The Clinical Pathological And Prognostic Analysis Of Pure Type Mitochondrial Myopathy And CPEO

Objective:To investigate the clinical,pathological and prognostic features of pure mitochondrial myopathy and CPEO in China.Material and methods:We investigated a total of 57 patients who came from the neuromuscular disease center of Qilu Hospital of Shandong University,including 18 cases of pure mitochondrial myopathy and 38 cases of CPEO patients diagnosed clinically and pathologically,and then collected the clinical data and pathological features of biopsied skeletal muscle specimens of them(Some patients had pathological materials of electron microscope).24 cases of them were followed up on the purpose of prognostic analysis.Finally the clinical,pathological features and prognosis of all the investigated patients were analyzed retrospectively.Result:In the 18 cases of pure mitochondrial myopathy,there were 10 male and 8 female. The age of onset ranged from 2 to 49 years,with an average of 18.9 years.4 patients in this group had positive family history.Most cases of pure mitochondrial myopathy were clinically characterized by exclusive skeletal muscle involvement and fluctuating proximal muscle weakness.Cardiac and extra-ocular muscles were spare. Most patients had moderately increased CK level(341～7407U/L).15 patients who had EMG examination showed myogenic changes in 10 cases,neurogenic in 4 cases and 1 case had not only myogenic changes but also neurogenic changes. Pathologically,17 cases had typical ragged red fibers or atypical ragged red fibers. COX deficiency was seen in12 cases(1 case with negative RRF)and total deficiency in 3 cases.To a certain degree,the percentage of RRF was parallel to the degree of muscle weakness.3 cases were observed by electron microscope and showed the abnormal quantity,shape and construction of mitochondria.Following-up data from 11 patients who were treated with vitamin B,vitamin E,CoQ₁₀and inosine showed that 10 patients' symptoms did not aggravate and had no evidence of other systems involved except 1 patient suffered from a sudden death with unknown reason.In 39 cases of CPEO,there were 18 cases of male,21 cases of female.The age of onset ranged from 4 to 62 years,with an average of 22.8 years.9 patients in this group had positive family history.Progressive external ophthalmoplegia was predominant in early stage in 28 cases.4 cases had ptosis of the right eye,3 cases had ptosis of the left eye(1 case had ptosis after paroxysmal blepharospasm for 2 years),3 cases had diplopia and 1 case had fatigue.In all 39 cases,23 cases had proximal weakeness.10 cases had diplopia,7 cases had dysphagia,6 cases had disturbance of hearing,5 cases had migraine,5 cases had heart conduction defect and 3 had retinal pigment disposition.The serum CK level was mildly elevated in 11 cases(305～1006U/L). EMG examination showed normal in 13 cases,myogenic changes in 5 cases and positive in repeating nerve electric stimulation test in 3 cases.The striking and common pathologic findings were the presence of RRF and the COX deficiency fibers in COX stains.Ultra-structural alterations included subsarcolemmal accumulation of mitochondria,increases of the number of mitochondria with abnormal shape, disarrangement of cristae and paracrystaline inclusion bodies.Following-up data showed that the symptoms of fatigue had improved after treatment with vitamin B, vitamin E,CoQ₁₀and inosine,the symptoms in the eyelid had no obvious improvement.Conclusion:Pure type mitochondrial myopathy may be a distinct subset of mitochondrial diseases that preferentially affects trunk and proximal muscles.Pathological characteristics included typical RRF and COX deficiency,and RRF is related to patients' condition.The clinical and pathological features of CPEO are basically similar to those reported by other countries.Ragged red fibers and COX deficiency fibers would be crucial pathological clues for the diagnosis of CPEO.RRF is unrelated to patients' condition.Both of two diseases have relative chronic process and benign prognosis.