Prevalence of subclinical neuropathy in diabetic patients: assessment by study of conduction velocity distribution within motor and sensory nerve fibres

Nerve conduction velocity distribution (CVD) study is a newly-developed electrodiagnostic method for detecting alterations in the composition of nerve fibres according to their conduction velocity. The presence of subclinical neuropathy was evaluated in 138 diabetic patients by CVD study of four motor nerves (external popliteal and ulnar nerves bilaterally) and two sensory nerves (median nerve bilaterally), and the data obtained were compared with standard electrophysiological parameters in the same nerve segments. CVD studies revealed an altered distribution pattern in 106 of 129 evaluable patients for motor nerves (82%) and in 67 of 115 evaluable patients for sensory nerves (58%), while standard examination gave abnormal findings in 92 of 137 patients (67%) and in 33 of 118 patients (11%), respectively. Of the patients adequately evaluated by both techniques, 21 of 129 patients (16%) revealed altered CVD data unaccompanied by slowing of maximum nerve conduction velocity, and 37 patients of 101 (37%) showed similar findings for sensory nerves. Subclinical alterations of motor and sensory nerve CVD were not significantly related to age or to metabolic control expressed as glycated haemoglobin levels; a significantly longer duration of disease was found in patients with motor and mixed subclinical neuropathy with respect to non-neuropathic patients. The CVD study allowed us to detect subclinical abnormalities of motor and sensory nerve fibres; often this is a more sensitive method than the standard electrodiagnostic study. This method can be very useful as a diagnostic tool and in research in the study of the progression of diabetic neuropathy. Received: 21 March 1997 Received in revised form: 8 September 1997 Accepted: 7 October 1997     

Prognosis of acute compressive radial neuropathy

Introduction: Small published case series suggest that compressive radial neuropathy is often a self‐limited phenomenon with a favorable prognosis. Due to paucity of data, we sought to clearly define prognosis. Methods: To define clinical and electrodiagnostic features in this condition, we retrospectively reviewed consecutive cases of compressive radial neuropathy confirmed using electrodiagnostic studies at a large tertiary center over a 10‐year period. Results: A total of 51 patients (26 men, 25 women, mean age 46 years ± 15; range, 19–83 years) with compressive radial neuropathy were identified and reviewed. All patients in whom clinical follow‐up was available (23 [45%] of the 51 patients identified) experienced complete recovery. Mean duration from onset to resolution of symptoms was 3.4 months. Conclusions: Our results support a good prognosis in essentially all patients with acute compressive radial neuropathies. This report provides valuable information to assist in counseling patients who may present with profound clinical deficits. Muscle Nerve 45: 893–894, 2012     

Electrodiagnostic consultation and identification of neuromuscular conditions in persons with diabetes

Introduction: Although the American Association of Neuromuscular and Electrodiagnostic Medicine recommends that electrodiagnostic procedures should be performed by physicians with specialty training, these procedures are increasingly being performed by non‐specialists. Methods: We used a nationally representative sample of Medicare beneficiaries with diabetes who used electrodiagnostic services in 2006 to examine whether specialists and non‐specialists were different in the rates of identifying common neuromuscular conditions. Results: Specialists (neurologists and physiatrists) performed 62% of electrodiagnostic consultations; non‐specialist physicians and non‐physicians performed 31% and 5%, respectively. After adjusting for age, race/ethnicity, diabetes severity, and comorbidities, specialists were 1.26–9 times more likely than non‐physicians to diagnose polyneuropathy, lumbosacral radiculopathy, cervical radiculopathy, carpal tunnel syndrome, and ulnar neuropathy. Almost 80% of electrodiagnostic studies performed by specialists included electromyography testing; fewer than 13% by non‐specialists did. Conclusions: Inadequate use of electromyography and fewer specific diagnoses suggest that many non‐specialists perform insufficiently comprehensive electrodiagnostic studies. Muscle Nerve, 2011     

The natural history of long thoracic and spinal accessory neuropathies

A cohort of 106 patients with electrodiagnostically confirmed long thoracic neuropathy (50 patients) or spinal accessory neuropathy (56 patients) seen at the Mayo Clinic over a 22-year period were retrospectively studied to better understand the natural history of these disorders and to determine the role of electrodiagnostic testing in predicting prognosis. Mean follow-up was 48 and 50 months, respectively. Good functional recovery was generally observed regardless of the results of electrodiagnostic studies, but improvement in the amplitude of the spinal accessory compound muscle action potential on serial nerve conduction studies tended to predict a good outcome. No electrodiagnostic findings correlated with poor outcome. Traumatic neuropathies generally did worse than neuropathies of other causes. In spinal accessory neuropathies, involvement of the dominant limb, scapular winging, and impaired arm elevation were associated with a poor outcome. Our data suggest that, contrary to other focal neuropathies, the electrodiagnostic findings do not predict functional outcome in these neuropathies.     

Sensory CIDP presenting as cryptogenic sensory polyneuropathy

The objective of this study was to report that patients with chronic inflammatory demyelinating polyneuropathy (CIDP) can present with a clinical picture of cryptogenic sensory neuropathy. Patients with distal sensory neuropathy and electrodiagnostic studies that are minimally abnormal or consistent with an axonal pathology are usually diagnosed as having cryptogenic sensory neuropathy if no cause for neuropathy can be found. Some of these patients, however, may have sensory CIDP. We reviewed the records of eight patients with CIDP, diagnosed by sural nerve biopsy, who presented with sensory neuropathy and electrodiagnostic studies that were minimally abnormal or revealed changes consistent with axonal neuropathy. All patients reported distal numbness and paresthesias and, on examination, had predominantly large fiber distal sensory loss and normal muscle strength. In most patients, deep tendon reflexes were reduced or absent. Sural nerve biopsies in all patients were consistent with chronic myelinopathy, with quantitative teased fiber analysis revealing segmental remyelination in 13-40% of the fibers. The four patients who received IVIg therapy had improved sensation and gait. Of the remaining four patients, one is being followed, one had spontaneous remission, one was lost to follow-up, and one, with contraindications to therapy, reported disease progression. Sensory CIDP may present as cryptogenic sensory polyneuropathy with normal or axonal electrophysiologic features. Sural nerve biopsy should be considered in patients with progressive, predominantly large fiber sensory neuropathy of otherwise unknown etiology, as they may have sensory CIDP that responds to therapy.     

Nerve ultrasound in a case of multifocal motor neuropathy without conduction block

Introduction: Multifocal nerve enlargements and ultrastructural changes either corresponding or not to sites of existing conduction blocks have been described in demyelinating polyneuropathies using multiple imaging techniques. Methods: Using the emerging technique of peripheral nerve ultrasonography we investigated the peripheral nerves of a patient with multifocal motor neuropathy (MMN) without conduction block. Results: In this case of MMN without conduction blocks we found multifocal nerve enlargements in the ultrasonography and electrodiagnostic signs of acute and chronic denervation associated with positive anti‐GM1 IgM antibodies. Conclusions: This case shows that nerve ultrasound can be a complementary tool for diagnosing multifocal motor neuropathy without typical electrodiagnostic features. Muscle Nerve 52 : 294–299, 2015     

Amyloid neuropathy mimicking chronic inflammatory demyelinating polyneuropathy

Introduction: Amyloid neuropathy is a rare peripheral neuropathy that classically presents as a progressive sensory neuropathy with prominent autonomic involvement. Methods: We describe 5 patients with amyloid neuropathy (familial amyloid polyneuropathy or acquired amyloidosis) who were initially mistaken to have chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) based on history, clinical examination, electrodiagnostic studies, and cerebrospinal fluid (CSF) analysis. Results: The diagnosis of CIDP had been retained on clinical and electrophysiological grounds for all patients, but we observed no improvement after immunomodulatory treatment. Nerve biopsy confirmed amyloid deposits in nerves, and molecular genetic analysis showed a mutation of the transthyretin (V30M) gene for 3 patients; the 2 other patients had acquired amyloidosis. Conclusions: This report emphasizes the need to look for an alternative diagnosis in CIDP patients who do not respond to treatment and to look carefully for symptoms or signs of autonomic involvement in such patients. Muscle Nerve 45: 26–31, 2012     

Demyelinating peripheral neuropathy in Creutzfeldt-Jakob disease.

We describe 2 patients of Jewish Libyan descent, who presented with a clinical syndrome compatible with Creutzfeldt-Jakob disease and who were found to have a mutation of codon 200 in the prion protein. The patients developed symptoms and signs of peripheral nerve involvement diagnosed by electrodiagnostic and histopathological studies as demyelinating neuropathy. This may be a rare manifestation of Creutzfeldt-Jakob disease.     

Practice parameter: utility of electrodiagnostic techniques in evaluating patients with suspected peroneal neuropathy: an evidence-based review

An evidence-based review of electrodiagnostic (EDX) techniques in the evaluation of peroneal neuropathy was conducted to determine whether these techniques are useful for diagnosis and prognostication in this disorder. A Medline search and a review of relevant sources were performed in 1999 and updated through July 2003 to identify articles describing the use of EDX in patients suspected to have peroneal neuropathy. From the 499 articles identified, 112 articles describing motor and sensory nerve conduction studies and needle electromyography in peroneal neuropathy were reviewed in detail; 11 articles met the predetermined literature inclusion criteria for the adequacy of EDX techniques employed. Six articles provided Class III evidence in support of a role for nerve conduction studies in making the diagnosis of peroneal neuropathy; five articles provided Class IV evidence. Implicit in making the diagnosis were normal EDX findings outside the distribution of the peroneal nerve. The current literature supports the use of EDX in patients with suspected peroneal neuropathy (Level C recommendation).     

Neuromuscular ultrasound in common entrapment neuropathies

Neuromuscular ultrasound involves the use of high‐resolution ultrasound to image the peripheral nervous system of patients with suspected neuromuscular diseases. It complements electrodiagnostic studies well by providing anatomic information regarding nerves, muscles, vessels, tendons, ligaments, bones, and other structures that cannot be obtained with nerve conduction studies and electromyography. Neuromuscular ultrasound has been studied extensively over the past 10 years and has been used most often in the assessment of entrapment neuropathies. This review focuses on the use of neuromuscular ultrasound in 4 of the most common entrapment neuropathies: carpal tunnel syndrome, ulnar neuropathy at the elbow and wrist, and fibular neuropathy at the knee. Muscle Nerve 48:696–704, 2013     

Sensory peripheral neuropathy of vitamin B12 deficiency: A primary demyelinating disease?

Summary In five patients with peripheral neuropathy due to vitamin B₁₂ deficiency, electrodiagnostic studies demonstrated severe reduction in sensory nerve conduction velocities compatible with a demyelinating disorder affecting sensory nerve fibres. It is suggested that in some patients lack of vitamin B₁₂ may cause primary sensory demyelinating neuropathy.     

Polyneuropathy associated with IgA monoclonal gammopathy of undetermined significance

Although polyneuropathies associated with IgM and IgG monoclonal gammopathies have been well described, polyneuropathy with IgA monoclonal gammopathy of undetermined significance (MGUS) is less commonly seen and has not been well studies. We reviewed the clinical and electrodiagnostic features of 5 such patients, and the sural nerve biopsy findings in 4 of them. One patient was diabetic, while 4 were free of other diagnoses commonly associated with neuropathy. Clinical presentations were varied. Electrodiagnostic and histological studies ranged from primary demyelination to primary axon loss to a mixed axonal/demyelinating picture. Three patients who were treated appeared to respond to prednisone or intravenous gamma globulin, despite clear clinical, electrodiagnostic, and histological differences. We conclude that the polyneuropathy associated with IgA MGUS is heterogeneous, similar to that in IgM and IgG MGUS. A trial of immunomodulating therapy appears to be warranted in such patients if the neuropathy is sufficiently servere. © 1993 John Wiley & Sons, Inc.     

Prognostic values of electrodiagnostic studies in traumatic radial neuropathy

It is important to have strong predictors of outcome in traumatic neuropathies so that appropriate management can be instituted early. Our objective in this study was to evaluate the prognostic value of electrodiagnostic studies in traumatic radial neuropathy. In this retrospective study, 33 of 67 subjects with traumatic radial neuropathy met the inclusion criteria. Good outcome was defined as grade 3 or higher strength on the Medical Research Council scale in wrist extensors. Compound muscle action potential (CMAP) responses from extensor indicis proprius (EIP) predicted prognosis: 92% of subjects with a recordable CMAP had a good outcome; and 65% of those with an absent response had a good outcome. Recruitment in brachioradialis was also predictive: 92% of those with full, central, or reduced recruitment had a good outcome; 67% of those with discrete recruitment had a good outcome; and only 33% of those with absent recruitment had a good outcome. Studies performed more than 3 months after injury produced more prognostic certainty than those performed earlier. We conclude that electrodiagnostic studies produce useful prognostic information in traumatic radial neuropathy. It is noteworthy, however, that 65% of subjects with an absent radial CMAP (suggesting complete or nearly complete axon loss) still have a good outcome.     

Chronic relapsing brachial plexus neuropathy with persistent conduction block

Idiopathic brachial plexus neuropathy (BPN) is an immune-mediated disorder characterized by an acute onset of painful weakness in one or both upper extremities. The course is usually monophasic with gradual improvement over months; however, occasionally BPN can recur. Electrophysiologic studies suggest the pathogenesis is primarily axonal in the majority of cases. We descibe an unusual case of BPN in which the patient had a chronic and relapsing course of painless weakness associated with conduction blocks and other electrophysiologic features of demyelination across the brachial plexus. The patient improved following treatment with intravenous immunoglobulin. The neuropathy falls within the spectrum of chronic inflammatory demyelinating polyneuropathy and multifocal motor neuropathy. © 1997 John Wiley & Sons, Inc. Muscle Nerve 20: 1303–1307, 1997     

Porphyric neuropathy

The hepatic porphyrias are a group of rare metabolic disorders characterized by enzymatic defects in the biosynthesis of heme, a metalloporphyrin that is the principal product of porphyrin metabolism. The hepatic porphyrias are genetically transmitted as autosomal-dominant disorders with variable expression that produce a particularly severe form of neuropathy. Most medical students readily recognize acute attacks of porphyria when the classic triad of abdominal pain, psychosis, and neuropathy is present. Yet, porphyric neuropathy is a source of confusion in practice, and patients with porphyria rarely receive the correct diagnosis early in the course of the illness. Porphyric neuropathy is manifest by symptoms, signs, and cerebrospinal fluid abnormalities resembling acute Guillain-Barré syndrome. However, accompanying psychological features, a proximal predilection of asymmetric weakness, and electrodiagnostic findings indicative of an axonal polyradiculopathy or neuronopathy all suggest the diagnosis of porphyria. Confirmation of the diagnosis depends on use of appropriate laboratory studies. The underlying pathophysiology of porphyric neuropathy has not been established, but it may be related to direct neurotoxicity of elevated levels of delta-aminolevulinic acid. The severity of the neuropathy and the availability of potential treatments, including avoidance of provocative factors, make identification important.     

Acute nutritional axonal neuropathy

Introduction: This study describes clinical, laboratory, and electrodiagnostic features of a severe acute axonal polyneuropathy common to patients with acute nutritional deficiency in the setting of alcoholism, bariatric surgery (BS), or anorexia. Methods: Retrospective analysis of clinical, electrodiagnostic, and laboratory data of patients with acute axonal neuropathy. Results: Thirteen patients were identified with a severe, painful, sensory or sensorimotor axonal polyneuropathy that developed over 2–12 weeks with sensory ataxia, areflexia, variable muscle weakness, poor nutritional status, and weight loss, often with prolonged vomiting and normal cerebrospinal fluid protein. Vitamin B6 was low in half and thiamine was low in all patients when obtained before supplementation. Patients improved with weight gain and vitamin supplementation, with motor greater than sensory recovery. Discussion: We suggest that acute or subacute axonal neuropathy in patients with weight loss or vomiting associated with alcohol abuse, BS, or dietary deficiency is one syndrome, caused by micronutrient deficiencies. Muscle Nerve 57 : 33–39, 2018     

Multifocal motor neuropathy without overt conduction block

One of the defining electrophysiological characteristics of multifocal motor neuropathy (MMN) is focal motor nerve conduction block. We have noted occasional patients with typical clinical features of MMN in whom there is no demonstrable conduction block. Upon review of 5 such cases, we conclude that otherwise typical MMN may present without overt conduction block. This subset of patients does not otherwise differ from patients with MMN in whom this hallmark electrodiagnostic feature is present. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 243–245, 1998.     

The utility of magnetic resonance imaging in evaluating peripheral nerve disorders

The evaluation of peripheral nerve injuries has traditionally relied primarily on information gained from the clinical history, physical examination, and electrodiagnostic testing. Taken together, all of this clinical and diagnostic information often allows one to determine the location and severity of the underlying peripheral nerve problem. However, it may not be sufficient in diagnosing a focal entrapment neuropathy superimposed upon a more generalized peripheral neuropathy; localizing a focal lesion along a long segment of nerve which may be difficult to assess accurately with electrodiagnostic studies; distinguishing early between an axonotmetic grade of injury, which can recover through axonal regeneration, and a neurotmetic grade which cannot and therefore may benefit from a surgical exploration and repair procedure; and noninvasively diagnosing and determining the surgical resectability of peripheral nerve mass lesions such as tumors. The goal of this review is to illustrate how standard and evolving magnetic resonance imaging techniques can provide additional information in dealing with some of these problems.     

Quantitative sensory testing: high sensitivity in small fiber neuropathy with normal NCS/EMG

We evaluated the diagnostic sensitivity of quantitative sensory testing (QST), using the CASE IV system, in 14 patients with clinically diagnosed small-fiber neuropathy and normal traditional electrodiagnostic studies. All patients had at least 1 abnormal threshold, 13 patients had abnormal heat-pain thresholds, 8 had abnormal cold thresholds, and 7 had abnormal vibration thresholds. QST is therefore highly effective in documenting dysfunction in small fiber neuropathy patients.