Diagnosis of motor neuropathy

Motor neuropathy is a clinical entity which leads to consideration of a wide spectrum of peripheral nerve disorders. Firstly, it may be distinguished from other causes of peripheral motor involvement such as muscle diseases and disorders of the neuromuscular junction. Secondly, it may be discussed in two different forms: acute and chronic. Acute chronic neuropathies are mainly observed in Guillain-Barré syndrome, in which electrophysiological studies allow us to recognize the classical demyelinating form and the axonal form. The other causes of acute motor neuropathy are mainly poliomyelitis and porphyrias. Chronic motor neuropathies are mainly observed in motor neuron diseases, mainly amyotrophic lateral sclerosis, but also Kennedy's disease and other lower motor neuron diseases which may be inherited or acquired. The other causes are multifocal motor neuropathy and the predominantly motor forms of chronic inflammatory demyelinating polyneuropathy. The characterization of these different types of chronic neuropathy is of major importance because of the therapeutic consequences which may lead to the proposal of specific treatments.     

Paraneoplastic peripheral neuropathies

Paraneoplastic peripheral neuropathies constitute a heterogeneous group of conditions. A link between the tumor and the neuropathy has been demonstrated in a subgroup only. Definite paraneoplastic neuropathies correspond to neuropathies associated with antibodies reacting with antigens common to the peripheral nervous system and the cancer. Neuropathies associated with anti-Hu antibodies are the most frequent and consist mainly in subacute sensory neuronopathy. Sensory or sensory-motor neuropathies with anti-CV2 antibodies are less frequent. The link between the cancer and the neuropathy is less clear in the other forms. The frequency of cancer in this group varies from 1 to 18 p.cent.These neuropathies include inflammatory demyelinating neuropathies, neuropathy and vasculitis, lower motor neurone diseases, and autonomic neuropathies. Occasionally, the neuropathy improves with treatment of the tumor. Recent data suggest that gangliosides may be the target of the immune process in neuropathies associated with melanoma.     

Chronic dysimmune neuropathies: Beyond chronic demyelinating polyradiculoneuropathy

The spectrum of chronic dysimmune neuropathies has widened well beyond chronic demyelinating polyradiculoneuropathy (CIDP). Pure motor (multifocal motor neuropathy), sensorimotor with asymmetrical involvement (multifocal acquired demylinating sensory and motor neuropathy), exclusively distal sensory (distal acquired demyelinating sensory neuropathy) and very proximal sensory (chronic immune sensory polyradiculopathy) constitute the variants of CIDP. Correct diagnosis of these entities is of importance in terms of initiation of appropriate therapy as well as prognostication of these patients. The rates of detection of immune-mediated neuropathies with monoclonal cell proliferation (monoclonal gammopathy of unknown significance, multiple myeloma, etc.) have been facilitated as better diagnostic tools such as serum immunofixation electrophoresis are being used more often. Immune neuropathies associated with malignancies and systemic vasculitic disorders are being defined further and treated early with better understanding of the disease processes. As this field of dysimmune neuropathies will evolve in the future, some of the curious aspects of the clinical presentations and response patterns to different immunosuppressants or immunomodulators will be further elucidated. This review also discusses representative case studies.     

Multifocal sensory demyelinating neuropathy: Report of a case

Introduction: Multifocal sensory demyelinating neuropathy has not been adequately reported in the literature. Methods: A 42‐year‐old man with numbness of the left hand for 3 years and of the right hand for 6 months had a pure multifocal sensory neuropathy involving both hands, most prominently affecting 2‐point discrimination, number writing, and object recognition of the left hand. Near‐nerve needle sensory and mixed nerve conduction studies were performed on the left ulnar nerve. Results: Studies of the left ulnar nerve documented a demyelinating neuropathy characterized by temporal dispersion and marked decrease in the amplitudes of the sensory and mixed compound nerve potentials in the above‐elbow‐axilla segment. With intravenous immunoglobulin treatment, there was improvement in his neuropathic condition. Conclusion: In this study I describe a case of multifocal sensory demyelinating neuropathy as a counterpart of multifocal motor neuropathy. Muscle Nerve 56 : 825–828, 2017     

Utility of somatosensory evoked potentials in chronic acquired demyelinating neuropathy

Chronic acquired demyelinating polyneuropathy (CADP) is a heterogeneous syndrome that may be classified into a number of subtypes. Somatosensory evoked potentials (SSEPs) assess proximal segments of sensory nerves, inadequately assessed by routine nerve conduction studies (NCSs). The aim of the present study was to determine the utility of SSEPs in diagnosing and classifying different CADP subtypes. Forty-seven patients with CADP were studied and classified in five groups based on conventional NCSs and SSEPs. Some patients in Group 1 were initially misdiagnosed as having either motor neuron disease or multifocal motor neuropathy due to normal sensory NCSs, but they exhibited abnormal tibial and median nerve SSEPs, as evidenced by marked prolongation or absence of peripheral potentials (N9-median nerve, and N20-tibial nerve). These were reclassified as having chronic inflammatory demyelinating neuropathy (CIDP). In CIDP patients (Group 2), SSEPs were abnormal, thereby confirming the presence of demyelination in the proximal peripheral nerves. Patients with distal acquired demyelinating neuropathy (DADS) (Group 3), as defined by conventional NCS, exhibited abnormal SSEPs when anti-MAG antibodies were present. Anti-MAG-negative DADS patients (Group 3) had normal SSEPs. In the pure sensory ataxic group (Group 4), SSEP studies disclosed poorly formed and delayed cortical potentials with absent lumbar (N20) potentials, thereby suggesting the presence of proximal demyelination. SSEPs were normal in the pure motor CIDP and multifocal motor neuropathy patients (MMN) (Group 5), thereby differentiating asymmetric forms of CIDP from MMN. These findings suggest that SSEPs may be an important complementary investigation to conventional NCSs in the diagnosis of CADP.     

Diagnosis of hereditary neuropathies in adult patients

This paper reviews the clinical diagnostic approach to hereditary neuropathies in adults by analysing: elements that point to a neuropathy of inherited origin, different modalities of presentation, laboratory and instrumental diagnostic tests, including molecular tests, symptoms and signs of involvement of other organs. Different phenotypes may be identified according to: disease course; involvement of motor, sensory, autonomic fibres; site of lesion (neuropathy versus neuronopathy); calibre of involved fibres (small-fibre versus large-fibre neuropathy); presence of distinctive symptoms (neuropathic pain); involvement of other organs or apparatus. Charcot-Marie-Tooth disease, Familial Amyloid Polyneuropathy, Hereditary Sensory and Autonomic Neuropathy, Fabry disease, Tangier disease, Porphyric Neuropathies, Refsum disease, Hereditary Neuropathy with liability to Pressure Palsies, Hereditary Neuralgic Amyotrophy, and other rare disorders involving the peripheral nervous system are reviewed.     

Immunotherapy of idiopathic inflammatory neuropathies

Evaluation of peripheral neuropathy is a common reason for referral to a neurologist. Recent advances in immunology have identified an inflammatory component in many neuropathies and have led to treatment trials using agents that attenuate this response. This article reviews the clinical presentation and treatment of the most common subacute inflammatory neuropathies, Guillain-Barré syndrome (GBS) and Fisher syndrome, and describes the lack of response to corticosteroids and the efficacy of treatment with plasma exchange and intravenous immunoglobulin (IVIG). Chronic inflammatory demyelinating polyneuropathy, although sharing some clinical, electrodiagnostic, and pathologic similarities to GBS, improves after treatment with plasma exchange and IVIG and numerous immunomodulatory agents. Controlled trials in multifocal motor neuropathy have shown benefit after treatment with IVIG and cyclophosphamide. Also discussed is the treatment of less common inflammatory neuropathies whose pathophysiology involves monoclonal proteins or antibodies directed against myelin-associated glycoprotein or sulfatide. Little treatment data exist to direct the clinician to proper management of rare inflammatory neuropathies resulting from osteosclerotic myeloma; POEMS syndrome; vasculitis; Sj?gren's syndrome; and neoplasia (paraneoplastic neuropathy).     

Treatment of immune-mediated, dysimmune neuropathies

This review focuses on the actual status and recent advances in the treatment of immune-mediated neuropathies, including: Guillain-Barre syndrome (GBS) with its subtypes acute inflammatory demyelinating polyradiculoneuropathy, acute motor axonal neuropathy, acute motor and sensory axonal neuropathy, Miller Fisher syndrome, and acute pandysautonomia; chronic inflammatory demyelinating polyneuropathy (CIDP) with its subtypes classical CIDP, CIDP with diabetes, CIDP/monoclonal gammopathy of undetermined significance (MGUS), sensory CIDP, multifocal motor neuropathy (MMN), multifocal acquired demyelinating sensory and motor neuropathy or Lewis-Sumner syndrome, multifocal acquired sensory and motor neuropathy, and distal acquired demyelinating sensory neuropathy; IgM monoclonal gammopathies with its subtypes Waldenstrom's macroglobulinemia, myelin-associated glycoprotein-associated gammopathy, polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes syndrome, mixed cryoglobulinemia, gait ataxia, late-onset polyneuropathy syndrome, and MGUS. Concerning the treatment of GBS, there is no significant difference between intravenous immunoglobulins (IVIG), plasma exchange or plasma exchange followed by IVIG. Because of convenience and absent invasiveness, IVIG are usually preferred. In treating CIDP corticosteroids, IVIG, or plasma exchange are equally effective. Despite the high costs and relative lack of availability, IVIG are preferentially used. For the one-third of patients, who does not respond, other immunosuppressive options are available. In MMN IVIG are the treatment of choice. Inadequate response in 20% of the patients requires adjunctive immunosuppressive therapies. Neuropathies with IgM monoclonal gammopathy may respond to various chemotherapeutic agents, although the long-term effects are unknown. In addition, such treatment may be associated with serious side effects. Recent data support the use of rituximab, a monoclonal antibody against the B-cell surface-membrane-marker CD20.     

Nerve ultrasound protocol in differentiating chronic immune‐mediated neuropathies

Introduction: In this study we evaluated a new neuropathy ultrasound protocol (NUP) for differentiating chronic immune‐mediated neuropathies. Methods: The NUP was evaluated in 110 patients with clinical presentations of chronic immune‐mediated neuropathy. All patients were first evaluated clinically and electrophysiologically and divided into 4 polyneuropathy groups: (a) symmetric demyelinating; (b) symmetric axonal; (c) asymmetric demyelinating; and (d) asymmetric axonal. During step 2, the NUP was evaluated prospectively for all 4 study groups. Results: Overall, the NUP led to correct classification in 42 of 49 (85.7%) patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 13 of 15 (86.9%) with multifocal motor neuropathy (MMN), and 5 of 5 (100%) with multifocal‐acquired demyelinating sensory and motor neuropathy (MADSAM). The NUP had >80% sensitivity and specificity in distinguishing CIDP, MMN, and MADSAM in all 4 study groups. Conclusions: The NUP is a useful addition in the differential diagnosis of chronic immune‐mediated neuropathies in everyday practice. Muscle Nerve 54 : 864–871, 2016     

Current treatments of chronic immune‐mediated demyelinating polyneuropathies

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy (MMN), and anti–myelin‐associated glycoprotein (anti‐MAG) neuropathy are three demyelinating acquired neuropathies, with distinct responses to immunotherapy. In placebo‐controlled, double‐blind, randomized trials, intravenous immunoglobulin (IVIg) has been effective for CIDP and MMN, and plasmapheresis has been effective for CIDP. Corticosteroids have been beneficial in controlled trials for CIDP. Other agents, including cyclophosphamide, rituximab, azathioprine, cyclosporine, interferons, fludarabine, mycophenolate mofetil, and etanercept, have been reported to benefit some patients with inflammatory demyelinating neuropathies in case series and case reports. This review examines the use and toxicity associated with these immunotherapy medications in treating patients with chronic immune‐mediated demyelinating neuropathies. Muscle Nerve, 2009     

Nerve conduction studies in polyneuropathy: practical physiology and patterns of abnormality

Nerve conduction studies are an essential part of the work-up of peripheral neuropathies. Many neuropathic syndromes can be suspected on clinical grounds, but optimal use of nerve conduction study techniques (in combination with needle electromyography) allows diagnostic classification and is therefore crucial to understanding and separation of neuropathies. Multifocal motor neuropathy, for example, may clinically present as ALS. Detection of evidence of demyelination (conduction blocks) leads to the correct diagnosis and to proper treatment. Nerve conduction studies provide essential information on (1) the spatial pattern of neuropathy, (2) the pattern of abnormalities distinguishing between primarily axonal and demyelinating pathology, and (3) the severity of neuropathic damage. This information is very comprehensive since many nerves and long segments of individual nerves can be sampled. Moreover the information is extremely detailed to the extent that the cellular pathology of a patient's neuropathy is usually defined best by physiological testing rather than by biopsy. Neuropathies can be generalized, focal, or multifocal; they can be symmetric or asymmetric; they can be distally predominant or proximal and distal. Primarily axonal neuropathies mainly affect sensory nerve and compound muscle action potential amplitudes, whereas demyelinating neuropathies lead to slowing of nerve conductions, and to increased temporal dispersion or conduction block. Usually, the pattern of demyelination allows to distinguish hereditary (uniform demyelination) from acquired (segmental demyelination) neuropathies. Electrodiagnostic criteria for primary demyelination are helpful to identify acquired demyelinating neuropathies.     

The diagnosis of acquired sensory neuropathies

INTRODUCTION: Peripheral neuropathies usually include a sensory component of various causes. The diagnosis approach requires careful a clinical assessment and a precise electrophysiological exploration. STATE OF ART: Axonal sensory polyneuropathies are classified according to the type of fibers involved (large or small fibers). While there is a large number of causes, current emphasis is placed on glucose intolerance as a source of small-fiber sensory neuropathies. Demyelinating polyneuropathies are often associated with a monoclonal IgM gammapathy with anti-MAG activity. Multiple sensory mononeuropathies are exceptional and suggest possible early-phase vasculities, sensorymotor neuropathy with conduction blocks or leprosy. Sensory neuronopathies can also suggest Sj?gren's syndrome or a paraneoplastic syndrome. Finally chronic sensory polyradiculoneuritis constitute a rare subgroup clearly defined as demyelinating inflammatory neuropathy. CONCLUSION: The diagnostic approach to sensory neuropathies requires careful nosological electroclinical classification to reduce the number of explorations performed for etiological diagnosis.     

Efficacy and tolerability of different brands of intravenous immunoglobulin in the maintenance treatment of chronic immune‐mediated neuropathies

High‐dose intravenous immunoglobulin (IVIg) is effective in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and multifocal motor neuropathy (MMN). Not all brands of IVIg are however licensed for these neuropathies. We reviewed six patients with CIDP and seven with MMN treated with maintenance therapy with IVIg from 2009 to 2013. In all patients, we measured the Medical Research Council (MRC) and Overall Neuropathy Limitation Scale (ONLS) scores before each infusion, registered the monthly dose and brand of IVIg, and recorded adverse events. Patients were treated for 25–60 months (mean 49 months) alternating different brands of IVIg including IgVena, Gammagard, Kiovig, and Flebogamma. Minor and transient side effects were equally observed with each brand. No difference in the MRC or ONLS scores was observed in relation to the brand of IVIg used. Chronic maintenance treatment with IVIg in patients with MMN and CIDP was not associated with a different tolerability or efficacy despite the use of different brands of IVIg.     

Demyelinating neuropathy and Sjögren's syndrome: a diagnostic pitfall

INTRODUCTION: Neuropathies induced by Sj?gren's syndrome (SS) are usually axonal. Nevertheless some demyelinating neuropathies have been described in patients with SS. To date, the relationship between demyelinating neuropathies and SS remains imprecise. CASE REPORT: A 75 year-old man presented with a chronic history of sensory disturbances linked to demyelinating neuropathy. Electroneuromyography revealed a demyelinating neuropathy and complementary tests revealed both Sj?gren's syndrome (SS) and HMSN IA. CONCLUSION: We suggested that an inherited affection might be researched before considering that demyelinating neuropathy might be a form of peripheral nervous system involvement in SS.     

Chronic acquired demyelinating motor neuropathy

A patient with chronic, acquired, demyelinating, pure or predominantly motor asymmetric neuropathy is described. Electrophysiological tests showed multifocal conduction block in motor nerves. The sensory system was intact and the first signs of slight trival involvement appeared after 4 years of disease duration. The antiganglioside antibodies were present in serum and the patient responded to immunosuppressive therapy (azathioprine). Distinction of such cases from motor neuron disease is critical since motor demyelinating neuropathy is treatable in most cases.     

Chronic inflammatory demyelinating neuropathies and their variants

The Chronic Inflammatory Demyelinating Polyradiculoneuropathies (CIDP) constitute a syndrome whose incidence is difficult to evaluate, and is probably underestimated. In the course of this presentation, we deliberately restricted discussion to issues raised in recent years concerning the extent of this syndrome. We discuss diagnostic criteria, especially electrophysiological ones. As the criteria proposed by the ad hoc committee of the American Academy of Neurology in 1991 have been questioned due to lack of sensitivity, new ones have been proposed recently. We briefly discuss the different types of chronic dysimmune demyelinating neuropathy: not only the CIDP, but also the Lewis and Sumner syndrome or multifocal inflammatory demyelinating neuropathy and the multiple conduction block neuropathies. At last, we point out the consistent finding of axonal involvement in the course of a chronic demyelinating neuropathy; over time, it can become predominant, which may make diagnosis difficult by suggesting a chronic axonal neuropathy that may be assumed to be primary. Consideration of these points may help clinicians recognize more chronic dysimmune neuropathies, for which immunosuppressive therapy has been found to be effective.     

Pathophysiology of immune‐mediated demyelinating neuropathies—Part II: Neurology

In the second part of this review we deal with the clinical aspects of immune‐mediated demyelinating neuropathies. We describe the relationship between pathophysiology and symptoms and discuss the pathophysiology of specific disease entities, including Guillain–Barré syndrome, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy, anti–myelin‐associated glycoprotein neuropathy, and POEMS syndrome. Muscle Nerve 49 : 4–20, 2014     

Sensory loss in multifocal motor neuropathy: A clinical and electrophysiological study

Some patients fulfilling the criteria for the diagnosis of multifocal motor neuropathy with conduction block (MMN‐CB) at the onset of disease may subsequently develop a sensory loss associated with electrophysiological sensory abnormalities. The latter could represent an overlap between MMN‐CB and multifocal acquired demyelinating sensory and motor (MADSAM) neuropathy. The objective was to specify the features of MMN‐CB with sensory loss (MMN‐CB‐Se). Five patients in a series of 11 consecutive patients who fulfilled the criteria of the American Association of Neuromuscular and Electrodiagnostic Medicine for MMN‐CB at the first examination and were treated periodically with intravenous immunoglobulin (IVIg) developed sensory loss in the course of the disease. In these five patients we compared the clinical, laboratory, and electrophysiological features found after the development of sensory loss with those at the first examination. The mean time to appearance of objective sensory signs was 7.2 years. In three of the five patients the sensory loss was preceded by intermittent paresthesias in the same nerve territories as the motor involvement. The most frequent electrophysiological abnormality was amplitude reduction of sensory nerve action potentials. There were no bilateral or symmetrical clinical and electrophysiological sensory abnormalities. Anti‐GM1 IgM antibodies were positive in four patients. MMN‐CB‐Se could be an overlap between MMN‐CB and MADSAM. It shares the distribution of the sensory disorders encountered in MADSAM, but it is closer to MMN‐CB on clinical and therapeutic levels. Study of more patients would be useful to classify this subgroup more accurately. Muscle Nerve, 2009     

Predominant arm weakness in acute idiopathic polyneuritis: a distinct regional variant

Acute idiopathic polyneuritis is a heterogeneous disorder with a number of clearly established variants. We describe four patients who present with an acute neuropathy predominantly affecting the arms which we believe should be considered as a distinct variant of acute polyneuritis. In two cases a primary demyelinating process affecting both motor and sensory nerves is suggested whereas in the other two the features were of a pure motor axonal degeneration. The relationship between these neuropathies, other variants of acute idiopathic polyneuritis and multifocal motor neuropathy is considered. Received: 11 May 1999/Received in revised form: 8 November 1999/Accepted: 16 December 1999     

Pathogenesis and treatment of inflammatory demyelinating polyradiculoneuropathy

Inflammatory demyelinating polyradiculoneuropathy causes a spectrum of conditions ranging from acute (Guillain-Barré syndrome), through subacute to chronic forms. The pathogenesis of acute forms is related to antibody responses against glycolipid epitopes which mimic bacterial, especially Campylobacter jejuni, structures but T cells are also involved. The pathogenesis of chronic forms is poorly understood. Different forms differ in their responses to steroids. Chronic inflammatory demyelinating polyradiculoneuropathy responds to steroids but a variant multifocal motor neuropathy and the acute forms of inflammatory demyelinating polyradiculoneuropathy do not. Acute and chronic forms respond to plasma exchange and intravenous immunoglobulin.