Diagnosis of McArdle's disease in an elderly patient: Case report and review of literature

R. Makary; A. Berger; N. Talpur; S. Shuja

摘要

McArdle's disease is caused by deficiency of the muscle-specific isoform of phophorylase enzyme. The enzyme splits glucose-1-phosphate from glycogen to fuel the glycolytic pathway needed for muscle activity. McArdle's disease, although being the commonest form of glycogenosis affecting skeletal muscle, is a rare disease. The disease is typically manifested in childhood/adolescence by exercise intolerance, muscle cramps/pain with the classic "second wind" phenomenon (improvement of symptoms after a short period of slowing down or rest). McArdle's disease with late-onset presentation is very rare and clinically more variable in its presentation than the early onset disorder. The disease may escape clinical diagnosis until progressive or persistent muscle weakness or atrophy occurs at advanced age. We report an atypical case of McArdle's disease diagnosed at the age of 65 years in a patient presenting with progressive fixed proximal muscle weakness with no previous history of episodic muscle dysfunction and discuss the clinical-pathological aspects of the disease. Introduction McArdle's disease (glycogenosis type V) is caused by deficiency of the enzyme alpha-1,4-glucan orthophosphate glycosyl transferase (myophosphorylase ). The enzyme plays a vital role in the liberation of glucose-1-phosphate from glycogen in skeletal muscles to create energy (1). There is currently no reliable data about the frequency of McArdle's disease, however the prevalence of the disease has been estimated to be 1:100,000 (2). The disease usually presents in adolescent and young adults with exercise intolerance and muscle cramps that improve after a short period of slowing down or rest, a characteristic feature known as “second wind” phenomenon (3). Late presentation of the disease in older age is rare (4) and the clinical diagnosis become difficult due to the atypical presenting symptoms (5). We report an unusual case of McArdle's disease diagnosed at the age of 65 years in a man presenting with progressive fixed myopathic picture, who did not have obvious episodic muscle dysfunction earlier in his life. Case report The patient was a 65 years old man complaining of weakness, more in proximal arm muscles than in his legs. The exact onset of his symptoms was unclear, as it had been slowly progressive. He had noticed some difficulty getting out of a chair and in raising both arms above the head, fasciculations and loss of muscle mass. He was on Lipitor for 4 years and recently his creatine kinase (CK) was in the 4,000 range which dropped to the mid-300s two months after discontinuation of Lipitor. However, he did not notice improvement in proximal arm strength. He has not had history of myalgias, muscle cramps, any rashes, joint pains, ocular or bulbar abnormalities. There was no family history of neurologic dysfunction. Physical examination revealed questionable atrophy of the proximal muscles with decreased strength in both upper extremities (deltoids 3/3-, biceps 4-/4-, triceps 4/4-). Deep tendon reflexes were trace at the right biceps, absent at the left biceps, trace at the triceps, absent at the brachioradialis bilaterally. In the legs, there was symmetric weakness of the iliopsoas (4+ to 5-) and minimal weakness of the gluteus maximus bilaterally (5-/5), otherwise the other muscles in the legs were normal. His sensory exam and routine labs were unremarkable. There was electrophysiological evidence of myopathic motor units and spontaneous activity in proximal arm and proximal leg muscles. Biopsy of Left quadriceps was performed. The biopsy showed subsarcolemmal vacuoles in many fibers with no abnormal contents on hematoxylin and eosin (fig. 1A), Masson's trichrome (fig. 1B) or Gomori stains (Fig.1C). Increased glycogen content (Fig. 2A) was present in several fibers on PAS stain (diastase sensitive). Myophosphorylase activity was absent using enzyme histochemistry (fig. 2B) with a positive control (Fig. 2C). Mild to moderate myopathic features were

机译：麦克阿德氏病是由磷酸化酶的肌肉特异性同工型不足引起的。该酶从糖原中分解出1-磷酸葡萄糖，以促进肌肉活动所需的糖酵解途径。麦卡德氏病虽然是影响骨骼肌的糖原异生的最常见形式，但却是一种罕见的疾病。该病通常表现为儿童/青少年运动不耐，肌肉痉挛/疼痛，伴有典型的“二次风”现象（短暂的减速或休息后症状改善）。迟发性表现的麦卡德氏病非常罕见，临床表现上比早发性疾病更易变。该疾病可逃避临床诊断，直到在晚期发生进行性或持续性肌无力或萎缩为止。我们报告了一名非典型的麦克阿德氏病病例，该病人在进行性固定性近端肌无力且没有发作性肌肉功能障碍的既往史的患者中诊断为65岁，并讨论了该疾病的临床病理方面。引言McArdle病（V型肝病）是由α-1,4-葡聚糖正磷酸葡糖基转移酶（肌磷酸化酶）缺乏引起的。该酶在骨骼肌糖原中释放1-磷酸葡萄糖时起重要作用（1）。目前尚无关于麦克阿德病发病率的可靠数据，但是据估计该病的患病率为1：100,000（2）。该病通常出现在运动不耐症的青少年中，并在短暂的减速或休息后出现肌肉痉挛，这种特征被称为“二次风”现象（3）。这种疾病晚于老年出现的情况很少见（4），并且由于非典型的表现症状而使临床诊断变得困难（5）。我们报告了一名男性，患有一名患有进行性固定性肌病照片的男性，在65岁时诊断出麦克阿德病的一例罕见病例，他一生中没有明显的发作性肌肉功能障碍。病例报告该患者是一名65岁的男子，他抱怨自己无力，手臂近端肌肉多于腿部。目前尚不清楚他的症状的确切发作，因为其进展缓慢。他注意到从椅子上出来，将双臂抬高到头顶上方时有些困难，扭动和肌肉质量下降。他在立普妥治疗4年，最近的肌酸激酶（CK）在4,000范围内，在立普妥停药两个月后降至300年代中期。但是，他没有注意到近端臂的力量有所改善。他没有肌痛，肌肉痉挛，任何皮疹，关节痛，眼或延髓异常的病史。没有神经系统功能障碍的家族史。体格检查发现近端肌肉可疑萎缩，两个上肢的力量下降（三角肌3 / 3-，二头肌4- / 4-，三头肌4 / 4-）。深肌腱反射出现在右二头肌，左肱二头肌不存在，肌腱反射在三头肌，双侧肱肱肌不存在。腿部有the骨对称性肌无力（4+至5），双侧臀大肌无力（5- / 5），否则腿部其他肌肉均正常。他的感官检查和例行实验室都没什么特别的。有电生理证据表明肌病性运动单位和近端臂和近端腿部肌肉自发活动。进行左四头肌活检。活检显示，在许多纤维中有肌膜下空泡，苏木精和曙红（图1A），马森三色（图1B）或Gomori染色无异常含量（图1C）。 PAS染色的几条纤维中存在糖原含量增加（图2A）（对淀粉酶敏感）。使用带有阳性对照的酶组织化学方法（图2B）不存在肌磷酸化酶活性（图2C）。轻度至中度肌病特征

Diagnosis of McArdle's disease in an elderly patient: Case report and review of literature

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