From the Guidelines
Neuromuscular diseases can be broadly categorized into several main types, including muscular dystrophies, motor neuron diseases, peripheral neuropathies, neuromuscular junction disorders, and myopathies, each with distinct pathophysiology and clinical manifestations. The main types of neuromuscular diseases include:
- Muscular dystrophies (like Duchenne and Becker), which cause progressive muscle weakness due to genetic mutations affecting muscle proteins 1
- Motor neuron diseases (such as ALS and spinal muscular atrophy), where motor neurons degenerate leading to muscle weakness and atrophy
- Peripheral neuropathies (including Charcot-Marie-Tooth disease and Guillain-Barré syndrome), which affect peripheral nerves causing sensory and motor symptoms
- Neuromuscular junction disorders (like myasthenia gravis and Lambert-Eaton syndrome), characterized by fatigable weakness due to impaired nerve-muscle communication
- Myopathies (such as polymyositis and metabolic myopathies), which directly affect muscle fibers 1. These conditions vary in onset, progression, and inheritance patterns, with symptoms typically including muscle weakness, atrophy, cramps, and sometimes sensory changes. The underlying pathophysiology generally involves disruption in the transmission of electrical signals from nerves to muscles or dysfunction within the muscle cells themselves, leading to impaired muscle contraction and function. For example, Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD) are both caused by mutations in the dystrophin gene, but have different severities and ages of onset, with DMD being more severe and progressing to loss of independent ambulation, usually during the second decade of life 1. In contrast, BMD is a milder and more variable phenotype, with patients not typically treated with glucocorticoids 1. Understanding the specific type of neuromuscular disease is crucial for providing appropriate management and treatment, as well as for improving outcomes and quality of life for patients.
From the Research
Types of Neuromuscular Diseases
- Neuromuscular diseases can be classified based on the site of injury, which can be in the cell bodies, axons, Schwann cells, neuromuscular junction, or muscle 2.
- Some common types of neuromuscular diseases include:
- Amyotrophic lateral sclerosis (ALS)
- Sensory ganglionopathies
- Axonal peripheral neuropathies
- Brachial plexopathies
- Chronic inflammatory demyelinating polyradiculoneuropathy
- Myasthenia gravis
- Lambert-Eaton myasthenic syndrome
- Inflammatory myopathy
- Muscular dystrophy
- Muscular dystrophies are a group of genetic, progressive, degenerative disorders with the primary symptom of muscle weakness, and can be further classified into:
- Duchenne muscular dystrophy (DMD)
- Becker muscular dystrophy (BMD)
- Facioscapulohumeral muscular dystrophy
- Myotonic dystrophy type 1
- Limb-girdle muscular dystrophy
- Emery-Dreifuss muscular dystrophy
- Oculopharyngeal muscular dystrophy 3
- Other types of neuromuscular diseases include:
- Spinal muscular atrophy (SMA), which is defined by the degeneration of the anterior horn cells in the spinal cord and destruction of motor neuron nuclei in the lower brain-stem caused by SMN1 gene deletion 4
Characteristics of Neuromuscular Diseases
- Neuromuscular diseases can be difficult to diagnose due to the multitude of possible sites of injury and the variability of clinical presentations 2.
- DMD and BMD are X-linked muscular dystrophies that result from mutations in the DMD gene, leading to reduced or absent dystrophin expression 5.
- SMA is caused by the loss of SMN1 protein, which can be partially compensated by SMN2 protein synthesis, and disease severity is affected by the success of SMN2 gene synthesis 4.