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|LETTERS TO EDITOR
|Year : 2016 | Volume
| Issue : 1 | Page : 173-174
Atypical initial manifestation of facioscapulohumeral muscular dystrophy mimicking neuralgic amyotrophy
Kee Hong Park, Dong-Wan Kang, Kwang-Woo Lee, Jung-Joon Sung
Department of Neurology, Seoul National University Hospital, Seoul, Korea
|Date of Web Publication||11-Jan-2016|
Department of Neurology, Seoul National University Hospital, Seoul
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Park KH, Kang DW, Lee KW, Sung JJ. Atypical initial manifestation of facioscapulohumeral muscular dystrophy mimicking neuralgic amyotrophy. Neurol India 2016;64:173-4
|How to cite this URL:|
Park KH, Kang DW, Lee KW, Sung JJ. Atypical initial manifestation of facioscapulohumeral muscular dystrophy mimicking neuralgic amyotrophy. Neurol India [serial online] 2016 [cited 2020 Jan 18];64:173-4. Available from: http://www.neurologyindia.com/text.asp?2016/64/1/173/173646
Facioscapulohumeral muscular dystrophy (FSHD) is the most common myopathy in adults. Its typical clinical feature is asymmetric facial and shoulder-girdle weakness followed by weakness of the anterior part of the arm, abdominal and pelvic girdle muscles. The weakness usually progresses very slowly. We present a patient of FSHD whose initial presentation was acute-onset shoulder pain followed by weakness and muscle atrophy.
A 19-year-old male patient presented with right shoulder pain and weakness. He had been playing baseball every day for 1 year. Two years before admission, he felt an electric shock-like pain in the right shoulder while throwing a baseball, and it lasted for 1 week. He could not elevate his right arm above 90 degrees 1 or 2 days after the onset of pain. Scapular protrusion was also observed. He did not complain of any sensory disturbances. The muscle power of his left arm and both legs was intact. On neurological examination, the right shoulder abduction was Medical Research Council (MRC) grade 4 under 90 degrees, but MRC grade 2 above 90 degrees. Mild weakness was observed on right elbow flexion and extension (MRC grade 4+). Winged scapula was found on the right side [Figure 1]. The facial muscles were spared and his sensory examination was normal.
|Figure 1: Photograph of the patient shows asymmetric scapular winging at the right shoulder|
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Neuralgic amyotrophy was our first impression because of acute-onset shoulder weakness and muscle atrophy after the precipitation of pain. Its distinctive features are extreme pain at the onset, rapid paresis and atrophy of the upper arm, and a slow recovery that occurs over months to years. However, the nerve conduction study was normal and electromyography revealed low amplitude polyphasic motor unit action potentials with an early recruitment pattern of short duration, which pointed towards the underlying features of myopathy. His serum creatine kinase was 489 U/L (normal, <270 U/L). The shoulder MRI revealed no abnormal lesion in the rotator cuff muscles, glenohumeral ligament, and of bony structures at the shoulder. The right deltoid muscle biopsy revealed nonspecific myopathic changes without any inflammatory cell infiltration. Detailed family history revealed that his maternal uncle has been suffering from both proximal arm and leg weakness. After considering these results, FSHD was suspected, and deoxyribonucleic (DNA) study was done using pulse-field gel electrophoresis method that has previously been described. The results of the test were confirmatory for an Eco RI restriction fragment of 29 kb.
Clinical manifestation of FSHD is variable, and there is a report of FSHD patient whose initial diagnosis was brachial plexopathy. In our case, the type of onset and initial pain misled us in making an improper clinical diagnosis. Muscle pain has been reported to be a prominent features of FSHD, but in most the cases, this pain has been primarily myalgic and not exercise related. Other atypical manifestations include facial sparing, foot drop, proximal leg weakness, epilepsy, and myogloblinuria. In approximately 5% of patients having FSHD2, DNA hypomethylation and heterochromatin markers at the D4Z4 repeat are observed that are similar to patients with D4Z4 contractions (seen in FSHD1). This commonality suggests that a change in D4Z4 chromatin structure unifies FSHD1 and FSHD2. The clinical heterogeneity of FSHD is a diagnostic challenge, and DNA testing for FSHD is important for confirming the diagnosis.
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