急性脑梗死脑磁图脑诱发磁场发生源空间位置特征研究

目的:研究急性脑梗死患者体感皮层中枢和听觉皮层中枢脑磁图(MEG)变化特征。方法:对15例急性脑梗死患者于发病后3-4周进行体感诱发磁场(SEFs)和听觉诱发磁场(AEFs)检测,同时检测健康志愿者作为对照。SEFs电刺激部位为腕部正中神经处,电流脉冲宽度0.3ms,刺激间隔0.5s。AEFs采用双耳纯音刺激,频率2KHz,声音强度90dB,刺激间隔ls,持续时间8ms,脑磁图检查后进行MRI超薄扫描。结果:SEFs的最主要波峰为M20,其ECD均位于体感皮层中枢,AEFs为M100,位于两侧颞横回。两侧ECD位置三维不对称性由(△X2+△Y2+△Z2)1-2表示,SEFs和AEFs测定患者组均较正常对照组不对称性增大。结论:MEG可灵敏地检测出急性脑梗死患者皮层中枢功能损伤。     

急性脑梗死听觉皮层中枢脑磁图特征

目的 研究急性脑梗死患者听觉皮层中枢脑磁图(MEG)变化特征。方法 对15例急性脑梗死患者于发病后3-4周进行听觉诱发磁场(AEFs)检测,同时检测9名健康志愿者作为对照。采用双耳纯音刺激,诱发双侧听觉皮层兴奋。纯音频率2 kHz,声音强度90 dB,刺激间隔1s,纯音持续时间8ms。脑磁图检查后进行MRI超薄扫描。AEFs波峰由等价电流偶极子(ECD)评估。结果两组AEFs的最主要波峰为M100,其ECD位于两侧颞横回。患者组多个AEFs参数均存在异常,即:(1)健康对照组两侧M100 ECD空间位置差值为(14.9±10.6)mm;患者组为(18.6±3.3)mm,患者组不对称性增大(P<0.05);(2)健康对照组M100潜伏期为(89.3±27.9)ms;患者组(97.0±6.0)ms.患者组潜伏期明显延迟(P<0.05);(3)患者患侧ECD强度为(17.2±4.8)nA,健侧ECD强度为(30.5±5.9)nA,患侧ECD强度减小(P<0.01)。结论 MEG可灵敏地检测出急性脑梗死患者听觉皮层中枢功能损伤,并能够客观地评价该病听觉皮层中枢的功能状态。     

急性枕叶脑梗死患者视觉皮质中枢脑磁图变化特征

目的研究急性枕叶脑梗死患者视觉皮层中枢脑磁图(MEG)的变化特征。方法对6例急性单侧枕叶梗死表现为对侧视野同向偏盲患者于发病后2周内行视觉诱发磁场(VEFs)测试,并检测8名健康志愿者作为正常对照。刺激选取黑白棋盘格翻转图形。分别记录两组受试者VEFs的M100波峰产生的潜伏期、波形、等电流偶极(ECD)强度和磁源性影像(MSI)。结果所有受试者VEFs反应的最基本波形为M100,位于距状裂两侧的皮质。与正常对照组相比,患者健侧枕叶的VEFs反应波形,潜伏期和ECD强度并无明显差异(均P>0.05),而患侧枕叶的VEF反应则出现了波形异常,潜伏期明显延长和ECD强度显著降低(均P<0.05)异常,且MSI显示其M100反应的ECD位置分布紊乱。结论MEG可检测出急性枕叶脑梗死患者视觉皮质中枢功能的损伤,并能够客观的评价患者视觉皮层中枢的功能状态。     

男性精神分裂症患者视觉诱发磁场的初步研究

目的:以脑磁图(MEG)研究精神分裂症患者视觉诱发磁场(VEFs)的特点. 方法:20例男性精神分裂症患者(患者组)和13名正常人(对照组),给予右眼左半垂直视野黑白翻转格图形视觉刺激,记录受试者VEFs的M100波形、潜伏期、振幅及激活脑区的等电流偶极(ECD)的磁源性影像(MSI)的XYZ值. 结果:所有受试者VEFs的最基本波形为M100,位于距状裂两侧的皮质.与对照组比较,患者组VEFs的M100波形存在异常,潜伏期明显延长,振幅显著降低(P均<0.05);且ECD的XYZ值显示其M100反应的ECD位置在X轴上分布偏移. 结论:MEG可检测出精神分裂症患者VEFs存在异常,其视觉皮质中枢功能亦存在异常.     

急性脑梗死患者图片命名脑磁图特征研究

目的:研究急性脑梗死患者在图片命名任务中脑磁图(MEG)的特征。方法:对13例单侧急性脑梗死表现出运动性失语症状的患者于发病后1～2周进行图片命名测试,同时用MEG记录了在此过程中大脑皮层相应功能区产生反应的潜伏期和磁场强度。结果:在图片命名任务中,有以下脑区域被激活:双侧枕叶、双侧颞枕叶交界区、优势半球Wernicke区、优势半球Broca区等脑区域。患者组出现:(1)优势半球Wernicke区反应ECD强度nAm与对照组nAm相比明显降低(P<0.05);(2)优势半球Broca区反应ECD强度降低;而潜伏期与对照组ms相比明显延迟。结论:MEG可灵敏的检测出急性脑梗死患者由于语言形成中枢相关皮质区域神经元及皮质下纤维的损伤而导致的优势半球Wernicke区和Broca区反应潜伏期和ECD强度发生的改变,并能客观的评价该中枢功能的损伤程度。     

脑中央区占位性病变患者体感诱发磁场的变化

目的 探讨脑中央区占位病变患者体感诱发磁场的变化.方法 应用脑磁图仪对9例脑中央区占位病变患者及60名正常对照者行腕部正中神经刺激,记录体感诱发磁场M20的潜伏期及磁源性影像三维定位;分析M20潜伏期及磁源性影像与脑中央占位病变性质的关系.结果 9例脑中央区占位病变患者中,2例M20潜伏期及三维定位正常,其手术后病理结果为脑膜瘤;7例潜伏期及三维定位异常患者的手术后病理结果6例为星形细胞瘤,1例为淋巴细胞瘤.结论 脑中央区占位病变患者体感诱发磁场变化对判断肿瘤性质有一定的意义.     

脑磁图在颅脑损伤中的应用

脑磁图与MRI融合后的磁源成像图在鉴别脑震荡后遗症状的患者是否存在脑功能障碍方面优于EEG或MRI,比EEG或MRI在轻型颅脑损伤中提供的客观依据更敏感,脑磁图磁场活性的异常低频表现为脑震荡后综合征患者提供了一个客观证据,并与症状恢复程度相关。近来研究对严重颅脑损伤后长期昏迷的患者用MEG测量刺激双侧正中神经引起的躯体感觉磁场区域来评估皮质体感功能,认为弥漫性脑损伤导致躯体感觉传入冲动在原躯体感觉皮层减少与延迟,并引起代偿性反应扩张。通过MEG测定的体感诱发区域的中潜伏期对严重颅脑损伤患者是有用的皮层功能测定。     

磁源成像在母语为汉语正常人的语言功能定位中的应用

目的 采用脑磁图（magnetoencephalograph，MEG）的等价电流偶极子定位法（Equivalent current dipole，ECD）和合成孔径磁场定位法（SAMSynthetic、Aperture Magnetometry，SAM）定位母语为汉语的健康自愿者的语占中枢，探讨汉字的语言处理过程。方法 对10例母语为汉语的健康受试者给予默读真词、假词的语言任务刺激，记录刺激后产生的诱发磁场，将采集的数据与MRI叠加获得磁源性影像（MSI Magnetic source imaging）语占功能区定位川同样的方法对4例胶质瘤患者进行术前语言功能区定位，术中皮层电刺激所定位语言功能区，明确是否产生言语障碍。结果 所有受试者真词、假词均在双侧大脑半球诱发出明显的晚期磁反应波，左侧大脑半球磁反应波分化较右侧大脑半球好，Broea区俯于额下回后部，Wernicke区位于颞中同、颢上回、缘上回，Wernieke区先于Broca区出现。胶质瘤患者术巾电刺激所定位的Broca区、Wernicke区均产生言语障碍：结论母语为汉语的正常人的Broca区Wernieke区与经典的语言中枢糕本相符，MEG定位语言中枢的技术是可行的。     

母语为汉语正常人听觉性语言中枢的定位

目的采用脑磁图(magnetoencephaiography MEG)的等价偶极子定位法(equivalent current dipole,ECD)和合成孔径磁场定位法(SAM Synthetic Aperture Magnetometry SAM)定位母语为汉语健康自愿者的听觉性语言中枢探讨汉字的语言加工过程。方法采用北京医科大学附属第一医院制定的利手评定标准,对15例母语为汉语的健康受试者进行利手评定。给予听动物名称、植物名称的语言任务刺激,采用MEG记录刺激后产生的诱发磁场。将采集的数据与MRI叠加获得听觉性语言中枢定位。结果所有受试者听动物名称、植物名称均在双侧大脑半球诱发出明显的晚发磁反应波,其中左侧大脑半球磁反应波分化较右侧大脑半球好。听觉性语言中枢定位于左侧颞中回、颞上回、缘上回。结论母语为汉语的正常人听觉性语言中枢与经典的语言中枢基本相符,即听觉性语言中枢定位于左侧颞中回、颞上回,缘上回。     

精神分裂症患者情绪图片刺激脑磁图比较

目的:比较精神分裂症患者不同情绪图片刺激脑磁图的差异。方法:精神分裂症患者和正常对照者均给予相同的情绪图片刺激,记录每次给图片刺激前150ms至刺激后750ms所诱发脑磁场的位置及频数。结果:与正常对照组相比,不同情绪图片刺激时精神分裂症患者所激活视觉皮质位置无明显偏移,顶叶、额叶、颞叶及枕叶所诱发的磁场频数均无明显差异;当抑郁情绪图片刺激时,精神分裂症患者扣带回和颞上回(尤其右颞上回)所诱发的磁场频数比正常对照组增多,而颞顶交界处所诱发的磁场频数减少;当愉快情绪图片刺激时,精神分裂症患者额极所诱发的磁场频数比正常对照组增多。结论:本研究证实精神分裂症患者情绪视觉信息加工过程存在异常。     

Magnetoencephalography for clinical pediatrics: The effect of head positioning on measurement of somatosensory-evoked fields

OBJECTIVE: At present, whole-head MEG systems are designed to accommodate adult heads, thereby introducing a technical issue unique to pediatric MEG. It is known that magnetic field strength decreases as a function of 1/distance(2). For pediatric patients, we questioned whether re-positioning the head to minimize the distance between the expected source location and the MEG sensor array would significantly improve source measurement. METHODS: Somatosensory-evoked fields (SEFs) were recorded in 17 children (mean=4.96 years) with their head placed centrally in the MEG, and then re-positioned laterally to reduce the distance between the cortical source and sensors. Equivalent current dipole (ECD) source models were evaluated for changes in residual variance (RV), signal-to-noise ratio (SNR), moment (strength), and location. RESULTS: Re-positioning the head closer to the sensors resulted in a significant shift in the mediolateral dipole coordinate location, accompanied by a significant increase in the SNR, decrease in the dipole RV, and a reduction in size of ECD confidence volumes. CONCLUSIONS: We conclude that for clinical pediatric measurement of the SEF, repositioning of the head to minimize the distance between the expected SEF source location and the sensor array will significantly improve SEF source measurement and concomitant ECD source modeling. SIGNIFICANCE: These issues are relevant to all pediatric MEG settings involving healthy or clinical populations and underscores the need for future development of a MEG helmet specifically designed for pediatric populations.     

Magnetoencephalographic representation of the sensorimotor hand area in cases of intracerebral tumour

OBJECTIVE: To assess the clinical value of magnetoencephalography (MEG) in localising the primary hand motor area and evaluating cortical distortion of the sensorimotor cortices in patients with intracerebral tumour. METHODS: 10 normal volunteers (controls) and 14 patients with an intracerebral tumour located around the central region were studied. Somatosensory evoked magnetic fields (SEFs) following median nerve stimulation, and movement related cerebral magnetic fields (MRCFs) following index finger extension, were measured in all subjects and analysed by the equivalent current dipole (ECD) method to ascertain the neuronal sources of the primary sensory and motor components (N20m and MF, respectively). These ECD locations were defined as the primary hand sensory and motor areas and the positional relations between these two functional areas in controls and patients were investigated. RESULTS: The standard range of ECD locations of MF to N20m was determined in controls. In 11 of the 14 patients, MRCFs could identify the primary motor hand area. ECD locations of MF were significantly closer to the N20m in the medial-lateral direction in patients than in controls. In patients with a tumour located below the sensorimotor hand area, relative ECD locations of MF to N20m moved anteriorly over the standard range determined in the control subjects. These MEG findings correlated well with radiological tumour locations. The mean estimated ECD strength of MF was significantly lower in patients than in controls. CONCLUSIONS: MRCF was useful in localising the primary motor hand area in patients with intracerebral tumour. The relative ECD locations of MF to N20m describe the anatomical distortion of the sensorimotor cortex.     

Quantitative analysis of MEG using modified sLORETA for clinical application

OBJECTIVE: To determine whether standardised low-resolution brain electromagnetic tomography modified for a quantifiable method (sLORETA-qm) can be used for quantitative analysis in magnetoencephalography (MEG). METHODS: Somatosensory evoked fields (SEFs) were obtained from 10 hemispheres of five healthy volunteers stimulated on the median nerve at 0.75, 1.0, 1.25, 1.5, 1.75 and 2.0 x threshold of thenar muscle twitch (TMT). N20 m intensity changes were analysed quantitatively using sLORETA-qm. Then, SEFs were measured with stimulation on the median nerve at 1.5 x TMT from 47 hemispheres in 24 subjects. sLORETA-qm intensity and the equivalent current dipole (ECD) moment of N20 m were calculated, and relationships between the values were evaluated. RESULTS: sLORETA-qm intensity increased linearly with stimulus intensity between 0.75 and 1.5 x TMT, and tended to reach a plateau or decrease at higher stimulus intensities. The distribution of sLORETA-qm intensity after natural logarithmic transformation was normal and a close correlation was found between the ECD moment and sLORETA-qm intensity (r(s)=0.91, p<0.001). CONCLUSIONS: The results of this study focusing on N20 m suggested that sLORETA-qm is reliable for quantitative analysis of MEG as well as ECD models. SIGNIFICANCE: sLORETA-qm appears promising for quantitative analyses of MEG for which ECD models are inappropriate.     

Maturation of somatosensory cortical processing from birth to adulthood revealed by magnetoencephalography

ObjectiveTo evaluate the maturation of tactile processing by recording somatosensory evoked magnetic fields (SEFs) from healthy human subjects.MethodsSEFs to tactile stimulation of the left index finger were measured from the contralateral somatosensory cortex with magnetoencephalography (MEG) in five age groups: newborns, 6- and 12–18-month-olds, 1.6–6-year-olds, and adults. The waveforms of the measured signals and equivalent current dipoles (ECDs) were analyzed in awake and sleep states in order to separate the effects of age and vigilance state on SEFs.ResultsThere was an orderly, systematic change in the measured and ECD source waveforms of the initial cortical responses with age. The broad U-shaped response in newborns (M60) shifted to a W-shaped response with emergence of a notch by 6 months of age. The adult-type response with M30 and M50 components was present by 2 years. The ECDs of M60 and M30 were oriented anteriorly and that of M50 posteriorly. These maturational changes were independent of vigilance state.ConclusionsThe most significant maturation of short latency cortical responses to tactile stimulation takes place during the first 2 years of life.SignificanceThe maturational changes of somatosensory processing can noninvasively be evaluated with MEG already in infancy.     

Somatosensory-evoked fields on magnetoencephalography for epilepsy infants younger than 4 years with total intravenous anesthesia.

OBJECTIVE: Patients must remain immobile for magnetoencephalography (MEG) and MRI recordings to allow precise localization of brain function for pre-surgical functional mapping. In young children with epilepsy, this is accomplished with recordings during sleep or with anesthesia. This paper demonstrates that MEG can detect, characterize and localize somatosensory-evoked fields (SEF) in infants younger than 4 years of age with or without total intravenous anesthesia (TIVA). METHODS: We investigated the latency, amplitude, residual error (RE) and location of the N20m of the SEF in 26 infants (mean age=2.6 years). Seventeen patients underwent TIVA and 9 patients were tested while asleep, without TIVA. RESULTS: MEG detected 44 reliable SEFs (77%) in 52 median nerve stimulations. We found 27 reliable SEFs (79%) with TIVA and 13 reliable SEFs (72%) without TIVA. TIVA effects included longer latencies (p<0.001) and lower RE (p<0.05) compared to those without TIVA. Older patients and larger head circumferences also showed significantly shorter latencies (p<0.01). CONCLUSIONS: TIVA resulted in reliable SEFs with lower RE and longer latencies. SIGNIFICANCE: MEG can detect reliable SEFs in infants younger than 4 years old. When infants require TIVA for MEG and MRI acquisition, SEFs can still be reliably observed.     

急性脑血管病患者血清和脑脊液中胰岛素样生长因子-1的测定及其临床意义

目的　探讨急性脑血管病患者血清及脑脊液中胰岛素样生长因子 - 1(IGF - 1)浓度的变化及其临床意义。方法　观察 40例脑血管病患者和 2 0例正常人血清及脑脊液IGF - 1浓度。病例组 :脑梗死组2 0例 ,脑出血组 2 0例 ,所有患者均在发病后第 3天抽取静脉血 2ml,其中脑梗死组在抽血当天作腰穿抽取脑脊液 2ml。IGF - 1采用酶联免疫分析方法测定。应用SPSS统计软件包进行统计分析 ,组间比较采用t检验。结果　病例组与对照组血清中IGF - 1浓度有明显统计学差异 (P <0 .0 1) ,脑梗死组与脑出血组血清中IGF - 1浓度无统计学差异 (P >0 .0 5 )。脑梗死组与对照组脑脊液中IGF - 1浓度有明显统计学差异 (P <0 .0 1)。结论　脑梗死和脑出血患者急性期血清IGF - 1浓度明显降低 ,脑梗死组患者急性期脑脊液IGF - 1浓度明显增高。     

急性脑梗死患者血浆同型半胱氨酸水平及其干预治疗探讨

目的 探讨急性脑梗死患者给予维生素B_(12)制剂(甲钴胺)和叶酸(Fa)治疗前后血浆同型半胱氨酸(Hcy)、叶酸和维生素B_(12)水平变化及其对预后的影响.方法 检测152例急性脑梗死患者和132例正常人血浆同型半胱氨酸(Hcy)、叶酸、维生素B_(12)水平,并对急性脑梗死患者进行神经功能缺损评分(NIHSS);将急性脑梗死组随机分为干预组和非干预组,干预组给予维生素B_(12)制剂(甲钻胺)联合叶酸治疗,治疗4周后复测血浆同型半胱氨酸(Hcy)、叶酸和维生素B_(12)水平,并再次进行神经功能缺损评分(NIHSS).结果 急性脑梗死组和正常健康对照组之间血浆Hcy水平、叶酸和维生素B_(12)水平存在明显差异(P<0.01),予以补充叶酸和维生素B_(12)(甲钴胺)治疗后,干预组血浆Hcy水平明显下降,神经功能缺损评分显著升高,与非干预组相比有显著性差异(P<0.05).结论 急性脑梗死患者血浆Hcy水平升高,补充叶酸、维生素B_(12)制剂有助于降低血浆Hcy水平,有利于脑梗死疾病的转归.

Abstract：

Objective To explore the changes of the levels of plasma homocysteine ( Hcy), folate and vitamin B_(12) and the relationship between the changes and the prognosis in patients with acute cerebral infarction who were treated with vitamin B_(12) preparation (methylcobalamin) and folate. Methods The plasma level of Hcy, folate and vitamin B_(12) ( VitB_(12)) of 152 patients with cerebral infarction and 132 healthy people were measured, and the patients with acute cerebral infarction were given a mark with the evaluation of neurological impairments (NIHSS). The patients with acute cerebral infarction were randomly divided into intervention group and non-intervention group. The intervention group was treated with vitamin B_(12) preparations (methylcobalamin) and folate. After 4 weeks, retested the plasma homocysteine (Hcy), folate and vitamin B_(12) levels, and carried out NIHSS score once again. Results In the plasma level of Hcy, folate and vitamin B_(12), there were significant differences between the acute cerebral infarction group and the healthy control group (P < 0.01 ). In intervention group, the plasma homocysteine levels decreased significantly, and the evaluation scores increased significantly after intervention treatment, and there was significant differences between intervention group and non-intervention group (P <0.05). Conclusion The levels of plasma Hcy increased in the patients with acute cerebral infarction. Being added with folate and vitamin B_(12) preparations was well to reduce the levels of plasma Hcy, and it was also conducived to the prognosis of acute cerebral infarction.