A neuromuscular disease is a disorder that affects the muscles and the nerves that control them. Neuromuscular disorders are conditions caused by impaired neuronal activity of the nerves that control the voluntary muscle activities. Children with neuromuscular disorders often experience muscle pain or weakness, muscle twitching, cramping, numbness and tingling, and muscle stiffness that causes joint deformities and sometimes difficulty in swallowing and breathing. Neuromuscular disorders in children may be present at the time of birth or may develop at later stages of life.
Abnormality of different components of the lower motor neuron may cause different disorders.
Abnormality of peripheral nerves and muscles
- Cerebral palsy: Cerebral palsy occurs in infants or early childhood and affects body movements, balance, posture, and muscle coordination. It is the result of damage to one or more parts of the brainthat control muscle movements. Babies with cerebral palsy may delay reaching developmental stages such as sitting, rolling, crawling, or walking. Treatment includes physical therapy, occupational therapy, use of specialized equipment, and medications to reduce spastic movements and prevent seizures. In certain cases, surgery may be necessary to cutsome of thenerves.
Abnormalities of the neuromuscular junction
- Myasthenia gravis: Myasthenia gravis is an autoimmune disorder in which your child’s immune system makes antibodies that block signalssent by the brain to the muscles. Children with myasthenia gravis often have problems with eye and eyelid movement, facial expression,chewing, swallowing and holding up their head. Medications are prescribedto help improve neuromuscular transmission and increase muscle strength. Sometimesthymectomy, the surgical removal of the thymus gland, helps reduce symptoms.
- Congenital myasthenia syndrome (CMS): This condition causes generalized weakness of the voluntary muscles and muscle fatigue involving all the muscles controlling mobility, eye movement, swallowing and breathing.
Abnormalities of the Peripheral Nerves
- Charcot-Marie-Tooth disease: Charcot-Marie-Tooth Disease (CMT) is a genetic nerve disorder that affects your peripheral nerves. The condition is caused by a defect in the genes for proteins involved in the structure and functioning of either the peripheral nerve axon (nerve fiber that conducts impulses) or the myelin sheath (insulating layer around nerves). Children with this condition often have muscle weakness and wasting as well as some loss of sensation in the feet, lower legs, hands and forearms. It may involve foot deformities as well.
- Dejerine-Sottas disease: Thisis an inherited neurological disorder that causes slow development of early motor milestones. Progression of the disease varies and is often associated with pain, weakness, numbness, and a tingling, prickling or burning sensation in the legs.
Inflammatory myopathies are a group of muscle diseases that involve chronic muscle inflammation and weakness. It is an autoimmune disorder in which the body’s white blood cells are attacked by its own immune system. Patients with inflammatory myopathies may have slow but progressive weakness that begins in the proximal muscles.
- Dermatomyositis: Dermatomyositis is characterized by reddish or purplish skin rashes, hard, painful calcium nodules under the skin, muscle pain and tenderness, and progressive weakness of the muscles of the hips, thighs, upper arms, upper back, shoulders and neck muscles.
- Polymyositis: Polymyositis involves inflammation of the skeletal muscles of both sides of the body. Symptoms such as progressive muscle weakness of the neck, throat, shoulders, hips and thighs may occur.
Muscular dystrophy refers to a group of hereditary diseases that weakens the muscles associated with movement. It is caused by agenetic deficiency of the muscle protein called dystrophin. There is no specific treatment for any form of muscular dystrophy, but certain medications, physical therapy and assistive devices can slow the progress of some forms. Muscular dystrophy can occur at infancy or childhood.Major forms of muscular dystrophy include:
- Duchenne muscular dystrophy: It is the most common kind of muscular dystrophy affecting only boys between the ages of 2 to 6. The condition is characterized by generalized muscle wasting and weakness first affecting the muscles of the hips, pelvic area, thighs and shoulders, and eventually involving all voluntary muscles.
- Becker muscular dystrophy: This form is similar to Duchenne muscular dystrophy and generally occurs between the ages of 2 and 16, but can appear as late as age 25. Children with this condition show generalized weakness and wasting of the muscles of the hips, pelvic area, thighs and shoulders, along with enlarged calves and heart complications.
- Emery-Dreifuss muscular dystrophy: The condition usually appears from childhood to the early teen years and affects only boys. It is characterized by weakness and wasting of the shoulders, upper arms and shin muscles, and may also cause joint deformities and heart complications.
- Facioscapulohumeral muscular dystrophy: Onset usually occurs from teens to early adulthood, and affects both boys and girls. The condition causes weakness and wasting of muscles around the eyes, mouth, shoulders, upper arms and lower legs.
- Myotonic muscular dystrophy: Myotonic muscular dystrophy (MMD) is also called Steinert’s disease. The condition causes inability to relax the muscles and muscle weakness.
- Congenital muscular dystrophy: This is a form of muscular dystrophy which is present at birth. The condition is characterized by generalized muscle weakness and joint deformities.
Motor neuron diseases
Spinal muscular atrophy is an inherited disease that attacks the nerve cells called motor neurons and is characterized by progressive muscle degeneration and weakness.
- Infantile progressive spinal muscular atrophy: Infantile progressive spinal muscular atrophy (SMA Type1) is the most severe form of spinal muscular atrophy. Infants with this type may have poor muscle tone, progressive weakness, lack of head control, trouble swallowing, sucking and breathing.
- Intermediate spinal muscular atrophy: Children with intermediate spinal muscular atrophy (SMA type 2) may have weakness in their arms, legs, upper and lower torso, and often have joint deformities.
- Juvenile spinal muscular atrophy (SMA type 3): This is the least severe form of spinal muscular atrophy and is characterized by weakness in the leg, hip, shoulder, arm and respiratory muscles.
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