic. Fluid specimens should be sent for Gram smear, culture, and susceptibility testing. Appropriate systemic antibiotics should be started. In most instances, the infected patient should be treated by external ventricular drainage and intraventricular antibiotics until the CSF is sterilized. The drain should then be removed and a new shunt placed. Immediate removal of the infected shunt with simultaneous replacement by a new shunt in a different location also has a high cure rate but carries an increased risk of subsequent infection. With few exceptions, antibiotic therapy alone or partial shunt revision will be unsuccessful, and these therapies carry increased morbidity and mortality rates due to prolonged shunt infection. Despite the frequency of shunt surgery and its high rate of infection, a well-organized investigational approach to this problem has been lacking. Both laboratory and clinical investigation needs to explore new shunting techniques, biomaterials, the role of antibiotics, and microbial factors involving host defenses and the shunt apparatus itself.     

Toxoplasmosis of the central nervous system

Toxoplasmosis is usually an asymptomatic infection, but symptomatic cases are becoming more common with the rise in AIDS cases and the increased number of patients receiving immunosuppressive therapy. Toxoplasmosis of the central nervous system occurs most often in immunocompromised hosts. Brain biopsy may be necessary for diagnosis. Pyrimethamine and sulfadiazine are active against T. gondii, but they do not affect the encysted organisms.     

AIDS of the central nervous system

The central nervous system of nearly every HIV-positive patient becomes affected by the AIDS virus itself or by one of the associated diseases during the course of the illness. Early diagnosis of lesions which demand therapeutic consequences is of the most importance concerning prolongation of life and improvement in its quality. In spite of the frequent underestimation of cerebral involvement by imaging methods and their unspecific findings they are often the only diagnostic means which permit-timely diagnosis and, at least in some diseases, therapeutic monitoring. Indications for cranial computed tomography (CCT) or magnetic resonance tomography (MRT) are already present with mild or transient neurological or psychiatric symptoms or the extracerebral manifestation of neurotropic organisms or tumours which metastasize to the brain, even in patients without subjective complaints.     

Alcohol and the central nervous system

Acute Wernicke-Korsakoff syndrome is an underdiagnosed cause of reversible coma in the alcoholic patient. Chronic toxic effects of ethanol include nutritional polyneuropathy, cerebellar degeneration, and diffuse cortical damage with resultant alcoholic dementia. The rapid correction of hyponatremia can result in the iatrogenic syndrome of central pontine myelinolysis.     

HIV and the central nervous system

Neurological complications of HIV infection are common with clinically recognized disorders ultimately affecting between 40% and 75% of patients. The spectrum of neurological disease is broad. This article highlights the common disorders of the central nervous system associated with HIV/AIDS.