Diseases of the Muscles
DISEASES OF THE MUSCLES
So far we have learnt about the various diseases of the brain and the nervous system. Now we will discuss the basic diseases of the muscles. We know that the brain regulates every part and organ of our body. This system consists of the large brain, small brain, spinal cord, the nerves emanating from them, the neuromuscular junction and muscles. In the previous chapter we have discussed in detail about the disease of the neuromuscular junction namely, Myasthenia Grams.
Now we will start with the hereditary muscular disorders i.e. hereditary myopathies which form the major chunk of muscular diseases.
1. Duchenne Muscular Dystrophy :
This hereditary disease is a sex-linked recessive disorder of muscles related to X- chromosome which is found in about 30 per one-Iakh boys. The females do not suffer from this disease but they are the carriers of the disease. This disease is present from birth but its symptoms are noticed at the age of 3 to 4 years. The child falls while walking, has difficulty in getting up and climbing stairs with a gradual increase in weakness. The muscles of the calves get enlarged which is known as Pseudo Hypertrophy. By the age of 10 -12 the patients need to take the support of a wheel chair. These patients are highly susceptible to aggressive and life threatening infections of the lungs. Such children may suffer from slow mental growth and heart diseases.
Diagnosis :
i. This disease is diagnosed as described below
ii. In the blood samples increased value of enzymes like C.P.K., SGOT and Aldolase are noted.
iii. Particular, definite changes are detected in the E.M.G test (Myopathic pattern).
iv. Microscopic examination of muscle biopsy gives a confirmatory diagnosis.
v. Symptoms of this disease may be seen in other male offsprings in the family, or in mother’s brothers and their sons.
Treatment :
No permanent cure has yet been discovered for this disease though steroids can control the disease to some extent. However, physiotherapy and willpower play an important role in supporting these patients. There are supportive groups like Muscular dystrophy association and D.M.D., which help the patients. Gene therapy seems to be promising in latest researches.
2. Becker Muscular Dystrophy :
This disease is a sex linked recessive disease linked to X- chromosome, in which the muscular weakness is similar to that of Duchenne Muscular Dystrophy, but the amount of the weakness is less and the speed of spreading of the disease is slow. The primary symptoms of the disease are seen in 5 to 15 years of age and the patient usually lives up to 4 to 5 decades.
3. Limb Girdle Dystrophy :
This muscular disorder is found in both males and females between the first and fourth decade of life. This gradually progressing disease causes weakness in the muscles of the back and shoulders. The weakness of the diaphragm can sometimes cause serious respiratory problems. Heart related problems could also occur.
4. Myotonic Dystrophy :
In this disease the muscles of the face become weak. The patient’s face gives the diagnosis. The muscles of the hands and the neck are also affected. Myotonia is seen in which if the fist is clenched, it cannot be opened easily. Mental retardation, heart diseases, cataract etc are also seen in the patients. Apart from this, in facio-scapulo-humeral muscular dystrophy there is weakness of the muscles of the mouth, shoulders and hands. In Myotonia a drug called phenytoin is given.
5. Congenital myopathy :
The muscular disorders seen in infants include the central core, nimeline and centro nuclear myopathy. Defects in the metabolic functions can also cause weakness in the muscles.
Besides this, any disorder of the main part of the cells namely mitochondria causes a congenital disease called mitochondrial myopathy.
6. Metabolic Myopathy :
Congenital metabolic disorders like glycogen storage, myophosphorylase, lipid storage, and some other mitochondrial myopathies are included in this. This is not a common Myopathy.
7. Periodic Paralysis :
A deficiency of potassium in the blood can cause hypokalemic periodic paralysis in which the shoulder muscles and the thigh muscles weaken. This disease can recur time and again. Sometimes, it can also affect the muscles of the eyes as well as the respiratory muscles, which can prove fatal if not treated properly. Fluctuations in the heartbeat are also seen. There is decrease in the amount of potassium in the blood. Tendon jerks are found to be sluggish.
Intravenous or oral potassium removes the weakness of the muscles. A doctor’s supervision is very essential in this matter, because overdose or low dose of potassium can cause serious side effects.
8. Hyperkalemic periodic paralysis :
An excessive amount of potassium in the blood also causes similar type of weakness in the muscles.
9. Paramyotoniacongenita :
In this disorder the muscular weakness can occur due to cold climate or without any apparent reason. This weakness increases with physical activity. Intake of glucose or other carbohydrates can alleviate this weakness. In the long run thiazide diuretics can be helpful.
10. Acquired Myopathy :
In this type there is no congenital defect in the muscles but the muscular weakness arises due to increase or decrease in thyroid hormone production, increase in the parathyroid hormone, excessive consumption of steroids, side-effect of other medicines, inappropriate treatment of diabetes, chronic diseases of the kidney or liver, excessive consumption of alcohol or vitamin deficiency etc. This can be treated after appropriate diagnosis.