Effects of stimulus frequency and duration on somatosensory discrimination responses

Somatosensory processing of duration and frequency changes was investigated using event-related potentials to vibrotactile stimuli. Intermittent vibration to the fingertips of either hand was presented using a two-stimulus odd-ball paradigm (deviant P = 0.10). One group (N = 12, 18–38 years) was presented with stimulus pairs of 20/70, 50/150 and 170/250 ms. A second group (N = 10, 19–34 years) was tested using frequency pairs of 200/70 Hz. A psychophysical study examined the subjects’ ability to discriminate between different stimulus pairs. A clear negative shift in the response to the deviant stimulus was recorded with all the stimulus conditions used in both experiments. Both frequency changes and duration increments/decrements revealed an initial negativity in the subtraction waveform with a mean onset of 90–170 ms and a following positivity, both of which were dependent on the duration of the stimulus used. A significant decrease in the amplitude of both components was observed with the 170/250 ms pairing, coinciding with a positive correlation between individual discrimination performance and amplitude. These results support the existence of a somatosensory mismatch response with features similar to those of the aMMN and highlight the relevance of the somatosensory-specific positivity. Results from the duration experiment also resolve some of the discrepancies between previous studies.     

Multimodality evoked potentials and electroencephalography in severe coma cases

In a neurosurgical intensive care unit 26 patients with unconciousness and unresponsiveness were investigated by means of multimodality evoked potentials and electroencephalography in order to obtain information on the functional state of the nervous system. Multimodality evoked potential techniques allowed us to differentiate patients with EEG alterations due to drug treatment from those without therapy. The functional state and prognosis can be better evaluated by means of evoked potential techniques. Patients with raised intracranial pressure seem to undergo some characteristic alterations in PEP and far field potential derivations.     

成都地区成人听觉脑干诱发电位正常值测定

测定成都地区成人听觉脑干诱发电位(BAEPs)正常值。方法:95例正常听力成人,其中60岁以下72例,男34例,女38例,年龄20-75岁,平均40.7±10.3岁。记录C_z,参考电极A_1和A_2,地极FPz。耳机给短声(click)刺激,对耳耳机有白噪声屏蔽,刺激强度90和100dBHL。结果:本组BAEPs在10ms内Ⅰ、Ⅲ和Ⅴ波出现率均为100％,Ⅱ波为90％,Ⅳ波仅为75％。各波潜伏期随刺激强度增强而缩短,且与性别无关。峰间期不受刺激强度影响,但要受性别影响。双耳潜伏期与峰间期的差值亦不受刺激强度(Ⅰ波除外)的影响,但与性别有关。Ⅲ～Ⅴ/Ⅰ～Ⅲ比值60岁以下,小于1.60岁以上为1.01,该比值与性别无关。结论:成都地区成人BAEPs正常值特点与国内一些作者报告基本一致。     

孤独症谱系障碍儿童的视觉诱发电位研究

目的 探索孤独症谱系障碍儿童棋盘格翻转视觉诱发电位的特点。方法 采用美国精神障碍统计与诊断手册第四版(DSM-Ⅳ)诊断标准入组孤独症谱系障碍组12人;正常对照组12人。对所有对象进行5个不同空间频率刺激下的视觉诱发电位测试。结果 1) 5个不同的空间频率刺激下的P100波的潜伏期孤独症谱系障碍组均较对照组延长,差异有显著统计学意义(P<0.05)。2)5个不同的空间频率刺激下的P100波的振幅孤独症谱系障碍组均较对照组减小,差异有显著统计学意义(P<0.05)。结论 孤独症谱系障碍儿童棋盘格翻转视觉诱发电位中P100波潜伏期延长,波幅减小,表明其视网膜神经节细胞至视觉中枢的信息处理存在着异常,视觉传导通路中小细胞通路异常。     

Brainstem auditory electrophysiology is supressed in term neonates with hyperbilirubinemia

BackgroundWhether hyperbilirubinemia suppresses electrophysiological activity of the neonatal auditory brainstem remains to be investigated.AimTo determine whether hyperbilirubinemia suppresses the brainstem auditory electrophysiology in term neonates.MethodsMaximum length sequence brainstem auditory evoked response (MLS BAER) was recorded shortly after confirming hyperbilirubinemia in 58 term neonates. Wave amplitudes of the response were analyzed in detail.ResultsCompared with age-matched term controls, the neonates with hyperbilirubinemia showed a significant reduction in the amplitudes of MLS BAER waves III and particularly V at all click rates 91–910/s. The reduction tended to be more significant at higher than lower rates. Wave I amplitude was reduced at 910/s. V/I amplitude ratio was decreased at all click rates. Therefore, the amplitudes of MLS BAER, particularly later, waves were all reduced. The amplitudes of all MLS BAER waves tended to be reduced with the increase in total serum bilirubin level. All wave amplitudes were correlated with the level of total serum bilirubin at some or most click rates.ConclusionsBrainstem auditory electrophysiology is suppressed in neonates with hyperbilirubinemia, which related to the severity of hyperbilirubinemia. Wave amplitudes are valuable BAER variables to detect functional impairment of the brainstem and auditory pathway in neonatal hyperbilirubinemia, and are recommended to be used in assessing bilirubin neurotoxicity to the neonatal brain.     

Conservative surgical and microsurgical techniques for the management of dental implants that impinge on the inferior alveolar nerve

Loss of sensation in the lip after insertion of an implant is annoying. The aim of this paper was to describe two techniques for management of osseointegrated dental implants that impinge on the mandibular nerve, the purpose of which is to improve sensation without unscrewing the dental implant.     

听神经瘤的耳声发射观察

目的 观察和分析听神经瘤的耳声发射特点,为评估听神经瘤患者的耳蜗功能和选择保护听力的术式提供参考依据.方法 对20例（22耳）听神经瘤患者行纯音听阈、阻抗、听性脑干反应（auditory brainstem response,ABR）、诱发性耳声发射（evoked otoacoustic emissions,EOAE）测试及CT和（或）MRI扫描,能引出EOAE的瘤耳检测其自发性耳声发射（spontaneous otoacoustic emissions,SOAE）和传出抑制功能.结果 28.57%听神经瘤耳能引出EOAE,按其畸变产物耳声发射（distortion product otoacoustic emissions,DPOAE）特点分为三型：①“耳蜗型”3耳;②“非耳蜗型”2耳;③“混合型”1耳;“非耳蜗型”耳能引出强大的SOAE;能引出EOAE的6耳均有内侧橄榄耳蜗传出系统功能障碍.结论 EOAE可精确分析听神经瘤患者的耳蜗（外毛细胞）功能,部分听神经瘤病人存在“离断耳”现象.耳声发射（otoacousticemissions,OAE）在诊断重度感音神经性聋（包括听神经瘤病人）方面有一定潜能.     

全凭静脉麻醉中丙泊酚联合咪达唑仑对内隐记忆的影响

目的探讨术中丙泊酚联合咪达唑仑对内隐记忆的影响,分析内隐记忆消失的中潜伏期听觉诱发电位(MLA-EP)参数界值。方法全凭静脉麻醉下行择期手术患者30例,随机分为丙泊酚组(P)和丙泊酚联合咪达唑仑用药组(PM),每组15例。所有患者切皮2min后,让患者听录音带即内隐记忆刺激。记录入室时(T1)、气管插管后5min(T2)、切皮前2min(T3)、切皮后2min(T4)、内隐记忆刺激完成即刻(T5)等时点的心率(HR)、平均动脉压(MAP)、MLAEP。术后6h进行记忆调查,测定患者的模糊辨听率。结果全麻后Pa、Nb波潜伏期延长、波幅降低(P<0.01);丙泊酚组与联合用药组MLAEP的变化无显著性差异(P>0.05)。术中所有患者的外显记忆和内隐记忆均消失;模糊辨听率比较,组内、组间相比均无统计学差异(P>0.05)。结论麻醉剂量的丙泊酚[4.0~6.0mg/(kg·h)]可以消除外显记忆和内隐记忆。丙泊酚联合咪达唑仑可以消除外显记忆和内隐记忆。MLAEP参数Pa、Nb波潜伏期、波幅可以作为评价术中镇静深度的客观监测指标。     

Challenging the challenge: A randomized controlled trial evaluating the inflammatory response and pain perception of healthy volunteers after single-dose LPS administration,as a potential model for inflammatory pain in early-phase drug development

Background and aimsFollowing an infection, cytokines not only regulate the acute immune response, but also contribute to symptoms such as inflammatory hyperalgesia. We aimed to characterize the acute inflammatory response induced by a human endotoxemia model, and its effect on pain perception using evoked pain tests in two different dose levels. We also attempted to determine whether combining a human endotoxemia challenge with measurement of pain thresholds in healthy subjects could serve as a model to study drug effects on inflammatory pain.Methods and resultsThis was a placebo-controlled, randomized, cross-over study in 24 healthy males. Twelve subjects were administered a bolus of 1 ng/kg LPS intravenously, and twelve 2 ng/kg LPS. Before days of placebo/LPS administration, subjects completed a full study day without study drug administration, but with identical pain threshold testing. Blood sampling and evoked pain tests (electrical burst and -stair, heat, pressure, and cold pressor test) were performed pre-dose and at frequent intervals up to 10hr post-dose. Data were analysed with a repeated-measures ANCOVA. For both dose levels, LPS induced an evident acute inflammatory response, but did not significantly affect any of the pain modalities. In a post-hoc analysis, lowering of pain thresholds was observed in the first 3 h after dosing, corresponding with the peak of the acute inflammatory response around 1–3 h post-dose.ConclusionMild acute systemic inflammation, as induced by 1 ng/kg and 2 ng/kg LPS intravenous administration, did not significantly change pain thresholds in this study. The endotoxemia model in combination with evoked pain tests is not suitable to study acute inflammatory hyperalgesia in healthy males.     

脑干听觉及体感诱发电位对重型颅脑损伤病人预后的判断

目的分析探讨脑干听觉诱发电位(BAEP)及体感诱发电位(SEP)与重型颅脑损伤病人预后的关系。方法应用诱发电位仪对85例重型颅脑损伤患者早期行BAEP及SEP检查,并进行动态监测。结果重复检查BAEP及SEP均正常者,预后良好;BAEP及SEP均异常者,预后极差,与其他几组比较均有显著性差异(P<0.05)。结论BAEP与SEP联合应用并重复检查,可以比较准确的评估重型颅脑损伤患者的预后。