A dominantly inherited form of distal myopathy with onset in early childhood was first reported in a 4-generation Australian family in 1995. In the present report we provide further information on the clinical phenotype and natural history of this myopathy, and on the electromyogram and magnetic resonance imaging findings in affected individuals. The pattern of muscle involvement was similar to that in the ‘tibial’ forms of distal myopathy such as the Finnish (Udd) and Markesbery–Griggs types, with additional involvement of the finger extensors and of some more proximal limb and neck muscles. However, the age of onset was earlier than in these other myopathies and rimmed vacuoles were not found in biopsies from two affected individuals. Evidence of possible anticipation was found in one branch of the family. The gene locus for this myopathy had been mapped to 14q11.2–q13. The linkage region has been refined to a 24 cM region between D14S283 and D14S49 and mutations have been excluded in the PABP2 gene for oculopharyngeal muscular dystrophy which lies within this region.

Epidemiologic studies have helped to define the prevalence and incidence of PM, DM, and IBM and have highlighted differences in risk between men and women and in the age at onset for the different forms of myositis. Additionally, these studies have shown that there is a substantially higher risk of PM and DM in certain racial groups which is likely to be genetically determined. These differences are all likely to be fundamental in terms of the pathogenesis of these diseases but, as yet, their full significance remains uncertain. They do, however, suggest that the interplay between genetic and environmental initiating factors is different in the three disorders. Additional population-based studies in homogeneous racial groups, in parallel with studies of susceptibility genes for autoimmune disease, such as those encoding the MHC and inflammatory cytokines, are needed to throw further light on the role of genetic factors in the pathogenesis of the IIMs [47]. Because of the paucity of epidemiologic data on IBM, further studies are required to determine the degree of variation in prevalence in different populations and racial groups, as well as the consistency of the male association and age spectrum of manifestations of the disease. The particularly strong association with DR3 in this form of IIM [48] clearly points to the importance of genetic factors in pathogenesis, but further studies of DR3-associated genes in the MHC and of other candidate genes are needed to define more precisely the genes that convey susceptibility to the disease in different racial groups. Epidemiologic studies also have the potential to identify environmental factors that may play a part in disease initiation in genetically susceptible individuals. Seasonal patterns of disease onset have been reported, particularly in patients with DM [49-51] as well as seasonal variation in the frequency of relapses [52], pointing to the probable involvement of intercurrent infections, ultraviolet light exposure, or other environmental factors in disease initiation and reactivation. Further prospective studies are required to determine the contribution of environmental exposures and how they interact with genetic susceptibility factors to lead to myositis. One of the major limitations of a number of the previous epidemiologic studies is the lack of precision in the diagnostic criteria used and the classification of cases of IIM. The Bohan and Peter criteria [1] which were used in most studies after 1975, were introduced before IBM was recognized as an entity distinct from PM; most of the published incidence and prevalence figures for PM are therefore likely to be inaccurate. Multicentered, interdisciplinary, prospective studies, incorporating comprehensive clinical, laboratory, and pathologic information, are needed to develop and validate better diagnostic and classification criteria and to determine the true prevalence and incidence of the many forms of IIM.

The present study has investigated the long-term changes in the organisation of the corticomotor projection to the hand in a group of subjects who had sustained a subcortical hemispheric stroke up to 15 years previously and had subsequently recovered normal or near-normal motor function. Transcranial magnetic cortical stimulation (TMCS) was employed to map the topography of the primary corticomotor projection to the hand and to obtain measures of cortical motor threshold, long-latency intracortical inhibition and corticospinal conduction. Changes in motor threshold and in motor-evoked potential (MEP) amplitude and latency in keeping with persisting impairment of conduction in the corticospinal pathway were still present in the majority of subjects, whereas the duration of the post-MEP silent period, reflecting the strength of long-latency intracortical inhibition, was usually normal. Topographic shifts in the corticomotor representation relative to the unaffected side were found in the majority of subjects. In some the shifts were in the mediolateral axis suggesting reorganisation within the primary motor cortex, while in the others anteroposterior shifts were present in keeping with recruitment of premotor or postcentral cortex. The present findings indicate that changes in the physiological properties of the corticomotor projection to the hand are frequently present in subjects who have recovered motor function after a subcortical stroke and may persist indefinitely. We postulate that these changes are the result of reorganisation at cortical level and that cortical reorganisation is one of the processes which contribute to motor recovery after a subcortical lesion and which may compensate for persisting impairment of conduction in the corticospinal pathway.

The differential patterns of muscle involvement in the upper and lower limbs in sporadic inclusion body myositis (sIBM) were examined in 18 patients using both quantitative and manual muscle testing as well as magnetic resonance imaging (MRI) in 9 patients. Weakness of the quadriceps femoris and the forearm flexors was present in most patients, but there was considerable variability in the patterns and severity of muscle involvement. MRI disclosed preferential patterns of muscle involvement within functional groups such as the quadriceps femoris, in which there was severe involvement of the vasti with relative sparing of the rectus femoris, and the triceps surae, in which selective involvement of the medial gastrocnemius was common. Involvement of flexor digitorum profundus on MRI was found in only one third of patients. The results emphasize the variability in the clinical phenotype and differential susceptibility of muscles to the disease process in sIBM. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1526–1534, 2001

Common impairments experienced by patients with myopathy include muscle weakness, reduced endurance and cardiovascular fitness. Strength-training programmes, incorporating isometric, isotonic or isokinetic exercise, have been shown to improve muscle strength in the short term, without evidence of increased muscle damage using biochemical markers. However, there is some evidence that eccentric exercise may have adverse effects in patients with myopathy. Aerobic training programmes using cycle ergometers or treadmills have demonstrated an improvement in cardiovascular fitness, muscle strength and endurance, again without evidence of increased muscle damage. Further research is needed to determine the optimum training protocols for patients with various types of myopathy, and in particular to improve the ability of patients to be active and independent in daily life.

A 10-year retrospective review was conducted to ascertain the prevalence of inclusion body myositis (IBM) in Western Australia. Seventeen patients with sporadic IBM aged 45–90 years were identified and the prevalence of IBM was calculated to be 9.3 × 10−6. The prevalence was higher in men (10.9 × 10−6) than in women (7.7 × 10−6). The mean age of onset of IBM was 56.6 years, and the mean delay between onset of symptoms and diagnosis was 4.4 years. The age-adjusted prevalence over the age of 50 years was 35.3 × 10−6. The results suggest a higher prevalence of IBM than has previously been reported. © 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 970–972, 2000

Objective: To obtain normal torque values for the knee extensors and flexors using a Kin-Com dynamometer in a large group of normal subjects.Design: We used a Kin-Com dynamometer to measure the isokinetic torque at 60 and 120 deg/sec and isometric torque of the knee extensors and flexors in a sample of 200 normal subjects aged 20 to 69 years.Results: Reliability coefficients for average and isometric torque were > 0.82 for both intra- and inter-session reliability. Male subjects exerted a significantly greater isokinetic and isometric torque than female subjects for both muscle groups and age was a significant predictor of torque for all tests. The 5th percentile values, as the lower limit of normal, are reported separately for gender and side of testing for each decade of age, and may be used for comparison to patient data providing that the specified testing protocol and a Kin-Com dynamometer are used.

Objective: To measure the strength of 17 muscle groups in the upper and lower extremities in a large group of healthy subjects using "break" testing with a hand-held myometer, and to examine the intrasession and intersession reliability of the testing protocol.Subjects and Instrumentation: A convenience sample of 20 men and 20 women in each decade of age from 20 to 69 years (n = 200) was tested using a Penny & Giles hand-held myometer.Results: Reliability coefficients were >.85 for both intrasession and intersession reliability, except for the ankle dorsiflexors. Men exerted a significantly greater force than women for all muscle groups. Age, weight, and side of testing were significant predictors of force in the majority of muscle groups. The fifth percentile values, as the lower limit of normal, are reported separately for gender and side of testing for each decade of age.Conclusion: Using the testing protocol specified in this study, data from patients with various neuromuscular diseases may be compared with the appropriate gender- and age-matched normal data to accurately identify the presence of weakness.

OBJECTIVES To determine the molecular basis for autosomal dominant intermediate hereditary motor and sensory neuropathy (HMSN) in a four generation family. The gene defects in families with intermediate HMSN are not known, but it has been suggested that most have X linked HMSN. METHODS All participating family members were examined clinically. Genomic DNA was obtained from 10 affected and seven unaffected members. Linkage analysis for the known HMSN loci was first performed. Mutations in the peripheral myelin protein zero gene (PMP0) were sought in two affected members, using one unaffected member for comparison, by amplification of the six exons of the gene followed by single strand conformation polymorphism (SSCP) analysis, dideoxy fingerprinting (ddF), and sequencing. Subsequently, the mutation was screened for in all affected and unaffected members in the family using Alu I digestion and in 100 unrelated control subjects using “snap back” SSCP analysis. Sequencing of cDNA from a sural nerve biopsy from an affected member was also performed. RESULTS The clinical phenotype was of variable severity, with motor nerve conduction velocities in the intermediate range. Linkage to PMP0 was demonstrated. Analysis of genomic DNA and cDNA for PMP0 identified a novel codon 35 GAC to TAC mutation. The mutation produces an inferred amino acid change of aspartate to tyrosine at codon six of the processed protein (Asp6Tyr) in the extracellular domain and was present in all affected family members but not in 100 unrelated controls. CONCLUSIONS The present findings further extend the range of phenotypes associated with PMP0 mutations and indicate that families with “intermediate” HMSN need not necessarily be X-linked as previously suggested.

OBJECTIVE:The mechanisms which lead to recovery of motor function after a stroke are poorly understood. Functional reorganization of cortical motor centres is thought to be one of the factors which may contribute to recovery. We have investigated the extent of reorganization which occurs at the level of the primary motor cortex after a lesion of the corticospinal pathway.METHODS:Transcranial magnetic stimulation was used to map the topography of the primary corticomotor projection to the abductor pollicis brevis muscle and study changes in cortical motor thresholds and corticospinal conduction in a group of 20 subjects with subcortical infarcts of varying duration (1 week to 15 years) and varying degrees of motor deficit.RESULTS:There was a broad correlation between motor evoked potential (MEP) amplitude and motor thresholds on the one hand and the severity of motor deficit and site and extent of the lesion on the other. Shifts in the cortical motor maps were found in both early and late cases, irrespective of the site of the lesion, but were more frequent in the longer standing cases. Shifts were usually along the mediolateral axis but anteroposterior shifts were found in some late cases.CONCLUSION:Our findings indicate that there is functional reorganization of the corticomotor projection in subjects who regain a degree of motor control following a subcortical lesion sparing the motor cortex.

A two generation family of Greek origin with mild myotonia, predominantly proximal muscle weakness, and cataracts compatible with the syndrome of proximal myotonic myopathy, is reported. In addition, brain MRI showed a diffuse leukoencephalopathy in the propositus. Molecular genetic studies showed the R894X mutation in exon 23 of the muscle chloride channel gene in the propositus but in only one of her two clinically affected offspring, indicating that it is not the mutation causing disease in this family.

A prospective open label trial of add on therapy with intravenous immunoglobulin (i.v.Ig) was carried out in 16 patients with inflammatory myopathy who had continued to deteriorate or had relapsed on conventional therapy. The response was assessed using isometric myometry, functional scales, MRC grading, and serum creatine kinase concentrations with a three month run in period before commencement of i.v.Ig. Five of seven patients with isolated dermatomyositis or polymyositis and all four patients with an overlap syndrome responded to i.v.Ig with partial or complete remission of disease and normalisation of serum creatine kinase concentrations. None of five patients with inclusion body myositis showed any functional improvement although myometry scores improved in some muscles in one case. It is concluded that i.v.Ig is an effective therapeutic option in patients with drug resistant polymyositis or dermatomyositis. However, further controlled trials are required to confirm the efficacy of this form of treatment and to establish optimal doses and administration regimes.

The frequency of clinical and biochemical relapses was determined in a group of 50 patients with polymyositis (PM), dermatomyositis (DM), or overlap syndromes who were followed for periods of up to 13 years. Relapses occurred in 30 of the 50 patients (60%) during the period of follow-up. The annual relapse rate was not significantly different in the three groups of patients. Subclinical relapses occurred in each group but were less frequent in the DM than in the PM and overlap groups. Relapses could occur at any time but were more frequent during periods of stable maintenance therapy. There was no correlation between relapses and initial disease severity, delay to diagnosis and commencement of treatment, or any class I or II histocompatibility locus antigen.

Campylobacter jejuni/coli (CJC) infection has been implicated in the immunopathogenesis of Guillain-Barré syndrome (GBS), acute motor axonal neuropathy (AMAN), and Miller Fisher syndrome (MFS). However, its role in chronic immune mediated neuropathies such as multifocal motor neuropathy (MMN) or chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is less clear. Anti-ganglioside antibodies are associated with chronic motor neuropathies such as MMN and IgM anti-GM1, and IgM anti-asialo GM1 antibodies have been shown to cross-react with CJC lipopolysaccharides. Molecular mimicry between CJC and IgG anti-GM1 antibodies has also been suggested. Therefore we have performed a retrospective assessment of anti-CJC-specific IgG, IgM, and IgA antibodies in a cohort of seven patients with clinical and electrophysiologically definite MMN. The control group consisted of 140 healthy blood donors with no history of enteric illnesses. We found elevated titres of anti-CJC-specific IgG in 5 of 7 patients, IgM in 3 of 7 and IgA in 1 of 7. At least 1 anti-CJC antibody was elevated in 6 of 7 patients, and 3 patients had elevations of both IgG and IgM antibodies. Three patients had significantly elevated titres of anti-ganglioside antibodies without a clear relationship to the anti-CJC titres. Therefore antibodies specific for CJC were found more frequently than expected in patients with MMN. Prior or ongoing infection with CJC may play a role in the actiopathogenesis of MMN.

Although there have been considerable advances in our understanding of the immunopathogenesis of the different forms of autoimmune inflammatory myopathy, the treatment of these conditions remains largely empirical, being based upon the use of immunosuppressive and immunomodulatory therapies which, for the most part, are non-selective in their actions. Corticosteroids are usually effective in adult and childhood cases of polymyositis and dermatomyositis, but are only rarely helpful in inclusion body myositis, which is usually also unresponsive to other forms of immunosuppressive therapy. Alternate-day corticosteroid therapy has a role in patients with mild disease and as a means of minimizing the side-effects of steroids. This may also be achieved by the early introduction of a second-line agent such as methotrexate or azathioprine, which will allow more rapid steroid withdrawal and may also improve the chances of inducing a remission in more severe cases. In patients who fail to respond adequately to oral corticosteroids, or who relapse after an initial response, intravenous immunoglobulin therapy or pulse therapy with intravenous methylprednisolone are promising approaches which appeal as safer alternatives to cytotoxic drugs. However these forms of treatment will require further evaluation in prospective clinical trials. The same applies to cyclosporin, which has a more selective action on T cells, and which has been reported to be effective in resistant cases of adult and juvenile polymyositis and dermatomyositis. In the longer term, the development of more specific forms of immunotherapy for these myopathies, aimed at blocking autoantigen presentation or its interaction with T cells, awaits the identification of the target antigens and T cells which initiate the autoimmune process.