Clinical,Radiological,and Myopathological Features Of Benign Monomelic Lower Limb Atrophy

Objetctives:To explore the epidemiological features,pathogenesis,clinical characteristics,auxiliary examinations of 33 cases of benign monomelic amyotrophy of lower limb(BMALL)by summarizing the general information,clinical manifestations,muscle enzyme examination,Electromyography(EMG),lumbar spine and lower limb muscle magnetic resonance imaging(MRI),Muscle biopsy and connectiong with related literatures in the domestic and abroad,which provides foundation for clinical research.Materials and Methods:33 patients with BMALL diagnosed in the Department of Neurology,First Affiliated Hospital of Nanchang University from March 2015 to March 2018 were included in this study.A retrospective analysis of 33 cases of unilateral lower limb atrophy was performed.Results:20 cases of man and13 cases of woman fulfilling the clinical features of benign monomelic amyotrophy of lower limb including with a ratio of 1.54:1,aging from 13 to 68 years old were included in this study.The onset ages were ranged from 0 to 68 years old.The time of onset to treatment was from 1 mouth to 51 years,with 60% of patients Consult physician in 1-5 years.The peaks of onset age were during young aged and middle aged.Conceal onset and slow progressed,4 patients had a clear family history,no poliomyelitis or other neuromuscular diseases.Typical clinical manifestations was unilateral lower limb muscle atrophy,3 cases had obvious bilateral lower limb involvement.The degrees of muscle weakness ranged from I-V,and 81.8% of patients were in level IV to V.Creatine kinase values were mightly elevated in 4 patients with the neurogenic changes of EMG,mild herniation of the intervertebral disc with no nerve compression of lumbar vertebral imaging.The MRI fat scores of 30 cases of BAMLL showed that the total fat scores of bilateral lower limb muscle fatification in each patient were significantly correlated with the disease course(OR=1.752 P=0.018,P<0.05).By evaluating the fat scores of different muscles about all patients,we found that the rate of muscle fat was most seriously affected in the posterior muscles of thigh such as the semitendinosus,semimembranosus and biceps femoris and the posterior muscles of calf such as the gastrocnemius,soleus and long flexor.According to the lower limb MRI results by evaluating the size of each muscle in the lower extremities,several clinical types were found in our patients that are astrophy in all of the lower extremity muscles,selective in the muscles of the lower limbs,in the thigh anterior muscles,in the entire thighs muscle,inthe posterior calf muscle in the calf muscles and severe asymmetry atrophy in the bilateral lower limb.In our study,there were no patients involved the anterior calf and posterior thigh muscles.Seven cases of muscle pathology showed markedly increased variation in fiber size,with atrophic and hypertrophic fibers,increased connective tissue,and increased internalized nuclei Groups of atrophic fibers,interstitial fat infiltration.During 1-3 years of follow-up,3(9.1%)patients had progressed.Conclusions:We reported the largest group of BMALL patients in China.The clinical heterogeneity of BMALL patients suggests that there may be multiple disease entities.Some patients have definite family histories,suggesting that genetic factors are involved.In this group of BMALL patients,markedly crural muscles atrophy were found mainly in gastrocnemius and soleus muscles and thigh muscles atrophy were found mainly in semitendinosus,semimembranosus,and vastus intermedius and lateralis muscles.The progress had been found in 3 patents,suggesting that BMALL are not static,and long-term follow-up is in great need for this type of disease.