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Título

Usefulness of ultrasound in detecting muscle involvement pattern in Pompe disease.

Resumo

Introduction: Pompe disease is a treatable autosomal recessive disorder caused by deficiency of acid alfa-glucosidase. Two classical phenotypes are described: the infantile and the late-onset forms. Among late-onset Pompe disease, most patients present with a limb-girdle weakness pattern, although axial involvement is common. Muscle ultrasound may evaluate clinical and subclinical involvement of muscles, identifying some particular distribution pattern, and acting as adjunct to the physical exam.

Objective: To describe the pattern of muscle involvement by ultrasound, including the tongue, paravertebral and diaphragm muscles in patients with Pompe disease.

Methods: Eight patients with molecular diagnosis of Pompe disease were clinically assessed and underwent muscle ultrasound using the setting for muscle evaluation with a fixed gain (Sonosite Edge, Fujifilm) with a 7-15MHz transducer. The followings segments were assessed: tongue, upper and lower limb (mostly for proximal muscles), abdomen, diaphragm and paravertebral muscles. For the diaphragm we measured the thickness during expiration and forced inspiration. All ultrasound images were obtained and scored based on Heckmatt’s rating scale.

Results: Five from eight patients were male. The mean age was 42 years old, with 10 years of disease duration. Only one patient complaint of dysphagia and five reported dyspnea. The most involved and weakest muscles were abdominal (mean MRC 2), gluteus maximus (mean MRC 2) and gluteus medius (mean MRC 3), and adductors (mean MRC 2.5). On ultrasound the most affected muscles were abdomen, vastus intermedius, adductors and lumbar paravertebral muscles, scaled as Heckmatt 3 in virtually all patients. We also observed a pattern of brachialis more involved than biceps brachii, and vastus intermedius more affected than rectus femoris in all patients. Five patients had imaging involvement of the tongue without any complaint of dysphagia. Considering diaphragm, seven patients had high echointensity, and all patients with Heckmatt 3 had a thickness ratio (considering inspiration and expiration thickness) lower than 30%, which was considerably lower than in Heckmatt 2 patients (which had a thickness ratio between 30 and 60%).

Conclusion: Muscle ultrasound was able to detect a recurrent pattern of muscle compromise in all patients. Subclinical involvement of the tongue and diaphragm may help early disease recognition and predict potential respiratory complication.

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Doenças Neuromusculares