Muscle Disorders

Your muscles help you move and help your body work. Different types of muscles have different jobs. There are many problems that can affect muscles. Muscle disorders can cause weakness, pain or even paralysis.

Causes of muscle disorders include

• Injury or overuse, such as sprains or strains, cramps or tendinitis
• A genetic disorder, such as muscular dystrophy
• Some cancers
• Inflammation, such as myositis
• Diseases of nerves that affect muscles
• Infections
• Certain medicines

Here is a detailed overview of muscle disorders — conditions that affect the structure, function, or metabolism of muscles.

Muscle Disorders: Detailed Overview

1. Classification of Muscle Disorders

Muscle disorders are broadly classified into:

A. Myopathies (Primary Muscle Diseases)

• Diseases where the muscle itself is affected, not the nerves.
• Types:
  • Inherited Myopathies
    • Muscular Dystrophies (e.g., Duchenne, Becker)
    • Congenital Myopathies
    • Metabolic Myopathies (e.g., McArdle disease)
    • Mitochondrial Myopathies
  • Acquired Myopathies
    • Inflammatory (e.g., polymyositis, dermatomyositis)
    • Toxic (e.g., statin-induced)
    • Endocrine-related (e.g., due to thyroid disorders)

B. Neuromuscular Junction Disorders

• Affect the connection between nerves and muscles.
• Examples:
  • Myasthenia Gravis
  • Lambert-Eaton Syndrome
  • Botulism

C. Neurogenic Muscle Disorders

• Caused by nerve damage that affects muscle control.
• Examples:
  • Amyotrophic Lateral Sclerosis (ALS)
  • Spinal Muscular Atrophy (SMA)
  • Peripheral neuropathies

2. Common Symptoms

• Muscle weakness (often progressive)
• Muscle cramps or stiffness
• Muscle pain (myalgia)
• Fatigue with exertion
• Muscle wasting (atrophy)
• Difficulty with mobility or coordination
• Drooping eyelids, difficulty swallowing or breathing (in neuromuscular junction disorders)

3. Diagnostic Tests

• Physical exam and patient history
• Blood tests (e.g., creatine kinase, autoantibodies)
• Electromyography (EMG) and nerve conduction studies
• Muscle biopsy
• Genetic testing (for inherited myopathies)
• MRI or ultrasound (to assess muscle tissue)

4. Treatment Options

Treatment depends on the type and cause of the disorder:

• Medications
  • Corticosteroids (e.g., for inflammatory myopathies)
  • Immunosuppressants (e.g., azathioprine, methotrexate)
  • Anticholinesterases (e.g., for myasthenia gravis)
• Physical therapy
  • To maintain strength and prevent contractures
• Respiratory support
  • For severe cases affecting breathing muscles
• Gene therapy or enzyme replacement therapy
  • For certain genetic disorders (ongoing research)
• Lifestyle adjustments
  • Nutrition, activity moderation, mobility aids

5. Prognosis

• Varies greatly:
  • Some muscle disorders are progressive and disabling (e.g., Duchenne Muscular Dystrophy).
  • Others can be managed effectively with treatment (e.g., myasthenia gravis).
  • Early diagnosis and intervention are key to better outcomes.