Distribution of catecholamines in the median eminence of rats following adrenalectomy]

Distribution of adrenergic and peptidergic nerve fibers in rat median eminence was studied three weeks after bilateral adrenalectomy. Fluorescence intensity in the external zone and in some of the nerve cell-bodies proved to be increased in the nucleus arcuatus. There were many nerve fibers with a bright fluorescence in the internal zone. A great number of the peptidergic nerve fibers appeared in the external zone. Reactions in the rostral, medial and caudal regions of the median eminence differed and were described.     

Degradation of CCK-8 by rat synaptosomal peptidases

By use of an antiserum raised against conjugated ovine corticotropin releasing factor (CRF_1–41), nerve fibres can be stained immunocytochemically in the external zone of the median eminence of rats. The presence of CRF-immunoreactive (CRF_i) nerve fibres and the plasma corticosterone response to ether stress were studied in rats 6–7 days after making various types of lesions in the hypothalamus. Complete anterolateral deafferentation of the mediobasal hypothalamus caused complete disappearance of CRF_i fibres from the median eminence and blocked the corticosterone response to stress. Incomplete anterolateral hypothalamic deafferentation did not prevent the stress-induced increase of corticosterone and in these rats, part of the CRF_i nerve fibres remained intact. A horizontal cut placed ventral to the paraventricular nuclei, completely prevented the corticosterone response in those rats that showed a complete disappearance of CRF_i nerve fibres from the median eminence. Some rats however, still exhibited CRF_i nerve fibres and these animals responded to stress with increased corticosterone levels. A similar horizontal cut made just dorsal to the paraventricular nuclei affected neither the corticosterone response to stress nor the appearance of CRF_i nerve fibres in the median eminence. We conclude that the presence of CRF_i nerve fibres in the median eminence is a prerequisite for rats to show a pituitary-adrenal response to ether stress and therefore represents the first functional evidence for the role of these hypothalamic CRF_i-neurons.     

Arteriovenous malformation of a persistent median artery with a bifurcated median nerve

A patient with arteriovenous malformations of the volar forearm and hand arising from a persistent median artery with an associated bifid median nerve is presented. Surgeons should be aware of high median nerve bifurcations, particularly when a persistent median artery is identified, and should remember that additional structures that can lead to nerve compression may be present in the carpal tunnel. Specifically, more than one median nerve may need to be identified and protected in such cases.     

Middle-latency somatosensory evoked potentials following median and posterior tibial nerve stimulation in Down's syndrome

Middle-latency somatosensory evoked potentials (SEPs) following median and posterior tibial nerve stimulation were studied in 40 patients with Down's syndrome and in age- and gender-matched healthy controls as well as in middle-aged and aged healthy subjects. In median nerve SEPs, latencies of the initial cortical potentials, N18 and P18, showed no significant difference, but the following potentials N22, P25, N32, P41 and P46 were relatively or significantly shorter in latency in Down's patients than in the controls. Amplitudes of all components in Down's patients were significantly larger than those of age- and gender-matched controls as well as of those of middle-aged healthy subjects, but there was only a small difference in their amplitudes from aged healthy subjects. Results of posterior tibial nerve SEPs were generally consistent with those of median nerve SEPs. Therefore, ‘short latency with large amplitude’ is the main characteristic of middle-latency SEPs in Down's syndrome, possibly related to accelerated physiological aging of the central nervous system.     

Assessment of Median Nerve Mobility by Ultrasound Dynamic Imaging for Diagnosing Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is the most common peripheral neuropathy and is characterized by median nerve entrapment at the wrist and the resulting median nerve dysfunction. CTS is diagnosed clinically as the gold standard and confirmed with nerve conduction studies (NCS). Complementing NCS, ultrasound imaging could provide additional anatomical information on pathological and motion changes of the median nerve. The purpose of this study was to estimate the transverse sliding patterns of the median nerve during finger movements by analyzing ultrasound dynamic images to distinguish between normal subjects and CTS patients. Transverse ultrasound images were acquired, and a speckle-tracking algorithm was used to determine the lateral displacements of the median nerve in radial-ulnar plane in B-mode images utilizing the multilevel block-sum pyramid algorithm and averaging. All of the averaged lateral displacements at separate acquisition times within a single flexion–extension cycle were accumulated to obtain the cumulative lateral displacements, which were curve-fitted with a second-order polynomial function. The fitted curve was regarded as the transverse sliding pattern of the median nerve. The R² value, curvature, and amplitude of the fitted curves were computed to evaluate the goodness, variation and maximum value of the fit, respectively. Box plots, the receiver operating characteristic (ROC) curve, and a fuzzy c-means clustering algorithm were utilized for statistical analysis. The transverse sliding of the median nerve during finger movements was greater and had a steeper fitted curve in the normal subjects than in the patients with mild or severe CTS. The temporal changes in transverse sliding of the median nerve within the carpal tunnel were found to be correlated with the presence of CTS and its severity. The representative transverse sliding patterns of the median nerve during finger movements were demonstrated to be useful for quantitatively estimating median nerve dysfunction in CTS patients.     

A morphological study of the peri- and epineurium in the compression zone of the median nerve in carpal tunnel syndrome

The structure of the peri- and epineurium of the median nerve in the carpal tunnel syndrome was studied by light and transmission electron microscopy. Electron microscopy confirms the flattened lamellar arrangement of the perineurial cells, but in contrast to the normal architecture the perineurial component of the median nerve in carpal tunnel syndrome consists of 20-25 layers of ramified squamous-type cells, each layer being separated from the adjacent one by a wide space containing thick bundles of collagen fibrils. The perineurial cells are bounded on both sides by a basement membrane which is of substantial thickness. A prominent feature is the occurrence of multiple pinocytotic vesicles and caveolae opening on both the internal and external aspects of the flattened cells. They also contain bundles of closely aggregated filaments. In the spaces between the perineurial cells we find, in some places, extremely disoriented and individually abnormal fibrils and fine filaments arranged in form of a spider web. Matrix vesicles can also be seen. The epineurium of the median nerve in the carpal tunnel syndrome is also considerably thickened, and the attachment is solid, so that the median nerve is relatively immobile constricted like an hourglass. The thick collagen fibers are orientated predominantly parallel to the axis of the nerve, but circular fibers can also be seen. Apart from fibroblasts, the outer layer of the epineurium contains mast cells and vasa nervorum as well as myelinated nervi nervorum. Variable quantities of fat are also present, particularly in the surrounding loose connective tissue.     

Resistance of peripheral and sub-cortical somatosensory pathway to electrical noise

The somatosensory system is vulnerable to large amounts of noise distortion. But how does the central nervous system distinguish the peripheral inputs which carry information to the brain from that which does not possess information? To address this question we studied the effect of electrical stimulation of the median nerve on tactile spatial frequency perception in healthy subjects and Parkinson's disease (PD) patients. Subjects were categorized in two groups (healthy and PD patients) and were asked to report if a test tactile frequency pattern (TFP) was the same as the reference TFP given to the other hand. In each case stimulation was either present or absent on the median nerve of the hand holding the test pattern. We observed no impairment of tactile performance in the presence of electrical stimulation of the median nerve. This result together with previous work on direct stimulation of the somatosensory relay nucleus of the thalamus in which the same result of no impairment of the tactile discrimination task was observed suggest a high degree of noise tolerance exists in the somatosensory pathway.     

Microfluorimetric quantitation of catecholamine fluorescence in rat median eminence. II. Turnover changes in hormonal states.

Catecholamine nerve terminals in the rat median eminence have been studied using the fluorescence histochemical technique of Falck and Hillarp in combination with quantitative microfluorimetry. The catecholamine fluorescence intensities recorded from various parts of the median eminence were all found to be within the linear part of the dopamine or noradrenaline concentration-fluorescence relationship as studied in an agar-albumin model system. The catecholamine fluorescence was also found to disappear with time in an exponential manner following tyrosine hydroxylase inhibition produced by alpha-methyl-p-tyrosine methylester (H44/68). Similar results were obtained when measuring the dopamine decline by mass fragmentography in the median eminence after H44/68 treatment. These results and analysis of fluorescence frequency histograms strongly indicate that the catecholamine fluorescence values recorded are proportional to the catecholamine concentration. It is concluded that the microfluorimetric technique used is a reliable method for catecholamine quantitation in discrete nerve terminal areas of the median eminence. The main advantages of the technique are that a high sensitivity and quantitative data on the transmitter content can be obtained in strict relation to the neuroanatomy. Measurement of the catecholamine fluorescence disappearance after H44/68 was used to evaluate catecholamine turnover during various endocrine states. The results showed that two dopamine systems with different transmitter turnover may be distinguished. Tuberinfundibular dopamine neurons projecting to the lateral palisade zone were thus shown to have a slower turnover than those projecting medially to the capillary loops. No definite changes in catecholamine turnover were observed after adrenalectomy and castration in the male, although there was a tendency toward increased noradrenaline turnover in both states. During pregnancy an increase in noradrenaline as well as dopamine turnover was noted. The present results therefore give further evidence for the view that catecholamine nerve terminals in the median eminence may participate in the regulation of gonadotrophin secretion.     

Anomalous pattern of median artery in the forearm of Indians

Various anomalous relations between the brachial plexus or its branches and arteries are reported. The present study was conducted on 134 limbs to note the origin and course of the median artery and its relation to the median nerve. In 2 limbs (1.5%), the median artery split the median nerve into two roots in the forearm and the artery passed through the nerve. In both of these limbs (1.5%), the median artery arose from the ulnar artery. The median artery in these 2 limbs (1.5%) was considerably large and supplied the hand. Both the origin of the median artery from the ulnar artery and the splitting of the median nerve by the median artery are rare anomalies which have not been reported in the available literature.     

The innervated anterolateral thigh flap: anatomical study and clinical implications

During the past 20 years, the neural anatomy of many flaps has been investigated, although no extensive studies have been reported yet on the anterolateral thigh flap. The goal of this study was to describe the sensory territories of the nerves supplying the anterolateral thigh flap with dissections on fresh cadavers and with local anesthetic injections in living subjects. The sensate anterolateral thigh flap is typically described as innervated by the lateral cutaneous femoral nerve. Two other well-known nerves, the superior perforator nerve and the median perforator nerve, which enter the flap at its medial border, might have a role in anterolateral thigh flap innervation. Twenty-nine anterolateral thigh flaps were elevated in 15 cadavers, and the lateral cutaneous femoral nerve, the superior perforator nerve, and median perforator nerve were dissected. In the injection study, the lateral cutaneous femoral nerve, superior perforator nerve, and median perforator nerve in 16 thighs of eight subjects were sequentially blocked. The resulting sensory deficit from each injection was mapped on the skin and superimposed on the marked anterolateral thigh flap territory. The study shows that the sensate anterolateral thigh flap is basically innervated by all three nerves. The lateral cutaneous femoral nerve was present in 29 of 29 thighs, whereas the superior perforator nerve was present in 25 of 29 and the median perforator nerve in 24 of 29 thighs. Furthermore, in the proximal half of the flap, the lateral cutaneous femoral nerve lies deep, whereas the superior perforator nerve and median perforator nerve lie more superficially. Whereas the lateral cutaneous femoral nerve innervates the entire flap, the superior perforator nerve innervates 25 percent of the flap and the median perforator nerve innervates 60 percent of the flap. Clinically, a small anterolateral thigh flap (7 x 5 cm) can be raised sparing the lateral cutaneous femoral nerve and using only the selective areas innervated by the superior perforator and median perforator nerves. Alternatively, a large anterolateral thigh flap can be raised with this multiple innervation. This can be helpful if one wants to harvest the flap under local anesthesia. Sensate bilobed flaps can be harvested when dual innervated flaps are required.     

显微手术治疗正中神经开放性损伤的临床效果分析

目的:分析显微手术治疗正中神经开放性损伤的临床效果。方法:选取2010年2月-2014年3月入住我院接受治疗的120例正中神经开放性损伤患者,随机分成观察组和对照组,每组60例。对照组行常规的手术治疗,观察组行显微手术进行治疗。术后随访6~48个月,比较两组患者正中神经的运动传导速度(MCV)、感觉传导速(SCV)以及正中神经功能优良率。结果:观察组正中神经功能优良率为93.33%,显著高于对照组70.00%(P0.05);两组患者治疗后正中神经MCV、SCV较治疗前均明显增加(P0.05);治疗后观察组MCV、SCV改善程度显著大于对照组(P0.01)。结论:显微手术治疗正中神经开放性损伤效果显著,为神经损伤修复奠定了理论基础,具有巨大的临床应用价值。     

Development of the innervation pattern in the upper limb of staged human embryos

The upper limb nerves of 8 human embryos (Carnegie stages 13-21) were studied by reconstruction. In stage 13, upper limb nerves (C5-T1) extended from the spinal cord. In stage 14, these nerves united to form the nascent brachial plexus. In stages 16 and 17, the median nerve, the radial nerve and the ulnar nerve entered into the hand plate. In stages 20 and 21, the upper limb nerves were observed in an orientation and arrangement similar to those in the adult.     

Cortical plasticity in patients with median nerve lesions studied with MEG

We have previously shown age- and time-dependent effects on brain activity in the primary somatosensory cortex (SI), in a functional magnetic resonance imaging (fMRI) study of patients with median nerve injury. Whereas fMRI measures the hemodynamic changes in response to increased neural activity, magnetoencephalography (MEG) offers a more concise way of examining the evoked response, with superior temporal resolution. We therefore wanted to combine these imaging techniques to gain additional knowledge of the plasticity processes in response to median nerve injury. Nine patients with median nerve trauma at the wrist were examined with MEG. The N1 and P1 responses at stimulation of the injured median nerve at the wrist were lower in amplitude compared to the healthy side (p?larger N1 amplitude (p?p?p?increased MEG response amplitude to ulnar nerve stimulation. This can be interpreted as a sign of brain plasticity.     

Comparison of the Effects of Flexion and Extension of the Thumb and Fingers on the Position and Cross-Sectional Area of the Median Nerve

Objective

To assess the separate effects of thumb and finger extension/flexion on median nerve position and cross-sectional area.

Methods

Ultrasonography was used to assess median nerve transverse position and cross-sectional area within the carpal tunnel at rest and its movement during volitional flexion of the individual digits of the hand. Both wrists of 165 normal subjects (11 men, 4 women, mean age, 28.6, range, 22 to 38) were studied.

Results

Thumb flexion resulted in transverse movement of the median nerve in radial direction (1.2±0.6 mm), whereas flexion of the fingers produced transverse movement in ulnar direction, which was most pronounced during flexion of the index and middle fingers (3.2±0.9 and 3.1±1.0 mm, respectively). Lesser but still statistically significant movements were noted with flexion of the ring finger (2.0±0.8 mm) and little finger (1.2±0.5 mm). Flexion of the thumb or individual fingers did not change median nerve cross-sectional area (8.5±1.1 mm²).

Conclusions

Volitional flexion of the thumb and individual fingers, particularly the index and middle fingers, produced significant transverse movement of the median nerve within the carpal tunnel but did not alter the cross-sectional area of the nerve. The importance of these findings on the understanding of the pathogenesis of the carpal tunnel syndrome and its treatment remains to be investigated.     

Aneurysm of the median artery causing recurrent carpal tunnel syndrome and anatomic review

A patient is presented who had recurrent carpal tunnel syndrome symptoms in his left hand 1 year after having undergone release of the transverse carpal ligament. On exploration, this was found to be due to an aneurysm of a median artery and possibly scarring due to this compression around the branches of the bifurcated median nerve. This represents the first case in the literature to comment on (1) the absence of bilaterality of the anatomic finding and (2) carpal tunnel syndrome relative to median artery aneurysm. With this in mind, a plea is made for careful exploration of the carpal tunnel, maintaining an incision as far to the ulnar side of the median nerve as technically possible with thorough visualization of the contents of the tunnel and any anatomic variance involved. The incidence of the combination of aberrant median artery with high bifurcation of the median nerve is unknown, as is the incidence of aneurysm of the median artery.     

Influence of 50 Hz-1 mT magnetic field on human median nerve

In this study, human median nerve was exposed to power frequency magnetic fields in order to provide clarification for possibly changeable nerve conduction mechanism. The nerve was exposed to 50 Hz magnetic field by utilizing a special Helmholtz applicator. The experiments were carried out with six healthy human-volunteers. Median motor distal amplitude/proximal amplitude ratios were recorded from adult human median nerve pre-exposure, during, and post-exposure to a 50 Hz, 1 mT magnetic field. The result of 18 measurements shows that median motor distal amplitude/proximal amplitude ratio significantly decreases in pre-exposure state as compare to post exposure of which. The results of this study may be useful for some nerve rehabilitation, excitation, and stimulation in more effective/safe physical therapy. Additionally, 50 Hz, 1 mT sinusoidal magnetic field should not be recognizing as safe for conduction mechanism on a nerve. These mechanisms would be cleared by new advanced engineering models in other future works.     

Resistance of peripheral and sub-cortical somatosensory pathway to electrical noise

The somatosensory system is vulnerable to large amounts of noise distortion. But how does the central nervous system distinguish the peripheral inputs which carry information to the brain from that which does not possess information? To address this question we studied the effect of electrical stimulation of the median nerve on tactile spatial frequency perception in healthy subjects and Parkinson's disease (PD) patients. Subjects were categorized in two groups (healthy and PD patients) and were asked to report if a test tactile frequency pattern (TFP) was the same as the reference TFP given to the other hand. In each case stimulation was either present or absent on the median nerve of the hand holding the test pattern. We observed no impairment of tactile performance in the presence of electrical stimulation of the median nerve. This result together with previous work on direct stimulation of the somatosensory relay nucleus of the thalamus (Abbassian et al., Stereotact Funct Neurosurg 76: 19–28, 2001) in which the same result of no impairment of the tactile discrimination task was observed suggest a high degree of noise tolerance exists in the somatosensory pathway.     

Validity of median nerve somatosensory evoked potentials in the diagnosis of supraclavicular brachial plexus lesions

Experience with median nerve SEPs in the diagnosis of brachial plexus lesions is analysed in 49 patients selected from a total material of 264 cases with brachial plexus problems tested by SEP techniques. Median nerve SEPs were always compared with the results of SEPs after stimulation of at least one other nerve relevant to the site of the lesion as suspected clinically and electromyographically. All patients presented with unilateral brachial plexus problems and all root lesions were verified by clinical presentation, EMG studies, myelogram or surgery. There were 19 brachial plexus injuries, 13 cases with cervical spondylopathic rediculopaties without myelopathy and 7 patients presented brachial plexopathy with systemic cancer. It was found that median nerve SEPs were always normal in injuries of upper trunk and root avulsions confined to one or two root levels. Median nerve SEPs were abnormal in multiple trunk lesions and multiple root avulsions. In patients with spondylopathic radiculopathies median nerve SEPs were normal apart from one case where involvement of multiple roots was present. Median nerve SEPs were useful in assessing patients presenting brachial plexus problems in the presence of systematic cancer apart from cases where lower trunk involvement was present.In general, median nerve SEPs are useful if they are combined with SEP testing of other nerves anatomically more closely related to the problem as outlined clinically and electromyographically.     

促生长素抑制素样免疫反应在大白鼠弓状核和正中隆起的超微结构分布

本文用免疫电镜方法证明:促生长素抑制素样免疫反应神经末梢分布于弓状棱并与未标记的树突形成轴树突触。在正中隆起的纤维层和栅状层内均可见上述免疫反应末梢,大多数紧贴门脉毛细血管基底膜周围甚至穿入基底膜内。免疫反应末梢尚可与未标记的末梢形成轴轴突触样结构。     

Pudendal and median nerve sensory perception threshold: A comparison between normative studies

Background: For the evaluation of sensory innervation, normative data are necessary as a comparison.

Aims: To compare our current perception thresholds (CPTs) with normative data from other research.

Methods: Healthy volunteers were assessed for 2000, 250, and 5?Hz CPTs of the median and pudendal nerve and data were compared with other studies.

Results: Normative data in the studied group n?=?41 (male: 21; female: 20) for the median nerve, 2?kHz, 250?Hz, and 5?Hz were respectively: 241.85?±?67.72 (140–444); 106.27?±?39.12 (45–229); 82.05?±?43.40 (13–271). Pudendal nerve CPTs 250?Hz were: 126.44?±?69.46 (6–333). For men 2?kHz: 349.95?±?125.76 (100–588); 5?Hz: 132.67?±?51.81 (59–249) and women 2?kHz: 226.20?±?119.65 (64–528); 5?Hz: 92.45?±?44.66 (35–215). For the median nerve no statistical differences for gender were shown. For the pudendal nerve, only 250?Hz showed no difference for gender (t-test: 0.516). Comparison of our data with CPTs of other normative data showed no agreement for the pudendal nerve. For the median nerve only 2?kHz showed agreement in three studies and for 5?Hz with one study.

Conclusion: Comparing normative data of multiple studies shows a variety of results and poor agreement. Therefore, referring to normative data of other studies should be handled with caution.