Duchenne muscular dystrophy
Estimated occurrence30:1,000,000 inhabitants. Only affects boys.
CauseA shortage of the protein dystrophin, which stabilizes muscle fibers. This lack of dystrophin results in deterioration of muscular fiber. Duchenne muscular dystrophy is an Xlinked inherited disorder. Female carriers have no symptoms. One-third of all cases are spontaneous mutations.
Symptoms normally present around the age of three. The child develops a waddling gait, has difficulty running, jumping and getting up off the floor. The thoracic girdle, the pelvic and the musculature of the back all become progressively weak. Upper arms and thighs are affected earlier than lower arms and calves. Curvature of the lumbar region develops. These boys generally stop being able to walk around the age of 10 to 12. Impaired cardiac function often develops. Muscular weakness increases over the years. Many individuals develop contractures and scoliosis. The respiratory musculature is weakened, and lung function reduced. Malignant hyperthermia has been reported and should be considered when treatment under general anesthesia. Reflux, vomiting and constipation are common. Many patients have a reduced learning ability, in particular regarding linguistic skills. There may be concentration problems and learning disability.
Weakness of the main muscles used for chewing, the facial muscles and the tongue. Malocclusions develop successively owing to muscular weakness and the changed morphology of the tongue. The jaws increase in width, more in the lower jaw than in the upper, which often results in a posterior cross-bite. A lateral open bite may appear and later on a frontal open bite can be seen. Cortisone treatment is common, which may cause osteoporosis and have a potential impact on the jawbone. Dryness in the mouth is a common side effect of medications such as melatonin, and if several different medicines are taken at the same time. The opening capacity of the mouth should be monitored. Reduced muscular strength and endurance of the chewing muscles in combination with lack of occlusal (bite) contact may result in difficulties masticating food. In late stages of the disease, swallowing difficulties often develop. The mouth opening capacity can be reduced.
Advice on follow-up and treatment
- Problems in managing oral hygiene and eating difficulties justify extra preventive dental care. Co-operation with a dental hygienist and an occupational therapist is recommended.
- It is important to bear in mind in relation to dental treatment, that individuals with cardiac and respiratory difficulties have trouble sitting in a reclining position.
- Stretching of the jaw opening is required if the jaw opening capacity is reduced.
- When treating medically compromised patients always contact their doctors for medical advice (bleeding problems, heart diseases etc.).
- There is an increased risk of malignant hyperthermia during general anaesthesia.
- When treating with bisphosphonate, the dental care service should be informed to enable the early detection of possible side effects of the substance.
- Eating and swallowing difficulties are investigated and treated by a specialist team at the hospital or multidisciplinary treatment centre.
- Speech and language difficulties are investigated by a speech therapist. Speech therapists may also be required to investigate and validate alternative and complementary communication (AAC).