Transcranial magnetic stimulation reduces nociceptive threshold in rats

Transcranial magnetic stimulation (TMS) is a procedure that uses magnetic fields to stimulate or inhibit nerve cells in the brain noninvasively. TMS induces an electromagnetic current in the underlying cortical neurons. Varying frequencies and intensities of TMS increase or decrease excitability in the cortical area directly targeted. It has been suggested that TMS has potential in the treatment of some neurological disorders such as Parkinson's disease, stroke, and depression. Initial case reports and open label trials reported by several groups support the use of TMS in pain treatment. In the present study, we evaluated the effect of TMS on the nociceptive threshold in the rat. The parameters used were a frequency of 60 Hz and an intensity of 2 and 6 mT for 2 hr twice per day. After 5 days of TMS treatment, rats were evaluated for mechanical, chemical, and cold stimulation. We observed a significant reduction in the nociceptive threshold in TMS-treated rats but not in sham-treated rats in all behavioral tests evaluated. When TMS treatment was stopped, a slow recovery to normal mechanic threshold was observed. Interestingly, i.c.v. MK-801 or CNQX administration reverted the TMS-induced pronociception. The results suggest that high-frequency TMS can alter the nociceptive threshold and produce allodynia in the rats; results suggest the involvement of NMDA and AMPA/KA receptors on TMS-induced allodynia in the rat.     

Increases of corticospinal excitability in self-related processing

Involvement of fronto‐parietal structures within the right hemisphere in bodily self recognition has gained convergent support from behavioural, neuropsychological and neuroimaging studies. Increases in corticospinal excitability via transcranial magnetic stimulation (TMS) also testify to right hemisphere self‐related processing. However, evidence for self‐dependent modulations of motor excitability is limited to the processing of face‐related information that, by definition, conveys someone’s identity. Here we tested the hypothesis that vision of one’s own hand, as compared with vision of somebody else’s hand, would also engage specific self‐hand processing in the right hemisphere. Healthy participants were submitted to a classic TMS paradigm to assess changes in corticospinal excitability of the right (Experiment 1) and left (Experiment 2) motor cortex, while viewing pictures of a (contralateral) still hand, which could either be their own (Self) or not (Other). As a control for body selectivity, subjects were also presented with pictures of a hand‐related, but non‐corporeal object, i.e. a mobile phone, which could similarly be their own or not. Results showed a selective right hemisphere increase in corticospinal excitability with self‐hand and self‐phone stimuli with respect to Other stimuli. Such a Self vs. Other modulation of primary motor cortex appeared at 600 ms and was maintained at 900 ms, but was not present at earlier timings (100 and 300 ms) and was completely absent following stimulation of the left hemisphere. A similar pattern observed for self‐hand and self‐phone stimuli suggests that owned hands and objects may undergo similar self‐processing, possibly via a different cortical network from that responsible for self‐face processing.     

Differential modulation of motor cortex excitability in BDNF Met allele carriers following experimentally induced and use-dependent plasticity

The purpose of this study was to investigate how healthy young subjects with one of three variants of the brain‐derived neurotrophic factor (BDNF) gene modulate motor cortex excitability following experimentally induced and use‐dependent plasticity interventions. Electromyographic recordings were obtained from the right first dorsal interosseous (FDI) muscle of 12 Val/Val, ten Val/Met and seven Met/Met genotypes (aged 18–39 years). Transcranial magnetic stimulation of the left hemisphere was used to assess changes in FDI motor‐evoked potentials (MEPs) following three separate interventions involving paired associative stimulation, a simple ballistic task and complex visuomotor tracking task using the index finger. Val/Val subjects increased FDI MEPs following all interventions (≥ 25%, P < 0.01), whereas the Met allele carriers only showed increased MEPs after the simple motor task (≥ 26%, P < 0.01). In contrast to the simple motor task, there was no significant change in MEPs for the Val/Met subjects (7%, P = 0.50) and a reduction in MEPs for the Met/Met group (?38%, P < 0.01) following the complex motor task. Despite these differences in use‐dependent plasticity, the performance of both motor tasks was not different between BDNF genotypes. We conclude that modulation of motor cortex excitability is strongly influenced by the BDNF polymorphism, with the greatest differences observed for the complex motor task. We also found unique motor cortex plasticity in the rarest form of the BDNF polymorphism (Met/Met subjects), which may have implications for functional recovery after disease or injury to the nervous system in these individuals.     

经颅多普勒超声在不明原因缺血性脑卒中的应用研究

目的探讨经颅多普勒超声(transcranial Doppler,TCD)技术结合生理盐水发泡试验在不明原因缺血性脑卒中患者卵圆孔未闭(PFO)筛查中的应用价值。方法收集51例55岁以下不明原因缺血性脑卒中患者,行TCD结合生理盐水发泡试验和经胸超声心动图(TTE)检查。结果 51例患者中,23例患者TCD检查栓子信号阳性,其中18例患者TTE检查发现PFO,而在28例TCD检查栓子信号阴性的患者中未发现PFO;TCD检查阳性患者中偏头痛发病率、合并下肢深静脉血栓比例以及房间隔瘤比例较阴性者高(P<0.05)。结论 TCD结合生理盐水发泡试验是筛查PFO的有效手段,可以作为不明原因缺血性脑卒中病因筛查的手段。     

经阴道彩色多普勒超声对输卵管妊娠及妊娠黄体的鉴别诊断

目的探讨阴道彩色多普勒超声对输卵管妊娠及妊娠黄体的鉴别诊断价值。方法分析46例输卵管妊娠及妊娠黄体的阴道彩色多普勒超声图像特点。结果 46例患者术前均行阴道彩色多普勒超声检查提示为输卵管妊娠,其中44例与手术及病理组织学符合,阴道彩色多普勒超声与病理组织学符合率为95.65%;2例术前阴道彩色多普勒超声诊断输卵管妊娠,手术中证实为妊娠黄体,1周后确诊为宫内妊娠。结论经阴道彩色多普勒超声检查对输卵管妊娠与妊娠黄体的鉴别诊断具有重要的临床应用价值。     

彩色多普勒超声诊断颈动脉狭窄205例分析

目的探讨颈动脉狭窄的彩色多普勒超声声像特征。方法对205例颈动脉狭窄患者行颈动脉超声检查,观察斑块的部位、形态、大小及回声特征,计算管腔狭窄程度及血流指数。结果 205例颈动脉狭窄患者,二维超声发现300支颈动脉IMT增厚,200支伴有斑块形成,彩色多普勒超声发现所有颈动脉狭窄患者收缩期及舒张末期流速均显著性增高。结论彩色多普勒超声能准确地判定颈动脉狭窄程度及狭窄位置,可作为颈动脉管壁病变的一种优良检查手段,为临床提供可靠诊断依据,也能作为治疗后随访手段。     

超声微泡造影剂经导管直接溶栓治疗犬股静脉血栓的实验研究

目的研究超声联合微泡造影剂在体内的溶栓效应,并探讨其与尿激酶的协同作用。方法 13只健康犬建立血栓模型,分为对照组,尿激酶组,尿激酶加超声和微泡组,给予相应的治疗,应用超声多普勒,X线血管造影对血管的再通率进行评价,并进行病理学检查,比较各组溶栓效果。结果治疗后血管再通率尿激酶组与尿激酶加超声及微泡组均为100%,尿激酶加超声及微泡组再通等级优于尿激酶组。对照组血管再通率为0%,差异有统计学意义。光镜下观察,对照组股静脉管腔完全梗阻,血管壁见附壁血栓。尿激酶组、尿激酶加超声及微泡组股静脉管腔内部部分融通,局部区域内皮细胞脱落。结论超声联合微泡造影剂有一定的溶栓效应,与尿激酶共同应用,可以起协同作用。     

超声造影对肝脏恶性肿瘤射频治疗的疗效评估

目的探讨实时超声造影在肝脏恶性肿瘤射频治疗疗效评估的临床应用价值。方法对149例肝脏恶性肿瘤患者(168个病灶)在射频消融治疗后进行Sonovue实时超声造影检查,并与增强CT检查比较。结果 168个病灶中实时超声造影检查显示37个病灶有残留,增强CT检查显示39个病灶有残留。结论超声造影是评价肝恶性肿瘤射频消融治疗疗效的一种可靠方法。     

微血管多普勒超声在颅内动脉瘤夹闭术中的应用

目的 评价微血管多普勒超声(MDU)技术在颅内动脉瘤夹闭术中的应用.方法 回顾性分析32例开颅夹闭术治疗颅内动脉瘤病人的临床资料,均在动脉瘤夹闭前后行MDU监测载瘤动脉及穿支血管.并评价术中MDU的监测作用.结果 术中MDU监测提示:载瘤动脉闭塞3例,载瘤动脉狭窄6例,调整动脉瘤夹或局部应用罂粟碱湿敷后,MDU监测均恢复正常;其他病人MDU监测均正常.无监测相关并发症发生.所有病人随访3～26个月,术中MDU监测正常,但术后出现栓子脱落至脑梗死1例;其他病人术后均恢复良好.结论 术中MDU监测具有操作简便、结果可靠、无并发症等优点,能降低动脉瘤夹闭术中载瘤动脉及穿支动脉闭塞和狭窄的发生率.