Saiko Nasu

Ultrasonographic detection of fasciculations markedly increases diagnostic sensitivity of ALS.

Objectives: To study the utility of muscle ultrasound (US) for detection of fasciculations and its contribution to diagnosis in amyotrophic lateral sclerosis (ALS). Fasciculations are characteristic features of ALS, and US can detect them easily and reliably. New diagnostic criteria for ALS, the Awaji algorithm, reintroduced fasciculations as evidence of acute denervation equivalent to that of fibrillations and positive sharp waves. Methods: In 81 consecutive patients with sporadic ALS, we prospectively performed needle EMG and US in 6 muscles (tongue, biceps brachii, first dorsalis interosseous, paraspinalis, vastus lateralis, and tibialis anterior), and diagnostic category were determined by revised El Escorial criteria and Awaji criteria. Results: Fasciculations were much more frequently detected by US than by EMG in the tongue (60% vs 0%), biceps brachii (88% vs 60%), and tibialis anterior muscles (83% vs 45%). The proportion of the patients with definite or probable ALS was 48% by revised El Escorial criteria and 79% by Awaji criteria using US. Conclusions: Muscle US is a practical and efficient tool to detect fasciculations, particularly in the tongue. A combination of US and EMG substantially increases the diagnostic sensitivity of ALS.

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. Methods Clinical and electrophysiological data were reviewed in consecutive POEMS syndrome (n=51) and typical CIDP (n=46) patients in a single Japanese hospital between 2000 and 2010. Results Both POEMS and CIDP patients showed symmetric polyneuropathy, physiological evidence of demyelination (70% of POEMS patients fulfilled the electrodiagnostic criteria for definite CIDP) and albuminocytological dissociation; 49% of the POEMS syndrome patients had neuropathy onset and 60% of them were initially diagnosed as having CIDP by neurologists. Clinically, POEMS neuropathy more frequently showed severe leg pain (76% vs 7%; p<0.001), muscle atrophy (52% vs 24%; p=0.005) and distal dominant muscle weakness. Electrophysiologically, POEMS syndrome was characterised by less prolonged distal motor latency (mean 5.6 ms vs 8.1 ms; p<0.001) and higher terminal latency index (0.42 vs 0.33; p=0.006) in the median nerves, and unrecordable tibial and sural responses (p<0.001), suggesting demyelination predominant in the nerve trunk rather than in the distal nerve terminals, and axonal loss in the lower limb nerves. Conclusions Before development of typical systemic manifestations, POEMS neuropathy can be distinguished from CIDP by the clinical profile and patterns of nerve conduction abnormalities. Recognition of these features leads to early diagnosis and proper treatment for POEMS syndrome.

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). Serum IgG antibodies against GM1, GM1b, GD1a and GalNAc-GD1a were measured by ELISA in the same laboratory. Electrodiagnostic criteria and results of serial electrophysiological studies were used for classification of GBS subtypes: acute inflammatory demyelinating polyneuropathy (AIDP) and acute motor axonal neuropathy (AMAN). Results In both Japanese and Italian cohorts, any of the antibodies were positive in 36% of the patients, and antibody positivity had a significant association with the AMAN electrodiagnosis. Approximately 30% of Japanese and Italian antiganglioside positive patients showed the AIDP pattern at the first examination whereas sequential studies showed that most finally showed the AMAN pattern. Clinically, seropositive patients more frequently had preceding diarrhoea and pure motor neuropathy in both Japanese and Italian cohorts; vibratory sensation was normal in 97% of Japanese and in 94% of Italian seropositive patients. Conclusions In GBS, clinical and electrophysiological features appear to be determined by antiganglioside antibodies, and the antibodies are associated with motor axonal GBS in both Japan and Italy. Classification of the GBS subtypes as a disease entity should be made, combining the results of antiganglioside assays and serial electrodiagnostic studies.

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). Multivariate analyses were performed using the Cox proportional hazard model. Threshold tracking was used to measure multiple axonal excitability indices in median motor axons, such as strength–duration time constant (SDTC; a measure of nodal persistent sodium current). Latent addition was also used to estimate the magnitude of persistent sodium currents. Results The overall median tracheostomy-free survival from onset was 37 months. Prolonged SDTC was strongly associated with shorter survival (adjusted HR 4.07; 95% CI 1.7 to 9.8; p=0.0018) compared with older onset age (>60 years; HR=1.80) and bulbar onset (HR=1.80). Estimated median survival was 34 months in the longer SDTC group and 51 months in the shorter SDTC group. This index was highly statistically significant even after multiple testing adjustments with age and site of onset (bulbar or limb). Latent addition study results were consistent with these findings. Conclusions Axonal persistent sodium currents, estimated by SDTC and latent addition, are strong and independent predictors for shorter survival in patients with ALS. Membrane hyperexcitability is possibly associated with motor neuronal death, and modulation of excessive sodium currents could be a novel therapeutic option for ALS.

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

Abstract 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. We measured CSF TDP-43 levels by the same ELISA in 27 ALS patients and 50 neurodegenerative or inflammatory disease controls such as Parkinsons disease, multiple sclerosis, and Guillain-Barré syndrome. Results showed that the CSF TDP-43 levels were increased only in ALS patients. Receiver operating characteristic (ROC) analyses showed a sensitivity of 59.3% and a specificity of 96.0%. We also found that lower CSF TDP-43 levels may be associated with shorter survival time. In conclusion, the CSF TDP-43 is a potential biomarker that supports a diagnosis of ALS. Moreover, among ALS patients, lower levels of CSF TDP-43 may reflect the accumulation of TDP-43 in the cortical and spinal motor neurons and thereby shorter survival time, although this should be confirmed in larger prospective studies.

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. Results: Interleukin (IL)–12 as well as VEGF levels were markedly increased (p < 0.0001) in all the patients (n = 23). Ten kinds of other proinflammatory cytokines such as IL-6 and tumor necrosis factor–α were also significantly increased in the POEMS syndrome group, but in some patients the serum levels of such cytokines remained within the normal ranges. After treatments, the IL-12 as well as VEGF levels significantly decreased with clinical improvements (p > 0.01 and p > 0.05, respectively). Conclusions: Our findings suggest that serum IL-12 is a biomarker of the disease activity in POEMS syndrome. The overproduction of IL-12, as well as VEGF, is likely to play an important role in the pathogenesis of the disorder, and could contribute to the peripheral nerve demyelination in POEMS syndrome.

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. In comparison of normal controls and CIDP patients, ROC analyses showed the sufficient area under the curves (82‐93%). When the cut‐off values in the detection of demyelination were determined as the point with 98% specificity vs. normal on the ROC curves (median, 6.6 ms; ulnar, 6.7 ms; peroneal, 7.6 ms; tibial, 8.8 ms), the sensitivity was 77% for CIDP, with a specificity of 90% vs. ALS and 95% vs. diabetic neuropathy. The distal CMAP duration is a useful index for the detection of distal demyelination. We suggest the above cut‐off values for each nerve as one of the electrodiagnostic criteria for demyelinating neuropathies, preferentially affecting the distal nerve terminals, such as CIDP.

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. The six muscles (trapezius, biceps, first dorsal interosseous, T10-paraspinalis, vastus lateralis, and tibialis anterior muscles) were examined by EMG, focusing on the presence of fasciculation potentials. The sensitivity of revised El Escorial (R-EEC) and Awaji criteria was compared. RESULTS Probable or definite ALS was diagnosed in 61% of the patients by R-EEC and 71% by Awaji criteria. By applying Awaji criteria; (1) 17 of the 44 patients categorized as possible ALS by R-EEC reached to probable/definite ALS, 11 of whom had bulbar onset, (2) in 48 patients with bulbar onset, the proportion of probable/definite ALS increased from 59% to 82%, (3) in 62 patients with limb onset, the proportion of probable/definite ALS was 61% (63% by R-EEC). CONCLUSIONS Awaji criteria improve the sensitivity of ALS diagnosis in patients with bulbar onset, but not in those with limb onset. SIGNIFICANCE Accepting fasciculation potentials as evidence of acute denervation increases the diagnostic sensitivity of ALS, particularly in patients with bulbar onset, and contributes to early diagnosis.

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. The effects of age, gender, and BMI on each nerve were estimated by multivariate linear regression analysis. RESULTS SNAP amplitude decreased with age in all five nerves. Women had greater SNAP amplitude than men in the upper limb nerves (median, ulnar, and radial), but not in the lower limb nerves (peroneal and sural). Similarly, greater BMI was associated with smaller amplitudes in the upper limb nerves, but not in the lower limb nerves. Multivariate analyses showed the three factors explained 50% of the variation in the median nerve, 46% in the ulnar nerve, and 22-32% in the remaining nerves. CONCLUSIONS The effects of age, gender, and BMI on SNAP amplitudes are not identical in different sensory nerves. Age was strongly correlated with SNAP amplitude in the nerves tested, whereas gender and BMI affect amplitudes only in the upper limb nerves. SIGNIFICANCE Age, gender, and BMI should be taken into account in clinical practice, but the extent of influence depends on the sensory nerves examined.

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. Methods In both APB and ADM motor axons of 21 patients with ALS and 17 age-matched normal controls, threshold tracking was used to measure excitability indices such as strength-duration time constant (SDTC; a measure of persistent sodium current) and threshold electrotonus. Results In normal controls, SDTC was significantly longer for APB than ADM axons, suggesting that axonal excitability is physiologically higher in APB axons. Compared with normal controls, patients with ALS had longer SDTC and greater threshold changes in depolarising threshold electrotonus in both APB and ADM axons. Furthermore, the difference in extent of SDTC prolongation between normal subjects and patients with ALS was greater in APB than ADM axons. Conclusions APB axons have physiologically higher excitability than ADM axons, and, in ALS, the hyperexcitability is more prominent in APB axons. Although cortical mechanisms would also be involved, more prominent hyperexcitability of APB axons may contribute to development of split hand, and the altered axonal properties are possibly associated with motor neuronal death in ALS.