Synonyms
Fazioscapulohumeral muscular dystrophy, FSHMD, muscular dystrophy Landouzy-Dejerine : FSH Dystrophy, Facioscapularhumeral (Muscular) Dystrophy. Facioscapulohumeral muscular dystrophy, often abbreviated FSHD, is the third most common form of hereditary muscular dystrophy. The name describes the early and particularly severely affected muscle areas: However, as the disease progresses, other muscle areas (leg, pelvic and trunk muscles) also become increasingly weak.
The first symptoms usually appear in adolescence and early adulthood, and often the individual muscle groups of the two halves of the body are affected to different degrees. The disease generally progresses relatively slowly, but the severity of the symptoms varies greatly between individuals. The genetic basis of facioscapulohumeral muscular dystrophy is known, but the exact mechanism of the disease is still only partially understood.
There is no causal therapy for the disease so far, but since the heart muscles are usually not affected, patients usually have a normal life expectancy.
- Face (lat. facies)
- Shoulder region (lat.
scapula = shoulder blade)
- Upper arm (lat. humerus).
FSHD is a disease from the muscular dystrophies group, which initially manifests itself through the main attack on the facial, shoulder girdle and upper arm muscles. The disease only affects the skeletal muscles, but the heart muscles are spared.
In the meantime, various subtypes of FSHD can be distinguished, mainly by human genetic methods. This article refers to the most common type, the “classical” FSHD1A. The fazioscapulohumeral muscular dystrophy occurs with a frequency of about 1:20000 equally in both sexes, making it the third most common muscular dystrophy.
The disease is inherited autosomal-dominantly, which means that children of affected persons have a 50% risk of contracting the disease themselves. Nevertheless, men are clinically often more severely affected than women and are diagnosed earlier, although the cause is unclear. The loss of a small fragment of the genetic material on chromosome 4 was found to be the cause of “classic” FSHD.
This probably leads to a misdirected activity of neighboring gene regions. The exact disease mechanism of FSHD is ultimately unclear. It is assumed that such a misregulation of several genes that play a role in muscle metabolism reduces the regenerative capacity of muscles, which ultimately leads to the loss of muscle tissue.
The (partial) loss of a nerve that supplies a certain muscle region, for example due to injury, or the loss of a brain region responsible for motor function, for example in the course of a stroke, also manifest themselves in the (partial) loss of function of this muscle region. The great difference in the course of the disease between individual patients makes it possible to consider various diseases that are clinically similar to the picture of FSHD. The differentiation from other muscle diseases is not always easy, especially when the symptoms of the affected person deviate from the classic picture of “facial shoulder-arm weakness”.
Clinically most patients become clinically conspicuous in adolescence or early adulthood due to weakness of the particularly affected muscle areas of the shoulders, upper arms and face. These can be difficulties in lifting the arms above the horizontal, complaints when performing overhead work (wallpapering, combing), drooping shoulders or similar malpositions. Relatively characteristic are the differences in the degree of weakness between the two halves of the body.
The weakness of the facial muscles can lead to the fact that the affected persons seem to have an “expressionless” or even “grumpy” facial expression, an asymmetrical facial expression, difficulties to close the eyes completely or, due to a hanging of the corners of the mouth, a salivation from the mouth. If the trunk and hip muscles are affected, patients have difficulty getting up from a lying position and when climbing stairs, an infestation of the lower leg muscles often manifests itself particularly in a weakness of the foot lifter muscles, which leads to frequent stumbling. Overall, the disease progresses slowly, and the course of FSHD varies greatly from patient to patient.
Some patients experience hardly any restrictions until old age, whereas about 10 – 20% of those affected depend on a wheelchair in the later course of the disease.However, since the disease affects only the skeletal muscles, life expectancy is not limited. In some cases, facioscapulohumeral muscular dystrophy may begin in childhood, in which case muscular atrophy appears to be more rapid and the overall prognosis is less favorable. There seems to be a connection between FSHD and hearing impairment (high frequency hearing loss) and retinal changes, but the clinical significance of FSHD is rather low.
As with all genetic diseases, it is very important to obtain a family medical history, which can provide clear indications of a hereditary disease and its mode of inheritance. FSHD only rarely develops spontaneously, and in most cases there are other people affected in the patient’s family. The clinical examination can show a quite typical pattern of muscular involvement, this and the presence of other cases of the disease in the family usually makes it possible to establish the position of the clinical diagonals.
An EMG (electromyography) records the electrical activity within a muscle and helps to distinguish causal muscle (self-)diseases from muscle changes due to e.g. nerve damage. From a human genetic point of view, the absence of the genetic sequence on chromosome 4 can be detected by a blood test. Such an examination takes place in specialized human genetic centers of larger clinics and can also be carried out, for example, if no symptoms are present at all, but cases of disease are known in the family (“predictive diagnostics”).
Such predictive diagnostics can be useful for the patient’s career planning, but can also be a psychological burden. In a few cases, a typical alteration of the genetic sequence on chromosome 4 cannot be detected despite a corresponding clinical picture. These may be subtypes of an FSHD (“atypical FSHD”).
Currently, there is no causal therapy for facial scapulohumeral muscular dystrophy. Numerous experiments with the asthma drug albuterol, which also has an effect on muscle metabolism, have been unsatisfactory, and individual case reports of therapeutic success with the antihypertensive drug diltiazem were initially refuted in a small clinical study. As is the case with many hereditary diseases, the hope of researchers and patients ultimately rests on a future gene therapy.
For this reason, conservative therapy has a high priority: physiotherapy is used to help patients maintain maximum mobility and prevent incorrect posture. Surgical measures can be used under certain circumstances to correct incorrect postures that have already occurred, but they must be carefully weighed up. For a long time, the benefits of physical training were not uncontroversial, as damage to the affected muscles is likely due to overuse. In the meantime, however, those affected are advised to engage in light physical activity, especially because of its positive effects on the cardiovascular and immune systems. Joining a self-help group can help patients to deal with the disease, exchange experiences and get addresses with muscle diseases from experienced therapists.
