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APRIL 2022 InTouch | 13 Myotonic Dystrophy (DM) is an inherited disorder and is abbreviated as DM as the Latin name for this condition is ‘Dystrophia Myotonica’. In Myotonic Dystrophy (DM), a defective gene causes progressive muscle weakness accompanied by myotonia, which is the delayed relaxation of muscles after contraction. It is a multi-systemic disorder, meaning that its effects are not limited to the voluntary muscle system, but can also affect tissues and organs throughout the body. Primarily the muscles of the face, neck, hands, forearms and feet are affected, although DM can have a wide range of effects on people. DM can be classified into several different types based upon the age of onset and the clinical symptoms experienced. Three main forms of DM have been identified so far: • DM1, also known as Steinert’s Disease • DM2, also known as Proximal Myotonic Myopathy (PROMM) • Congenital Myotonic Dystrophy (CMyD) DM affects males and females. Age of onset is variable from birth through to old age. It is a rare condition that affects 1 in 8,000 individuals. CMyD is much rarer and affects 1 in 100,000. The disorder has an effect called “anticipation”. This means that DM can get progressively worse with each generation. This effect is influenced by which parent passed on the condition. Myotonic Dystrophy (DM) YOUR CONDITION IN REVIEW What are the Features of Myotonic Dystrophy? DM1 Myotonia will often be experienced as stiffness or heaviness in the muscles with delayed relaxation, particularly in cold temperatures. This can occur in any muscle. If myotonia significantly affects individuals, it can be treated with medication. Individuals typically present with muscle weakness and wasting. This is often apparent in the facial muscles of individuals with DM1, and can include a dropping of the eyelids (ptosis), an inability to fully close the eyes and to hold the jaw closed. Neck muscles may also weaken, resulting in difficulty with lifting the head or sitting up quickly. Weakness often occurs in the distal muscles of the hands, lower legs, and feet. They may experience difficulty in tasks requiring fine hand movements, such as writing. Individuals can experience gait disturbance and may be prone to tripping due to foot drop, so have an exaggerated walk due to inability to control the foot at the ankle. Wrist supports, ankle-foot orthoses, canes and walkers can assist individuals where necessary, and can be discussed with a physiotherapist. Respiratory (breathing) muscles can become weak, affecting the lungs and depriving the body of oxygen, which can contribute to individuals with DM1 feeling sleepy all the time. Regular sleep patterns can be helped with medication. To aid with breathing, a portable ventilator is commonly used. Individuals may also experience difficulty swallowing (dysphagia) and can lead to choking. Vomiting can be very dangerous and sometimes fatal. A head-down position is crucial to prevent inhaling the vomit. A specialist can help people learn to swallowmore safely and, if needed, how to change the consistencies of foods and liquids so they can be swallowed more easily. Abnormalities of the conduction system in the heart are common and are a major cause of early mortality. The electrical signal that keeps the heart beating can get blocked and cause death. The most common signs are fainting or dizzy spells and these should not be ignored. Heart problems can be checked with an electrocardiogram (ECG) which measures the beating patterns of the heart. Severe problems can be corrected surgically with the insertion of a pacemaker. In DM, many of the body’s internal involuntary muscles can weaken and have myotonia, including the digestive tract, the uterus and blood vessels. Spasms and weakness of the upper digestive tract can impair swallowing and it may feel like food is getting stuck. Occasionally food may be inhaled into the lungs. Care in swallowing, with advice from