Clinical And Pathological Study On 49 Patients With Myotonic Dystrophy

Objective:Myotonic dystrophy (DM) is an autosomal, dominant inherited, neuromuscular disorder that was first described by Steinert in 1909. Clinical expression of DM is extremely variable, presenting a progressive muscular dystrophy that affects distal muscles more than proximal and is associated with the inability to relax muscles appropriately (myotonia), cataracts, cardiac arrhythmia, testicular atrophy and endocrine system disorder. The prevalence of DM in most populations is approximately 4.9-5.5/10 and DM families are highly affected by the phenomenon of anticipation, as a result of which the disease has an earlier onset and a more severe course in subsequent generations. We investigated 49 patients from the neuromuscular disorder lab of Qilu Hospital, Shandong University to know better about the clinical and pathological characteristics of DM.Material and methods:We investigated 49 patients from the neuromuscular disease center of Qilu Hospital of Shandong University during 1990-2010 including the clinical data and pathological features of biopsied skeletal muscle specimens of them. And the clinical, pathological features and prognosis of all the investigated patients were analyzed retrospectively.Result:1. Of the total 49 patients,31 cases were male, and 18 were female. Age at onset was from 16 to 67 years. Mean age was 35.47±11.26 years. The course of disease was from 1 to 20 years. There are 25 patients with family history. The frequent symptoms were myotonia, muscle weakness and muscle atrophy. There are also other systemic symptoms such as cataract, hair losing or bald and gonadal atrophy, sexuality disfunction, heart damage, intelligence impairment.2. The pathological findings were as bellows:①There were marked variation in fiber size. Most of the small fibers were angular. There were also hypertrophic fibers.②The fibers with centrally placed nuclei and sarcoplasmic mass were frequently seen on H&E and MGT staining.③There were a lot of pyknotic nuclear clumps and chained nuclear can be seen, while necrotic and regenerating fibers were rarely be seen.④On NADH staining, there were type I fiber atrophy and compensative type II fiber hypertrophy.⑤There were also other pathological findings such as rimmed vacules, RRF and COX deficiency fibers.Conclusions1. The clinical expression of DM is variable, presenting a progressive muscular dystrophy that affects distal muscles more than proximal and is associated with the inability to relax muscles appropriately (myotonia), cataracts, cardiac arrhythmia, testicular atrophy and insulin resistance. A family history can make the diagnosis easier.2. The EMG (electromyogram) and NCV (nerve conduction velocity) are also important to the diagnosis, which are related to the muscle pathology.3. The pathological features of DM are centrally placed nuclei, pyknotic nuclear clump, sarcoplasmic mass and type I fibers atrophy.