Lumbar spinal stenosis: analysis of pre- and postoperative somatosensory evoked potentials

Cortical somatosensory evoked potential (CSEP) examinations were performed of 20 patients with lumbar spinal stenosis a day prior to surgery and 10 to 12 days after spinal decompression and bilateral lateral fusion. CSEPs were recorded to Cz-Fz (10-20 international EEG system) following stimulation of 32 tibial, peroneal and sural nerves and 16 saphenous nerves. A total of 110 nerves were examined. Using CSEP P1 latency as criteria for inclusion in the study, 21 tibial, 20 peroneal and 17 sural nerves were subjected to paired two-tailed t tests to determine whether the CSEP changes that occurred postoperatively were statistically significant (p less than 0.05). Postoperative P1 latencies of tibial, peroneal, and sural nerves changed significantly as well as N1 latencies and P1-N1 amplitudes of tibial and peroneal nerves. Nineteen patients improved clinically. It is postulated that pathologic narrowing of the spinal canal in spinal stenosis leads to nerve root compression and ischemia with resultant dysfunction primarily affecting large diameter myelinated fibers and that decompression procedure may adequately relieve the underlying pathologic processes. Improvement in CSEPs may be from increase in available numbers of functioning large diameter myelinated fibers, conversion to normal from a conduction block, and, perhaps, improved axoplasmic flow.     

Effects of alcohol on bone, muscle and nerve

The acute and chronic effects of alcohol on bone, muscle and peripheral nerves are not well appreciated. Bone complications include traumatic fractures, osteoporosis and osteonecrosis. In muscle, a sustained bout of heavy drinking may cause rhabdomyolysis, while chronic alcohol abuse may produce proximal myopathy. In peripheral nerves, acute alcohol intoxication may lead to pressure neuropathy and chronic abuse may cause peripheral neuropathy.     

大鼠坐骨神经挤压伤后基质金属蛋白酶-2和-9的表达及意义

目的观察大鼠坐骨神经挤压伤后基质金属蛋白酵（MhiP）-2和-9的表达，及其随损伤后恢复时程的变化。方法建立大鼠坐骨神经挤压伤模型，用明胶酶谱测定损伤后神经组织内btMP-2和bthiP-9的活性变化；Westernblot检测确认所消化条带的属性。结果正常坐骨神经组织内仅表达MMP-2，不表达MMP-9；坐神经挤压伤后1d时，MMP-9表达水平最高；MMP-2在坐骨神经损伤后表达水平略有增加，7d时最高。Westernblot检测确认所消化的条带是MMP-2和MMP-9。结论MMP-2和MMP-9参与坐骨神经损伤后的损伤修复过程。     

THE NERVES OF THE CAPILLARIES,WITH REMARKS ON NERVE-ENDINGS IN MUSCLE : A NEW THEORY OF LYMPH-FORMATION AND OF GLANDULAR SECRETION.

1. The endings of the motor nerves in striped muscle remain on the outside of the sarcolemma. Aside from the surfaces of contact of muscle and nerve fibre, the end fibres are covered down to their tips with the sheath of Schwann and are provided with nuclei. The precise condition of things at the places of contact of muscle and nerve is an unsolved problem of histology. 2. The ivy-like or festooned arrangement of motor nerves in the frog''s muscle has been misinterpreted. Properly interpreted it demonstrates that the nerve fibres that are to influence the muscle fibre are not naked and that they need not be end fibres. It shows that mere contact between muscle fibre and nerve fibre is all that is necessary. 3. The sheath of Henle in the frog and in the smaller muscle fibres of the snake is open, thus permitting escape of the cerebrospinal fluid. 4. In other animals Henle''s sheath extends over the end fibres of the motor nerve and the cells lining it envelop the end fibrils. I find that the so-called "Sohlensubstanz" of Kühne is derived from the cells of Henle''s sheath. 5. The terminal nerves in smooth muscle form a network entwining the bundles of muscle fibres. I consider it improbable that each plain muscle fibre has a special terminal nerve fibril. 6. In muscular tissue fine non-medullated nerves, probably belonging to the centrifugal, vasomotor system, proceed from the fasciculi of motor nerves. These nerves can be traced directly to a network of nerves surrounding the capillaries. From this network fine, nucleated, nerve fibres pass to the walls of the capillaries, with which they are very closely united. 7. The nerves supplying the capillaries connect also with sensory nerves and with nerves surrounding the larger blood-vessels, both arteries and veins. 8. The branches of the chorda tympani in the submaxillary gland do not pass to the gland cells, but they terminate on the capillaries. 9. In muscular and glandular tissues—and perhaps throughout the body—there is a vast peripheral nervous plexus belonging to the capillary blood-vessels. These nerves of the capillaries, which may perhaps be regarded as nutritive nerves, regulate the production and transudation of lymph, and are concerned in the mechanism of glandular secretion. They may be called into activity both by peripheral influences and by impulses received from the central nervous system and the sympathetic ganglia. They may influence, through their connections with the vasomotor nerves on the arteries and veins, the blood supply to a part.     

Anatomy of the cervical spine: implications for the upper limb tension test

A detailed investigation of the anatomy of the lower cervical nerves and associated structures was undertaken, as these structures would most likely be affected by any stresses generated in the nerves of the brachial plexus during the upper limb tension test (ULTT). The investigation used dissection of three adult human spines and histological sections of three cervical spines. The results support the hypothesis that the lower cervical nerves have a specialised anatomical arrangement which may protect them from forces generated in the upper limb and cervical spine by the ULTT. The fifth, sixth and seventh cervical nerves are securely attached to many structures as they emerge from the spinal cord to form the brachial plexus. Furthermore, the posterior longitudinal ligament anchors the nerve roots to the vertebral bodies and intervertebral discs. The results suggest that innervated structures other than neuromeningeal tissue may also need to be considered when evaluating a patient's positive ULTT response.     

Handcuff neuropathy: two unusual cases

Handcuff applications may result in compression of peripheral nerves at the wrist, and most reported cases involve only the superficial radial nerve. In this report, two cases of bilateral handcuff neuropathy involving multiple nerves were confirmed by electrodiagnostic findings of membrane instability, prolonged latencies and/or conduction block. In addition to the superficial radial nerves, one case involved the median nerves, and a second case the ulnar nerves. It was postulated that injury might occur to any nerve at the wrist as a result of pressure and edema from handcuffs, with the radial nerve most frequently involved due to its superficial location. Radial nerve injury has been described as functionally insignificant; however for the two cases presented, in which the median or ulnar nerves were involved, significant disability resulted, and a rehabilitation program was indicated.     

Imaging of the glossopharyngeal, vagus, and accessory nerves

The origination and course of the glossopharyngeal, vagus and accessory cranial nerves explains their function and localizes pathology. Abnormalities of these lower cranial nerves may be intrinsic or extrinsic and is due to a multiplicity of disease processes. The clinical presentation of the involved cranial nerve helps to guide imaging evaluation. Magnetic resonance imaging without and with contrast is the mainstay of imaging of cranial nerves IX, X and XI pathology, but computed tomography provides substantial information as well.     

FURTHER EXPERIMENTAL STUDIES IN TETANY

It has been our aim to determine in what particular the blood is altered during tetany so that it can produce hyperexcitability of the motor nerves. As a working hypothesis it has been assumed that (1) there may be a lack of calcium in the blood and tissues; (2) there may be a circulating poison which like an oxalate could render inactive the circulating calcium; and (3) there may be a substance in circulation vaguely resembling strychnia in its action upon the nervous system and directly causing the hyperexcitability. It is impossible to decide with our present knowledge which, if any, of these explanations is the true one, but certain experimental results are brought forward. If tetany blood be used to perfuse a normal leg the excitability of the nerves rises to a characteristically high level and the addition of parathyroid extract to the blood has little or no effect in lowering this excitability. Parathyroid extract whether from the ox or the dog fails when injected into the circulation of an animal in tetany to reduce the excitability of the nerves markedly or permanently, although it seems to affect the more sensitive ganglion cells thus cutting off excessive impulses to the periphery. Although the nerves remain hyperexcitable, tetany is usually much diminished or abolished entirely. This seems to be analogous to the action of ether or any other anesthetic which may inhibit the activities of the ganglion cells, although it leaves the nerves excitable and able to conduct impulses. An animal in tetany relaxes instantly on being given ether although the excitability of the nerves to electric currents is little changed. Bleeding followed by the replacement of the blood with an indifferent solution free from calcium stops tetany and lowers the excitability of the nerves. Probably this cannot be ascribed to the removal of a circulating poison, but rather to a general disturbance of the nutrition of the nervous system. Oxalate-like substances introduced into the circulation rapidly, and for a short time only, may kill the animal, but they seem to produce no change in the excitability of the nerves. If the solution is injected very slowly and over a long period the protective action of the body seems to be overcome and the excitability of the nerves rises to high levels. This seems to resemble somewhat the latent period after the destruction of the parathyroid before tetany begins. Direct analysis of the blood shows that as compared with the normal, the blood of an animal in tetany is very poor in calcium. Administration of parathyroid extract does not increase this calcium content. On the contrary, if the extirpation of the parathyroids has been incomplete so that tetany does not appear, the calcium content of the blood is that of the normal animal. Even yet, therefore, in spite of our efforts to shake it, the theory that tetany is closely dependent upon a disturbance of the calcium content of the blood is supported by stronger evidence than any other idea, but much remains to be done before a clear conception of the process is reached.     

Sciatica

The sciatic nerves are the largest nerves in the body—about as big around as your finger. They start in the lower spine, pass behind the hip joint, and go down the buttock and back of the leg to the foot. Pain from this nerve, called sciatica, may be felt from the hip to the big toe.     

Endoneurial pathology of the needlestick‐nerve‐injury model of Complex Regional Pain Syndrome,including rats with and without pain behaviors

Current rodent models of neuropathic pain produce pain hypersensitivity in almost all lesioned animals and not all identified experimental effects are pain specific. 18G needlestick‐nerve‐injury (NNI) to one tibial nerve of outbred Sprague–Dawley rats models the phenotype of Complex Regional Pain Syndrome (CRPS), a post‐traumatic neuropathic pain syndrome, leaving roughly half of NNI rats with hyperalgesia. We compared endoneurial data from these divergent endophenotypes searching for pathological changes specifically associated with pain‐behaviors. Tibial, sural, and common sciatic nerves from 12 NNI rats plus 10 nerves from sham‐operated controls were removed 14 days post‐surgery for morphometric analysis. PGP9.5⁺ unmyelinated‐fibers were quantitated in plantar hindpaw skin. Distal tibial nerves of NNI rats had endoneurial edema, 30% fewer axons, twice as many mast cells, and thicker blood‐vessel walls than uninjured tibial nerves. However the only significant difference between nerves from hyperalgesic versus non‐hyperalgesic NNI rats was greater endoneurial edema in hyperalgesic rats (p < 0.01). We also discovered significant axonal losses in uninjured ipsilateral sural nerves of NNI rats, demonstrating spread of neuropathy to nearby nerves formerly thought spared. Tibial and sural nerves contralateral to NNI had significant changes in endoneurial blood‐vessels. Similar pathological changes have been identified in CRPS‐I patients. The current findings suggest that severity of endoneurial vasculopathy and inflammation may correlate better with neuropathic pain behaviors than degree of axonal loss. Spread of pathological changes to nearby ipsilateral and contralateral nerves might potentially contribute to extraterritorial pain in CRPS.     

Amaurosis and primary reticulum cell sarcoma of the brain: clinicopathologic study of a case.

A 63-year-old man developed headache, left hemiparesis, and progressive visual loss. Craniotomy demonstrated reticulum cell sarcoma within the right temporal lobe. Necropsy revealed extensive involvement of optic nerves by primary RCS. Autopsy suggested that local compression of optic nerves by tumor cell infiltrates may produce atrophy in addition to sustained, generalized elevation of intracranial pressure.     

Dual-mode laparoscopic fluorescence image-guided surgery using a single camera

Iatrogenic nerve damage is a leading cause of morbidity associated with many common surgical procedures. Complications arising from these injuries may result in loss of function and/or sensation, muscle atrophy, and chronic neuropathy. Fluorescence image-guided surgery offers a potential solution for avoiding intraoperative nerve damage by highlighting nerves that are otherwise difficult to visualize. In this work we present the development of a single camera, dual-mode laparoscope that provides near simultaneous display of white-light and fluorescence images of nerves. The capability of the instrumentation is demonstrated through imaging several types of in situ rat nerves via a nerve specific contrast agent. Full color white light and high brightness fluorescence images and video of nerves as small as 100 μm in diameter are presented.     

Hyperhidrosis and hypohidrosis.

Sweating has an important physiological function concerned with both temperature and fluid balance. Hypohidrosis is uncommon and rarely recognized by the patient. It usually represents damage to the central nervous system or peripheral nerves. Hyperhidrosis may be a feature of general medical diseases such as thyrotoxicosis and fevers. It may also be due to damage of the central of peripheral sympathetic nerves. Localized hyperhidrosis tends to occur on the palms, the soles, the axillae and, to a lesser extent, the face. Treatment of local hyperhidrosis with topical aluminium salts, or with topical or oral anticholinergics, may help some patients but surgery may be indicated in those with severe hyperhidrosis.     

Architectural configuration and microstructural properties of the sacral plexus: a diffusion tensor MRI and fiber tractography study

The ability to investigate microstructural properties of the central nervous system with diffusion tensor imaging (DTI) has been shown in many studies. More recently, DTI is being applied outside the brain showing promising results, for instance, for investigating muscle tissue. In this work, we demonstrate the feasibility of diffusion tensor imaging (DTI) and fiber tractography to study the nerves of the sacral plexus in humans in vivo and to assess the architectural configuration and microstructural properties of these peripheral nerves. For this research goal we optimized the acquisition parameters of a DTI sequence and acquired data from 10 healthy adults and one 12-year patient having spina bifida and neurogenic bladder dysfunction. For the healthy volunteers, we estimated the fractional anisotropy (FA) and mean (MD), axial (AD), and radial diffusivities (RD) of the sacral plexus nerves which may serve as a baseline for future studies. We demonstrated that tractography of the sacral plexus on a 3 Tesla MR scanner is feasible, giving 3D insight in the general anatomy and organization of the nerves L4 to S3. In addition, branches to the pudendal nerve were also found in 4 volunteers. There were no significant differences in any of the estimated diffusion measures between the right and left sided nerves or between the nerves L4 to S3 on an intra-subject basis. Furthermore, clinical feasibility of DTI and tractography in a child having spina bifida and neurogenic bladder dysfunction is demonstrated. The architectural configuration of the child's sacral plexus was comparable with the healthy volunteers and no significant disrupted nerve fibers were observed. However, there are strong indications that abnormal diffusion characteristics are present at the level of the neural tube defect due to incomplete segments of the nerves that are close to the vertebrae. These findings are encouraging for using DTI as a means to investigate changes in microstructural properties of the nerves of the sacral plexus. Moreover, this new methodology may provide a new avenue to a better analysis and diagnosis of neurogenic bladder dysfunctions.     

Innervation of airway smooth muscle. Efferent mechanisms

The classical view, with one excitatory (cholinergic) and one inhibitory (noradrenergic) component, of the innervation of airway smooth muscle is incomplete and at least two other, possibly peptidergic, types of innervation must be included when the innervation of airways is considered. A summary of these neuronal components is given in Fig. 1 and their possible origin is outlined. Besides the inhibitory noradrenergic innervation of the airways observed in some species, an inhibitory NANC (i-NANC) innervation has been demonstrated. The polypeptide, VIP, seems to be the most likely candidate for the neurotransmitter in the i-NANC innervation of the airways. The excitatory cholinergic innervation is present in the airways from the trachea down to the peripheral bronchi. In the guinea-pig bronchi an excitatory NANC (e-NANC) innervation has been demonstrated as well. The e-NANC nerves may correspond to chemosensitive primary afferent nerves with substance P or a related tachykinin as transmitter. When the innervation of airway smooth muscle of different mammalian species is compared it is evident that all nerve components except the cholinergic, show a considerable variability among species. The cholinergic innervation seems to be present in all mammalian species whereas the other components may be completely absent from some species. Distinct regional variations in the innervation of the airways may occur, which is exemplified by the distribution of the autonomic innervation in the guinea-pig tracheo-bronchial tree. Cholinergic neurotransmission in for example the guinea-pig and human airways can be modulated by NA via prejunctional inhibitory alpha 2-adrenoceptors. Furthermore, the e-NANC neurotransmission in the guinea-pig airways may be modulated by NA or by selective alpha 2-adrenoceptor agonists, acting via prejunctional inhibitory alpha 2-adrenoceptors. The clinical importance of the NANC innervation in relation to asthma is discussed. The i-NANC nerves may exert a modulating effect on bronchoconstriction, and a functional defect would presumably lead to an exaggerated response to constrictor stimuli. The e-NANC nerves in the airways may also be clinically relevant since the transmitter (tachykinins) from these nerves can produce bronchoconstriction and promote inflammation of the airway epithelium, either by direct mechanisms or indirectly by activation of mast cells, and thus contribute to the features of asthma.(ABSTRACT TRUNCATED AT 400 WORDS)     

Local delivery of recombinant human bone morphogenetic protein-2 increases axonal regeneration and the expression of tau protein after facial nerve injury

This study explored the function and possible mechanism of bone morphogenetic protein-2 (BMP-2) in the healing of injured peripheral nerves in vivo. Rabbit facial nerves were injured by clamping and then treated with recombinant human BMP-2 (rhBMP-2) or phosphate-buffered saline (control) by injecting once during surgery and twice a day post-injury for 7 days. Facial nerve fragments within 5 mm of the clamping point were examined at different times post-surgery. Axon structures visualized by Bielschowsky staining were similar in experimental and control nerves 2 and 6 weeks post-injury. At 4 weeks post-injury, cross-section images of facial nerves showed that axons treated with rhBMP-2 were denser and thicker, and levels of tau protein were increased. It is concluded from these data that rhBMP-2 may affect injured facial nerve regeneration by inducing more neurons to return to embryonic patterns of tau gene expression.     

Measuring longitudinal nerve motion using ultrasonography

While it is known that peripheral nerves slide longitudinally in response to limb movements, the clinical relevance of this phenomenon remains largely speculative. This technical note introduces a new application for noninvasive measurement of longitudinal movement of peripheral nerves. The rationale for developing the technique is given including a brief overview of nerve motion theories and how these are related to clinical practice. Current ultrasound applications for nerves and tissue motion are outlined and details of the Doppler measurement procedure are described. Limitations of the technique and potential future applications are discussed. Spectral Doppler ultrasound may provide an effective method for noninvasive quantification of longitudinal nerve motion.     

重金属中毒所致周围神经损害的电生理研究

目的：探讨处于重金属环境中的作业工人急、慢性中毒性周围神经损害的电生理改变。方法：应用常规肌电图技术对30例重金属接触者进行肌电图(EMG)、神经传导速度(NCV)检测。结果：30例患者的电生理检查均呈周围神经损害．其中急性起病18例．以轴索损害为主；慢性蓄积性中毒12例，以脱髓鞘损害为主；电生理改变下肢较上肢明显．感觉神经传导异常重于运动神经传导。结论：电生理学检查对研究重金属中毒所致的周围神经损害提供了重要的客观依据。可作为临床诊断、鉴别诊断以及了解病损程度的动态随访指标。     

Imaging evaluation of cranial nerves 3, 4, and 6

Neuropathies of the oculomotor, trochlear, and abducens nerves may present with isolated or complex neurologic findings. An understanding of the anatomy of these cranial nerves as they traverse the brainstem, basilar cisterns, and cavernous sinus on their way to the orbit can assist in localizing the suggested site of pathology and help to focus imaging protocols. Differential diagnostic possibilities for specific anatomic locations are reviewed.     

Human dermal microvascular endothelial cells produce nerve growth factor: implications for wound repair

Following cutaneous injury, sensory nerves regenerate into the dermis and epidermis. Tissues that are innervated by sensory nerves synthesize neurotrophins such as nerve growth factor (NGF). The close anatomic proximity of nerves and capillaries throughout the skin suggests that mutual regulation may exist between nerve fibers and microvascular endothelial cells (MECs) during wound repair. Release of the neuropeptide substance P by sensory nerves induces endothelial cell rounding, capillary leak, and cytokine upregulation. We propose that dermal endothelial cells produce neurotrophins required for nerve fiber maintenance and regeneration. In this study, we demonstrate that substance P stimulates NGF messenger RNA expression by cultured human dermal MECs. Likewise, enzyme-linked immunosorbant assay demonstrated that conditioned medium from cultured dermal MECs contains NGF. NGF bioactivity in the supemates was verified by conditioned medium-induced clonal rat pheochromocytoma (PC-12) cell differentiation. This activity was inhibited by anti-NGF antibodies. Therefore, we have demonstrated that substance P, an inflammatory neuropeptide released by sensory nerve fibers, induces endothelial cells to produce NGF. Our data suggest that MECs may be unrecognized contributors to nerve regeneration after cutaneous injury.