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Introduction Mercury is a neurotoxic metal that is potentially a risk factor for amyotrophic lateral sclerosis (ALS). Consumption of methylmercury contaminated fish is the primary source of US population exposure to mercury. Methods We used inductively coupled plasma mass spectrometry to measure levels of mercury in toenail samples from patients with ALS (n = 46) and from controls (n = 66) as a biomarker of mercury exposure. Results Patients with ALS had higher toenail mercury levels (odds ratio 2.49, 95% confidence interval 1.18-5.80, P = 0.024) compared with controls, adjusted for age and sex. We also estimated the amount of mercury consumed from finfish and shellfish and found toenail mercury levels elevated overall among patients with ALS and controls in the top quartile for consumption (P = 0.018). Discussion Biomarker data show that ALS is associated with increased with mercury levels, which were related to estimated methylmercury intake via fish. Replication of these associations in additional populations is warranted. Muscle Nerve, 2018.

To evaluate the effect of SMN2 copy number on disease severity in spinal muscular atrophy (SMA), we stratified 45 adult SMA patients based on SMN2 copy number (3 vs. 4 copies). Patients with 3 copies had an earlier age of onset and lower spinal muscular atrophy functional rating scale (SMAFRS) scores and were more likely to be non-ambulatory. There was, however, no difference between the groups in quantitative muscle strength or pulmonary function testing. Functional scale may be a more discriminating outcome measure for SMA clinical trials.

Neurology E. A. Oppenheimer Borasio, W. G. Bradley, M. B. Bromberg, B. R. Brooks, E. J. Kasarskis, T. L. Munsat and R. G. Miller, J. A. Rosenberg, D. F. Gelinas, H. Mitsumoto, D. Newman, R. Sufit, G. D. American Academy of Neurology evidence-based review): Report of the Quality Standards Subcommittee of the Practice parameter: The care of the patient with amyotrophic lateral sclerosis (an This information is current as of August 7, 2006 http://www.neurology.org/cgi/content/full/52/7/1311 the World Wide Web at: The online version of this article, along with updated information and services, is located on ISSN: 0028-3878. Online ISSN: 1526-632X. Print published continuously since 1951. Copyright © 1999 by AAN Enterprises, Inc. All rights reserved. Neurology is the official journal of AAN Enterprises, Inc. A bi-monthly publication, it has been

To clarify the question of whether Guillain–Barre syndrome (GBS) patients treated with intravenous immune globulin (IVIG) relapse at a higher frequency than those treated with plasma exchange (PE), 54 patients with GBS were studied retrospectively. A higher frequency of relapses was noted in the PE-treated patients than in those receiving IVIG. The presence of an associated medical condition correlated with an increased risk of relapses, while earlier onset of treatment resulted in a decrease of relapses of GBS. This study found no support for prior suggestions of increased relapses in patients with GBS treated with IVIG as opposed to those treated with PE. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:1327–1330, 1998.

A computer model of denervation and complete reinnervation in skeletal muscle was originally developed for the purpose of furthering an understanding of the underlying mechanisms of motor unit reorganization in neurogenic diseases. We now describe its successor, a computer model for investigating different rates of denervation and reinnervation, as well as incomplete reinnervation. The new model introduces the concept of permanent denervation and features enhanced interactive control over the distribution of motor unit centers and additional measures of dispersion and co-dispersion of muscle fibers. The use of this model for investigating pathophysiologically significant issues in denervating diseases is illustrated pathophysiologically significant issues in denervating diseases is illustrated with five different sets of parameters. These simulate some of the processes that may be operational in chronic spinal muscular atrophy, amyotrophic lateral sclerosis, and progressive postpolio muscular dystrophy. The enhanced model will allow in-depth analysis of the influence of hypothesized pathophysiological processes on clinical, electrophysiological and pathological outcomes in human disease. © 1993 John Wiley & Sons, Inc.

The lack of effective therapy for many of the chronic neuromuscular diseases such as amyotrophic lateral sclerosis, hereditary motor sensory neuropathy (Charcot-Marie-Tooth disease), spinocerebellar degenerations and idiopathic polyneuropathy has led to a search for substances that may stimulate peripheral nerve regeneration. Two such agents that have been proposed are gangliosides (mixed purified bovine brain gangliosides, Cronassial) and thyrotropin releasing factor (TRH). Studies on both of these agents were initially reported with enthusiasm to be successful, but later double-blind controlled studies have failed to confirm these findings. This review provides critical analysis of the designs of studies of potentially effective agents in chronic neuromuscular diseases, and emphasizes the power of the placebo response, and the importance of designing placebos which are indistinguishable from the trial medication other than in the active effect.

We describe a patient with a 3 year history of progressive polyneuropathy that rendered him severely quadriparetic and bedridden. Work up revealed an IgG lambda monoclonal spike and multifocal osteosclerotic myeloma. Remarkable improvement followed combined treatment with surgical excision, radiation therapy, and chemotherapy using chlorambucil, danazol, and hydrocortisone. Hence, we believe that aggressive local therapy associated with systemic chemotherapy should be considered in severely affected patients with multifocal osteosclerotic myeloma and peripheral neuropathy.

Acetylcholinesterase (AChE) activity was measured in the presence of the specific inhibitor of pseudocholinesterase, iso-OMPA, in plasma from patients with amyotrophic lateral sclerosis (ALS), progressive muscular atrophy (PMA), neuromuscular disease controls, and normal controls. Both AChE and Na-K ATPase activities were measured in erythrocyte ghost membranes from ALS and normal controls. Activities of erythrocyte ghost AChE and Na-K ATPase did not differ between ALS and control patients, suggesting that erythrocyte membranes were normal in ALS. However, the activity of plasma AChE in patients with ALS and PMA was increased significantly over plasma activity in disease controls and normal controls. In addition, in an animal model of human PMA, the Wobbler mouse, plasma AChE activity was increased significantly over littermate controls. The explanation for the increase in plasma acetylcholinesterase was not clear; however, a number of potentially useful clinical points followed from this study. First, there was no relationship between a specific subtype of motor neuron disease and the level of AChE activity. Second, AChE activity appeared to vary directly with the duration of PMA but not with the severity of PMA. This did not correlate with either the duration or severity of ALS. Last, plasma AChE activity was normal in about 30% of patients who had motor neuron disease; therefore, AChE assay had limited use in the diagnosis of ALS or PMA.

Peripheral electrophysiological studies are of particular value of elucidating the anatomy and pathophysiology of neuromuscular diseases, but they can also help in providing clues to the etiology of the disease. Recent studies of the motor units in chronic denervating conditions including amyotrophic lateral sclerosis (ALS) are reviewed. These indicate that reinnervation is a relatively active process which compensates for the progressive loss of motoneurons in ALS until more than 50% of the motoneurons have died. There seems to be no predilection for death of motoneurons of any particular size in ALS. Fasciculations may arise both proximally and distally. The dying-back change is not a major feature of ALS. These and other data cast doubt on the etiological theories that ALS arises from premature aging of motoneurons, deficiency of motoneuron trophic factors, or an inhibitor of a motoneuronal sprouting factor, and point to the need to study metabolic changes intrinsic to the motoneuron in ALS.

Quantitation of muscle metabolites in vastus lateralis needle biopsies from human subjects at rest and following exercise is evaluated using three different methods of normalization of the data, i.e., total protein, total creatine, and NAD+. Coefficients of variation between patient analyses are similar when the metabolite data are normalized by any of the descriptors in resting muscle and in muscle samples obtained following vigorous exercise. When multiple samples are taken from individual patients the intrapatient coefficient of variation is less than that for interpatient comparisons. Normalization to total creatine or NAD+ yields significantly smaller coefficients of variation than does normalization to total protein in these intrapatient comparisons (P less than 0.05). Based on these comparisons, we conclude that any of these methods evaluated for normalizing metabolite content is adequate for studying human subjects, but the total creatine and NAD+ methods may offer some advantage because of the lower variability obtained with these analyses.

There is a need for a practical and statistically manageable quantitative index of fiber type co-dispersion in skeletal muscle to allow investigation of the distribution of motor units in normal muscle and their rearrangement in pathological states. A new measure for this purpose, the Co-Dispersion Index (CDI), is introduced. This measure is based on contingency table analysis of nearest-neighbor relationships between muscle fibers. The CDI has a continuous range of values from -1 to +1, in which larger negative values indicate a greater tendency toward regular intermixing of fibers of different types, and larger positive values a greater segregation of fiber types. CDI evaluation overcomes the limitations of previously published quantitative methods for co-dispersion measurement and is well correlated with subjective human estimates of fiber type grouping.