Muscular dystrophy
Table of Contents
What is Muscular dystrophy?
Muscular dystrophy is an inherited disorder with progressive muscle destruction. The patient who has inherited this condition gets progressively weaker without the involvement of the nervous system. Muscular dystrophy is very different from other muscular diseases by four obligatory criteria such as
• It is a primary myopathy
• There is a genetic basis for the disorder
• The course is progressive
• Degeneration and death of muscle fibers occur at some stage of the disease
Onset is often in the childhood, although some patients, especially those with myotonic dystrophy may present as adult.
What are the sign and Symptoms of Muscular dystrophy?
The Patient suffering from muscular dystrophy will show these signs and symptoms
- Wasting and weakness are usually symmetrical
- There is no fasciculation
- Tendon reflexes are preserved until a late stages.
- There is no sensory loss.
- Myotonia ( After voluntary contraction of skeletal muscle leads to delayed relaxation of the muscles, and shows an abnormal EMG.)
- Weakness is usually proximal, except in myotonic dystrophy type 1 when its distal.
- Muscle pain
- Cardiomyopathy and respiratory failure
- Pain in shoulder girdle common,
- deafness
- Mild lower limb weakness
- Contractures develop early
- Cognitive impairment
How to diagnose Muscular Dystrophy?
The diagnosis of muscular dystrophy can be confirmed by specific molecular genetic testing, supplemented with EMG and muscle biopsy if necessary. Creatine kinase is markedly elevated in dystrophinopathies (Duchenne and Becker) but is normal or moderately elevated in the other dystrophies. Screening for associated cardiac abnormality (cardiomyopathy or dysrhythmia) is important.
- Muscle biopsy is diagnostic: Shows areas of degeneration and regeneration in the muscle.
- EMG studies: Supports diagnosis and forms an important investigation to detect early cases with no specific family history. It shows denervated potentials in skeletal muscles in DMD.
- ECG, and echocardiogram to assess cardiac status.
- Genetic counseling: This obviously applies to having the next child or marriage counseling for carriers of gene.
- Serum muscle enzyme estimations: Creatine phosphokinase (CPK) levels are greater than 10 times normal in children with DMD, 2-5 times normal in carriers. Measurement of post-exercise CPK levels increases sensitivity of test. Other muscle enzymes like carbonic anhydrase III, pyruvate kinase and lactate dehydrogenase are also elevated.
Types of Muscular Dystrophy
Various types of muscular dystrophy seen in different patients are as follows
- Myotonic dystrophy (DM1)
- Proximal myotonic myopathy (PROMM; DM2)
- Duchenne muscular dystrophies
- Becker muscular dystrophies.
- Facioscapulohumeral (FSH) muscular dystrophies.
- Oculopharyngeal muscular dystrophies.
- Emery–Dreifuss muscular dystrophies.
Myotonic dystrophy (DM1)
Myotonic dystrophy begins in adulthood. Myotonia is an abnormal relaxation of a muscle after voluntary contraction of the muscle. It is a progressive and multisystem genetic disorder.
Age of onset:
- Mild Myotonic Dystrophy: 20 to 60 years (typically after age 40 years).
- Childhood Myotonic Dystrophy: Age 10.
- Myotonic Dystrophy Type II: median age 48 years.
Clinical feature :
- It is a multisystem disorder that affect somatic and smooth muscles, and ophthalmological, endocrine, cardiovascular, and central nervous systems as well.
- facial diplegia( paralysis of both side of face )
- dysarthria (difficulty in speaking )
- Expressive aphasia( partial loss of ability of language )
- Distal muscle weakness is the most common symptom in Classic Myotonic Dystrophy.
- Due to foot drop, there might be an abnormal gait pattern.
- In Myotonic Dystrophy Type II their early-onset cataracts and weakness or stiffness of the proximal muscle.
Duchenne muscular dystrophy
Duchenne muscular dystrophy is an X-linked recessive where there are deletions in the dystrophin gene Xp21 is one of the most severe of muscular dystrophy. Males are affected more than females who are carriers.
Age of onset: < 5 years
Muscle affected: Proximal and limb-girdle
Clinical feature :
• Poor head control in infancy is noticed. Weakness of neck flexors is an early sign.
• The extensors of hip are weak and to compensate for this child may assume lordotic posture and gait.
• Gowers’ sign: due to pelvic muscle weakness these patients show Gowers’s sign.
Proximal myotonic myopathy (PROMM; DM2)
Proximal myotonic myopathy occurs when there is proximal, especially thigh, sometimes muscle hypertrophy. It is an Autosomal dominant muscular myopathy. The proximal, especially the thigh, sometimes muscle hypertrophy most affected in this type of muscular dystrophy.
Age of onset: 8–50 years
Clinical feature :
- Myofascial pain.
- Cataracts early-onset.
- They are varying grip myotonia.
- Hearing loss.
- The weakening or stiffness of muscles closer to the center of your body.
Becker muscular dystrophies.
Becker muscular dystrophy is an X-linked recessive with deletions in the dystrophin gene Xp21. The muscles affected by this muscular dystrophy are the Proximal and limb girdle.
Age of onset: Childhood/early adulthood
Clinical feature :
- Becker muscular dystrophy patients have difficulty in walking and jumping.
- Loss of muscle mass
- Walking on toes
- weak neck and arm muscle
Facioscapulohumeral muscular dystrophy
FSH muscular dystrophy is an Autosomal dominant where the tandem repeats deletion chromosome 4q35. The muscles affected in this muscular dystrophy are the face and upper limb girdle, and distal lower limb weakness.
Age of onset: 7–30 years
Clinical feature :
- Asymmetrical facial muscle weakness
- Ptosis
- Bilateral winging of the scapula
- hyperlordotic
- bilateral hearing aids
- The eye remains open during sleep.
- The extra ocular muscles become weak.
- Foot drop may be present because of the weakness of dorsiflexion.
- Involvement of chest and upper back muscles.
- There may be flattening or even concavity of the deltoid contour.
Oculopharyngeal muscular dystrophies.
Oculopharyngeal muscular dystrophies is an autosomal dominant and recessive; triplet repeat expansion in PABP2 gene chromosome 14q. The muscles affected are Ptosis, external ophthalmoplegia, dysphagia, and tongue weakness.
Age of onset: 30–60 years
Clinical feature :
- dysphagia
- Eyelid drooping
- Facial muscle weakness.
- Tongue shrinking
- Leg and arm weakness.
- external ophthalmoplegia
How to treat Muscular dystrophy?
There is no specific therapy for muscular dystrophy but physiotherapy and occupational therapy help patients cope with their disability occurring in various type of muscular dystrophy.
Medication
- Glucocorticoids can be used in Duchenne muscular dystrophy but side-effects should be anticipated and avoided by dose modification.
- Ataluren is a compound given by infusion to affected individuals that may ‘override’ the stop sign in Duchenne, theoretically leading to the normalization of muscle proteins and potentially reducing or arresting functional deteriorations.
Physiotherapy
Exercise: Endurance exercises are performed with many repetitions and minimal resistance to the point of muscle fatigue.
Splints and Braces
• A spinal brace is given to prevent scoliosis.
• A lumbar corset may be given for treating lumbar lordosis.
• Foot drop splint.
Breathing Exercises: Breathing exercises are taught to the patient, as in the later stage the respiratory muscles might get involved and lead to chest infections. This also increases vital capacity and oxygenation.
Wheelchair: A correctly fitting wheelchair must be ordered so that a good sitting position may be maintained, with minimal room on either side of the chair to prevent the patient from leaning or slanting to one side. The feet should be supported at a right angle position on a footrest.
Counseling: This is crucial in care of a muscular dystrophy patient and his/her family. Grief in the family will increase with disease exacerbation and changes in the patient’s functional ability. Later there is social withdrawal, frustration, and anxiety secondary to a fear of dying. The child grows into a young adult fully aware of what he is unable to do, especially of things that he was able to do.
Sociovocational activities and occupational therapy
In muscular dystrophy, the child is mentally and emotionally normal, he or she needs to find new interests like collecting stamps, playing computer games, or other recreational activities to pass the time. The Internet is a huge resource for education and leisure activities for patients with muscular dystrophy who would otherwise have been greatly deprived of these.
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