Differential diagnoses
Depending on the prevailing symptoms, other myotonic diseases (delayed muscle relaxation) or other muscular dystrophies (muscle atrophy) may be considered as differential diagnoses. Furthermore, diseases of the nervous system can also lead to weakness and atrophy of the muscles controlled by the affected nerves.
Diagnostics
Clinically pioneering is the presence of myotonia (delayed relaxation) of the muscles with muscle atrophy (reduction and shrinkage of the muscles). Accordingly, measurement of the electrical muscle activity in the EMG (electromyogram) reveals a characteristic finding from low levels of individual deflections (as in muscular dystrophies) and the occurrence of rapid discharge series (as in myotonia, so-called “dive bomber noise”). Blood tests reveal the symptoms of muscle cell death (elevated levels of a muscle enzyme, “CK”) and possibly the consequences of hormone system involvement (lowered levels of sex hormones). Human genetic testing can detect in blood cells the prolongation of a section on chromosome 19, which is characteristic for myotonic dystrophy. If myotonic dystrophy has been diagnosed, it is important to clarify the function of the heart at least by means of an ECG (electrocardiogram) in order to find indications of a possible functional disorder at an early stage.
Therapy
A causal therapy of myotonic dystrophy is currently not possible. Cardiac arrhythmias can be treated with drugs and, if necessary, with a pacemaker, while muscle cramps can be treated with drugs that have a stabilizing effect on the activation state of the muscle cell. If hormone disorders are present, they can also be treated with medication. To a certain extent, the symptoms of muscle weakness can be treated with physiotherapy to ensure the patient’s mobility and prevent incorrect posture.
Prognosis
The disease progresses slowly and varies from patient to patient. The life expectancy of patients is reduced to an average of 50 – 60 years, and death from heart failure is common.
