One fairly common feature of FSHD is an asymmetry of weakness: where one side of the body is more affected than the other (particularly early on). This is often evident in the shoulders. It is also usually the right side which is first affected in right-handed people.
The degree of weakness or disability can vary quite widely between different affected members in the same family, but it can show even greater variation between people in different families. For some, it can result in weakness not only of facial muscles and shoulders/upper arms, but also of additional combinations from the neck, forearms, wrists, fingers, hips, legs, ankles and the back muscles.
About 10 to 20 percent of people with FSHD eventually require a wheelchair. By contrast, up to one third remain unaware of symptoms at least into old age, although they may well have subtle signs of FSHD only noticeable to a doctor/specialist. The majority of people with FSHD come somewhere between these two extremes.
Early weakness at the ankles can cause ‘foot drop’. In over 50 percent of people some degree of weakness at the knees or hips develops by middle age. Together with weakness in the back muscles, this can result in a typical backward-leaning and high-stepping style of walking.
In general, the people most severely affected tend to be the first members of a family to be diagnosed, and where the symptoms of weakness are evident from early childhood.
The earlier in life the weakness appears, the more severe it will eventually be. It is hard to predict how arm or leg weakness will progress. Although in more than 50 percent of cases the legs are affected to some degree, where this happens in early adulthood, it is unlikely that person will ever need a wheelchair.
Can any other problems be anticipated?
In some cases where symptoms of FSHD start in early childhood, learning difficulties and epilepsy are possible.
Hearing loss is common but may not be symptomatic of the condition.
Some people experience conjunctivitis and ulceration of their cornea because of limited blinking and an inability to close their eyes properly, during the day and when sleeping. Using artificial tears and protecting the eyes during sleep may help. Specific problems with blood vessels at the back of the eye (retinal vasculopathy) can occur, and although this rarely causes visual problems, it may be useful to have periodic eye checks.
Muscle pain is quite a frequent complaint in FSHD, often in its early stages. This may relate to inflammation within the muscles, which seems to occur more in FSHD than other muscular dystrophies. A physiotherapist can recommend mild exercises to help alleviate the pain. Treatment with simple painkillers and anti-inflammatory drugs is common, but how much relief this gives can vary.
Lung function is usually normal. However, in a minority of patients, weak breathing muscles may result in respiratory failure. This causes shortness of breath and nocturnal hypoventilation (morning headaches, feeling sleepy in the daytime, not feeling refreshed in the morning, dizziness). Patients with respiratory failure can be more likely to get chest infections. Patients with swallowing difficulties might also be at risk of aspiration pneumonia.
If the breathing function is affected, and if supplemental oxygen is required during a respiratory crisis, it must be carefully controlled and carbon dioxide levels monitored.
Non-invasive ventilation (NIV) may be required. Assisted coughing with chest physiotherapy and breath-stacking techniques with an AMBU bag helps to clear fluids in the lower airways during acute chest infections. The same techniques can help prevent problems when breathing may be difficult. A cough assist machine can also help.
At what age does FSHD usually become noticeable?
In large families where several members have FSHD, a person usually first becomes aware of muscle weakness in their teenage years or early adulthood. He or she may experience difficulty in raising one or both arms, or may notice prominent shoulder blades or the weakening or wasting of their upper arm muscles.
In the more severe cases, difficulty moving the facial muscles, particularly around the mouth, can be evident by early childhood. This can be followed by weakness in the shoulder and upper arm. These children may experience progressive weakness of the legs by their teenage years, and may need a wheelchair.
By contrast, in the families less severely affected, people inheriting the condition may remain unaware of symptoms until late in adulthood
Does FSHD affect life-expectancy?
Generally speaking, life-expectancy is not affected. The exception could perhaps be in the most severe cases, where not being able to move about much increases the risk of chest infections. Some recent reports suggest increased risk of heart rhythm disorders, but only in a few cases, and these respond to medication. Adults with FSHD should see their GP (or hospital doctor) every few years for a simple heart check.