Facial and Skeletal Muscle Magnetic Resonance Imaging In Oculopharyngodistal Myopathy

Abstract

OBJECTIVE: Oculopharyngodistal myopathy (OPDM) has been reported as a rare, adult-onset hereditary muscle disease. Patients show progressive oculopharyngeal and distal limb muscle involvement. As the genetic defect underlying OPDM is not known yet, the diagnosis currently rests upon clinical and histopathological features. This study aimed at investigating patterns of muscle alterations of OPDM patients by MRI and to search for possible clues to make differential diagnosis by using a non-invasive method.

METHODS: Facial, upper and lower extremity muscles of 10 patients with OPDM, followed by the Neuromuscular Unit, Department of Neurology, Istanbul Faculty of Medicine, who had undergone detailed evaluation with manual muscle testing and who had different disease severity were evaluated with a 1.5-Tesla Philipps Achieve MR scanner using conventional T1 and T2 weighted axial images. The degree of muscle involvement on MRI was evaluated according to a modified 5-point scale.

RESULTS: The mean age of onset was 20.1± 8.2 years (range 7- 39 years) and the mean disease duration was 14.5± 12.4 years (range 2-41 years). Seven patients showed dominantly distal (mild to severe/wheelchair bound), one patient dominantly proximal weakness and two patients had no weakness. The patients without weakness had normal imaging, but facial muscle MRI from one of them revealed mild involvement. Zygomatic and nasal muscles were the most severely and earliest involved muscles. MRI of all patients with muscle weakness showed a consistent selective muscle involvement pattern. Distal extremity muscles were more affected than proximal muscles. Earliest and most sever changes were found in semimembranous, biceps femoris and medial head of gastrocnemius and soleus muscle. Interestingly, sartorius, gracilis and semitendinous muscles and the lateral head of gastrocnemius were well-preserved in OPDM.

CONCLUSION: Muscle MRI by showing selective involvement of exteremity muscle may be a non-invasive tool in the differential diagnosis of OPDM.