Magnetic Resonance Imaging Findings of the Skeletal Muscle of a Patient with Nemaline Myopathy.

Abstract

This is the first magnetic resonance imaging (MRI) report of nemaline myopathy in which muscle atrophy was not apparent clinically in the lower extremities because of subcutaneous fat. The patient is a 38-year-old womanwhowas admitted to our hospital because of muscle weakness of the four extremities. Until the age of 17 years, she was asymptomatic except that her running speed was slow. The Tx-weighted image of muscle MRIat the mid-thigh level showed hyperintensity of the quadriceps femoris muscle and relatively spared hamstring muscle. The T2-weighted image of muscle MRI at the maximumdiameter of the lower leg showed hyperintensity of the tibialis anterior muscle and a relatively spared triceps surae muscle. The biopsy specimen of the right deltoid muscle showed nemaline bodies and type II fiber deficiency. (Internal Medicine 37: 776-779, 1998) Key words: type II fiber deficiency, extensor muscle group, magnetic resonance imaging (MRI) IntroductionNemalinemyopathyis a neuromuscular disorder characterized by muscle weakness and the presence of nemaline bodies (rods) in the muscle fibers, in the absence of other known conditions sometimes associated with rods (1), such as polymyositis, central core disease, chronic alcoholic myopathy, human immunodeficiency virus infection, congenital muscular dystrophy, multiple acylCoA dehydrogenase deficiency (2) and adult-onset rod disease (3). Reports of muscle magnetic resonance imaging (MRI) in nemaline myopathy are rare (4). This is the first MRIreport of nemaline myopathy in which the muscle atrophy was not apparent clinically in the lower extremities due to subcutaneousfat. Wereport a case ofnemaline myopathy in which muscle MRIwas useful in evaluating the distribution and severity of myopathy. Case ReportThe patient is a 38-year-old womanwho was admitted to our hospital because of muscle weakness of the four extremities. Until the age of 17 years, she was asymptomatic except that her running speed was slow. At the age of 18, she noticed mild weakness in her lower extremities. She has not been able to climb stairs since the age of33. She noticed difficulty in walking at the age of 36. In addition to the weakness in the lower extremities, she began to have weakness in the upper extremities at the age of 38. Her past history was unremarkable. Her family history showed that her healthy parents were cousins and that she had a sister with nemaline myopathy and a healthy brother. The sister was a 42-year-old womanwith a clinical picture similar to the present patient and the diagnosis was based on muscle biopsy findings but muscle MRIof the sister had not been taken. On admission, she was 150 cm tall with a body weight of 40.2 kg, blood pressure 126/82 mmHg,pulse rate 108 and regular. Physical examination of the chest and abdomenwas normal. Oval face, pes cavus and pes equinovarus were noted but dysmorphicface was absent. Her consciousnesswasclear, speech normal, and mini-mental state examination score was 30 points; mild facial weakness and moderate atrophy and weakness ...

In vivo characterization of skeletal muscle function in nebulin‐deficient mice

“…We observed that the extent of fatty infiltration was negligible for the two groups even though the magnitude was slightly higher in the Neb ‐cKO mice compared with WT. Our results are in line with the small amount of fatty tissue infiltration in the hindlimb muscles ( i.e ., <5%) of two other NEM mouse models, whereas large fat infiltration has been reported in NEM patients . Therefore, our MRI data provide evidence that the Neb ‐cKO mouse model does not reproduce the large fatty infiltration typically observed in NEM patients.…”

“…Our results are in line with the small amount of fatty tissue infiltration in the hindlimb muscles (i.e., <5%) of two other NEM mouse models, whereas large fat infiltration has been reported in NEM patients. [27][28][29] Therefore, our MRI data provide evidence that the Neb-cKO mouse model does not reproduce the large fatty infiltration typically observed in NEM patients.…”

Unusual Fatty Infiltration of the Soleus Muscle in a Patient with Congenital Nemaline Myopathy: Fat-suppression Muscle MRI.

“…The soleus muscle was relatively normal on MRI. Histochemical aspects in that patient revealed nemaline bodies and type II fiber deficiency ( 12). Previous radiological hallmarks support that the gastrocnemius and tibialis anterior muscles are affected early in congenital nemaline myopathy.…”

“…However, muscle histochemistry was not described in that report (1 1). In another report (12) of an ambulatory case, MRI exhibited remarkable hyperintensity in the quadriceps femoris, caput medialis of the gastrocnemius and tibialis anterior muscles. The soleus muscle was relatively normal on MRI.…”