Haptic localization and the internal representation of the hand in space

As the hand actively explores the environment, contact with an object leads to neuronal activity in the topographic maps of somatosensory cortex. However, the brain must combine this somatotopically encoded tactile information with an internal representation of the hand's location in space if it is to determine the position of the object in three-dimensional space (3-D haptic localization). To investigate the fidelity of this internal representation in human subjects, a small tactual stimulator, light enough to be worn on the subject's hand, was used to present a brief mechanical pulse (6-ms duration) to the right index finger before, during, or after a fast, visually evoked movement of the right hand. In experiment 1, subjects responded by pointing to the perceived location of the mechanical stimulus in 3-D space. Stimuli presented shortly before or during the visually evoked movement were systematically mislocalized, with the reported location of the stimulus approximately equal to the location occupied by the hand 90 ms after stimulus onset. This pattern of errors indicates a representation of the movement that fails to account for the change in the hand's location during somatosensory delays and, in some subjects, inaccurately depicts the velocity of the actual movement. In experiment 2, subjects were instructed to verbally indicate the perceived temporal relationship of the stimulus and the visually evoked movement (i.e., by reporting whether the stimulus was presented before, during, or after the movement). On average, stimuli presented in the 38-ms period before movement onset were more likely to be perceived as having occurred during rather than before the movement. Similarly, stimuli in the 145-ms period before movement termination were more likely to be perceived as having occurred after rather than during the movement. The analogous findings of experiments 1 and 2 indicate that the same inaccurate representation of dynamic hand position is used to both localize tactual stimuli in 3-D space and construct the perception of arm movement.     

Functional imaging and localization of electromagnetic brain activity

Functional imaging of electric brain activity requires specific models to transform the signals recorded at the surface of the human head into an image. Two categories of model are available: single-time-point and spatio-temporal methods. The instantaneous methods rely only on the few voltage differences measured at one sampling point. To create a spatial image from this limited information, they require strict assumptions that rarely conform with the underlying physiology. Spatio-temporal models create two kinds of images: first, a spatial image of discrete equivalent multiple dipoles or regional sources, and second, an image of source current waveforms that reflect the temporal dynamics of the brain activity in circumscribed areas. The accuracy of the spatial image is model dependent and limited, but it can be validated from the spatio-temporal data by the "regional source imaging" technique, introduced here. The source waveforms are linear combinations of the scalp waveforms, and thus, specific derivations which image local brain activities at a macroscopic level. Brain source imaging of somatosensory evoked potentials revealed temporally overlapping activities from the brainstem, thalamus and from multiple sources in the region of the contralateral somatosensory projection areas.     

Preoperative anxiety and postoperative pain in women undergoing hysterectomy. A repeated-measures design

OBJECTIVES: To determine whether psychological variables such as preoperative anxiety can serve as predictors for the postoperative pain response. METHODS: The study sample included women who underwent elective abdominal hysterectomy (n=53). Two weeks prior to surgery, characteristics such as trait anxiety, coping style, and perceived stress were evaluated. Throughout the perioperative period, state anxiety, pain, as well as analgesic consumption were assessed at multiple time points. The anesthetic and surgical management were carefully controlled for and postoperative pain management was standardized. RESULTS: Path analysis demonstrated that there are both direct and indirect effects of preoperative state anxiety on postoperative pain. Preoperative state anxiety is a significant positive predictor of the immediate postoperative pain (beta=0.30), which, in turn, is a positive predictor of pain on the wards (beta=0.54). Pain on the ward, in turn, is predictive for pain at home (beta=0.30). CONCLUSION: The results of this study indicate that preoperative anxiety may have a critical role in the chain-of-events that controls the postoperative pain response.     

术中超声引导切除不可触及的乳腺病变

应用术中超声引导技术切除 65例女性患者 83处不可触及的乳腺病变 (nonpalpablebreastlesions ,NPBL) ,并对切除新鲜标本超声扫描确定NPBL是否已切除。 48处采用放射状切口 ,3 5处采用乳晕旁切口。切除标本最大直径10～ 3 0mm (平均 17 5mm) ,标本NPBL最大直径 5～ 17mm (平均 10 7mm) ,超声NPBL最大直径 6～ 19mm (平均11 9mm) ,NPBL的超声最大直径与标本最大直径呈高度一致 ,P <0 0 0 1。 83处NPBL首次切除标本中 ,4处超声未探及病灶 ,立即再切除获得成功。病理检查 :良性 78处 ,分别为 61处纤维腺瘤 ,5处管内乳头状瘤 ,12处纤维囊性乳腺病 ;恶性 5处 ,其中 2处为病理早期癌。恶性 5例追加改良根治术乳房标本无癌组织残留。良性患者术后 3～ 10个月随访 ,乳晕旁切口较放射状切口瘢痕更轻微 ,超声未发现复发病灶。初步研究的结果提示 ,术中超声引导切除NPBL是一种准确可行的手术方法 ,可以发现早期乳腺癌     

食管腔内超声食管癌术前分期评价

目的 评价腔内超声(EU)对食管癌术前分期的准确性.方法30例食管癌患者术前进行EU(5MH_z直径 10mm)检查,其中8例(26.7%)因狭窄严重未能对肿瘤进行全面探测.全部患者均接受手术治疗,将术前临床分期.EU分期的结果与术后病理分期进行对比分析.结果 术前临床分期正确率仅为40%.EU对肿瘤外侵程度(T)、区域淋巴结受累情况(N)及术前分期的正确率在全组分别为76.7%、66.7%和70.0%,若去除严重狭窄病例后上升为77.7%、77.7%和77.3%.结论 EU能相当准确地对食管癌进行术前分期,提示肿瘤有无外侵或淋巴结转移,为治疗提供指导.病灶周围炎症反应、肿瘤微转移灶及严重狭窄是影响分期正确性的重要因素.     

食管腺癌单纯手术与合并术前化疗比较

[目的]比较食管腺癌单纯手术与合并术前化疗的预后。[方法]单纯手术组91例，术前DDP，5FU联合化疗组16例，术前VP16、ADM、DDP联合化疗组22例，比较3组的生存率。[结果]单纯手术组91例手术死亡率2％，2年生存率24％，4年生存率8％。术前DDP、5FU联合化疗组16例，化疗后完全缓解1例（16％），部分缓解5例（31％），无效10例（63％），12例手术切除，1例由于化疗有关死亡，1例手术死亡，2、4年生存率均为42％。术前DDP、ADM、VP16联合化疗组22例，化疗后1例完全缓解（5％），11例部分缓解（50％），10倒无效（45％），18例手术切除，无手术死亡，2年生存率58％。[结论]术前化疗能明显提高食管腺癌病人的生存率，同时治疗应个体化。     

腔内超声对直肠癌术前分期诊断的应用价值

目的:评价腔内超声(ELUS)对直肠癌术前分期诊断的准确性及局限性.方法:对58例直肠癌术前行ELUS检查,参考TNM分期标准进行术前分期诊断,并与手术及术后病理结果对照.结果:ELUS对58例直肠癌浸润深度诊断符合率达79.3%,T1、T2、T3、T4各期诊断灵敏度分别为100%、58.8%、87.5%、83.3%.对T2期诊断灵敏度最低,误诊7例中6例过深判断为T3期,且均为溃疡型腺癌.ELUS对54例直肠癌淋巴结转移诊断灵敏度、特异度、准确度分别为76.9%、75.0%、75.9%.淋巴结转移ELUS漏诊6例,淋巴结转移ELUS诊断假阳性7例.结论:ELUS对直肠癌浸润深度及肠周淋巴结转移诊断准确度较高,可成为直肠癌术前分期诊断良好的方法.对T2期的过深判断为影响诊断符合率的重要因素,肿瘤导致肠腔明显狭窄或肿瘤位于直肠上段也影响ELUS的准确性.     

Dipole-source analysis in a realistic head model in patients with focal epilepsy

PURPOSE: By the use of three different head models in EEG dipole analysis, we tried to model the origin of interictal and ictal epileptic activity as precisely as possible. Further, as a control, a second evaluation was made by an independent group to control for interindividual reliability of the dipole source analysis. With the realistic head model (CURRY) considering cortex, skull, and skin segmentation, the spike source was located. METHODS: In five patients with mesial temporal epileptogenesis, confirmed by successful epilepsy surgery, the spike source was close to the hippocampus, with a mean distance of the dipole source from the hippocampus of 13.6 mm (range, 9-17.2 mm). In one case the ictal EEG also could be analyzed and resulted in a dipole-source localization comparable to the interictal source. RESULTS: In both head models using either pure cortex segmentation only or a concentric three-shell model, the dipole source was systematically dislocated in a more superior position. Data analysis by a second group with independently chosen EEG samples and identical individual head model resulted in deviations of <5.3 mm. Data analysis using independently selected spikes and independently segmented head models resulted in deviations < or =16.7 mm. CONCLUSIONS: In four cases of extratemporal epileptogenesis, the origin of interictal epileptiform discharges was localized to the suspected primary epileptogenic zone.