Differential Diagnosis for Left Shoulder Pain

The patient presents with intermittent left shoulder pain that worsens with certain movements, is not located at the joint, and feels like a pinched nerve. The patient has tried medication for swelling with limited relief. Here is a differential diagnosis organized by category:

• Single Most Likely Diagnosis

  • Subacromial Bursitis or Rotator Cuff Tendinitis: These conditions are common causes of shoulder pain, especially when the pain is exacerbated by movement and not directly at the joint. The feeling of a pinched nerve could be referred pain from the inflamed bursa or tendon.

• Other Likely Diagnoses

  • Adhesive Capsulitis (Frozen Shoulder): Although it typically presents with more restricted movement and pain at the joint, some patients may experience pain in a more diffuse area around the shoulder.
  • Thoracic Outlet Syndrome: This condition involves compression of the nerves and/or blood vessels that pass into the thoracic outlet (the space between your collarbone and first rib). It can cause shoulder pain and a feeling of a pinched nerve.
  • Cervical Radiculopathy: This refers to damage or irritation of the roots of the spinal nerves in the cervical spine, which can cause pain and other symptoms in the shoulder area, including a feeling of a pinched nerve.

• Do Not Miss Diagnoses

  • Myocardial Infarction (Heart Attack): Although less common, shoulder pain can be a referred pain from a heart attack, especially if the pain is accompanied by other symptoms like chest pain, shortness of breath, or nausea.
  • Pulmonary Embolism: In rare cases, a pulmonary embolism can cause referred pain in the shoulder, especially if the embolism is large and affects the upper parts of the lung.
  • Pancoast Tumor: A type of lung cancer located at the top of the lung, which can cause shoulder pain due to local invasion of the tumor into the brachial plexus or ribs.

• Rare Diagnoses

  • Brachial Plexitis (Neuralgic Amyotrophy): An inflammatory condition affecting the brachial plexus, leading to severe pain in the shoulder and arm, followed by weakness and atrophy of the muscles.
  • Osteonecrosis of the Humeral Head: Although more common in the hip, osteonecrosis can occur in the shoulder, causing pain that may not be directly at the joint.
  • Polymyalgia Rheumatica: An inflammatory condition that causes widespread muscle pain and stiffness, particularly in the shoulders, but it's less likely to cause a pinched nerve sensation.

Each diagnosis should be considered in the context of the patient's full medical history, physical examination, and potentially, diagnostic imaging or other tests to determine the underlying cause of the shoulder pain.