During the period between birth and childhood, some children experience episodes of sustained muscle tensing particularly in the skeletal muscles including the muscles of the tongue, face, or even hind limbs, i.e. Congenital Myotonia which restricts the skeletal muscles from normal relaxation. Named after a German professor Peter Emil Becker, Becker’s Myotonia is a progressive disorder as well as one of the commonest recessive subtypes of Myotonia Congenita. The Becker’s disease is genetically present from the time of birth; however, the onset is delayed. According to some medical journal, although this disease condition is an autosomal recessive trait but people who are an asymptomatic heterozygous carrier for this disease generally do not manifest any symptoms of this illness.
What is Becker’s Myotonia?
Becker’s Myotonia is the most popular subtype of Myotonia Congenita. Becker’s Myotonia is actually an inherited autosomal recessive pattern, which means this condition is developed by a defective gene, i.e. CLCN1 gene mutation. The onset of Becker’s Myotonia begins from the later stage of life such as between the ages of 4 and 6 years. Usually, people with this condition may often experience short-term attacks of muscle weakness, mainly in the hands and arms, while moving those muscles after a resting period of time. Over time, the muscle weakness becomes permanent.
Symptoms of Becker’s Myotonia
Children with this Becker’s Myotonia often looks well-developed or muscular and the symptoms become apparent after the age of 4 years till 12 years and are quite common in males. However, very rarely, the onset may begin as late as about 18 years of age. Some of the common symptoms of this disease include the following:
- Patients suffering from this disease often feel muscle weakness for shorter periods of time, specifically in the arms and hands; the muscles of these structures are unable to contract after periods of rest.
- Incapability of the muscle to relax after some sorts of voluntary movement.
- Severe sense of Myotonia.
- Muscle stiffness together with transient weakness.
- Difficulty in swallowing or movement of eyeballs.
- Stiffness in movements of certain muscles which improves on further repetition.
- Frequent falling during movement.
- Unusual enhancement of the size of some of the skeletal muscles, especially in the parts of back muscles, buttocks, legs and also in shoulder, arms, or hands.
- As the disease progresses, it affects the muscle of the face.
- Hypertrophy of the hind limb muscles.
- The child experiences disabled weakness following the attacks of Myotonic stiffness.
Epidemiology of Becker’s Myotonia
Becker’s Myotonia is a genetic disease usually seen in the later stage of childhood and is more common in males than females. It is calculated to affect approximately 1 in 100,000 people all over the world and is more common in the northern Scandinavian population.
Prognosis of Becker’s Myotonia
The progression of Becker’s Myotonia is highly variable. Symptoms only start to occur after a period of the first movement. After a few repetitions of the same movement, the muscle starts relaxing and thus becomes normal. The severity of the disease condition may be indicated by age of onset of the symptoms. People with this condition generally do well, but the quality of life of the patients is impacted by the symptoms of the disease condition. Even, there are some people who experience the symptoms that improve somewhat in the later phase of life.
Causes of Becker’s Myotonia
Autosomal recessive Becker’s Myotonia is a nondystrophic skeletal muscle disorder that is more severe and common than Thomsen disease. This genetically inherited disorder is caused by compound heterozygous mutation of the gene CLCN1 coding for chloride channel-1 of skeletal muscles on chromosome 7q34. Generally, when the CLCN1 gene gets mutated it loses its normal function to encode calcium channel protein which thereby helps in skeletal muscle cell repolarization process.
Usually, Becker’s Myotonia is inherited by two copies of defected genes in every cell and although both parents of the affected individual carry one copy of this defective genes, but they typically don’t show any symptoms of the disease condition. According to different medical literature, even parents of various patients suffering from this disease condition can also be closely related by blood relation, i.e., consanguineous.
Pathophysiology of Becker’s Myotonia
Normally for each body movement, skeletal muscles usually contract and relax in a very much coordinated manner. This contraction and relaxation of different muscles are regulated by the flow of various ions in and out of muscle cells. Specifically, the CLCN1 gene encodes a protein that forms ion channel that normally controls the flow of negatively charged chlorine ions into the cells in order to stabilize the electrical charge inside the cells, which prevents the skeletal muscles from abnormal contraction.
Mutations in the CLCN1 gene alter the normal structure and function of these chloride channels. Therefore, these defective channels cannot regulate ion flow in a proper manner, which decreases the movement of chloride ions into the muscle cells. This interruption in chloride ions flow results in sustained muscle contractions, which is one of the common symptoms of Becker’s Myotonia.
Risk Factors of Becker’s Myotonia
The probable risk factors for the occurrence of Becker’s Myotonia include the following:
- Family History of Becker’s Myotonia: Couples who already have a family history of the disease are likely to have a child with this syndrome. A newborn is at high risk of inheriting this disease condition if one of the parents already suffers from Becker’s myotonia. When both the parents carry the defective or mutated gene, then their child is very much sure to inherit the illness.
- Ritalin Exposure as a Risk Factor of Becker’s Myotonia: According to some studies, a chemical called Ritalin which is used for treating different disorders like Attention Deficit Hyperactivity Disorder, Narcolepsy, depression, or fatigue, may promote or cause the symptoms of this disease because this chemical usually contains active components of methylphenidate hydrochloride, which is actually responsible for causing Becker’s Myotonia.
Complications of Becker’s Myotonia
The possible complications that can occur due to the severe manifestation of the disease include the following.
- Difficulty in swallowing may cause Aspiration Pneumonia.
- Excessive weakness in abdominal muscles.
- Chronic problems in different joints of the body.
- Frequent episodes of gagging or choking are noticed in infants.
- Injury may occur due to sudden falls.
Diagnosis of Becker’s Myotonia
The doctor may easily diagnose the disease by the manifestation of the series of symptoms if the patient already has a family history of autosomal recessive inheritance of Becker’s Myotonia. Other investigation methods may include the following:
- Electromyography or EMG, which is a test to measure the electrical activity of different muscles, generally reveals bursts of extensive muscle tension.
- Elevated concentration of serum creatinine kinase concentration.
- Biopsy of muscles.
- Clinical genetic testing to detect mutations in the CLCN1 gene.
Treatment of Becker’s Myotonia
Some cases of Becker’s Myotonia syndrome do not require any treatment if the symptoms are quite mild and thus can be controlled without any medication. Some patient’s also don’t receive any treatment because of the possible side effects of various medications that actually outweigh the probable benefits of the treatment.
If the symptoms are severe, then the disease can be treated with the help of the following medicines:
- Carbamazepine or Tegretol.
Treatment can also be done by using different sodium-channel blocking agents like diphenylhydantoin or mexiletine. Other treatment options that are used for treating serious instances of the disease include different hormone and vitamin therapies and physical therapy. Genetic counseling is also sometimes helpful.
If an individual suffers from a mild case of the condition, he can easily avoid the disease condition by following a routine of regular exercise, physical workouts, or Yoga therapy. All these therapies aid in better relaxation of the muscles after contractions. Even following a nutritious as well as healthy diet can also keep the muscles in absolutely well-maintained condition. Consumption of sodium-rich diet is also helpful in order to eliminate the disease symptoms; however, this is not recommended for patients having high blood pressure.
Special supports or services including social, vocational, or other medical assistance may also be beneficial.
Prevention of Becker’s Myotonia
As such, there are not much preventive measures to be followed to prevent the occurrence of this disease condition. The only thing that could be done is that the couples who already have a family history of any types of congenital myotonia in their genes should go for a genetic counseling before planning a child in order to prevent the further prevalence of Becker’s Myotonia syndrome.
Becker’s Myotonia is an inherited harmless genetic condition that affects very few people. In most of the cases, the symptoms are too mild to be diagnosed, but sometimes the symptoms can be a serious condition. However, one can easily avoid this serious symptomatic condition by doing physical exercise regularly and following proper medications. Even, different support groups also provide a valid guideline to fight with the disorder for the patients suffering from Becker’s Myotonia and their families.