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  • Miscellaneous myopathies.

    12 December 2017

  • Inclusion body myositis

    20 November 2017

  • Mitochondrial cytopathy

    20 November 2017

  • Diagnose myasthenia gravis

    20 November 2017

  • Reduced oxidative phosphorylation and proton efflux suggest reduced capillary blood supply in skeletal muscle of patients with dermatomyositis and polymyositis: A quantitative<sup>31</sup>P-magnetic resonance spectroscopy and MRI study

    28 January 2018

    Quantitative MRI and phosphorus magnetic resonance spectroscopy ( 31 P-MRS) were used to investigate skeletal muscle metabolism in vivo in patients with dermatomyositis (DM) and polymyositis (PM) in order to evaluate the role of mitochondrial abnormalities in the pathogenesis and clinical expression of these conditions. Nine patients with DM (mean age ± SD, 57 ± 14 years) and five with PM (42 ± 12 years) and with age at disease onset 53 ± 16 and 38 ± 12 years, respectively, were included in the study together with 18 agematched controls. Post-exercise 31 P-MRS indices of muscle oxidative metabolism were all impaired in DM and PM. In both groups of patients, the phosphocreatine and adenosine diphosphate recovery half-times were almost twice as long as in controls (P < 0.05 for each variable) and the maximum rate of mitochondrial ATP production was half that found in normal subjects (P < 0.001). The rate of proton efflux from muscle fibres was significantly reduced in DM (P < 0.001) and PM (P = 0.02). The impairment of 31 P-MRS recovery indices in DM and PM patients was similar to that found in a group of 10 patients with a primary mitochondrial disorder that showed a normal proton efflux rate. There was no correlation between the MRS-detectable abnormalities and the degree of inflammation or fatty infiltration of the muscle, as measured by MRI. The in vivo findings in DM and PM patients indicate impaired muscle aerobic function, which, considering the reduced proton efflux, is likely to be secondary to an impaired blood supply. Our results suggest that the abnormal mitochondria seen in some muscle biopsies are unlikely to be the primary cause of the oxidative insufficiency in these patients.

  • McArdle's disease

    20 November 2017

  • Classification and diagnosis of myopathies - An update

    20 November 2017

    Myopathies are uncommon, even within neurological practice. It is unreasonable to expect general neurologists to have a detailed knowledge of rare conditions that they might only encounter once in a lifetime. But, they must have sufficient knowledge to recognise the basic nature of the problem, to initiate appropriate and avoid inappropriate investigations, and to then point the patient in the right direction for further management. Armed with a simple classification system and a few pointers to the clinical approach, such patients should present an enjoyable, rather than nerve-wracking, challenge.

  • Oculopharyngeal muscular dystrophy phenotypic and genotypic studies in a UK population

    7 February 2018

    Oculopharyngeal muscular dystrophy (OPMD) is an autosomal dominant disorder of late onset that commonly presents with ptosis and dysphagia. The genetic basis of the condition has been identified recently as a stable trinucleotide repeat expansion in exon 1 of the poly(A) binding protein 2 gene (PABP2), in which (GCG) 6 is the normal repeat length. The prevalence of OPMD is greatest in patients of French-Canadian origin. It is not clear if expansion repeat length is a reliable test in other populations. In this study, we analysed the phenotypic and genotypic characteristics of 31 patients with OPMD in the UK. Ptosis was the first reported symptom in two-thirds of the patients, and half of the subjects studied had evidence of ophthalmoplegia. All but one family had a pathological expansion in the PABP2 gene, ranging from (GCG) 8 to (GCG) 13 . In contrast to the French-Canadian population, (GCG) 10 was almost as common as (GCG) 9 , evidence against a strong founder effect in the UK population. There was a weak association between repeat length and age of disease onset. Patients with longer repeat lengths, such as (GCG) 13 , developed severe limb weakness early in the disease. We were unable to detect the (GCG) 7 polymorphism in over 200 normal controls, suggesting that the frequency of this expansion is lower than that found in the French-Canadian population. One family was negative for the expansion. Affected members presented with the classical features of OPMD, namely ptosis, dysphagia and cytoplasmic inclusions on muscle biopsy, although with some atypical features, such as early age of onset, high serum levels of creatine kinase and a profound ophthalmoplegia. This family is an example of a GCG expansion-negative oculopharyngeal syndrome requiring further genetic investigation. We conclude that PABP2 analysis is a reliable non-invasive diagnostic test for OPMD in the UK population.