正中神经副根变异1例

<正>笔者在解剖1具男性尸体时,发现其左侧正中神经起始部位存在1副根变异。经查阅相关资料,此类变异较为少见,为积累解剖学资料并为临床工作提供形态学依据,现报道如下。尸体来源于华北理工大学基础医学院解剖学教研室,成年男性,50岁左右,身长168cm。该例左侧臂丛各根、干、股、束形成正常。正中神经由来自臂丛内、外侧束的3根合成,其中1根来自臂丛内侧束,2根来自臂丛外侧束(包括1外侧主根和1外侧副根)。正中神经内侧根自臂丛内侧束发出,长5.     

Variations of Median Nerve in Carpal Tunnel and its Distribution in Hand

Aim of the study was to study the variations in the branching pattern of median nerve in the carpal tunnel and hand, which would form useful data for hand surgeons doing open/endoscopic carpal tunnel release. Median nerve and its branches were explored by dissection in fifty hands of twenty-five formalin fixed adult human cadavers over a period of three years. We found variations in 35 out of 50 hands. Based upon Lanz classification, frequency of variations in present series was variation in the course of thenar branch (58%), accessory branches at the distal portion of the carpal tunnel (34%), high divisions of the median nerve (8%) and accessory branches proximal to the carpal tunnel (nil). Rare variations including transligamentous median nerve and multiple thenar branches were also observed. Medial take off of thenar branch as observed in this series has special clinical significance in carpal tunnel release. Knowledge of the variable anatomy of median nerve would help to avoid incomplete decompression at operations for nerve entrapment and injury to thenar branch.     

Responses to Median and Tibial Nerve Stimulation in Patients with Chronic Neuropathic Pain

Somatosensory evoked magnetic fields and electrical potentials were measured in eight patients with unilateral neuropathic pain. After median nerve stimulation on the painful side, the amplitudes of the evoked responses were enhanced 2 to 3 times at a latency of about 100 ms compared to the responses of the contralateral, unaffected side. After posterior tibial nerve stimulation an enhancement was found at latencies around 110 ms and 150 ms. The scalp distribution of the magnetic field at the latencies of abnormal responses was dipolar and the responses could be ascribed to a current dipole. Three (of the eight) patients underwent spinal cord stimulation (SCS) for their pain. The enhancement of the evoked responses to stimulation of the painful side decreased after spinal cord stimulation. After a long period of spinal cord stimulation only (e.g., a year) during which the patient reported to be pain free, these abnormal responses were no longer observed.     

Charcot-Marie-Tooth 1A Concurrent with Schwannomas of the Spinal Cord and Median Nerve

We identified Charcot-Marie-Tooth disease type 1A (CMT1A) in a family with schwannomas in the spinal cord and median nerve. The CMT1A in this family showed an autosomal dominant pattern, like other CMT patients with PMP22 duplication, and the family also indicated a possible genetic predisposition to schwannomas by ''mother-to-son'' transmission. CMT1A is mainly caused by duplication of chromosome 17p11.2-p12 (PMP22 gene duplication). A schwannoma is a benign encapsulated tumor originating from a Schwann cell. A case of hereditary neuropathy with liability to pressure palsies (HNPP) concurrent with schwannoma has been previously reported. Although it seems that the co-occurrence of CMT1A and schwannomas in a family would be the result of independent events, we could not completely ignore the possibility that the coincidence of two diseases might be due to a shared genetic background.     

Variability and Reliability of Paired-Pulse Depression and Cortical Oscillation Induced by Median Nerve Stimulation

Paired-pulse depression (PPD) has been widely used to investigate the functional profiles of somatosensory cortical inhibition. However, PPD induced by somatosensory stimulation is variable, and the reasons for between- and within-subject PPD variability remains unclear. Therefore, the purpose of this study was to clarify the factors influencing PPD variability induced by somatosensory stimulation. The study participants were 19 healthy volunteers. First, we investigated the relationship between the PPD ratio of each component (N20m, P35m, and P60m) of the somatosensory magnetic field, and the alpha, beta, and gamma band changes in power [event-related desynchronization (ERD) and event-related synchronization (ERS)] induced by median nerve stimulation. Second, because brain-derived neurotrophic factor (BDNF) gene polymorphisms reportedly influence the PPD ratio, we assessed whether BDNF genotype influences PPD ratio variability. Finally, we evaluated the test–retest reliability of PPD and the alpha, beta, and gamma ERD/ERS induced by somatosensory stimulation. Significant positive correlations were observed between the P60m_PPD ratio and beta power change, and the P60m_PPD ratio was significantly smaller for the beta ERD group than for the beta ERS group. P35m_PPD was found to be robust and highly reproducible; however, P60m_PPD reproducibility was poor. In addition, the ICC values for alpha, beta, and gamma ERD/ERS were 0.680, 0.760, and 0.552 respectively. These results suggest that the variability of PPD for the P60m deflection may be influenced by the ERD/ERS magnitude, which is induced by median nerve stimulation.     

MRI-Apparent Localized Deformation of the Median Nerve Within the Carpal Tunnel During Functional Hand Loading

In MR images, the median nerve of carpal tunnel syndrome (CTS) patients frequently appears flatter than in healthy subjects. The purpose of this work was to develop a metric to quantify localized median nerve deformation rather than global nerve flattening, the hypothesis being that localized median nerve deformation would be elevated in CTS patients. Twelve patients with CTS and 12 matched normals underwent MRI scanning in eight isometrically loaded hand conditions. 2D cross sections of the proximal and distal tunnel were analyzed for nerve cross sectional area, flattening ratio, and a position shift to the dorsal side of the tunnel. Additionally, new metrics based on the angulation of the nerve perimeter in 0.5-mm lengths around the boundary were calculated. The localized deformation metrics were able to detect differences between CTS patients and healthy subjects that could not be appreciated from the flattening ratio. During most hand activities, normal subjects had a higher average percentage of locally deformed nerve boundary than did CTS patients, despite having a rounder overall shape. Less local nerve deformation in the CTS patient group resulting from its interaction with flexor tendons suggests that the nerve may be less compliant in CTS patients.     

Cortical Characterization and Inter-Dipole Distance Between Unilateral Median Versus Ulnar Nerve Stimulation of Both Hands in MEG

Summary Contralateral somatosensory evoked fields (SEF) by whole head MEG after unilateral median and ulnar nerve stimulation of both hands were studied in 10 healthy right-handed subjects. Major parameters describing cortical activity were examined to discriminate median and ulnar nerve evoked responses. Somatic sensitivity showed high similarity in the 4 study conditions for both hand and nerve. The brain SEFs consisted of 7–8 major peak stages with consistent responses in all subjects at M20, M30, M70 and M90. Comparable inter-hemispheric waveform profile but high inter-subject variability was found. Median nerve induced significantly shorter latencies in the early activities than those of the ulnar nerve. The 3D cortical maps in the post stimulus 450 ms timeframe showed for both nerves two polarity reversals, an early and a late one which is a new finding. Dipole characteristics showed differential sites for the M20 and M30 in the respective nerve. Higher dipole moments evoked by the median nerve were noticed when compared to the ulnar. Furthermore, the results of the dipole distances between both nerves for M20 were calculated to be at 11.17 mm ± 4.93 (LH) and 16.73 mm ± 5.66 (RH), respectively after right hand versus left hand stimulation. This study showed substantial differences in the cortical responses between median and ulnar nerve. Especially the dipole distance between median and ulnar nerve on the cortex was computed accurately for the first time in MEG. Little is known however of the cortical responses in chronic pain patients and the parameter(s) that may change in an individual patient or a group. These results provide precise basis for further evaluating cortical changes in functional disorders and disease sequelae related to median and ulnar nerves.     

正中神经返支血供的解剖学研究及其临床意义

目的:为修复正中神经返支提供带血管蒂神经桥接的理论基础和有关数据。方法:用体视学方法研究了60例灌注红色乳胶液的返支营养血管,观察其长度和内径、来源、进入神经干的方式。结果:营养动脉长度2.86±0.12mm,内径0.23±0.03mm,从返支主干的近1/3进入占88.8％,由神经的掌面,尺侧进入占74.5％。来源动脉起自掌浅弓凹侧的筋膜支,起占至“零点”的距离11.64±2.27mm,内径0.52±0.08mm,长度10.04±1.26mm。结论:返支营养动脉的来源动脉适宜做带血管蒂神经移植的受体血管。     

右正中神经电刺激对高血压脑出血后昏迷患者早期促醒治疗的研究

目的 探讨早期右正中神经电刺激对于高血压脑出血后昏迷患者的促醒效果以及对其远期康复的影响。方法 选择2016年1月~2018年6月安徽医科大学附属安庆医院收治的高血压脑出血性昏迷患者41例,按照随机数字表法分为对照组（n=20）和实验组（n=21）,对照组给予常规临床治疗,实验组在此基础上增加右正中神经电刺激治疗。通过比较两组患者治疗前后的脑电图（EEG）评分、格拉斯哥昏迷量表（GCS）、残疾分级量表（DRS）评分、NICU住院日以及6个月时两组患者的苏醒率,了解早期右正中神经电刺激对于高血压脑出血性昏迷患者的疗效。结果 在接受不同治疗措施后,实验组NICU住院日低于对照组,6个月的苏醒率高于对照组,两组间差异有统计学意义（P＜0.05）;在治疗后的不同时间维度,实验组的EEG评分,GCS评分,DRS评分均优于对照组,差异有统计学意义（P＜0.05）。结论 右正中神经电刺激治疗可提高HICH昏迷患者苏醒率,减少NICU平均住院日,改善患者预后,提高生存质量。该方案经济有效,操作简便,作为一种早期临床辅助促醒治疗措施,值得临床借鉴应用。     

Clustering of Early Cortical Responses to Median Nerve Stimulation from Average and Single Trial MEG and EEG Signals

Summary: Median nerve electrical stimulation (MNES) produces early and strong averaged magnetoencephalography (MEG) or electroencephalography (EEG) signals, despite considerable single trial (ST) variability, demonstrated in separate MEG and EEG studies. Here, simultaneous MEG/EEG recordings are used to assess whether same or different aspects of ST variability are influencing EEG and MEG. Clustering techniques provided groupings for the ST timeseries for cortical responses to MNES derived from one modality. These groupings were applied to the corresponding ST timeseries derived from the other modality to quantify the similarity in variability captured by MEG and EEG signals. Estimates of early cortical activity elicited by MNES derived from MEG and EEG signals were very similar, provided ongoing mu rhythm was removed. Similarity between EEG and MEG estimates included both results based on average signals and measures of ST variability. Either MEG or EEG can provide a robust measure of the early cortical activity elicited by MNES as well as of its variability. Reliable indices of early cortical responses to MNES can be derived from either MEG or EEG data. These indices can be based on average signals, as is routinely done with clinical EEG, but it could also rely on hitherto little utilized measures of ST variability.     

Median artery revisited

This study confirms that the median artery may persist in adult life in 2 different patterns, palmar and antebrachial, based on their vascular territory. The palmar type, which represents the embryonic pattern, is large, long and reaches the palm. The antebrachial type, which represents a partial regression of the embryonic artery is slender, short, and terminates before reaching the wrist. These 2 arterial patterns appear with a different incidence. The palmar pattern was studied in the whole sample (120 cadavers) and had an incidence of 20%, being more frequent in females than in males (1.31), occurring unilaterally more often than bilaterally (41) and slightly more frequently on the right than on the left (1.11). The antebrachial pattern was studied in only 79 cadavers and had an incidence of 76%, being more frequent in females than in males (1.61); it was commoner unilaterally than bilaterally (1.51) and was again slightly more prevalent on the right than on the left (1.21). The origin of the median artery was variable in both patterns. The palmar type most frequently arose from the caudal angle between the ulnar artery and its common interosseous trunk (59%). The antebrachial pattern most frequently originated from the anterior interosseous artery (55%). Other origins, for both patterns, were from the ulnar artery or from the common interosseous trunk. The median artery in the antebrachial pattern terminated in the upper third (74%) or in the distal third of the forearm (26%). However, the palmar pattern ended as the 1st, 2nd or 1st and 2nd common digital arteries (65%) or joined the superficial palmar arch (35%). The median artery passed either anterior (67%) or posterior (25%) to the anterior interosseous nerve. It pierced the median nerve in the upper third of the forearm in 41% of cases with the palmar pattern and in none of the antebrachial cases. In 1 case the artery pierced both the anterior interosseous and median nerves.     

神经导管修复周围神经损伤的研究进展

随着神经修复技术特别是显微外科的发展，神经损伤修复的质量有了进一步的提高；利用神经导管桥接神经断端以实现修复周围神经损伤是目前的一个研究热点。本综述了神经导管修复周围神经损伤的发展历史，分析比较了非神经组织、非生物降解材料、可生物降解材料神经导管在神经损伤修复中的效果，讨论了导管的形态及导管内微环境对神经再生的影响。     

Brain Cortical Mapping by Simultaneous Recording of Functional Near Infrared Spectroscopy and Electroencephalograms from the Whole Brain During Right Median Nerve Stimulation

To investigate relationships between hemodynamic responses and neural activities in the somatosensory cortices, hemodynamic responses by near infrared spectroscopy (NIRS) and electroencephalograms (EEGs) were recorded simultaneously while subjects received electrical stimulation in the right median nerve. The statistical significance of the hemodynamic responses was evaluated by a general linear model (GLM) with the boxcar design matrix convoluted with Gaussian function. The resulting NIRS and EEGs data were stereotaxically superimposed on the reconstructed brain of each subject. The NIRS data indicated that changes in oxy-hemoglobin concentration increased at the contralateral primary somatosensory (SI) area; responses then spread to the more posterior and ipsilateral somatosensory areas. The EEG data indicated that positive somatosensory evoked potentials peaking at 22 ms latency (P22) were recorded from the contralateral SI area. Comparison of these two sets of data indicated that the distance between the dipoles of P22 and NIRS channels with maximum hemodynamic responses was less than 10 mm, and that the two topographical maps of hemodynamic responses and current source density of P22 were significantly correlated. Furthermore, when onset of the boxcar function was delayed 5–15 s (onset delay), hemodynamic responses in the bilateral parietal association cortices posterior to the SI were more strongly correlated to electrical stimulation. This suggests that GLM analysis with onset delay could reveal the temporal ordering of neural activation in the hierarchical somatosensory pathway, consistent with the neurophysiological data. The present results suggest that simultaneous NIRS and EEG recording is useful for correlating hemodynamic responses to neural activity.     

Median sep and blink reflex in thyroid diseases

Pathological disturbances of thyroid hormones is associated with central and peripheral nervous system disturbances. The aim of this study is to evaluate median nerve stimulated somatosensory evoked potential (SEP) and blink reflex of thyroid patients (hypo and hyperthyroidism). Median SEP was performed in 40 patients (21 with hyperthyroidism and 19 with hypothyroidism). We evaluated the latencies of N9, N11, N13, P9, P11, P14, N20 and P25 waves and the N9-N20, N9-N13, N13-N20 and P14-N20 interpeak latencies. We compared the results of patients with the control group (26 persons). We found that the N20 latency was longer in patients with hyperthyroidism than in the control group and the difference was statistically significant. There was not any statistically significant difference regarding the N9, N11, N13, P9, P11, P14, N20 and P25 latencies and the N9-N20, N9-N13, N13-N20 and P14-N20 interpeak latencies between hypothyroid patients and controls. We performed the blink reflex study in 28 of 40 patients (14 patients with hyperthyroidism and 14 patients with hypothyroidism). Comparing the R1, R2, CR2 (contralateral R2) latencies and durations of the patients and controls, we found that R2 and CR2 duration was shorter in patients with hyperthyroidism. This difference was statistically significant.     

Median frequency of the myoelectric signal

Summary A study was performed to investigate the existence of any distinction in the fatiguability of corresponding contralateral muscles in the hand as a function of hand dominance. The first dorsal interosseous muscle was studied. The median frequency of the myoelectric signal was employed to describe the fatigue behavior of the muscle. It was found that during sustained contractions the median frequency decreased faster in the non-dominant hand of right handed individuals, whereas, no statistically significant distinction could be found in left handed individuals. This distinction was evident in both male and female subjects. This study demonstrates that continued preferential usage of a muscle is associated with altered electrical properties of the myoelectric signal and that the median frequency of the signal provides an appropriate measure of the modifications. It is argued that the findings may provide an indication of modifications in the metabolic properties of muscle fibers induced by a lifetime of preferred functional use. Dr. Sabbahi is now with the Texas Woman's University School of Physical Therapy in Houston, Texas, USA     

Median (third) occipital condyle

Abnormalities of the craniovertebral junction, most of which are associated with the occipital bone, are of interest not only to anatomists but also to clinicians because many of these deformities produce clinical symptoms. The occipital bone in humans is formed by the fusion of the sclerotomes corresponding to the roots of the hypoglossal nerve. In lower vertebrates, the cranial half of the first cervical sclerotome forms a separate bone between the atlas and occipital bone, the proatlas; in man it may contribute to anomalous structures around the foramen magnum. One such structure, a median occipital condyle, which exhibited an articular facet for the odontoid process, was observed in an adult male skull at the anterior margin of the foramen magnum. This anomaly is discussed in light of available literature.     

Median frequency of the myoelectric signal

Summary A study was performed to investigate the changes that occur in the median frequency of the myoelectric signal during local ischemia or reduction of intramuscular temperature produced by surface cooling. Data was obtained from experiments which involved the first dorsal interosseous muscle of 10 female and 16 male subjects. These subjects were asked to perform isometric constant-force abduction contractions of the index finger at 20% and 80% of maximal voluntary contraction level. The initial median frequency (IMF) of the myoelectric signal during the first 0.5 s of contraction was calculated. Results showed a significant reduction of the IMF in contractions performed under ischemic conditions; upon release, the IMF recovered quickly. At 80% maximal voluntary level of contraction, a greater decrease of the IMF was recorded. Similar results were demonstrated during reduction of intramuscular temperature with gradual recovery of the IMF after cooling. These results demonstrate that the median frequency of the myoelectric signal displays behavior similar to that reported for conduction velocity and this is consistent with the notion that accumulation of metabolic byproducts in muscle tissue causes a decrease in the conduction velocity of the muscle fibers.Dr. R. Merletti was on a leave of absence from the Institute of Electrical Engineering, Politecnico di Torino, Italy