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INTRODUCTION: McArdle disease, or glycogen storage disease type V (GSD 5), is a rare metabolic myopathy linked to an autosomal recessive myophosphorylase deficiency. CASE REPORT: We report the case of a 17-year-old male patient who was referred to the emergency department for the management of acute inflammatory low back pain, without traumatic context, associated with an increase of CK at 66,336 UI/L (N<192UI/L) and a CRP at 202mg/L. The immunological assessment was negative and the spinal MRI showed images in favor of necrotizing fasciitis affecting the erector spinae muscles, among others. Faced with the description of difficulties in practicing physical activities since childhood and a non-ischaemic forearm exercise test showing no elevation in lactacidemia, genetic tests were carried out, finding two heterozygous variants in the PYGM gene: c.1963G>A (p.Glu655Lys) class 5 and c.2178-1G>A class 4, confirming the diagnosis of McArdle disease. DISCUSSION: GSD 5 is a disease characterized essentially by muscular fatigability during exercise. The case reported here is original in the clinical circumstances leading to the diagnosis, i.e., inaugural acute low back pain with rhabdomyolysis. This symptomatology had already been described before, but in a patient whose diagnosis was already known. Spinal MRI showed non-specific muscle inflammation and necrosis. Muscle biopsy only found necrosis but no pathological elements typical of the diagnosis. If the symptoms are suggestive, it may be preferable to directly perform a non-ischaemic forearm exercise test, in order to go directly to molecular genetic analysis. There is no specific curative treatment of GSD 5. However, some measures can be implemented to limit the symptoms, such as learning physical exercises, limiting intense efforts and adopting dietary recommendations.
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AIM: To perform a systematic review of the literature on the concurrent validity, predictive validity and responsiveness of radiographic metric measurement of femoro-acetabular joint space width (JSW) in hip osteoarthritis (OA). ELIGIBILITY CRITERIA: studies reporting any data on (1) JSW on X-rays in hip OA patients and (2) concurrent validity (correlations with clinical symptoms), predictive validity (correlations with future symptomatic state, joint space loss or joint replacement), and/or responsiveness (JSW change over time evaluated using the standardized response mean (SRM)). SEARCH STRATEGY: Medline PUBMED and Embase databases. STATISTICAL ANALYSIS: Random-effects models were constructed to obtain pooled SRMs. RESULTS: Of 448 articles, 79 met the abstract inclusion criteria and were read for further screening. Of these, 15 reported measures of validity and 11 reported measures of responsiveness. Concurrent validity: Five studies suggested an association between JSW and symptoms in the general population. Two evaluated the correlations between JSW and symptoms in hip OA patients, with conflicting results. Five demonstrated that JSW is predictive of future hip joint replacement. Responsiveness was moderate (SRM=0.66; 95% confidential interval (95%CI): 0.41, 0.91), but tended to be lower in randomized clinical trials than in cohort studies (0.35 vs 0.83), using an intention to treat rather than a completer analysis (0.30 vs 0.80), and using manual rather than computer-based measurement (0.47 vs 1.12). CONCLUSION: There is evidence of a weak association between JSW and symptoms, of predictive validity for subsequent joint replacement, and of moderate responsiveness of metric measurement of JSW.
