A neuromuscular disease is a disorder that affects the muscles and their nervous control. Neuromuscular disorders are the 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, muscle stiffness causing 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 in early childhood and affects body movements, balance, posture, and muscle coordination. It is the result of damage to one or more parts of the brain that control muscle movements. Babies with cerebral palsy may delay in 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.
Abnormalities of the Neuromuscular Junction
- Myasthenia gravis: Myasthenia gravis is an autoimmune disorder in which your child's immune system makes antibodies to block the messages sent by the brain to muscles. Children with myasthenia gravis often have trouble with eye and eyelid movement and facial expression as well as problems chewing, swallowing and holding up their head. Medications are used to help improve neuromuscular transmission and increase muscle strength. Sometimes thymectomy, the surgical removal of the thymus gland, helps to reduce the symptoms.
- Congenital Myasthenic Syndrome (CMS): This condition causes generalized weakness of voluntary muscles and muscle fatigue involving all the muscles controlling mobility, eye movement, swallowing and breathing.
Abnormalities of the Peripheral Nerve
- Charcot-Marie-Tooth Disease: Charcot-Marie-Tooth Disease (CMT) is a genetic nerve disorder that affects the peripheral nerves. The condition is caused by a defect in the genes of proteins that are found in the structure and function of either the peripheral nerve axon or the myelin sheath. Patients with this condition often have muscle weakness and wasting. They also may experience loss of sensation in the feet, lower legs, hands and forearms as well as foot deformities.
- Dejerine-Sottas Disease:This is 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 muscle weakness. These are autoimmune disorders in which the body's white blood cells are attacked by its own immune system. Patients with inflammatory myopathies may have slow but progressive muscle 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, and upper arms, upper part of the 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 neck and throat, shoulder, hip and thigh may occur.
Muscular dystrophy refers to group of hereditary diseases that weaken the muscles associated with movements. Muscular dystrophy is caused by a genetic 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 of muscular dystrophy. Tendon release surgery is performed to relieve contractures. Muscular dystrophy can occur at infancy or childhood. Major forms of muscular dystrophy may include:
- Duchenne muscular dystrophy - This is the most common kind of muscular dystrophy affecting only boys between the ages of 2 to 6. It is characterized by generalized muscle weakness and muscle wasting 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. It 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, enlarged calves, and heart complications.
- Emery-Dreifuss muscular dystrophy - The condition usually appears from childhood to early teen years and affects only males. It is characterized by weakness and wasting of shoulder, upper arm, and shin muscles and may also cause joint deformities and heart complications.
- Facioscapulohumeral muscular dystrophy - Onset usually occurs in the teens to early adulthood and affects both men and women. The condition causes weakness and wasting of muscles around the eyes and mouth, and of the shoulders, upper arms, and lower legs.
- Myotonic muscular dystrophy - Myotonic muscular dystrophy (MMD) is also called Steinert's disease. MMD may appear from infancy through adulthood and rarely occurs in newborns. The condition causes inability to relax muscles as well as muscle weakness.
- Congenital muscular dystrophy - This is a form of muscular dystrophy that 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. Infants with this type may have poor muscle tone, progressive weakness, lack of head control, trouble swallowing and sucking, and breathing problems.
- Intermediate Spinal Muscular Atrophy: Children with intermediate spinal muscular atrophy (SMA type 2) may have weakness in arms, legs, upper and lower torso, and often have joint deformities.
- Juvenile Spinal Muscular Atrophy (SMA Type 3): Juvenile spinal muscular atrophy (SMA Type 3) is the least severe form of the disease and is characterized by weakness in leg, hip, shoulder, arm and, respiratory muscles.