Distal myopathy with rimmed vacuoles: clinical and pathological study in 9 Chinese cases / 中华神经科杂志

ABSTRACT

Objective To investigate the clinical and pathological features of distal myopathy with rimmed vacuoles(DMRV). Methods Clinical manifestations and pathological features of biopsied muscle specimens were summarized and analysed retrospectively. Muscle specimens were collected from biceps brachii (3 cases), tibialis anterior (2 cases), quadriceps femoris (1 case)and gastrocnemius (3 cases) respectively. 6 cases were observed by electronic microscope. Results The onset of disease was ranged in age from 15 to 33 years, averaging 25 years. It is more common in women than in men in a ratio of 2∶1. Distal muscle weakness and atrophy of the lower extremities was predominant in early stage. Varied involvement of proximal and trunk muscles, with sparing of the facial, extraocular, bulbar, intercostal and diaphragm muscles was recognized in the advanced stage. The striking and common pathologic finding was the presence of rimmed vacuoles in muscle fibers with little evidence of necrotic or regenerative processes. Electronic microscopic study showed an accumulation of myeloid structure in 5 cases, cytoplasmic inclusion bodies in 4 cases and intranuclear filamentous inclusions in 2 cases. A perforated nuclear envelope and extrusion of filaments in adjacent cytoplasm were found in an enlarged nucleus filled with tubulofilementous inclusion.Conclusion The clinical and pathological findings of DMRV occurred in China is basically similar to those reported by Japanese. Ultrastructural study suggested that sarcoplasmic filamentous inclusions might originate from perforated nuclei with inclusion body, which predicts that the rimmed vacuoles are likely to be the end products of nuclear disintegration and focal myofibrillar degeneration.