What are Neuromuscular Disorders?
Neuromuscular disorders are a group of diseases that affect the functioning of voluntary muscles either directly or by affecting the nerves that control these muscles. Certain conditions affect the junctions of the nerves and muscles. Sensory nerves or nerves that carry information to the brain may also be affected. Neuromuscular disorders can result in muscle weakness and wasting, paralysis, improper coordination, loss of sensation, abnormal sensations, and pain thereby disrupting body functions and mobility.
Causes of Neuromuscular Disorders
Causes of neuromuscular disease include:
- Hereditary or genetic disorder
- Autoimmune disorder
- Hormonal disorders such as diabetes
- Inflammatory muscle disorders such as polymyalgia rheumatica
- Bacterial infections
- Viral infections
- Exposure to chemicals or poisoning
- Metabolic disorder
- Dietary deficiency
Types of Neuromuscular Diseases
Neuromuscular diseases can be broadly divided into:
- Motor Neuron Diseases: In these conditions the motor neurons (nerve cells) supplying the muscles gradually degenerate leading to muscular atrophy or deterioration. e.g. Amyotrophic lateral sclerosis (ALS), spinal muscular atrophy, Guillain-Barré syndrome.
- Peripheral Neuropathies: The peripheral nervous system plays a major role in transmitting signals from the brain and spinal cord to the other parts of the body.
- Certain conditions affect the functioning of the peripheral nerves e.g.Diabetic Neuropathy, Charcot-Marie-Tooth disease
- Neuromuscular junction disorders: In these conditions, the transmission of nerve impulses across the nerve-muscle junction is interrupted e.g. Myasthenia gravis
- Myopathies/Dystrophy: Maintenance and repair of muscle tissue are affected in these conditions causing deterioration of the muscles and joint stiffness. e.g.congenital muscular dystrophy, Duchenne muscular dystrophy, Becker muscular dystrophy
- Spinal muscular atrophy (SMA): This is a genetically inherited condition that causes degeneration of the motor neurons, nerves in the spinal cord that control muscle movement. The muscles become extremely weak and deteriorate due to a lack of activity.
- Amyotrophic lateral sclerosis (ALS): This condition is characterized by the gradual breakdown and death of nerve cells, resulting in muscle weakness and impaired physical function.
- Multiple sclerosis: This is an autoimmune disorder that damages the myelin sheath of the nerve cells. This interrupts the transmission of information from the brain to different parts of the body resulting in difficulty with coordination.
- Myasthenia gravis: This is an autoimmune disorder caused due to the disruption of signals between the nerves and muscles resulting in muscle fatigue and weakness. It can affect the muscles of the face and eyes and the muscles responsible for swallowing.
- Guillain–Barré syndrome: This is a rare disorder in which your immune system attacks the nervous system. It initially causes muscle weakness and tingling and later paralysis.
- Polymyositis: This is a rare inflammatory condition that causes muscle weakness, tenderness, swelling, and tissue damage in the muscles close to the trunk.
- Cerebral palsy: This is a condition in which brain development is affected resulting in muscle weakness and difficulty with movement and maintaining posture and balance.
Symptoms of Neuromuscular Diseases
Symptoms of neuromuscular disease may vary based on the condition and its cause. Some of the common symptoms include:
- Twitching
- Muscle cramps
- Loss of balance
- Drooping eyelids
- Muscle weakness
- Breathing issues
- Muscle stiffness (spasticity)
- Numbness and tingling sensation
- Muscle pain
- Vision problems
- Joint deformities
- Fatigue
- Rigidity
Diagnosis of Neuromuscular Disorders
Your doctor will review your medical history and symptoms and based on this physical and neurological examination will be performed. Your doctor may also recommend the following diagnostic tests:
- Blood tests: Blood tests are performed to look for certain substances or the presence of elevated enzymes in the blood that can indicate infection or disease.
- Muscle biopsy: This is an image-guided procedure in which a small sample of muscle tissue is taken and observed under the microscope.
- Magnetic Resonance Imaging (MRI) Scan: An imaging study that uses a large magnetic field and radio waves to detect the presence of any lesions in the brain and spinal cord.
- Electromyography: This method involves the use of small electrodes inserted into the muscles to record electrical activity.
- Nerve conduction studies: These tests determine how well the nerves conduct electrical impulses to assess nerve damage.
- Lumbar puncture: Also known as a spinal tap, this is a procedure in which fluid is aspirated from the spinal canal and analyzed to detect inflammation or the presence of any antibodies to rule out any infections.
- Genetic testing: This may be performed to identify the gene mutation.
Treatment for Neuromuscular Disorders
There are no specific cures for neuromuscular disorders. Treatment measures depend on the type of disease and may help manage or slow the progression of symptoms, increase mobility, and improve the quality of life. Treatments include:
- Medications: Your doctor may prescribe medications such as:
- Immunosuppressive drugs: This helps treat nerve and muscle disorders by suppressing the autoimmune system.
- Anticonvulsants and antidepressants: Thesehelprelieve pain.
- Physical therapy: Your doctor may recommend physical therapy to strengthen muscles and to relieve joint stiffness and restore functional ability and movement.
- Occupational therapy: This involves therapy in self-care and work, it helps maintain physical and mental function.
- Plasma exchange: This is a treatment to control the autoimmune disease. It involves the removal of plasma from the blood that contains antibodies that mediate the disease and replacing it with a substitute.
- Bracing and custom shoes: Braces for the knee, ankle, and foot may be recommended to support and strengthen weak muscles and bones.
- Assistive devices: Devices such as crutches and motorized wheelchairs can help with mobility.
- Speech and swallowing therapy: This therapy helps treat speech and swallowing disorders.
- Botulinum toxin injections: These injections help when muscle spasticity is present.
If conservative methods fail to improve the symptoms, surgery will be recommended. Surgery may involve tendon lengthening or tendon transfer procedures, spinal fusion, hip reconstruction, osteotomies to realign bones and neurosurgery.