The Study Of Muscle Injuries In Patients With Duchenne Muscular Dystrophy Via Muscle Magnetic Resonance Imaging

1 PurposeAlthough the diagnosis of Duchenne muscular Dystrophy(DMD)is relatively easy,there is no effective radical cure method,and it progresses rapidly and the disability rate and mortality is high.So far,an effective,feasible and sustainable evaluation and detection method is lacking to study the muscle injury pattern and dynamic changes of DMD.This research used muscle MRI(magnetic resonance imaging,MRI)to check the proximal muscles of lower limbs of DMD patients in different age groups,and observe the lower limbs muscle MRI damage modes and the dynamic change in different age groups,and explore the pattern of muscle injury in different age groups of DMD patients,looking for the best way to evaluate the condition of DMD,provide an important basis for the prognosis of DMD patients.2 Methods2.1 Selection of enrolleesThe enrolled patients were all 51 patients with DMD confirmed by clinical,muscular pathology and immunohistochemistry.All patients were selected from hospital affiliated to institute of neurology,Anhui University of Traditional Chinese Medicine between January 2015 and December 2019.2.2 Preparation before group entryFirst of all,establish the diagnostic criteria for admission,that is to say,through clinical presentation,blood creatine kinase(CK),electromyography and muscle pathology can definite diagnosis of DMD.Then the pathological findings,CK,hematoxylin-eosin(HE)staining and immunohistochemical characteristics of anti-myatrophy protein(Dystrophin,Dys)were summarized.To choose the lower extremity thigh muscle group as the muscle MRI examination site of the patients in the group,and observe the cross-sectional injury of 10 muscles in gracilis muscle,great adductor muscle,long adductor muscle,semitendinosus,semimembranosus,sartorius,musculus rectus femoris,medial vastus muscule,vastus intermedius muscule,vastus lateralis muscle.At the same time,according to the degree of muscle fat infiltration:no abnormal high-signal focus,the presence of point-like high-signal focus,the presence of scattered high-signal focus,the presence of large areas of fusion high-signal focus,skeletal muscle all diffuse high-signal focus,respectively rating:0,1,2,3,4,5.2.3 Muscle MRI study of the enrolled patientsDMD patients who meet the entry criteria,was divided into three groups by the age,that was<6 years old,6～9 years old and>9 years old.The thigh muscles of lower limbs MRI T1WI and STIR fat suppression sequence were examined.Fat infiltration score was used to evaluate the severity of fat infiltration in 10 muscles of gracilis muscle,great adductor muscle,long adductor muscle,semitendinosus,semimembranosus,sartorius,musculus rectus femoris,medial vastus muscule,vastus intermedius muscule,vastus lateralis muscle.At the same time,the blood CK and the general pathological and immunohisto chemical tests of muscles of 51 DMD patients were retrospectively analyzed,and the correlation between age and CK,muscle pathological changes and MRI manifestations and fat infiltration score of each skeletal muscle were further statistically analyzed.3 Results3.1 General data of DMD patientsA total of 51 DMD patients were enrolled in this study,with an admission age of 7.53±2.91years,an onset age of 3.20±1.94years,a course of disease of 4.3 1 ±2.64 years,and a delayed diagnosis time of 3.24±2.04 years.Among the 51 patients with DMD in this study,there were 18 patients in the group of<6 years old,17 patients in the 6～9 years old group and 16 patients in the>9 years old group.All the 51 cases had different degrees of muscle weakness,mainly lower limb weakness,positive Gowers sign,and different degrees of pseudohypertrophy of bilateral calves.Serum CK was significantly increased,and CK gradually decreased with the increase of age and the prolonged course of disease.All EMG showed myogenic damage.3.2 Results of muscular pathology in patients with DMDThe pathological results of common muscle in 51 DMD patients showed mild muscle pathological injury in 5 cases,moderate muscle pathological injury in 42 cases and severe muscle pathological injury in 4 cases.By correlation analysis,the age of muscle biopsy was positively correlated with the degree of muscle pathological lesion in 51 DMD patients.All of the 51 patients were found to lack expression in the Dys-rod area of muscle immunohistochemistry.3.3 MRI results of muscles in DMD patientsThe total MRI results of 51 patients with DMD showed that there were 0 normal cases,18 mild injuries,17 moderate injuries,12 severe injuries,and 4 extremely severe and advanced injuries.The results of MRI cross-sectional 10 muscle injuries of the lower extremities of the DMD patients showed that the other 7 thigh muscles were more serious than those of gracilis muscle,sartorius muscle and semitendinosus muscle.With the increase of age,the injury was more serious,especially the four muscles of musculus rectus femoris,medial vastus muscle,vastus intermedius,vastus lateralis muscle.At the same time,4 DMD patients with extremely severe and late injury were found to have only 1 point of injury of gracilis muscle,sartorius muscle and semitendinosus muscle,while the other 7 muscle injuries reached 5 points.MRI examination results of lower extremity thigh muscles in the three groups of DMD in this study showed that of the 18 patients in the<6 years old group showed mainly mild injury,the 3 muscles of gracilis muscle,sartorius and semitendinosus were basically normal,and the other 7 muscles were mildly injured.MRI of the thigh muscles of the lower extremities of the 17 DMD patients aged from 6 to 9 years showed that moderate injuries were the main type,the 3 muscles of gracilis muscle,sartorius and semitendinosus were mild,and all the other 7 muscles were moderately injured.MRI of lower extremity thigh muscles of DMD patients in the>9years old group showed that the major injuries were severe,the 3 muscles of gracilis muscle,sartorius and semitendinosuswere mild,and the other 7 muscles were severely injured or even extremely severely injured.3.4 The correlation between serum CK,muscle pathology and muscle MRI and age in DMD patientsThe CK value and age,course of disease,onset age,delay diagnosis time and start walking time of 51 DMD patients were analyzed by Spearman correlation analysis.There was no correlation between CK change and onset age,delayed diagnosis time and start walking time(P>0.05),but the correlation coefficients with age and course of disease were respectively rs=-0.40 and rs=-0.42,all of them P<0.01.Spearman correlation analysis of 51 patients DMD age and muscle pathological results rs=0.57,P<0.01.The age correlation between musculus rectus femoris,medial vastus muscle,vastus intermedius,vastus lateralis muscle was rs=0.97,P<0.01,the age correlation between great adductor muscle,long adductor muscle and.semimembranous muscle was rs=0.96,P<0.01,and that betweengracilis muscle,sartorius muscle and semitendinosus muscle was rs=0.84,P<0.01.4 Conclusion4.1The degree of muscle pathological injury in DMD patients is closely related to the age of biopsy.4.2The thigh muscle injury of lower limbs of DMD patients was not balanced,the gracilis muscle,sartorius and semitendinosus damage in patients with DMD damaged relatively lighter,and the great adductor,long adductor,semimembranosus,musculus rectus femoris,medial vastus muscule,vastus intermedius muscule,vastus lateralis muscle of the 7 pieces of thigh muscle injury were heavier,and increased with age.4.3MRI examination of muscle can provide visual and dynamic objective basis for the outcome of DMD patients.