What are other known Names for this Condition? (Also known as/Synonyms)
- Scapuloperoneal Muscular Dystrophy
- Scapuloperoneal Syndrome, Myopathic Type
- X-Linked Dominant Scapuloperoneal Myopathy
What is Scapuloperoneal Myopathy? (Definition/Background Information)
- Myopathy refers to a disorder where a muscle fiber is damaged or is dysfunctional. Myopathy, literally meaning muscle disease in Greek, causes muscle wasting and consequential weakness in the affected muscles
- There are specific neuromuscular subtypes of dysfunction, such as Scapuloperoneal Myopathy, which is a very rare condition. In Scapuloperoneal Myopathy, the shoulder blade (scapula) and the small muscle group of the lower leg (peroneal) are the sites of dysfunction
- Scapuloperoneal Myopathy is a disorder that may be inherited in an autosomal dominant or X-linked dominant manner. Therefore, a positive family history of the condition is a risk factor for developing Scapuloperoneal Myopathy
- Although the cause of Scapuloperoneal Myopathy is a defective gene and it may be hereditary, the disease is also known to develop spontaneously due to new genetic mutations
- Stiffness in the affected muscles, muscular cramps and shrinkage may occur in individuals with Scapuloperoneal Myopathy. The diagnosis may involve understanding personal and family history of the patient, blood tests, and genetic tests (when warranted)
- At this time, no specific therapies have been reported to cure Scapuloperoneal Myopathy. The administration of corticosteroids is reported to be useful in relieving discomfort. A regulated and monitored exercise regimen, along with physiotherapy is known to provide further relief to Scapuloperoneal Myopathy patients as well
- The prognosis depends on the severity of the symptoms. The progression of the disorder is generally observed to be slow (taking years), although faster progressions have also been reported. While some patients with Scapuloperoneal Myopathy may be able to live a near-normal life, others might face debilitating muscle problems
Who gets Scapuloperoneal Myopathy? (Age and Sex Distribution)
- Scapuloperoneal Myopathy is an extremely rare genetic disorder. Presently, there are no accurate reports on the prevalence of this condition available
- Both children and adults are susceptible to Scapuloperoneal Myopathy
- Both males and females can be affected
- All races and ethnic groups can be affected
- In the USA, the office of Rare Diseases of the National Institutes of Health has listed Scapuloperoneal Myopathy as rare, due to the fact that it affects less than 200,000 of the US population
What are the Risk Factors for Scapuloperoneal Myopathy? (Predisposing Factors)
- Since Scapuloperoneal Myopathy is an inherited disorder, a family history of the condition is a key risk factor
It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.
Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.
What are the Causes of Scapuloperoneal Myopathy? (Etiology)
Scapuloperoneal Myopathy is mostly an inherited disorder affecting the muscles.
- The defective gene can be inherited in an autosomal dominant manner. Some cases are known to be inherited in an X-linked dominant manner too
- The defective gene causes abnormal levels of blood proteins, hormones, and inflammation that can potentially cause myopathy signs and symptoms to occur. The defective gene is on chromosome 22
- In some cases, Scapuloperoneal Myopathy is reported to develop through a spontaneous gene mutation, with no family history of the disorder
Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly functioning gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.
X-linked dominant: X-linked dominant conditions are traits or disorders that occur when one copy of an abnormal gene has been inherited on a sex chromosome (X or Y chromosome). In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene is capable of causing the condition, even though the other gene is normal, because of a masking effect. If the mutant gene is on the father’s X chromosome, all daughters will inherit the disease but no sons will get it. If, however, the mother carries the abnormal X gene, both daughters and sons will have a 50% chance of inheriting the disease.
What are the Signs and Symptoms of Scapuloperoneal Myopathy?
The symptoms of Scapuloperoneal Myopathy are reported to be generally limited to the shoulder blade area and the legs, below the knees. The symptoms begin in the shoulder area first, in most cases, and then progress to the legs. However, it is also possible for the symptoms to start in the legs first and subsequently move up to the shoulders.
The following are some known symptoms of Scapuloperoneal Myopathy in the affected body areas.
- Muscle cramps and stiffness
- Muscle spasms
- Muscular shrinkage
- Muscle wasting
- Severity of the signs and symptoms vary from one individual to another
In rare cases, the muscles of the face might get affected as well.
How is Scapuloperoneal Myopathy Diagnosed?
The diagnosis of Scapuloperoneal Myopathy may involve eliminating other disorders with similar symptoms, such as facioscapulohumeral dystrophy. The following information may be required to arrive at an accurate diagnosis:
- A detailed personal and family medical history
- Complete physical exam
- Blood tests to detect abnormal levels of proteins, such as pyruvate kinase, creatine kinase, and lactic dehydrogenase (LDH)
- Genetic testing to determine the mutation in the defective gene
Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.
What are the possible Complications of Scapuloperoneal Myopathy?
Scapuloperoneal Myopathy causes damage to the muscle, leading to their weakening. A multitude of complications may result because of this weakening. As the disorder progresses, the affected individual may become completely debilitated. Respiratory problems may also occur as progression of the disorder continues.
Additionally, medications used to treat myopathy might pose potential side effects such as:
- Bone loss causing osteoporosis; which may lead to frequent fractures
- High blood pressure
How is Scapuloperoneal Myopathy Treated?
The treatment measures for Scapuloperoneal Myopathy are geared toward managing the symptoms and decreasing the rate of progression. The following may be prescribed for effective management of symptoms to offer relief to the patients:
- Corticosteroids: These have been shown to be effective medications to relieve discomfort. Further damage is generally delayed in patients and muscle strength may improve
- Supplemental vitamins may be recommended to offset the side effects of the corticosteroids.
- Therapeutic exercise regimen and physiotherapy
- In some cases, a surgery may be required to treat the condition
- Spirometry exercises: If the breathing muscles are severely damaged, a spirometer has been shown to help breathing in some cases (since it is not possible to strengthen these muscles)
How can Scapuloperoneal Myopathy be Prevented?
- Currently, there are no specific methods or guidelines to prevent Scapuloperoneal Myopathy, since it is a genetic condition
- Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
- If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
- Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders such as Scapuloperoneal Myopathy
What is the Prognosis of Scapuloperoneal Myopathy? (Outcomes/Resolutions)
- The prognosis of Scapuloperoneal Myopathy depends on the severity of the signs and symptoms
- The rate of progression of the disorder may differ from one individual to another individual, as may the severity of symptoms
- While some individuals are able to live a near-normal life with minimal symptoms, others may face chronic symptoms due to a significant decrease in muscle strength.
Additional and Relevant Useful Information for Scapuloperoneal Myopathy:
The following DoveMed website link is a useful resource for additional information: