Neuromuscular disorders, or disorders of the peripheral nervous system, are some of the most common diseases faced by our aging population. Neuromuscular disorders involve the motor neurons, nerve roots of the spine, brachial and lumbar plexus, neuromuscular junction and muscle.
Patients seek help from a neuromuscular specialist for a variety of reasons. Problems with the motor neurons lead to progressive, painless muscle weakness. When these motor neurons become unhealthy or die, communication between the central nervous system and muscles breaks down, and muscles weaken and waste away. The weakness can lead to twitching, cramps, joint pain and movement problems. As some neuromuscular diseases progress, patients can develop breathing and swallowing difficulties.
Problems with the nerve roots
Problems with the nerve roots are called radiculopathies. These usually involve some sensation loss, weakness of voluntary muscle innervated by a specific nerve root, and pain in the spine or along a limb. Plexus lesions also may present this way.
Nerve problems range from simple (carpal tunnel) to complex (multifocal motor neuropathy). Symptoms can include numbness; imbalance and walking instability from loss of sensation; weakness of voluntary muscle that might cause foot drop or difficulty with opening a bottle or opening a button or clasp; and extra sensations, such as burning or tingling.
Problems with the neuromuscular junction and muscle
Problems with the neuromuscular junction and the muscle may cause muscle weakness. The classic neuromuscular junction disorder, myasthenia gravis, commonly causes double vision (diplopia) and droopy eyelids (ptosis), in addition to painless muscle weakness that leads to fatigue during the day. The most commonly seen muscle disorders cause weakness in the shoulders and hips and may reduce the individual’s ability to lift items overhead or rise from a low chair without using his or her arms.
Examples of neuromuscular disorders
- Amyotrophic lateral sclerosis (Lou Gehrig’s disease)
- Spinal muscular atrophy
- Cervical and lumbar radiculopathies
- Acute and chronic inflammatory demyelinating polyradiculoneuropathy (AIDP or Guillain-Barre, and CIDP)
- Hereditary neuropathy (Charcot Marie Tooth disease)
- Acquired neuropathies (diabetes related to toxins and chemotherapy, etc.)
- Myasthenia gravis and neuromuscular junction disorders
- Muscular dystrophy
- Metabolic myopathies (mitochondrial disorders, myophosphorylase deficiency)
- Inflammatory myopathies (dermatomyositis, polymyositis, inclusion body myositis)