Diagnosis Of Peripheral Nerve Disorders Research Articles

Median Nerve Anatomy and Entrapment Syndromes

Peripheral neuropathies, including entrapment or injury, are quite common and are encountered frequently. To ensure accurate diagnosis and effective treatment for these conditions, it is essential to have a comprehensive understanding of peripheral nerve anatomy and assessment techniques. This may involve the use of methods like ultrasonography, as well as requiring clinical proficiency. The median nerve, which is one of the main nerves in the upper extremity, primarily controls motor function in the flexor muscles of the forearm and hand. It is responsible for actions such as wrist flexion and the movement of the first three fingers. The purpose of this article is to enhance understanding and improve the diagnosis of peripheral nerve disorders, with a particular focus on neuropathies associated with the median nerve.

Normal structure and pathological features in peripheral neuropathies.

Normal nerve architecture is basic to a complete understanding of nerve pathology. Here, normal components of the nerve are illustrated, including myelinated and non-myelinated nerve fibres, stromal elements, and vascular components. These are relevant because the differential diagnosis of neuropathy depends on the pathological processes affecting axon, myelin, interstitial space, and blood vessels. Thus, we present a description of the general pathological characteristics for the diagnosis of peripheral nerve disorders.

Normal neurophysiologic parameters of the median nerve among adult healthy Sudanese population

Background: Nerve conduction studies (NCSs) help in delineating the extent distribution of neural lesion, and the diagnosis of peripheral nerve disorders. Because normative nerve conduction parameters were not yet established in Sudan EMG laboratories, this study aims towards having our own reference values, as we are using the American and British parameters. This will allow avoiding the discrepancies that might be induced by many factors. Methods: NCSs were performed in 200 Median nerves of 100 adult healthy Sudanese subjects using standardized techniques. Results: The median SNAP (sensory nerve action potential) values were as follows: distal latency, 2.6±3 ms with a range of (2.3-2.9); peak latency, 3.5±0.5 ms (3.0-4.0); amplitude, 47.7±18.0μV (29.7-65.7); conduction velocity, 53.0±7.8 m/s (45.2-60.8). The following values were obtained for the Median nerve CMAP (compound muscle action potential) at wrist stimulation: distal latency, 3.5±0.5 ms with a range of (3.0-4.0); peak latency, 9.4± 1.0 ms (8.4-10.4); duration, 5.9±0.9 ms (5.0-6.8); amplitude, 12.3±2.5 mV (9.8-14.8); area, 43.0±10.4 mVms (32.6-53.4); conduction velocity, 63.6±6.2 m/s (57.4-69.8). The F wave was 28.4±1.8 ms (26.6-30.2). Conclusion: The overall mean sensory and motor nerve conduction parameters for the tested nerve compared favorably with the existing literature with some discrepancies that were justified.

Improved visualization of diffusion-prepared MR neurography (SHINKEI) in the lumbosacral plexus combining high-intensity reduction (HIRE) technique

PurposeThis study attempted to improve visualization of the pelvic nervous system using the high-intensity reduction (HIRE)-nerve-SHeath signal increased with INKed rest-tissue RARE Imaging (SHINKEI) technique that involves subtracting signals of 3D heavily T2W images from SHINKEI images. We identified the optimum TE value for 3D heavily T2W images and assessed the usefulness of the HIRE-SHINKEI technique. Materials and methodsCoronal lumbosacral plexus images were acquired from six healthy volunteers at 3 T. We optimized the TE of the 3D heavily T2-weighted (T2W) images in HIRE-SHINKEI and compared HIRE-SHINKEI images with conventional SHINKEI images with respect to nerve depiction, and vein, bladder, and cerebrospinal fluid (CSF) signal suppression using a 5-point scale. ResultsIn 3D heavily T2W images optimized by HIRE-SHINKEI technique, the signal corresponding to nerves became significantly lower at TE = 400 ms (p < 0.0005), while that of veins occurred at TE = 400 ms and 600 ms (p < 0.05). The suppression of bladder signals was significant at TE = 400, 600, and 800 ms (p < 0.05); however, there was no difference in signal inhibition from CSF at all TEs tested. Based on these results, an optimal TE of 600 ms was identified for 3D heavily T2W images; these images corresponded to the minimal loss of nerve signal and simultaneous maximum subtraction of signals from the bladder, vein, and CSF with dissimilar T2 values. Compared with SHINKEI images, the optimized HIRE-SHINKEI images selectively delineated nerves in greater detail, and along with significant signal suppression of the bladder (p < 0.0001) and veins (p < 0.05). ConclusionHIRE-SHINKEI can be used to better visualize the lumbosacral plexus with higher signal suppression of other pelvic structures. Such detailed Magnetic resonance neurography and selective depiction of nerves are useful for the diagnosis of peripheral nerve disorders.

Nerve Ultrasound as a Diagnostic Tool in Peripheral Neuropathies

Peripheral nerve ultrasound is a relatively new technique for the diagnosis of peripheral nerve disorders. Although much of the experience has been in

Estimation of ultrasound reference values for the upper limb peripheral nerves in adults: A cross-sectional study.

The objective of this study is to estimate the reference values for the upper limb peripheral nerves in adults.The demographics and physical characteristics of 69 adult healthy volunteers were evaluated and recorded. In addition, the side to side differences of the estimated reference values and their correlations with the age, weight, height, and body mass index (BMI) were evaluated.Cross-sectional area reference values of the upper limb nerves did not correlate with height; however, they correlated with age, weight, and BMI in some scanned sites.The data obtained in this study could be helpful in future diagnosis of peripheral nerve disorders of the upper limb.

Peripheral Nerve Disorders in the Neonate

The diagnosis of peripheral nerve disorders in the neonate is challenging because of a wide range of conditions that can present with similar clinical features. The neonate with peripheral nerve disorders typically manifests generalized hypotonia with or without respiratory insufficiency. Diseases with lesions at various levels of the central or peripheral nervous system, as well as myriad systemic conditions, can all present with the same clinical features at birth. Neurophysiologic testing, appropriate genetic evaluation including detailed family history, cerebrospinal fluid analysis, and most importantly, careful neurologic examination and observation of the clinical course will help narrow down the differential diagnosis. This review aims to introduce representative forms of peripheral nerve disorders during the newborn period. We will discuss clinical features, how to differentiate between the disease entities, and the implications of early diagnosis and prognosis.

Ultrasonography of Peripheral Nerves

Over the last decade, neuromuscular ultrasonography has emerged as a useful tool for the diagnosis of peripheral nerve disorders. This article reviews sonographic findings of normal nerves, including key quantitative ultrasound measurements that are helpful in the evaluation of focal and possibly generalized peripheral neuropathies. It also discusses several recent articles outlining the evidence base for the use of this technology, as well as new findings in compressive, traumatic, and generalized neuropathies. Ultrasonography is well suited for use in electrodiagnostic laboratories, where physicians, experienced in both the clinical evaluation of patients and the application of hands-on technology, can integrate findings from the patient's history, physical examination, electrophysiological studies, and imaging for diagnosis and management.

ARTIFICIAL NEURAL NETWORKS IN THE IDENTIFICATION OF PERIPHERAL NERVE DISORDERS

The recent years have witnessed an increase in the use of newer analytical tools in the field of medicine to assist in diagnostic procedure. Among the new tools, artificial neural networks (ANNs) have received particular attention because of their ability to analyze complex nonlinear data sets. This study suggests that ANNs can be used for the diagnosis of peripheral nerve disorders particularly the carpal tunnel syndrome (CTS) and neuropathy. This paper aims at building a classifier using a feed forward neural network that can distinguish between CTS, neuropathy, and normal controls using a reduced set of measurements or features from nerve conduction study (NCS) data. Three different ANN training algorithms, viz. Levenberg–Marquardt (LM), Conjugate gradient (CGB), and resilient back-propagation (RP) are used to see which algorithm produces better results and has faster training for the application under consideration. The data used were obtained from the Neurology Department, Kannur Medical College, Kerala, India. The obtained resultant confusion matrix indicated only a few misclassifications in all the three cases. The analysis showed that the CGB and RB algorithms provide faster convergence on pattern recognition problems, but the best performance in terms of accuracy is given by the LM algorithm. The accuracy obtained for the LM, CGB, and RB were 98.3%, 97.8%, and 97.2%, respectively. The respective sensitivities were 96.1%, 94.1%, and 94.1%, while the specificities were found to be equal to 99.4%, 98.8%, and 97.5%, respectively. The study aims at showing that ANNs may prove useful in combination with other systems in providing diagnostic and predictive medical opinions. However, it must always be kept in mind that ANNs represent only one form of computer-aided diagnosis, and the clinician's responsibility and overall control of patient care should never be underestimated.

Infectious Neuropathies

The purpose of this review is to address bacterial, viral, and other infectious causes of neuropathy or neuronopathy, with an emphasis on clinical manifestations and treatment. Most infectious neuropathies have been well described for some time and treatments are well established. An exception is HIV-associated distal symmetric polyneuropathy, which is an area of active research. Current work in this area focuses on epidemiology, risk factors, and underlying mechanisms. Infectious diseases are an important part of the differential diagnosis of peripheral nerve disorders because they are among the most amenable to treatment. However, diagnosis of infectious peripheral neuropathy may be challenging because of variability in a number of factors, including the pattern of deficits, geographic distribution of pathogens, length of time from the onset of infection to the development of neuropathy, and mechanism of nerve injury.

Assessment of Epidermal Nerve Fibers

Today, skin biopsies can play an important role in the diagnosis of peripheral nerve disorders and have yielded another diagnostic tool for the neurologist. One of the commonly reported neuropathologic abnormalities observed in skin biopsies is a reduction of epidermal nerve density. Analyzing the changes in the morphology and density of epidermal nerves is of immense diagnostic and prognostic value in peripheral neuropathies. These changes also provide an assessment of disease progression and of tissue responses to regenerative treatments. Combined with immunohistochemical studies, newly evolved skin biopsy and epidermal count techniques have the potential to provide significant information about the pathogenesis of many peripheral nervous system diseases. They have great potential for impacts on both research and clinical approaches to treatment. Evolution of a standardized and validated counting methodology and significant advances in procuring skin biopsies have opened up a wide spectrum of applications that make the technology easy to apply in practice. The application of this technology may lead to early detection of many common peripheral nerve diseases and an enhanced understanding of disease onset and progression. In this article we review the state of current research and clinical practice in the use of skin biopsies and epidermal nerve densities.

Usefulness of muscle denervation as an MRI sign of peripheral nerve pathology

Peripheral nerve disorders may be classified into compressive or entrapment neuropathies and non-compressive neuropathies. Muscle denervation recognized on MRI may be a useful sign in the diagnosis of peripheral nerve disorders. Acute or subacute denervation results in prolonged T2 relaxation time, producing increased signal in skeletal muscle on short tau inversion-recovery and fat-suppressed T2-weighted images. Chronic denervation produces fatty atrophy of skeletal muscles, resulting in increased muscle signal on T1-weighted images. This review will outline and illustrate the various ways that muscle denervation as seen on MRI may assist in the diagnosis and localization of peripheral nerve disorders.

Morphological features of nerves in skin biopsies

Skin biopsy is an effective test for diagnosis of peripheral nerve disorders. The most commonly reported indication of abnormality in a skin biopsy is reduction of epidermal nerve density. Morphological changes of epidermal nerves and the underlying subepidermal nerve plexus provide added evidence for the presence of neuropathy. We determined the prevalence of epidermal axon swellings, dermal axon swellings, and a unique type of epidermal nerve that we call a crawler, in a group of normal subjects, diabetic subjects, and patients with idiopathic small fiber neuropathy. Other morphologic features examined include thinning of the subepidermal nerve plexus, sprouts at nerve terminals, encapsulated endings, and immunoreactive basal cells.

Technology Insight: visualizing peripheral nerve injury using MRI

Currently, the evaluation of peripheral nerve disorders depends on clinical examination, supplemented by electrophysiological studies. These approaches provide general information on the distribution and classification of nerve lesions-for example, axonal versus demyelinative-but nerve biopsies are still required to obtain morphological and pathophysiological details. In this article, we review recent progress in the imaging of peripheral nerve injury by magnetic resonance (MR) neurography. Axonal nerve injury leads to Wallerian degeneration, resulting in a hyperintense nerve signal on T2-weighted MR images of the distal nerve segment. This signal is lost following successful regeneration. Concomitant denervation-induced signal alterations in muscles can further help us to determine whether nerve trunks or roots are affected. These signal changes are caused by various combinations of nonspecific tissue alterations, however, and are not related to particular pathoanatomical findings, such as inflammation, demyelination or axonal injury. New experimental MR contrast agents, such as gadofluorine M and superparamagnetic iron oxide particles, allow visualization of the dynamics of peripheral nerve injury and repair. Further clinical development of these MR contrast agents should allow these functional aspects of nerve injury and repair to be assessed in humans, thereby aiding the differential diagnosis of peripheral nerve disorders.

Diagnostic value of sural nerve biopsy in chronic inflammatory demyelinating polyneuropathy

OBJECTIVETo investigate the additional diagnostic value of sural nerve biopsy of 64 patients in whom chronic inflammatory demyelinating polyneuropathy (CIDP) was considered, as sural nerve biopsy is recommended in the...

Principles and pitfalls of nerve conduction studies.

This report reviews the fundamental principles and the changing concepts of nerve stimulation techniques, and discusses the proper application of these techniques in the differential diagnosis of peripheral nerve disorders. Nerve conduction studies help delineate the extent and distribution of the neural lesion and distinguish two major categories of peripheral nerve disease: demyelination and axonal degeneration. Although the method is based on simple principles, pitfalls abound in practice. Variability in nerve conduction measurement may result from temperature change, variations among nerve segments, and the effects of age. Other sources of error include excessive spread of stimulation current, anomalous innervation, temporal dispersion, and inaccuracy of surface measurement. Unlike a bipolar derivation, which selectively records near-field potentials, a referential recording may give rise to stationary far-field peaks from a moving source. Overlooking this possibility can lead to an incorrect interpretation of findings. Conventional nerve conduction studies deal primarily with measurements of the distal nerve segments in an extremity. More recent techniques are applicable to less accessible anatomical regions, as illustrated by elicitation of the blink reflex, F wave, and H reflex, and the use of the inching technique. Other methods used to assess special aspects of nerve conduction include the ischemic test and studies of slow-conducting fibers.