CLINICAL CASE 6 The Muscular System Robert Smith is a 19-year old male, immobile
ID: 3478492 • Letter: C
Question
CLINICAL CASE 6 The Muscular System Robert Smith is a 19-year old male, immobile and hospitalized for pneumonia. In the first year of his life, Robert reached many gross motor skill milestones, such as holding his head up, rolling over, sitting, and standing. However, he did not walk until age 16 months, and by age two, started to assume a lordotic posture while standing. A Gower's sign was noted by age four, as was a Trendelenberg gait. Over the next several years, he suffered progressive muscle weakness, most notably in the proximal musculature of the arms, pelvis, and legs. By age 9, he required orthotic braces to assist his walking, and by age 11, he was confined to wheelchair ambulation. In his early teen years, Robert was still able to use eating utensils, write, and type on a keyboard, though these functions have declined over the past year. At 16, he was hospitalized with bronchitis. The only medications that he normally takes are calcium and fluoride supplements. Robert has a younger sister in good health and a younger brother (age 10) who is confined to a wheelchair with problems similar to Robert's. Questions: 1. Robert suffers from a condition called Duchenne muscular dystrophy Explain the full meaning of this name. 2. At age 4, Robert underwent a biopsy of the right gastrocnemius muscle and were found histopathologic changes suggestive of Duchenne muscular dystrophy. Describe the typical microscopic changes. 3. Which muscles are most severely affected by this disease process? 4. Robert had an elevated serum creatine kinase (i.e. creatine phosphokinase) level of 26,000 IU/ L (normal level isExplanation / Answer
Ans 1: Duchenne muscular dystrophy or DMD is the most common and severe form of muscular dystrophy. It is a genetic situation which is exemplify by progressive weakening of voluntary muscles. Muscles of the pelvic girdle are severely affected in this disease. It is caused due to the absence of dystropin which is a protein present inside the muscle cell this protein helps in keeping the muscle cells intact and this is a x-linked recessive disease in which destruction of muscle fibers occur by fat and connective tissue.
Ans 2: Dystrophy means defective nourishment. In muscular dystrophy muscle become dead and is replaced by fat and connective tissue with concomitant metabolic defects. In this condition skeletal muscle fibers are degenerated and there is a proliferation of connective tissue around the degenerating muscle cells. Numerous macrophages can be seen in the area. Muscle fibers appears to be more dense or dark in colour.
Ans 3: Muscles of the pelvic girdle are severely affected in this disease. Muscles involved in walking on the toes are the gastrocnemius (also called leg triceps, large posterior muscle of the calf of the leg) and the soleus. The Gastrocnemius muscle lies on top of the soleus running from the knee to the ankle joints. The tibialis anterior muscles are weaken which fails to pull the toes up i.e., opposing the gastrocnemius muscles.
Ans 4: Creatine kinase transfers phosphate from ATP to creatine to form creatine phosphate which is an important short term energy source for muscle tissue. Creatine kinase is an enzyme located inside skeletal muscle cells but it is released into the bloodstream after destruction of muscle cells. When muscles are at rest ATP increases and ATP is consumed during contraction of muscles. Large amounts of creatine kinase in blood indicate the destruction of muscle cells since Duchenne muscular dystrophy causes muscle cell membranes to break down and release Creatine kinase into the bloodstream.
Ans 5: A weakness in proximal leg muscles and due to this he uses his hands to compensate for the weak leg muscles i.e., he uses his hands to push on legs to stand.
Ans 6: Scoliosis results in the abnormal curvature of the spine. As leg muscles became weak and started using a wheel chair. Use of wheel chair conforms scoliosis to get worse. It is important for the patient to take calcium and fluoride supplements because calcium provides material to build bone extracellular matrix while fluoride helps in stimulating bone building activity of osteoblasts.
Ans 7: Duchenne muscular dystrophy is a disease caused due to a mutation in the dystrophin gene and results in the muscle weakness and their degradation. This will effect muscle movement around the body including the heart. This condition is inherited from the mother and can also be caused by a point mutation.The dystrophin gene is located on the X chromosome which codes for the protein dystrophin. This protein is found in skeletal and cardiac muscle.
The symptoms of this disease first appear when the child is 2 to 5 years old and affect the muscles of the lower limbs. This condition results in walking on toes, hypertrophic calves, unable to climb stairs and the Gower sign in which lower limbs becomes too weak to be used alone to stand up.
With the progresses of disease with age larger muscle groups are affected which results in poor posture which will eventually progress to lordosis and scoliosis i.e., curvature of the spine. And most of the patients become wheelchair (between age 9 to 12). Respiratory problems also arise due to weak respiratory muscles. Also there is a drastic weight changes due to reduced energy requirements and pain during chewing and swallowing. It also causes distention, abdominal pain and vomiting.
It can be diagnose by measuring the creatine kinase levels in the blood. Large amounts of creatine kinase in blood indicate the destruction of muscle cells since Duchenne muscular dystrophy causes muscle cell membranes to break down and release Creatine kinase into the bloodstream. Muscle biopsies can also detect presence of the dystrophin protein.
Ans 8: Physical therapy can help through general exercises, breathing assistance, mobility aids and braces. Exercise Prevent tightness and shortening of muscles.
General exercises include a variety of motion and streatching exercise which help the movements of limbs as muscles and tendons get shorten. Walking and swimming can also help.
Breathing assistance since muscles used for breathing become weaker therefore, delevring oxygen with the help of devices improve oxygen intake.
Mobility aids like wheelchairs and walkers can help in walking.
Braces helps in keeping the muscles and tendons stretched and help slow their shortening.
Ans 9: Currently there is no cure for Duchenne muscular dystrophy. But there are ways by which it can be managed by using steroid hormones like glucocorticoid corticosteroids hormones which help in decreasing the inflammations