A neuromuscular disorder (NMD) is a medical term that encompasses a wide range of conditions. The common thing between these conditions is the impairment of muscle function.

This could occur in two main ways:

  • Direct injury to the muscles
  • Impairment of the peripheral nervous system, which is responsible for muscle contraction

For muscle contraction to happen (e.g., moving your finger), nerve cells (i.e., neurons) will send signals to voluntary muscles to contract. The area where a neuron connects to the muscle is known as the neuromuscular junction (NMJ).

Therefore, a neuromuscular disorder either affects the peripheral nerves themselves or the NMJ, which leads to a variety of signs and symptoms. A classic symptom of neuromuscular disorders is weakness, which eventually leads to muscle waste.

In severe cases, neuromuscular disorders can impact the muscles that control your breathing (i.e., the diaphragm).

From an epidemiological perspective, myasthenia gravis is the most common neuromuscular disease. It is an autoimmune condition that leads to the production of antibodies targeting the neuromuscular junction.

As a result, your nerves will be unable to send signals to those muscles.

Myasthenia gravis presents with many symptoms that develop gradually and at different rates.

The causes of neuromuscular disorders are still unclear. However, researchers managed to pinpoint some risk factors.

In general, you need to be genetically predisposed and get exposed to environmental factors in order to develop a neuromuscular disorder.

Here are the most common risk factors of neuromuscular disorders:

  • Genetic predisposition (e.g., DNA mutation)
  • Autoimmunity
  • Viral infections
  • Metabolic disorders
  • Hormonal disorders
  • Exposure to certain chemicals and toxins
  • Idiopathic (i.e., of an unknown origin)

The diversity of neuromuscular disorders translate to a wide range of signs and symptoms. Additionally, depending on the severity of the condition, you could experience largely different symptoms.

Here is a shortlist of common neuromuscular symptoms, ranging from somewhat mild to life-threatening:

  • Muscular fatigue
  • Amyotrophy (i.e., muscle waste)
  • Muscular cramps
  • Muscle stiffness
  • Joint deformities
  • Severe muscle pain
  • Dysphagia (i.e., difficulty swallowing)
  • Dyspnea (i.e., difficulty breathing)

Hereditary neuromuscular disorders refer to a number of conditions that get transmitted from the parents to their children.

These may include:

  • Congenital myopathies (e.g., muscle weakness that presents at birth)
  • Muscle dystrophy (e.g., Duchenne muscular dystrophy)
  • Metabolic myopathies (e.g., cramping syndromes, exercise intolerance, mitochondrial disorders)

Acquired neuromuscular disorders refer to conditions that develop without an identified parental connection.

Examples of such conditions include:

  • Inclusion body myositis – inflammatory disorders that lead to muscle weakness
  • Dermatomyositis – inflammatory disorders that affect the muscles and skin
  • Necrotizing myopathy – extensive muscle destruction
  • Polymyositis

Some types of NMDs are quite rare. As a result, healthcare professionals may face difficulties in making an accurate diagnosis.

A key point to make an accurate diagnosis is to conduct a comprehensive history taking, followed by a thorough physical examination. Your physician will check your reflexes and objectify any muscle deficits. Moreover, genetic testing can be helpful to diagnose hereditary NMDs.

Some of the tests that help with the diagnosis of NMDs include:

  • Laboratory tests to measure the levels of creatine kinase and other enzymes in your blood
  • Muscle biopsy to study the microscopic features of your NMD
  • Electromyography (EMG) to analyze the electrical currents running through your muscles
  • Magnetic Resonance Imaging (MRI) to objectify any anatomical deformations
  • Cerebrospinal fluid (CSF) collection to analyze the levels of pro-inflammatory markers

The vast majority of neuromuscular disorders have no definitive cure.

Therefore, the goal of treatment is to slow down the progression of the disease and improve the patient’s quality of life. For instance, regular exercise can be an effective tool to cope with gradual amyotrophy.

In one study that inspected the effects of exercise on muscle dystrophy and Charcot-Marie-Tooth disease, researchers found that the latter benefited greatly from exercise. Unfortunately, muscle dystrophy showed no clinical improvement.

Therefore, the effects of exercise on neuromuscular disorders are not always prominent. Regardless, exercise is indispensable to improve the patient’s quality of life.

Another important aspect of managing neuromuscular disorders is physiotherapy, which includes:

  • Respiratory therapy
  • Occupational therapy
  • Clinical psychology
  • Wearing orthotics
  • Wheelchair services

While a primary care physician will be important to manage your condition and monitor progression, consulting a neurologist is vital to ensure that you are getting the best possible care.