What is Facioscapulohumeral Muscular Dystrophy?
Facioscapulohumeral muscular dystrophy (FSHD) is a hereditary disease that impacts the muscles, passed down from parents to children through dominant genes. It mainly affects muscles in the face, shoulders, and lower body, but not evenly on both sides. The symptoms usually start in the face and then move outwards to other muscle groups.
In addition to muscle problems, about half of the people with FSHD also experience minor high-frequency hearing loss and retinovasculopathy – a condition affecting the small blood vessels in the retina, the light-sensing part of the eye. These symptoms are often less noticeable but form part of the disease’s impact on the individual.
What Causes Facioscapulohumeral Muscular Dystrophy?
Facioscapulohumeral muscular dystrophy (FSHD), a muscle-weakening disorder, is caused by a complex interaction of genetic factors, involving a protein known as DUX4 and a specific location on our chromosomes. Normally, our body regulates and controls the DUX4 protein. However, in FSHD, the control is disrupted, leading to an excessive amount of DUX4 protein which can damage our muscles.
The DUX4 gene is located on our chromosomes numbered 4 and 10 and is controlled by a sequence of genetic repeats called D4Z4. Normally, these repeats help to keep the DUX4 gene under control. In healthy people, there are around 11 to 100 repeats of the D4Z4 sequence that help control DUX4 protein production.
In FSHD, however, there are fewer D4Z4 repeats, between 1 and 10. But, this problem leading to FSHD only happens when this decrease occurs on chromosome 4. So far, researchers haven’t found that a decrease on chromosome 10 leads to this disease.
FSHD is further divided into two subtypes based on how this control gets disrupted. In about 95% of cases (FSHD type 1), the loss of D4Z4 repeats is the issue. In the remaining 5% of cases (FSHD type 2), the issue arises from a different route which isn’t caused by losing these repeats.
Regardless of the subtype, the end result is the overproduction of the DUX4 protein, which is normally only made in the reproductive cells, but starts to be produced in other cells, especially muscle cells, in individuals with FSHD. This protein is toxic to muscle cells, leading to their damage and eventually causing muscle weakness and atrophy seen in patients with this disease.
Risk Factors and Frequency for Facioscapulohumeral Muscular Dystrophy
Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common types of muscular dystrophy because those affected usually have less severe symptoms and live longer. FSHD affects around 3.2 to 4.6 out of every 100,000 people, and it impacts all racial groups equally. However, there is a difference in how it affects men and women. Women generally experience less severe symptoms and are usually diagnosed at an older age compared to men.
Signs and Symptoms of Facioscapulohumeral Muscular Dystrophy
Facioscapulohumeral muscular dystrophy (FSHD) is a genetic condition with symptoms that can emerge at any age, but most typically occur during one’s teen years. How severely a person is affected by FSHD can vary significantly from person to person, with symptoms usually developing slowly over a long period of time. Considering FSHD is inherited, family history of the disease is often found in patients. For example, parents of young patients may have noted that their child had difficulty closing their eyes during sleep or displayed unusual shoulder blade positioning.
Commonly, the first noticeable symptom in FSHD is the person’s struggle to lift their arms at the shoulder joint, with muscles being unevenly affected. As the disease progresses, the muscles in the legs, particularly the ones farthest away from the body such as those in the calf and shin, begin to become affected. When the muscles of the torso and spine are impacted, patients might display an exaggerated inward curve of the lower spine. While other forms of muscular dystrophy often lead to muscle contractures (shortening and hardening of muscles), this is uncommon in FSHD. If facial muscles are affected, issues such as an inability to close the eyes completely, fewer wrinkles on the forehead, an uneven or absent smile, and failure to tense face and neck muscles can arise.
In the case of the upper body, muscle wasting, meaning the muscles become small or shrink, around the shoulders in a forward rounding pattern becomes noticeable. An interesting point is that the deltoid muscle, located in the upper arm and shoulder, often remains unaffected by FSHD. This causes the trapezius muscles of the neck to stand out. This particular interaction of the deltoid and trapezius muscles frequently reveals a so-called ‘poly hill sign,’ where the pattern of muscles appears as a series of peaks and valleys.
Testing for Facioscapulohumeral Muscular Dystrophy
Facioscapulohumeral muscular dystrophy (FSHD), a type of muscle condition, is usually identified through genetic testing. This method is widely accepted as the best approach to verify the disease. Doctors look for a specific marker: less than eight repeats of a particular gene segment (known as the D4Z4) at a site (the 4q35) in our genetic material.
However, sometimes the disease can display ambiguous signs. In such cases, doctors rely on other tools to ensure a correct diagnosis. These include electromyography (EMG), a test that measures the electrical activity in your muscles, MRIs, lab tests, and muscle biopsies.
When performing an EMG, doctors typically notice weaker electrical signals that last only for short periods in the muscles. On the other hand, an MRI can show specks of abnormal tissue sprinkled among healthy muscle tissue, indicating that fat and fibrous tissue are gradually replacing the muscle. Initially, these diseased muscles also show higher water content in T2 MRI images.
Muscle biopsies, where a small tissue sample is taken from your muscle, reveal a mixed picture under the microscope. Damage and repairs occur side by side, along with increased inflammation, fibrosis (formation of excess fibrous connective tissue), and a higher number of nuclei inside muscle cells.
Finally, the blood tests of FSHD patients generally show an increase in creatine kinase, a marker of muscle damage. Nonetheless, it usually doesn’t go beyond five times the upper normal limit.
Treatment Options for Facioscapulohumeral Muscular Dystrophy
At present, there are no treatments available that can alter the course of FSHD (Facioscapulohumeral Muscular Dystrophy). Therefore, the primary focus in managing FSHD is providing care that helps patients manage their symptoms and maintain their quality of life, rather than curing the disease.
Most of this care involves physical therapy and rehabilitation exercises. For instance, a clinical trial conducted in 2016 looked into the effectiveness of home exercise therapy, a combination of aerobic workouts and strength training for patients with FSHD. The study found that those who took part in a six-month program saw significant enhancements in their muscle function without causing any additional harm to the affected tissue.
For more severe cases, physical therapy alone might not be sufficient to overcome the disease’s limitations. In such situations, assistive devices can prove highly useful, and they can be tailored to meet each patient’s specific needs. For instance, a condition known as foot drop, where a patient has difficulty lifting the front part of the foot, can be partially corrected with the help of devices like ankle-foot-orthoses or a combination of knee-ankle-foot orthoses.
Extreme scapular winging, a condition where the shoulder blades stick out, can be addressed through a surgical procedure known as scapular fixation. While clinical trials have not fully tested this approach’s effectiveness, case studies show it can improve shoulder movement, reduce pain, and enhance the patient’s ability to carry out daily activities. However, more research is needed to determine whether scapular fixation should be a standard part of FSHD management.
Finally, it’s crucial to manage pain and fatigue in FSHD patients because these symptoms can significantly impact a patient’s mental well-being. Chronic pain can be managed with pain relievers and antidepressants to improve the quality of life of FSHD patients.
What else can Facioscapulohumeral Muscular Dystrophy be?
FSHD, a type of muscular disease, can often be mistaken for several other genetic muscle conditions. These may include:
- Limb-girdle muscular dystrophy
- Subacute necrotizing encephalomyelopathy
- Acid maltase deficiency
- Myotonic dystrophy
- Polymyositis
When the symptoms of these conditions are very similar, doctors usually rely on genetic testing to accurately identify the disease.
What to expect with Facioscapulohumeral Muscular Dystrophy
In terms of FSHD, a certain form of muscular dystrophy, the overall life expectancy isn’t affected. However, the quality of life can vary greatly. Approximately 20% of individuals with this condition will experience a significant decrease in their mobility to the point where they will need a wheelchair.
Possible Complications When Diagnosed with Facioscapulohumeral Muscular Dystrophy
The main issues encountered in FSHD (Facioscapulohumeral muscular dystrophy) are long-lasting pain and difficulties carrying out day-to-day activities, both of which can significantly affect mental health. About 77% of people with FSHD will suffer from constant pain. Few people with FSHD may also experience complications such as problems with swallowing, hearing loss, eyesight problems (specifically retinal disease), and difficulties in breathing.
- Long-term pain
- Difficulty in day-to-day activities
- Impact on mental health
- Problems with swallowing
- Hearing loss
- Retinal disease (eye problems)
- Breathing difficulties
Preventing Facioscapulohumeral Muscular Dystrophy
Studies have found that people with FSHD (which stands for Facioscapulohumeral muscular dystrophy, a type of muscle disease) who experience chronic (long-term) pain can learn to better manage it through a combination of coping strategies, understanding what the pain means, and avoiding extreme negative thinking (referred to as ‘catastrophizing’). These elements all play a part in how one experiences and perceives their pain levels, and they can significantly impact a person’s mental health and wellbeing. Consequently, it’s crucial for these patients to be taught about this biological, psychological, and social (or ‘biopsychosocial’) approach to dealing with pain. By boosting their social support network and changing how they think about their pain, those with FSHD can improve their quality of life and daily functioning abilities.
