Duration of the distal compound muscle action potential for diagnosis of chronic inflammatory demyelinating polyneuropathy: effects of low-cut filters.

Purpose: In current electrodiagnostic criteria for chronic inflammatory demyelinating polyneuropathy, the cutoff values of distal compound muscle action potential (DCMAP) duration are defined using electromyogram low-cut filter setting of 20 Hz. We aimed to assess effects of low-cut filter on DCMAP duration (10 vs. 20 Hz).

Safety and efficacy of intravenous ultra-high dose methylcobalamin treatment for peripheral neuropathy: a phase I/II open label clinical trial.

Objective: No clinically effective treatment for promoting peripheral axonal regeneration has yet been established. Several experimental studies in vitro and in vivo have shown that a high dose of methylcobalamin (MeCbl), an analogue of vitamin B12, promotes axonal growth in peripheral nerve injury. We herein assessed the safety and efficacy of an ultra-high dose MeCbl treatment for patients with peripheral neuropathy and chronic axonal degeneration.

Bortezomib-induced neuropathy: axonal membrane depolarization precedes development of neuropathy.

Objective: Bortezomib is a proteasome inhibitor with high efficacy for multiple myeloma but with severe peripheral neurotoxicity, leading to dose modification and severe neurological disability. This study aimed to investigate the pathophysiology of bortezomib-induced neuropathy.

Methods: Threshold tracking was used to assess the excitability of sensory and motor axons.

Prominent fatigue in spinal muscular atrophy and spinal and bulbar muscular atrophy: evidence of activity-dependent conduction block.

Objectives: To clarify whether patients with spinal muscular atrophy (SMA) or spinal and bulbar muscular atrophy (SBMA) suffer disabling muscle fatigue, and whether activity-dependent conduction block (ADCB) contributes to their fatigue. ADCB is usually caused by reduced safety factor for impulse transmission in demyelinating diseases, whereas markedly increased axonal branching associated with collateral sprouting may reduce the safety factor in chronic lower motor neuron disorders.

Methods: We assessed the fatigue severity scale (FSS) in 22 patients with SMA/SBMA, and in 100 disease controls (multiple sclerosis, myasthenia gravis, chronic inflammatory demyelinating polyneuropathy (CIDP), and axonal neuropathy).

Split hand syndrome in amyotrophic lateral sclerosis: different excitability changes in the thenar and hypothenar motor axons.

Background: In amyotrophic lateral sclerosis (ALS), muscle wasting preferentially affects the abductor pollicis brevis (APB) and first dorsal interosseous over the abductor digit minimi (ADM), and this is termed 'split hand'. Previous axonal excitability studies have suggested increased nodal persistent sodium current and reduced potassium current in motor axons in ALS, but the extent of excitability changes in APB and ADM axons in ALS has never been compared.

Objective: To elucidate the peripheral axonal pathophysiology of split hand.

Ambiguous effects of anti-VEGF monoclonal antibody (bevacizumab) for POEMS syndrome.

Objective: Vascular endothelial growth factor (VEGF) plays an essential role in the pathophysiology of polyneuropathy, organomegaly, endocrinopathy, M-protein and skin changes (POEMS) syndrome. Anti-VEGF antibody (bevacizumab) appears to be an attractive therapeutic option. The aim of this study is to investigate the effects of bevacizumab for patients with POEMS syndrome.

Markedly upregulated serum interleukin-12 as a novel biomarker in POEMS syndrome.

Objective: To systematically study abnormalities in cytokine profiles in polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes (POEMS) syndrome, which has been increasingly recognized as a cause of demyelinating neuropathy associated with plasma cell dyscrasia and elevated serum level of vascular endothelial growth factor (VEGF).

Methods: In this case-control study, we measured serum levels of 27 cytokines in patients with POEMS syndrome using a multiplex suspension array system, and compared them with those of controls. In 10 patients, serial changes after treatment were analyzed.

Motor axonal excitability properties are strong predictors for survival in amyotrophic lateral sclerosis.

Objective: The aim of this study was to investigate whether axonal excitability indices are associated with survival in patients with amyotrophic lateral sclerosis (ALS). Previous nerve excitability studies suggested increased persistent sodium currents in motor axons of patients with ALS, which lead to axonal hyperexcitability and potentially enhance neuronal death.

Methods: 112 patients with sporadic ALS were followed up until endpoint (death or tracheostomy).

Different neurological and physiological profiles in POEMS syndrome and chronic inflammatory demyelinating polyneuropathy.

Background: POEMS (polyneuropathy, organomegaly, endocrinopathy, M protein and skin changes) syndrome, a rare cause of demyelinating neuropathy associated with multiorgan involvement, has been increasingly recognised. Polyneuropathy is often an initial manifestation and therefore the disorder can be misdiagnosed as chronic inflammatory demyelinating polyneuropathy (CIDP). Objective To elucidate whether POEMS syndrome and CIDP are differentiated based on profiles of neuropathy.

Differences in excitability between median and superficial radial sensory axons.

Objective: The aim of this study was to investigate differences in excitability properties of human median and superficial radial sensory axons (e.g., axons innervating the glabrous and hairy skin in the hand).

Antiganglioside antibodies are associated with axonal Guillain-Barré syndrome: a Japanese-Italian collaborative study.

Background: Whether or not antiganglioside antibodies are related to axonal or demyelinating Guillain-Barré syndrome (GBS) is still a matter of controversy, as detailed in previous studies conducted in Western and Asian countries.

Objective: To clarify whether antiganglioside antibodies are associated with axonal dysfunction in Japanese and Italian GBS patient cohorts.

Methods: Clinical and electrophysiological profiles were reviewed for 156 GBS patients collected from Japan (n=103) and Italy (n=53).

Markedly reduced axonal potassium channel expression in human sporadic amyotrophic lateral sclerosis: an immunohistochemical study.

Fasciculations are characteristic features of amyotrophic lateral sclerosis (ALS), suggesting abnormally increased excitability of motor axons. Previous nerve excitability studies have shown reduced axonal potassium currents in ALS patients that may contribute to the hyperexcitability and thereby generation of fasciculations. To clarify changes in axonal ion channel expression in motor axons of ALS, we performed immunohistochemistry of potassium and sodium channels in the C7 and L5 ventral/dorsal roots obtained from five autopsy cases of sporadic ALS.

Awaji ALS criteria increase the diagnostic sensitivity in patients with bulbar onset.

Objective: To assess whether Awaji criteria improve the sensitivity of diagnosis for amyotrophic lateral sclerosis (ALS). In Awaji ALS criteria, fasciculation potentials are regarded as evidence of acute denervation in the presence of chronic neurogenic changes on needle electromyography.

Methods: We reviewed clinical and neurophysiological data of 113 consecutive patients who were suspected as suffering ALS.

Detection of bone lesions by CT in POEMS syndrome.

Objective: To study the utility of CT for detection of small bone lesions in POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein, and skin changes) syndrome. For patients with a solitary bone lesion, irradiation is a first-line treatment, whereas systemic chemotherapy is indicated for patients with multiple bone lesions. Therefore it is important to correctly identify the number of bone lesions.

Activity-dependent changes in impulse conduction of single human motor axons: a stimulated single fiber electromyography study.

Objective: The aim of this study is to develop a novel method to assess activity-dependent hyperpolarization in human single motor axons at a constant stimulus frequency by using intra-muscular axonal stimulating single fiber electromyography (s-SFEMG).

Methods: We performed s-SFEMG in the extensor digitorum communis (EDC) muscle of 10 normal subjects, and measured changes in latencies for single muscle fiber action potentials (MAPs) during 500 stimuli delivered at 5, 10 and 20 Hz. The data were analyzed with a repeated measurement analysis, and multiple comparisons were performed.

Distal motor axonal dysfunction in amyotrophic lateral sclerosis.

Nerve conduction slowing in amyotrophic lateral sclerosis (ALS) is usually caused by loss of fast motor axons. We studied the frequency, extent, and distribution of prominently prolonged distal motor latencies in ALS. We reviewed results of median, ulnar, and tibial nerve conduction studies in 91 patients with ALS, 24 with lower motor neuron disorders, and 36 with axonal neuropathy.

Elevated CSF TDP-43 levels in amyotrophic lateral sclerosis: specificity, sensitivity, and a possible prognostic value.

TAR DNA binding protein of 43 kDa (TDP-43) is likely to be the major pathogenetic protein in amyotrophic lateral sclerosis (ALS). A previous study has shown that levels of TDP-43 in CSF measured by an ELISA are significantly higher for ALS patients than for controls. The aim of this study was to investigate whether elevated CSF TDP-43 levels are specific to ALS, and are associated with clinical profiles in ALS patients.

Altered axonal excitability properties in juvenile muscular atrophy of distal upper extremity (Hirayama disease).

Objective: Juvenile muscular atrophy of distal upper extremity (Hirayama disease) is characterized by juvenile-onset of asymmetric amyotrophy, but the pathophysiology has not been fully clarified. "Cold paresis", aggravation of muscle weakness with exposure to cold, is a characteristic feature of this disease. The aim of this study was to investigate changes in axonal excitability properties in Hirayama disease.

Multifocal conduction blocks in sarcoid peripheral neuropathy.

Peripheral neuropathy is a rare manifestation of sarcoidosis, and previous studies have shown axonal degeneration as the main pathology. We herein report three patients with sarcoidosis who presented with multiple mononeuropathy as the initial manifestation. Nerve conduction studies showed prominent multifocal conduction blocks in the intermediate nerve trunk.

Mexiletine suppresses nodal persistent sodium currents in sensory axons of patients with neuropathic pain.

Objective: To investigate changes in axonal persistent Na(+) currents in patients with neuropathic pain and the effects of mexiletine, an analogue of lidocaine, on axonal excitability properties.

Methods: The technique of latent addition was used to estimate nodal persistent Na(+) currents in superficial radial sensory axons of 17 patients with neuropathic pain/paresthesias before and after mexiletine treatment. Brief hyperpolarizing conditioning currents were delivered, and threshold change at the conditioning-test interval of 0.

Utility of the distal compound muscle action potential duration for diagnosis of demyelinating neuropathies.

To assess the significance of distal compound muscle action potential (CMAP) duration for diagnosis of demyelinating neuropathies, electrophysiologic data were reviewed from 471 subjects, including 145 normal controls, 60 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 205 with other neuropathy, and 61 with amyotrophic lateral sclerosis (ALS). The duration of distally evoked CMAP was measured in the median, ulnar, tibial, and peroneal nerves. Optimal cut-off values were calculated with receiver-operating characteristic (ROC) curves.

The effects of age, gender, and body mass index on amplitude of sensory nerve action potentials: multivariate analyses.

Objective: Previous studies have shown that age, gender, and body mass index (BMI) affect amplitude of sensory nerve action potentials (SNAP), but the total effects of multiple factors or the most prominently affected nerves have not been elucidated. This study systematically investigated effects of these factors.

Methods: Amplitude of SNAP of the median, ulnar, superficial radial, superficial peroneal, and sural nerves was measured in 105 healthy subjects.