Physical Examination of Muscles in Systemic Disease

How to examine patients and report findings in patients with suspected muscle diseases:

• Abnormal movements
  • Fasciculation → peripheral nerve injury
  • Tremor
    • Resting → Parkinsonism (with bradykinesia and rigidity)
    • Intention → cerebellar issue → look for additional signs of cerebellar problems (e.g., ataxia)
  • Myoclonus (involuntary purposeless jerks of limbs) → toxic metabolic issues (e.g., hypoxia, uremia, serotonin syndrome, opioid intoxication) or upper motor neuron lesion
• Muscle tone
  • Flaccid → lower motor neuron lesion or hyperacute CNS lesion (brain, spinal cord)
  • Normal → myopathy
  • Increased → dystonia
  • Spastic → lower motor neuron lesion
  • Rigid
    • Parkinsonism
    • Neuroleptic malignant syndrome
  • Impaired relaxation = myotonia
• Muscle Bulk
  • Decreased (atrophy) → lots of things can cause this
    • Deconditioning
    • Cachexia
    • Motor neuron disease
    • Muscular dystrophy
  • Normal → neuromuscular junction diseases or early inflammatory myopathies
  • Hypertrophic (bulky and strong) → physical conditioning, anabolic steroid use
  • Pseudohypertrophic (bulky and weak) → muscular dystrophies
• Muscle tenderness
  • Rhabdomyolysis
  • Also, sometimes seen in myopathies
• Power, strength
  • Diminished → myopathy, especially when proximal
  • Fatigability → hallmark of myasthenia gravis
  • Increased → physical conditioning, anabolic steroid use
• Muscle stretch reflexes (deep “tendon” reflexes)
  • Diminished or absent → Lower motor neuron disease, late stages of myopathies
  • Delayed upstroke → Hypothyroid myopathy
  • Normal → Early stages of most myopathies
  • Hyperreflexia
    • Thyrotoxic myopathy
    • Serotonin syndrome
    • Upper motor neuron disease (remember: hyper goes with upper, while diminished or absent goes with lower)
•  Gait
  • Waddling (myopathic) gait → pelvis tilts downward on the side of the limb that is in the air (secondary to weakness in hip abductor muscles) resulting in side-to-side tilting of pelvis (waddling) with each step.

Watch this excellent one and half minute YouTube video which demonstrates and explains the myopathic gait:

Reference

• Neurology: A Clinician’s Approach (2010)