The age of onset, progression and severity of FSHD vary a great deal.
Usually, symptoms develop during the teen years, with most people noticing some problems by age 20, although weakness in some muscles can begin as early as infancy and as late as the 50s. In some people, the disease can be so mild that no symptoms are noticed. In these cases, the disease may only be diagnosed after another, more affected member of the family comes to medical attention.
People with FSHD often don’t go to the doctor until their shoulder or leg muscles become involved and they experience difficulty reaching over their heads or going up and down stairs. When questioned closely, many people can remember having symptoms in childhood, such as shoulder blades that stuck out or trouble throwing a ball. Very often, people say they’ve never been able to whistle or blow up a balloon, or that they’ve had trouble drinking through a straw, but they may not have associated these problems with muscular dystrophy.
FSHD doesn't cause learning disabilities or other cognitive impairments, nor does it affect sensation, ability to control the bladder and bowels, or sexual function.
In most people with FSHD, the disease progresses very slowly. It can take as long as 30 years for the disease to become seriously disabling, and that doesn’t happen to everyone. Estimates are that about 20 percent of people with FSHD eventually use a wheelchair at least some of the time. For more on corrective measures for some of these symptoms, see Medical Management.
In many people with FSHD, weakness develops in the muscles of the abdomen. These can weaken early in the disorder. As abdominal weakness progresses, the person develops a lordosis, an exaggerated curve in the lumbar (lower) region of the spine.
Some abnormalities in the blood vessels of the retina, the “screen” on the back of the eye onto which visual images are projected, are often detected in people with FSHD. Fortunately, very few people have any problems with vision resulting from this, but it should be monitored by an eye doctor. For reasons that aren’t clear, the problem is generally more common in infantile-onset FSHD. The origin of the retinal problem isn’t well understood in either form of the disease.
Although cardiac involvement can sometimes be a factor in FSHD, it’s rarely severe and is often discovered only with specialized testing. Some experts have recently recommended monitoring of cardiac function in those with FSHD.
The muscles used for breathing commonly aren't affected in FSHD, as they are in other forms of muscular dystrophy. However, testing of pulmonary function at intervals may be recommended for some patients.
|Facial weakness can make it hard to use a straw or even smile.|
Facial weakness is often the first sign of FSHD. It may not be noticed right away by people with FSHD, and usually is brought to their attention by somebody else.
The muscles most affected are those that surround the eyes and mouth. It’s hard to smile or pucker up or get much strength in the mouth, which is why people with the disease have trouble with balloons, straws and whistling.
Of somewhat more concern is the weakness in the eye muscles, which can keep the eyes from closing completely during the night. As the disease progresses, the eyes can sometimes dry out overnight, which can injure them. Waking up in the morning with gritty, burning or dry eyes may be a sign that eye closure isn’t complete.
Wearing an eye shield or patching the eyes during sleep may be necessary.
In some people, weakness of the hip muscles that surround the pelvis (he pelvic girdle) also occurs. This doesn’t happen to everyone. Weakness of the hips seems to start most often in middle adulthood, if it happens at all.
Hip weakness causes trouble with rising from a chair or negotiating stairs and can lead to the need for a wheelchair, especially for long distances. Upper leg muscles are sometimes also affected. Pelvic girdle weakness may result in a waddling gait and contribute to the lordosis so often seen in FSHD.
In children with FSHD, hip weakness may be the first thing parents notice, since it causes trouble with walking and running.
When muscle weakness is prolonged, it can lead to freezing of joints in one position, called a contracture. In FSHD, if contractures occur at all, they’re likely to be in the ankle joints. See Medical Management for information on exercising with FSHD.
The spinal column is actually made up of many joints between the vertebrae. The spine is designed to be flexible, somewhat like a Slinky toy, so when the muscles surrounding the spine weaken, the column is pulled out of alignment.
The misalignment often takes the form of lordosis, where the spine curves in to an excessive degree and the stomach sticks out. But it also can take the form of scoliosis, in which the spine curves to the side, like an S. The scoliosis that sometimes occurs in FSHD usually isn’t severe.
As FSHD progresses, the muscles on the front and sides of the lower legs often weaken. These are the muscles that allow us to raise the front of the foot when walking so we don’t trip over our toes.
When these muscles weaken, the foot stays down after pushing off during walking, sometimes tripping the walker. This condition is called foot drop.
The doctor may say, “Walk on your heels, like a penguin” to test the strength of these foot-lifting muscles.
When questioned, people will say, “I seem to catch my foot when I walk” or “I seem to fall over my own feet.” Trouble with stairs and with uneven surfaces is common.
Not everyone with FSHD develops this lower leg problem.
Hearing loss sometimes occurs in FSHD, but it’s usually mild and mostly affects perception of high-pitched sounds. Often, it’s so minor that it isn’t noticed until careful testing is done (for example, as part of a study). In those with adult-onset FSHD, some experts have even questioned whether hearing loss is really more common than it is in adults in general. The reason for the hearing loss, when it occurs, isn’t clear.
When FSHD starts in childhood, loss of hearing in the higher pitch ranges can be more profound than in adult-onset FSHD. The reason for this isn't yet understood.
Inflammation of muscles — an attack by certain types of cells of the immune system — occurs in some muscular dystrophies and can be extensive in some people with FSHD.
For this reason, FSHD is sometimes misdiagnosed as another type of muscle disease, polymyositis, a nongenetic disorder in which the immune system attacks the muscles. An important difference is that polymyositis is treatable with prednisone, a corticosteroid drug that suppresses inflammation, but prednisone doesn’t affect the course of FSHD. The many side effects of corticosteroids make them impractical to use just to relieve discomfort.
Pain in FSHD may also come from the way weakened muscles pull bony structures, such as the spine and shoulder blades, out of alignment.
|Top: Because of weakness in the shoulders and back, muscles that normally don’t show from the front are visible in FSHD. Bottom: This man also shows a typical nonsymmetrical pattern of weakness, with scapular winging and slight scoliosis.|
Most people with FSHD notice weakness in the area of the shoulder blades — the scapulae — as the first sign that something is amiss.
The shoulder blades are normally fairly fixed in their position. They act as fulcrums that allow the arm muscles to get leverage for lifting things, including their own weight.
In FSHD, the muscles that hold the shoulder blades in place weaken, allowing these bones to move excessively. The shoulder blades stick out and rise up toward the neck as they move, which is called scapular winging, because the protruding bone resembles a wing.
Leverage is at least partially lost. The weakness often isn’t the same on both sides of the body.
Early on, the person with FSHD notices things like being unable to throw a ball effectively. Later, it may be hard to lift the arms over the head to do one’s hair or reach a high shelf or hang something. These problems are due to weakening of the muscles around the shoulder and in the upper arm. For information about shoulder surgery for this problem, see Medical Management.
In most people with FSHD, weakness differs at least a little bit between the left and right sides of the body. In some people with FSHD, this difference between sides can be quite striking. The reason for this lack of symmetry, which is not seen in most types of muscular dystrophy, is not clear.