Usefulness of sural nerve biopsy in the genomic era

The value of peripheral nerve biopsy is now sometimes questioned due to the high complication rate and the recent development of noninvasive molecular techniques for diagnosis of hereditary neuropathy. However, the disorders that can be diagnosed by genetic analysis are limited and sural nerve biopsy is still a powerful tool for making a correct diagnosis of peripheral neuropathy. Histological evaluation of the sural nerve has long focused on changes of the two major components of peripheral nerves, axons and myelin, as well as on the detection of diagnostic changes such as amyloid deposits, sarcoid tubercles, and vasculitis. In addition to these components, the sural nerve biopsy specimen contains various important cells, including perineurial cells, mast cells, endothelial cells, pericytes, and lymphocytes. Among these cells, the endothelial cells and pericytes form the blood‐nerve barrier (BNB) and investigation of these cells can reveal important information, especially in inflammatory neuropathies. To better understand the biological basis of BNB, we established rat and human immortal cell lines from the endothelial cells and pericytes of endoneurial microvessels. Characterization of these cell lines is now underway at our laboratory. These BNB cell lines should provide useful information concerning the pathophysiology of peripheral neuropathy, and we should obtain a new perspective for the investigation of nerve biopsy specimens after understanding the molecular background of the BNB.     

EFNS guidelines on the use of skin biopsy in the diagnosis of peripheral neuropathy

Skin biopsy has become a widely used tool to investigate small calibre sensory nerves including somatic unmyelinated intraepidermal nerve fibres (IENF), dermal myelinated nerve fibres, and autonomic nerve fibres in peripheral neuropathies and other conditions. Different techniques for tissue processing and nerve fibre evaluation have been used. In March 2004, a Task Force was set up under the auspices of the European Federation of Neurological Societies (EFNS) with the aim of developing guidelines on the use of skin biopsy in the diagnosis of peripheral neuropathies. We searched the Medline database from 1989, the year of the first publication describing the innervation of human skin using immunostaining with anti-protein-gene-product 9.5 (PGP 9.5) antibodies, to 31 March 2005. All pertinent papers were rated according to the EFNS guidance. The final version of the guidelines was elaborated after consensus amongst members of the Task Force was reached. For diagnostic purposes in peripheral neuropathies, we recommend performing a 3-mm punch skin biopsy at the distal leg and quantifying the linear density of IENF in at least three 50-mum thick sections per biopsy, fixed in 2% PLP or Zamboni's solution, by bright-field immunohistochemistry or immunofluorescence with anti-PGP 9.5 antibodies (level A recommendation). Quantification of IENF density closely correlated with warm and heat-pain threshold, and appeared more sensitive than sensory nerve conduction study and sural nerve biopsy in diagnosing small-fibre sensory neuropathy. Diagnostic efficiency and predictive values of this technique were very high (level A recommendation). Confocal microscopy may be particularly useful to investigate myelinated nerve fibres, dermal receptors and dermal annex innervation. In future, the diagnostic yield of dermal myelinated nerve fibre quantification and of sweat gland innervation should be addressed. Longitudinal studies of IENF density and regeneration rate are warranted to correlate neuropathological changes with progression of neuropathy and to assess the potential usefulness of skin biopsy as an outcome measure in peripheral neuropathy trials (level B recommendation). In conclusion, punch skin biopsy is a safe and reliable technique (level A recommendation). Training in an established cutaneous nerve laboratory is recommended before using skin biopsy as a diagnostic tool in peripheral neuropathies. Quality control at all levels is mandatory.     

神经活检在周围神经疾病诊断中的意义及与电生理检查相关性分析

目的探讨神经活检在周围神经病诊断中的意义,并分析病理检查与神经电生理检查结果的一致性。方法收集2009-2011年作者医院行腓肠神经活检的16例周围神经病患者的临床诊断、电生理诊断和病理诊断资料;分析电生理诊断、光镜诊断和电镜诊断在判断轴索损害或/合并髓鞘损害的一致性,并分析其结果不一致的可能原因。结果电生理检查结果示异常12例(12/16),其中表现为轴索损害为主5例(5/16),髓鞘损害为主7例(7/16);病理检查结果示15例(15/16)患者有不同程度的髓鞘或轴索损害;4例(4/16)患者经神经活检后原有的诊断得到了补充或修改;进一步分析神经病理对于周围神经损害的诊断与电生理诊断无统计学差异。结论 (1)神经活检能够发现一些间质改变和亚临床、亚电生理的神经损害,从而对疾病的认识和治疗提供帮助。(2)神经病理对于周围神经损害的诊断与电生理诊断相关性较好,但当电生理表现为轴索损害时其一致的趋势欠佳,可能与轴索损害的多样性有关。     

Approach to the evaluation of small fiber peripheral neuropathy and disorders of orthostatic intolerance

Small fiber peripheral neuropathy is a frequently encountered neurological disorder, which can be difficult to diagnose. In this article, the differential diagnosis of small fiber neuropathy is discussed, along with role of autonomic testing, skin biopsy, and quantitative sensory testing, in establishing a definitive diagnosis of small fiber peripheral neuropathy. Disorders of orthostatic intolerance, including postural orthostatic tachycardia syndrome (POTS), are also discussed, emphasizing diagnostic evaluation and a treatment approach to these disorders.     

Contribution of nerve biopsy to unclassified neuropathy

OBJECTIVES: To evaluate the diagnostic yield of nerve biopsy in patients with peripheral neuropathy of undetermined cause despite extensive diagnostic workup. METHODS: From November 2001 through January 2004, 38 patients underwent nerve biopsy because of unclassified neuropathy. RESULTS: The etiology of the neuropathies could be defined in 14 patients (37%), i.e. in 15% of chronic symmetric, 30% of chronic asymmetric, 50% of subacute symmetric and 62.5% of subacute asymmetric neuropathies. The biopsy was diagnostic in 6 patients (16%), where it showed a vasculitis, and supportive in 8 patients (21%). CONCLUSIONS: The contribution of nerve biopsy to the diagnosis of peripheral neuropathy was highest in acute and subacute asymmetric forms of neuropathy and lowest in chronic symmetric forms. The main indication for nerve biopsy remains the diagnosis of vasculitic neuropathy, a potentially treatable disorder.     

Skin biopsy as a diagnostic tool in peripheral neuropathy

Skin biopsy is a safe, minimally invasive, painless and cheap tool for providing diagnostic information on small nerve fibers, which are invisible to routine neurophysiological tests. Biopsy can be performed in hairy skin to investigate unmyelinated and thinly myelinated fibers and in glabrous skin to examine large myelinated fibers. Morphometric analysis of skin nerves is readily accomplished through the use of immunohistochemical techniques, and has proved to be reliable, reproducible and unaffected by the severity of neuropathy. One further advantage of skin biopsy over conventional nerve biopsy is that it allows somatic nerve fibers to be distinguished from autonomic nerve fibers. Morphological changes, axonal degeneration and abnormal regeneration occur in cutaneous nerves very early in the course of peripheral neuropathies, making skin biopsy a promising tool for investigating the progression of neuropathy and the effect of neuroprotective treatments in clinical practice and trials. This article reviews the techniques that are used to investigate the innervation of human skin, the possible uses of skin biopsy in diagnosing and monitoring peripheral neuropathies, and correlations between skin biopsy findings and those of other diagnostic methods.     

Subacute axonal neuropathy in Parkinson's disease with cobalamin and vitamin B6 deficiency under duodopa therapy

We describe two patients who developed subacute axonal peripheral neuropathy under duodopa treatment. Comprehensive diagnostic workup including muscle and sural nerve biopsy revealed that the most probable cause of subacute axonal peripheral neuropathy was cobalaminand vitamin B6 deficiency in both the patients. © 2010 Movement Disorder Society     

Skin biopsy in the management of peripheral neuropathy

Skin biopsy has been widely used in recent years for the investigation of small-calibre sensory nerves, including somatic unmyelinated intraepidermal nerve fibres, dermal myelinated nerve fibres, and autonomic nerve fibres in peripheral neuropathies, with different techniques for tissue processing and nerve fibre assessment. Here, we review the techniques for skin biopsy, the processing and assessment of the biopsy sample, their possible uses in different types of peripheral neuropathy, and their use in the follow-up of patients and in clinical trials. We also review the association between morphological measures of skin innervation and function and the limits of this method in the aetiological classification of peripheral neuropathies.     

Electrophysiologic studies in critical illness associated weakness: myopathy or neuropathy--a reappraisal.

OBJECTIVE: Unexplained weakness in critically ill patients is recognized with increasing frequency. However, it is debated whether the condition is a peripheral neuropathy or a myopathy. Diagnostic difficulties can arise from multiple sources that are not generally a factor in other neuromuscular conditions. Conventional electrodiagnostic techniques may provide only non-specific data, clinical examination is often hampered, and muscle biopsy is not a practical screening tool. METHOD: To improve diagnostic yield, we studied 22 consecutive patients with critical illness associated weakness with additional electrodiagnostic techniques, including direct muscle stimulation, quantitative electromyography, and motor unit number estimation. RESULTS: The applied techniques supported an underlying myopathy in all the patients examined. The diagnosis was confirmed by muscle biopsy in 9 patients. Additional lesser features of neuropathy were concomitantly present in one patient who also underwent sural nerve biopsy. CONCLUSIONS: The study suggests that myopathy is much more common than polyneuropathy in critical illness. Suspicion of this entity should be high in this setting even without exposure to corticosteroids or non-depolarizing blocking agents.     

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.     

Ultrasound elastography for the evaluation of peripheral nerves: A systematic review

Peripheral nerve disorders are commonly encountered in clinical practice. Electrodiagnostic studies remain the cornerstone of the evaluation of nerve disorders. More recently, ultrasound has played an increasing complementary role in the neuromuscular clinic. Ultrasound elastography is a technique that measures the elastic properties of tissues. Given the histological changes that occur in diseased peripheral nerves, nerve ultrasound elastography has been explored as a noninvasive way to evaluate changes in nerve tissue composition. Studies to date suggest that nerve stiffness tends to increase in the setting of peripheral neuropathy, regardless of etiology, consistent with loss of more compliant myelin, and replacement with connective tissue. The aim of this systematic review is to summarize the current literature on the use of ultrasound elastography in the evaluation of peripheral neuropathy. Limitations of ultrasound elastography and gaps in current literature are discussed, and prospects for future clinical and research applications are raised.     

腓浅神经与腓骨短肌联合活体组织检查的诊断意义初探及15例临床病理报告

目的 开展单一切口下的腓浅神经与腓骨短肌联合活体组织检查,通过回顾相关病例的临床和病理资料,分析联合活体组织检查的诊断意义.方法 共15例患者,女性7例,男性8例,年龄14 ～72岁,其中亚急性6例、慢性9例,均患有周围神经病,3例临床上合并肌肉病.周围神经病的临床类型包括对称性感觉和运动性神经病7例、多发性单神经病5例、对称性感觉性神经病3例.在外踝前上方纵切口,取材腓浅神经与腓骨短肌.神经和肌肉病理结论的意义评价分为3级:(1)具有确诊意义;(2)对诊断有帮助:(3)对诊断无帮助.结果 活体组织检查病理结论有确诊意义者7例,包括血管炎5例、炎性脱髓鞘性周围神经病1例和淀粉样变性1例.有帮助者5例:病理改变分别为:慢性髓鞘性神经病伴洋葱球样肥大纤维;小血管病变伴轻度炎性反应;轻度间质炎性反应;脂褐素沉积等.无帮助者3例.最终12例通过活体组织检查得以确诊.结论 联合活体组织检查的诊断阳性率较高,血管炎周围神经病和淀粉样变性等适用联合活体组织检查.     

Magnetic resonance imaging of the peripheral nervous system

The diagnostic work up of patients with peripheral neuropathy largely depends on clinical and electrophysiological investigations. In contrast to disorders of the CNS, magnetic resonance imaging (MRI) has not been widely used as a diagnostic tool in the PNS except for detection of nerve compressing mass lesions. Normal nerves appear isointense to the surrounding tissue on T1- and T2-weighted (w) MRIs, but upon injury the nerves become hyperintense and thus visible on T2-w MRI. These signal alterations can be exploited to diagnose nerve damage in vivo and to follow regeneration. In patients with peripheral nerve disorders, MRI has been especially useful in detecting focal intrinsic and extrinsic nerve lesions and may reveal treatable conditions even in the absence of gross electrophysiological alterations. This clinical review provides practical guidelines on the performance of nerve imaging by MRI and will focus on focal lesions exemplified by case presentations.     

Utility of Skin Biopsy to Evaluate Peripheral Neuropathy

Skin biopsy for epidermal nerve fiber analysis provides an important objective test for the diagnosis of peripheral neuropathy, particularly small fiber sensory neuropathy (SFSN). The determination of epidermal nerve fiber density (ENFD) is reliable, with high diagnostic specificity and good sensitivity. Because of false negatives, biopsy results must be interpreted in conjunction with neurologic findings and laboratory results, including objective tests of sensory and autonomic function. SFSN most commonly is length dependent and is idiopathic in about half the patients. Biopsy of a proximal site (thigh) and a distal site (calf) typically shows greater abnormality of ENFD distally than proximally. More severe abnormality of ENFD in the thigh than in the calf raises the possibility of a non–length-dependent SFSN. The causes of this type of neuropathy, such as Sjögren’s syndrome, sarcoidosis, and celiac disease, may be treatable.     

Clinical utility of peripheral nerve biopsy

Histopathologic evaluation of nerve biopsy specimens provides important diagnostic information in some patients with peripheral neuropathy. The role of nerve biopsy is more restricted than that of muscle biopsy. Nerve biopsy is utilized mainly for diagnosis of vasculitis and infiltrative neuropathies. It is also utilized in diagnosis of atypical inflammatory demyelinating neuropathies in which the clinical, electrodiagnostic, and laboratory features are inconclusive. In addition, the study of nerve histopathology can also enhance our understanding of disease pathogenesis.     

Nerve excitability testing and its clinical application to neuromuscular diseases.

Non-invasive nerve excitability testing measures the membrane polarization, ion channel function and paranodal/internodal condition of peripheral nerves. This technique has been recently used for various neuromuscular disorders, such as pure motor conduction block in multifocal motor neuropathy, conduction block in carpal tunnel syndrome and Na(+) channel function disorders in diabetic neuropathy, to shed light on their pathophysiology. Here, we review the basics of ion channel functions and membrane properties that influence nerve excitability, the basic principles of nerve excitability testing and the reported findings in various disorders.     

Polyneuropathy: diagnosis and treatment]

Polyneuropathy is a common disorder with heterogenic clinical presentation and many possible etiologies. This review presents diagnostic clues for physicians and neurologists without specialist competence in neuromuscular disorders. Diagnostic procedure of polyneuropathy include cerebrospinal fluid examination, electrophysiological examinations, and sural nerve biopsy. Although pathologic examinations using biopsied sural nerve rarely reach specific diagnosis and are recently seem to be underestimated, careful scrutiny of the morphology of each myelinated nerve fiber as well as evaluation of clinical/pathological correlation may be powerful tools to reach proper diagnosis. Polyneuropathy presents symmetric motor and sensory impairment with "gloves and stockings" distribution. This characteristic clinical presentation is based on two different types of pathophysiology. One, neuronal malfunction which leads to inability in keeping homeostasis of axonal endings; the other, the "sum" of scattered focal lesions throughout the peripheral nervous system: longer axons have more chances to get local injuries. The former pathomechanism is shared by most of hereditary neuropathies and toxic neuropathies, and the latter includes inflammatory neuropathies as well as some vasculitic neuropathy, and possibly, diabetic neuropathy. Hence, we should keep in mind that the exact lesion site does not necessarily present at sural nerve, especially in inflammatory neuropathies and vasculitic neuropathies.     

Neuromuscular complications of connective tissue diseases

The connective tissue diseases, such as rheumatoid arthritis, Sj?gren's syndrome, systemic lupus erythematosus, systemic sclerosis, and vasculitis, may cause various disorders of the peripheral nervous system. In this review, the clinical effects of the connective tissues diseases on nerve and muscle are examined with particular attention to mononeuritis multiplex, distal symmetric neuropathy, fulminant motor neuropathy, compression neuropathy, sensory neuronopathy, and trigeminal sensory neuropathy.     

Peripheral neuropathy in CADASIL

Background Cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) is a hereditary cerebral microangiopathy associated with mutations in the Notch 3 gene. The clinical phenotype is characterized by cerebral impairment even though typical microvascular changes are diffuse. Objective To assess peripheral neuropathy in patients with CADASIL. Patients and Methods We enrolled eleven CADASIL patients with variable phenotype including clinical signs of peripheral nerve involvement. In all patients electromyography and nerve conduction velocities were performed. Peripheral nerve biopsy was performed in three cases. Results We found sensory motor neuropathy in 7/11 patients. Nerve biopsy revealed axonal and demyelinated findings. Conclusion Our findings suggest that peripheral neuropathy may be part of the CADASIL phenotype.