Bell's Palsy

Muscular Dystrophy, types of muscular dystrophy

What is Muscular dystrophy?

Muscular dystrophy is an inherited disease. Due to gene mutation and alteration, lack of protein dystrophin occurs which causes damage and weakness of muscles.

How dystrophin cause muscular dystrophy? or How does someone get muscular dystrophy?

About 4 lac proteins are present in human body. each protein is made up of 3 nucleotides. Only dystrophin protein is made of 23 lac nucleotides. It is the largest protein of human body. So, chance of mutation increases.

Nucleotide attach at abnormal place.
Gene mutation occur
Changes in protein function
muscular dystrophy
Function of dystrophin:

Dystrophin protein transmit force of contraction to muscles and protect them from injury or wear and tear during contraction and relaxation. Dystrophin is basically muscular protein but in some cases nerves also get involved. In neurons to generate action potential calcium ion entry is compulsory which owes to dystrophin protein. Actin binds to myosin just because of dystrophin protein. During contraction actin and myosin filament intermingle to contract muscle. If dystrophin is not working normal actin will not attach with myosin and no contraction occurs. Muscular dystrophy occurs in a following manner:

Dystrophin Abnormal Actin will not attach with myosin No muscle contraction occurs Atrophy of muscles Fibrous tissue formation inelasticity of tissues increases Contracture formation starts Muscular dystrophy

Pattern of muscular dystrophy:

Dystrophy moves from proximal to distal segment. Initially lower limb is affected and then upper limb in the later stages. Flexors, extensors, calf muscles and quadriceps are primarily affected.

Stair climbing becomes difficult limited to wheelchair Upper limb affect No more Fine movements Trunk involvement Diaphragm muscles affected Breathing muscles Cardiac muscles Respiratory muscles Cardiac or respiratory arrest Death.

Causes of MD:

  • Gene mutation
  • Lack of dystrophin protein
  • Faulty genes

Symptoms of muscular dystrophy:

What are the signs of muscular dystrophy in adults?

Patients with muscular dystrophy are toe walkers with increased base of support. They have poor muscle co-ordination, frequent falling. Problem in swallowing and, have shoulder and pelvic muscles weakness. Let’s discuss the symptoms in a sequential manner:

Stair climbing: Due to weak hip flexors stair climbing, walking and running becomes difficult.

GOVR’s sign: Ask patient to sit and stand. He would be unable to do sit stands due to weak quadricep muscles. Muscular dystrophy patients have positive GOVR’s sign.

Calf muscle hypertrophy: Due to inelastic fibrous tissue formation calf muscles look bigger than normal. Contracture formation starts there.

CK test: Normal value for CK is up to 200. In Duchenne muscular dystrophy CK level is very high in thousands. Even CK level 200,000 have been seen.

High arch foot: Due to tightness of calf muscles. High arch is seen.

Gait: Patient with muscular dystrophy have lordotic, waddling (toe walking) gait.

Club foot formation: Walking stops and patient is now in sitting position or on wheelchair.

Fine movements: Fine movements are ok. The patients suffering from dystrophy are not mentally retarded but a few.

Diagnostic Test:

Creatine kinase enzyme is found in brain, heart, muscles and in tissues. During muscle damage this enzyme creatine kinase is secreted into blood stream. CK test is performed to check muscle functioning. In patients with muscular dystrophy CK test shows higher values.

Patient’s appearance:

  • Poor balance
  • Thin weak thighs
  • Foot drop
  • Sway back
  • Belly sticks out due to weak abdominals
  • Toe walking (wide base)
  • To stabilize, patient retracts the shoulders and hold arms backward.

Organs affected in muscular dystrophy:

Cardiac, spine, eyes, brain, endocrine and respiratory system is affected. Cardiac arrest and respiratory arrest might cause death.

At what age is muscular dystrophy diagnosed?

It is a genetic defect but there are different types of muscular dystrophies diagnosed at different ages. Most commonly it is diagnosed in 3-6 years of age. It can affect anyone from teenage to even sixty years of age. Males are primarily affected.

Why males are more affected from muscular dystrophy? or How common is muscular dystrophy in females?

It is an autosomal recessive disease. Males have only one X chromosome while females have 2X chromosomes. In females if one chromosome is not performing normal function even then second chromosome would be normal. While in males damage of single X chromosome will cause prevalence of muscular dystrophy. Males are primarily affected while only 8% of females can suffer from dystrophy.

Muscular dystrophy

Types of Muscular Dystrophy:

TypesAge of OnsetSpecific symptomsOther organs involved
Duchenne (DMD)Before 4-5 Yrs.Scoliosis, kyphosis, weak hip, shoulder & breathing musclesCardiac
Becker’s (BMD)Early childhood to adultWeak hip, shoulder & breathing muscles, slow progressionCardiac
Limb girdle (LGMD)Early childhood to adultWeak hip & shoulder musclesCardiac
Facioscapulohumeral (FSHD)Before 19-20 Yrs.Weakness of face, scapular & humeral musclesNone
Congenital (CMD)By birthHypo tone, delayed milestones, contracturesMentally retarded, eye problems
Myotonic (MMD)11-20 Yrs.Weak face, shoulder & arm musclesMentally retarded, eye, heart problems
Oculopharyngeal (OPMD)40-60 Yrs.Weak shoulder & arm muscles, contracturesNone
What are the most common types of muscular dystrophy?

Duchenne Muscular Dystrophy:

Diagnosed in 3-4 years of age. Physiotherapy can increase flexibility and can slow down the progression rate. But death occurs by the 10 years of age. Maintain ROM of knee, ankle, wrist and elbow. Active ROM, stretching in case of contractures. Transcutaneous electrical nerve stimulation and EMS. Resisted exercises are contraindicated. to preserve dystrophin. On each single contraction dystrophin protein is consumed. So, our purpose should be to preserve dystrophin.

Becker Muscular Dystrophy:

Named on scientist. Onset is at the age of 8 to 10 years. Symptoms are less severe than Duchenne’s dystrophy. CK test value is less than 2000. Symptoms progress slowly. GOVR’s sign is positive but at a very later stage. Ambulation is maintained and patient can survive up to 30 to 40 years after onset of disease.

Limb girdle dystrophy:

Scapula, shoulder and pelvis is involved. Both upper and lower girdles are affected. Limb girdle dystrophy moves from proximal to distal segment. Proximal areas are most affected. This dystrophy do not affect cardiac and respiratory systems. It is less severe. CK level is less than 2000. Patient with limb girdle dystrophy take smaller steps. Patient have problem during elevation, abduction and flexion of arm. On arm elevation winging of scapula is seen.

Facioscapulohumeral dystrophy:

Facial, Scapular and humeral muscles are involved. Onset is in between 15 to 16 years of age can even occur after 20 years of age. Normal activities of these muscles are affected. Due to facial muscles involvement chewing, eating, swallowing becomes difficult. Due to scapular muscles involvement problem in flexion and elevation of arm. winging of scapula is seen.

Facial MusclesHumeral MusclesScapular muscles
Orbicularis Oculi
(Closure of eye)
Deltoid
(Arm abduction)
Subscapularis
(Internal rotation)
orbicularis Ores
(Closure of mouth)
Bicep
(Elbow flexion)
Infraspinatus
(Arm Extension)
Buccinator
(Chewing)
Brachialis
(Elbow flexion)
Supraspinatus
(Arm Abduction)

Note: Deltoid is responsible for abduction till 120 degrees. Supraspinatus is responsible for abduction beyond 120 degrees.

Treatment for muscular dystrophy:

What is the best treatment for muscular dystrophy?

Muscular dystrophy have no treatment but corticosteroids can slow down the rate of progression of dystrophy. Physiotherapy can prevent the symptoms from getting worse.

  • Corticosteroids
  • Basic steroid Deltacortril is is used.
  • Infrared for muscle relaxation
  • ROM
  • Stretching in case of contractures and for Tibialis anterior tightness
  • Active assisted exercises
  • Aerobic exercises

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