经颅多普勒血管搏动指数与脑血管反应性的关系

目的 研究经颅多普勒(TCD)搏动指数(PI)与脑血管反应性(CVR)的关系.方法 对70例PI增高患者(PI增高组)应用TCD行CO2吸入、过度换气和屏气试验检测CVR,并与PI正常者(正常对照组)进行比较.结果 (1)CO2吸入试验:PI增高组的大脑中动脉(MCA)平均血流速度(Vm)增加率[(21.61±7.39)%]明显低于正常对照组[(44.86±10.18)%] (P<0.01).(2)过度换气试验: PI增高组MCA Vm下降率[(21.89±6.60)%]明显低于正常对照组[(33.63±8.62)%](P<0.01).(3)屏气试验:PI增高组Vm增高率为(22.69±8.37)%、屏气指数为(0.58±0.24),显著低于正常对照组[(46.53±11.83)%、(1.16±0.37)](均P<0.01).结论 TCD PI增高可反映CVR下降.     

经颅多普勒超声结合二氧化碳试验评价颈内动脉狭窄患者的脑血管反应

目的:检测颈内动脉(intracranial artery,ICA)狭窄患者的脑血管反应性(CVR),探讨其狭窄程度与脑血管反应性之间的关系,以期为临床治疗及预防提供依据.方法:对不同程度ICA狭窄患者,采用德国DWL型经颅多普勒超声(TCD)检测仪,结合二氧化碳试验分别测得过度换气、吸入CO2气体、屏气后的大脑中动脉(MCA)的脑血流速度以计算CVR.结果:①病例组中ICA-MCA狭窄患者通过过度换气、吸入CO2气体、屏气后MCA的最大速度变化率、平均速度变化率均显著低于对照组(P＜0.05);②病例组轻、中、高度ICA狭窄或者闭塞ICA-MCA狭窄患者吸入CO2气体后各组MCA血流速度增加率依次减低,并且两两比较,P＜0.05,差异有显著意义.ICA-MCA狭窄患者由于血管狭窄、闭塞、血流受阻使CVR功能降低,狭窄程度越重,CVR功能越差,发生低灌注的危险性越大.结论:经颅多普勒超声检测CVR可行,可作为评估CVR的简便手段之一.     

经颅多普勒超声检测MCA与OA在原发性高血压病中的脑血流储备研究

目的运用经颅多普勒超声对高血压病患者大脑中动脉(MCA)和眼动脉(OA)血流储备及血管反应性研究,探讨其检查结果及临床意义。方法门诊随机抽取20例原发性高血压病患者40只眼及同时期体检健康20例正常对照组40只眼,运用经颅多普勒超声检查2组患者MCA及OA的平均血流速度(Vm)、屏气后的平均血流速度(Vm’)、搏动指数(PI)、屏气后的搏动指数(PI’)和屏气指数(BHI)的参数进行对比分析。结果高血压组与对照组比较:OA的平均血流速度(Vm)、屏气后的平均血流速度(Vm’)、搏动指数(PI)、屏气指数(BHI)与对照组比较均有统计学意义(P<0.05);MCA的搏动指数(PI)、屏气后的搏动指数(PI’)与对照组比较均有统计学意义(P<0.05)。结论通过对高血压患者MCA、OA的脑血管反应性检测,可以为高血压病患者早期及时提供防治依据。     

眼动脉血管反应性在2型糖尿病患者脑血管病变中的诊断价值

目的 评估眼动脉血管反应性在2型糖尿病脑血管病变中的临床诊断价值.方法 运用经颅多普勒诊断仪,对27例2型糖尿病患者和23例健康体检者行TCD检查,对比分析两组人群大脑中动脉(MCA)及眼动脉(OA)的平均血流速度(Vm)、搏动指数(PI)、屏气指数(BHI)的差异程度.结果 糖尿病组与对照组比较,OA的平均血流速度(Vm)、屏气后的平均血流速度(Vm’)、屏气指数(BHI)均降低,与对照组比较均有统计学意义;糖尿病组与对照组比较,MCA的搏动指数(PI)、屏气后的搏动指数(PI’)均增高,与对照组比较均有统计学意义.结论 糖尿病患者MCA、OA的脑血管反应性检测,能早期识别2型糖尿病大血管和微血管病变,为2型糖尿病患者早期及时提供防治依据.     

阻塞性呼吸睡眠暂停综合征与高血压并存患者脑血管功能状态的TCD初探

目的 研究分析阻塞性呼吸睡眠暂停综合征(OSAS)与高血压并存患者脑血管功能状态.方法 采用EME公司的COMPIONEⅡ型号经颅多普勒检查仪(TCD),对85例OSAS与高血压并存患者进行TCD检查,判断血管状态,采用屏气试验评价脑血管反应性,记录大脑中动脉(MCA)的平均血流速度(Vm)、搏动指数(PI),屏气指数(BHI)并与对照组比较,进行统计学分析.结果 两组间血管异常情况经χ~2检验,χ~2=4.1,P<0.05,差异有统计学意义.两组间的Vm经配对t检验,t=1.80,P>0.05差异无统计学意义.两组间的PI经配对t检验,t=1.62,P>0.05,差异无统计学意义.两组间BHI经配对t检验,t=4.75,P<0.01,差异有统计学意义.结论 OS-AS与高血压并存患者的脑血管功能状态与对照组比较脑血管反应性较差,更易发生动脉硬化,形成管腔狭窄.     

2型糖尿病视网膜病变患者的脑血管储备研究

目的通过对2型糖尿病伴视网膜病变(DR)与糖尿病无视网膜病变(NDR)患者的眼动脉(OA)反应性对比分析,为临床提供诊断及治疗依据。方法运用TCD诊断仪,分别对20例DR和21例NDR患者行TCD检查,收集2组患者大脑中动脉(MCA)及OA的平均血流速度(Vm)、搏动指数(PI)、屏气指数(BHI)的参数进行对比分析。结果 DR组与NDR组比较:OA的Vm、屏气后平均血流速度(Vm`)、屏气后搏动指数(PI`)、BHI,MCA的Vm均比较差异有统计学意义(P<0.05)。结论通过对2型糖尿病患者OA血管反应性检测,能发现DR患者OA血流储备下降更明显,该检查有助于早期发现病变,利于及时采取更加积极的治疗,防止失明。     

大脑中动脉狭窄患者脑血管反应性变化与脑梗死的关系

目的探讨大脑中动脉狭窄患者脑血管反应性变化与脑梗死的关系。方法 56例大脑中动脉狭窄患者（观察组）,按影像学表现和临床症状分为无脑梗死组（I组）30例,脑梗死（II组）26例,另设60例年龄、性别配对的健康者为对照组。常规经颅多普勒检查后进行屏气试验,记录屏气前后中动脉收缩期流速、舒张期流速、平均流速、搏动指数,计算屏气指数。结果观察组56例中,大脑中动脉单侧狭窄31例,双侧狭窄25例;中度狭窄37条血管,重度狭窄44条血管;屏气后各组搏动指数均减低,但对照组有显著性差异,中动脉狭窄组没有显著性差异;对照组屏气指数显著高于中动脉狭窄组,无症状组显著高于有症状组,中度狭窄组显著高于重度狭窄组。结论大脑中动脉狭窄患者脑血管反应性和脑储备功能减低,屏气指数是检测脑血管储备功能的重要指标,可以用于脑卒中的预测。     

大脑中动脉狭窄患者的脑血管反应性与脑梗死相关性研究

目的分析不同临床表现的大脑中动脉狭窄(MCAS)患者的脑血管反应性,探讨其与脑梗死的相关性。方法经经颅多普勒超声(TCD)检测大脑中动脉狭窄患者105例和48例健康对照组,根据症状、体征及脑CT或脑磁共振(MRI)检查将患者分为Ⅰ组(脑梗死组)和Ⅱ组(无脑梗死组),采用TCD屏气试验检测大脑中动脉的屏气指数(HBI),比较Ⅰ组和Ⅱ组与对照组之间的HBI,比较I组和Ⅱ组之间的HBI和血管危险因素。结果Ⅰ组和Ⅱ组的HBI明显低于对照组(P=0.000,P=0.004);Ⅱ组的HBI明显高于Ⅰ组(P=0.000)。Logistic回归分析HBI降低(P=0.000)和高血压(P=0.003)与大脑中动脉狭窄后脑梗死发生密切相关。结论脑血管反应性与脑梗死的发生有关,定期对高血压患者进行TCD及屏气试验监测并进行早期干预,能够预防脑梗死的发生。     

经颅多普勒超声结合屏气试验评价健康吸烟者脑血管反应性

目的 应用经颅多普勒超声联合屏气试验研究健康吸烟者脑血管反应性。方法 选取男性健康吸烟者46例,男性健康不吸烟者42例,采用经颅多普勒超声检测并记录双侧大脑中动脉（middle cerebral artery,MCA）多普勒频谱,检测参数包括收缩期峰值流速（peak systolicvelocity,PSV）,搏动指数（pulsatility index,PI）,阻力指数（resistance index,RI）,嘱受检者做屏气试验,记录屏气末双侧MCA多普勒频谱,测量参数同上,并计算屏气前后各参数变化率,通过参数变化率的大小分析脑血管反应性。结果 屏气后两组MCA峰值流速均表现为随屏气时间延长而增快,两组的PI及RI均降低,屏气前后各参数差异有统计学意义（P <0.05）。吸烟组屏气试验后PSV变化率为（23±7）％,不吸烟组为（37±9）％,两组间差异有统计学意义（P <0.05）;吸烟组屏气试验后PI值变化率为（19±5）％,不吸烟组为（25±8）％,两组间差异有统计学意义（P <0.05）;吸烟组屏气试验后RI值变化率为（21±6）％,不吸烟组为（35±7）％,两组间差异有统计学意义（P <0.05）。结论 健康吸烟者屏气后MCA的PSV、PI及RI的变化率均较健康不吸烟者减低,吸烟可使脑血管反应性降低。     

颈动脉狭窄患者的脑血管反应性研究

目的测定不同程度颈动脉狭窄患者的脑血管反应性,探讨颈动脉狭窄程度与脑血管反应性(CVR)的关系。方法应用TCD屏气试验,检测37例不同程度颈动脉狭窄患者双侧大脑中动脉(MCA)的屏气指数(BHI)及其不对称指数(AI),并对狭窄程度与BHI值的相关性进行评定。结果颈动脉狭窄程度≥70%的患者BHI值及不对称指数显著下降,狭窄程度与BHI值具有相关性。结论颈动脉重度狭窄患者的脑血管反应性明显降低,且与狭窄程度相关。     

Diagnostic Difficulties and Treatment Implications

Summary: Differentiation between types of epileptic seizures has been aided in recent years by the introduction of intensive neurodiagnostic techniques and the development of increasingly detailed classification systems. Paradoxically, these developments have not simplified the task of matching the appropriate antiepileptic drug to a particular seizure type. It is reasonable to assume that anticonvulsant drugs will have different effects on different types of seizures, but faulty, circular reasoning can enter the picture if one also assumes that responses of seizures to different drugs signify different seizure types. There are several examples of differential diagnoses that can fall prey to this problem, including the diagnosis between partial seizures with secondary generalization and generalized tonic-clonic seizures, and the diagnosis between complex partial seizures and absence seizures with automatisms, among others. Considerations of etiology in future classification systems can further complicate the problem: should one then choose an anticonvulsant drug on the basis of individual seizure type or on the basis of the type of epilepsy? Ramifications of this issue extend even to the drug approval process. Official sanction is not given for use of a drug for a seizure type not included in the original efficacy studies, even if later scientific evidence shows that seizure type to be related to a type that is included. New trials must be undertaken. These problems arise from how we choose to classify seizures.     

Cognitive Dysfunction Associated with Antiepileptic Drug Therapy

Summary: Epilepsy is frequently associated with cognitive dysfunction. However, the reasons for this correlation are unclear. Possible influential factors include patient age; duration, frequency, etiology, and type of seizures; hereditary factors; psychosocial issues; and antiepileptic drug (AED) therapy. Whereas many of these factors are beyond the physician's control, AED therapy is one element that can be addressed in treatment decisions by recognizing the potential cognitive effects of particular AEDs. For example, phenobarbital impairs memory and concentration; phenytoin affects attention, problem solving ability, and performance of visuomotor tasks. In contrast, carbamazepine may affect concentration, while valproate would appear to have minimal effects on cognition. Moreover, cognitive effects of AEDs are amplified with coadministration of multiple anticonvulsants (polytherapy). A review of studies on the cognitive effects of monotherapy with AEDs, as opposed to those of polytherapy, provides evidence that drug-related cognitive dysfunction can be reversed if patients are switched to a simpler therapeutic regimen. Future research should be directed toward developing reliable measures for assessing and monitoring cognition, and understanding the particular cognitive side effects of each AED. Physicians also need to revise their opinions about which side effects are "tolerable" for epileptic patients.     

Hepatic Considerations in the Use of Antiepileptic Drugs

Summary: Virtually all of the major antiepileptic drugs (AEDs) can cause hepatotoxicity, although fatal hepatic reactions are rare. The mechanisms, incidences, and risk profiles for such reactions differ from drug to drug. With carbamazepine and phenytoin, hepatotoxicity may be due to drug hypersensitivity. Although the profiles of patients at risk have not been well-defined for these two antiepileptic drugs, it would appear from reports in the literature that older adolescents and adults are at higher risk than children of developing serious or fatal hepatotoxicity. Once hepatotoxicity develops, mortality rates are 10–38% with phenytoin and 25% for carbamazepine. The risk profile for valproate fatal hepatotoxicity has been more clearly defined. Those at primary risk of fatal hepatic dysfunction are children under the age of 2 years who are receiving multiple anticonvulsants and also have significant medical problems in addition to severe epilepsy. The risk is considerably lower for patients over the age of 2 years on valproate monotherapy. In contrast to the risk profile with other AEDs, adults receiving valproate as monotherapy have the lowest risk of hepatotoxicity. Fatal hepatic dysfunction coincident with valproate may be the result of aberrant drug metabolism. Concomitant use of AEDs that induce microsomal P450 enzymes (e.g., phenytoin and phenobarbital) may enhance the production of a toxic metabolite, and hence the greater risk of hepatotoxicity with polypharmacy.     

Vascular Malformations and Epilepsy: Clinical Considerations and Basic Mechanisms

Summary: Vascular malformations (VMs) are associated with epilepsy. The natural history of the various VMs, clinical presentation, and tendency to provoke epilepsy determine treatment strategies. Investigations have probed the mechanisms of epileptogenesis associated with these lesions. Electrophysiologic changes are associated with epileptogenic cortex adjacent to VMs. Putative pathophysiologic mechanisms of epileptogenesis include neuronal cell loss, glial proliferation and abnormal glial physiology, altered neurotransmitter levels, free radical formation, and aberrant second messenger physiology.     

Carbamazepine Efficacy in Adults With Partial and Generalized Tonic-Clonic Seizures

Summary: Carbamazepine and phenytoin are drugs of choice in initial monotherapy for adult partial and secondarily generalized tonic-clonic seizures. These designations reflect the results of the Veterans Administration Epilepsy Cooperative Study Group of 1985. An earlier comparative study of carbamazepine and phenytoin by Ramsay and associates found both drugs equally effective in controlling new-onset seizures. Among the advantages of carbamazepine is that it causes relatively few cognitive and dysmorphic side effects. Its disadvantages are its unavailability in parenteral formulation and its metabolic autoinduction. The latter must be compensated for by planned dosage increases to maintain therapeutic plasma steady-state levels during the first 2 or 3 months of treatment. Carbamazepine is judged a drug of choice in the treatment of these secondarily generalized tonic-clonic seizures, and the drug of choice in children, adolescents, and women susceptible to the dysmorphic side effects associated with other anticonvulsant agents.     

Etiologic and Preventive Aspects of Epilepsy in the Child–Bridging the Gap Between Laboratory and Clinic

Summary: Four broad categories of basic phenomena are pertinent to developing ways to prevent epilepsy. These include mechanisms of epileptogenesis, ictal initiation and temporary entrainment by the seizure discharge of normally functioning brain, seizure propagation, and control mechanisms that function both to restrain the cascade of epileptic events culminating in a seizure and to arrest the epileptic event and restore the interictal state. In newborns and children, hypoxia-ischemia is a major factor leading to epileptogenesis, and several schemes are proposed to classify, quantify, and prevent hypoxic-ischemic encephalopathy. Control mechanisms must be better understood in order to develop prophylactic recommendations for epilepsy, and an experimental model of "kindling antagonism" may increase our understanding of these. Programs of prevention of seizures in children will evolve only if basic researchers and clinicians work productively together to develop an adequate understanding of factors important in epileptogenesis and antiepileptogenic control mechanisms.     

Carbamazepine Efficacy and Utilization in Children

Summary: Carbamazepine is effective for preventing partial and generalized tonic-clonic seizures in children. Although absence epilepsies are more common in children than adults, an estimated 80% of children with epilepsy have seizure types or epilepsies that are potentially responsive to carbamazepine. The differential diagnosis of ictal staring is an especially important issue in children because absence and atypical absence seizures are more prevalent in children than adults. Age-related pharmacokinetic differences and drug interactions are major considerations in children. On average, children have higher clearance rates of carbamazepine, shorter half-lives, and higher ratios of carbamazepine-10, 11-epoxide to carbamazepine than adults. In addition, children with severe epilepsy are more likely to require multiple-drug therapy, which can lead to complex drug interactions. When carbamazepine is administered along with valproate, drug protein binding interactions can cause intermittent side effects.     

Predisposing and Causative Factors in Childhood Epilepsy

Summary: We review information from large studies of defined populations, examining the role of known factors and especially of prenatal and perinatal factors in contributing to nonfebrile seizure disorders of early childhood. We depend especially, but not exclusively, on the recently completed analyses from the Collaborative Perinatal Project of the National Institute of Neurological and Communicative Disorders and Stroke, the NCPP. About 4% of children in the NCPP who had at least one non-febrile nonsymptomatic seizure by the age of 7 years had a previous seizure during acute neurologic illness, such as meningitis or during the acute illness after trauma. Many such seizures should potentially be preventable. Of children with seizures, 10% had had a neonatal seizure and 13% had had a febrile seizure. Among the hundreds of prenatal and perinatal factors explored as predictors of childhood seizure disorders, the principal predictors identified were congenital malformations of the fetus, cerebral and noncerebral; family history of certain neurologic disorders; and neonatal seizures. In agreement with the British National Child Development Study, labor and delivery factors in the NCPP appeared to contribute very little to childhood seizure disorders. Maldevelopment, rather than damage at birth to an initially intact nervous system, appeared to be the more common mechanism. Most seizure disorders of early childhood remained unexplained by the large set of prenatal and perinatal characteristics examined.     

Classification of methods in transcranial Electrical Stimulation (tES) and evolving strategy from historical approaches to contemporary innovations

Transcranial Electrical Stimulation (tES) encompasses all methods of non-invasive current application to the brain used in research and clinical practice. We present the first comprehensive and technical review, explaining the evolution of tES in both terminology and dosage over the past 100 years of research to present day. Current transcranial Pulsed Current Stimulation (tPCS) approaches such as Cranial Electrotherapy Stimulation (CES) descended from Electrosleep (ES) through Cranial Electro-stimulation Therapy (CET), Transcerebral Electrotherapy (TCET), and NeuroElectric Therapy (NET) while others like Transcutaneous Cranial Electrical Stimulation (TCES) descended from Electroanesthesia (EA) through Limoge, and Interferential Stimulation. Prior to a contemporary resurgence in interest, variations of transcranial Direct Current Stimulation were explored intermittently, including Polarizing current, Galvanic Vestibular Stimulation (GVS), and Transcranial Micropolarization. The development of these approaches alongside Electroconvulsive Therapy (ECT) and pharmacological developments are considered. Both the roots and unique features of contemporary approaches such as transcranial Alternating Current Stimulation (tACS) and transcranial Random Noise Stimulation (tRNS) are discussed. Trends and incremental developments in electrode montage and waveform spanning decades are presented leading to the present day. Commercial devices, seminal conferences, and regulatory decisions are noted. We conclude with six rules on how increasing medical and technological sophistication may now be leveraged for broader success and adoption of tES.     

Anticonvulsant Drugs and Cognitive Function: A Review of the Literature

Summary: Alterations of cognitive function are separate from disturbances of behavior seen in association with epilepsy. The nature of the cognitive disability may to a certain extent depend on the seizure type. Partial seizures, mainly derived from a temporal lobe focus, impair memory tasks, while generalized seizures seem to have more effect on attentional abilities. A number of studies, reviewed in this paper, suggest that anticonvulsant drugs further impair cognitive function. Maximal impairments are seen in patients receiving polytherapy: rationalization of polytherapy improves cognitive abilities. Studies in children and adults have allowed differentiation of the effects of various commonly used antiepileptic agents. Maximal cognitive deficits are seen with. phenytoin, while phenobarbital and sodium valproate induce moderate disturbances, and carbamazepine seems relatively free from such toxicity. Further research is needed on the interrelationship between types of seizure disorders, types of anticonvulsant medications, and cognitive function.