McArdle's disease: an underestimated or underdiagnosed myopathy in rheumatologic practice? Cases series and literature review / Doença de mcardle: uma miopatias subestimada e subdiagnosticada na pratica reumatológica? série clínica e revisão de literatura

OBJECTIVE: McArdle's disease is a metabolic myopathy that manifests with varied clinical conditions and is often confounded with other diagnoses. Herein, the authors report a case series and carry out a literature review. METHODS: A cross-sectional single-center study evaluating 12 patients with McArdle's disease was conducted. RESULTS: Mean age at onset of symptoms was 28.0±17.4 years, while age at disease diagnosis was 39.0±14.8 years. History of intolerance to physical exercises was observed in 10 cases; muscle weakness in 9, second wind phenomenon in only 1 case. The presence of cramps, fatigue and myalgia was observed in 12, 11 and 9 of the cases respectively. Median creatine phosphokinase level was 5951U/L. Most of the patients (83.3%) were initially diagnosed with another condition (polymyositis, inclusion body myositis, fibromyalgia and/or muscular dystrophy), and approximately half had received glucocorticoids and/or immunosuppressants prior to definitive diagnosis. All patients underwent muscular biopsy, which revealed the presence of subsarcolemmal vacuoles characterized by glycogen deposits, and negative histochemical reaction for the myophosphorylase enzyme. CONCLUSION: The present study reinforces the presence of clinical variability among patients and shows that McArdle's disease should be considered one of the differential diagnoses of inflammatory myopathies and other rheumatic diseases.

OBJETIVO: A doença de McArdle é uma miopatia metabólica que se manifesta com condições clínicas variadas e muitas vezes é confundida com outros diagnósticos. Os autores relatam uma série de casos e realizam uma revisão de literatura. MÉTODOS: Estudo transversal de um único centro em que foram avaliados 12 pacientes com doença de McArdle. RESULTADOS: A média de idade no início dos sintomas foi de 28,0±17,4 anos, enquanto a idade no diagnóstico da doença foi de 39,0±14,8 anos. História de intolerância ao exercício físico foi observada em 10 dos casos; fraqueza muscular em 9; fenômeno do "second wind" em apenas 1 caso. A presença de câimbras, fadiga e mialgia foi observada, respectivamente, em 12, 11 e 9 dos casos. O nível mediano de creatinafosfoquinase foi de 5951U/L. Oito pacientes foram inicialmente diagnosticados com outra condição (polimiosite, miosite de corpos de inclusão, fibromialgia e/ou distrofia muscular), e aproximadamente metade havia recebido glicocorticoides e/ou imunossupressores antes do diagnóstico definitivo. Todos os pacientes foram submetidos à biópsia muscular, que revelou a presença de vacúolos subsarcolêmicos caracterizados por depósitos de glicogênio e reação histoquímica negativa para a enzima miofosforilase. CONCLUSÕES: O presente estudo reforça a presença de variabilidade clínica entre pacientes e mostra que a doença de McArdle deve ser considerada um dos diagnósticos diferenciais de miopatias inflamatórias e outras doenças reumáticas.

Falso diagnóstico de caminador en puntillas de pies; sospecha de enfermedad de McArdle / False diagnosis of idiopathic toe walker (ITW); suspicion of McArdle disease

El caminar en puntillas de los pies es una condición patológica en la cual las personas caminan en las puntas de los pies sin presentar ninguna condición ortopédica o neurológica. Se ha encontrado que los caminadores en puntillas de pies presentan diferentes características en los músculos gastrocnemios, el tendón de Aquiles y en el pie. La enfermedad de McArdle es una condición médica autosómica recesiva caracterizada por la baja tolerancia a la actividad física, la atrofia de los músculos de la cintura escapular y, en algunos casos, con episodios de mioglobinuria después de realizar ejercicio vigoroso. Este reporte explica el caso de una paciente diagnosticada como caminadora idiopática en puntillas de pies, pero con los signos clínicos de la enfermedad de McArdle. Este reporte busca comentar las características clínicas que diferencian a los caminadores idiopáticos en puntillas de pies y a los pacientes con la enfermedad de McArdle.

Idiopathic Toe Walking is a pathological condition in which the gait takes place on the tip toes. ITW is diagnosed on the absent of any orthopedic or neurological condition. The physiological characteristics of the gastrocnemios muscles, the Achilles tendon, and the foot of Idiopathic toe walkers are different to individuals that are not affected by toe walking. McArdle disease is a medical autosomal-recessive condition, characterised by low exercise tolerance, muscular atrophy at the shoulder girdle, and in some cases myoglobinuria episodes have been reported after vigorous physical activities. In this case study we present a patient diagnosed as Idiopathic toe walker, but with the clinical characteristics of McArdle diseases. The aim of this case study is to present the clinical characteristics that differentiate these two pathological conditions.

The Significance of Clinical and Laboratory Features in the Diagnosis of Glycogen Storage Disease Type V: A Case Report

Glycogen storage disease type V (GSD-V) is the most common disorder of muscle glycogenosis with characteristic clinical and laboratory findings. A 32-yr-old woman complained of exercise intolerance and myoglobulinuria since early adolescence. She reported several episodes of second-wind phenomenon. Physical examination did not show any neurological abnormality, including fixed muscle weakness or atrophy. Serum creatine kinase level was 1,161 IU/L at rest. The result of the non-ischemic forearm exercise test was compatible with GSD-V. Mutation analysis identified the compound heterozygous mutations of the PYGM, p.D510fs and p.F710del, which has not yet been reported in Korea. The present case recognizes that detail clinical and laboratory analysis is the first step in the diagnosis of GSD-V.

Recurrent acute kidney failure due to mcardle disease

We present an adolescent with McArdle disease and recurrent acute kidney failure due to rhabdomyolysis. The patient was admitted with acute kidney failure for 3 times and due to a history of proximal weakness, fatigue, and muscular cramps after physical activities a glycogen-storage disease was suspected. Serum creatine phosphokinase and urine myoglobin were found to be elevated. McArdle disease was diagnosed based on pathologic examination of muscle tissue specimen. Patients presenting with rhabdomyolysis following strenuous exercise should be evaluated for McArdle disease