Differential Diagnosis for Right Arm Pain
- Single most likely diagnosis
- Sleep-related nerve compression or positional neuropathy: The fact that pain occurs only at night and the recommendation not to sleep on the right side suggests that the pain might be related to nerve compression due to sleeping position. This is a common and relatively benign condition that can cause significant discomfort.
- Other Likely diagnoses
- Rotator cuff tendinosis or bursitis: Although the special tests (Apley scratch test, empty can test, Neer's, Hawkins test) were negative, these conditions can still be present, especially if the pain is intermittent or not severe enough to cause significant limitation in range of motion or tenderness on palpation.
- Referred pain from the cervical spine: Although the patient denies paresthesias, cervical spine issues can refer pain to the arm without neurological symptoms. The absence of tenderness and normal range of motion does not rule out this possibility entirely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Thoracic outlet syndrome: This condition can cause arm pain, especially at night, and can be due to compression of the nerves or vessels between the clavicle and first rib. It's crucial to consider this diagnosis due to potential complications like vascular compromise.
- Pancoast tumor: A type of lung cancer that can cause shoulder and arm pain due to invasion of the brachial plexus. It's a rare cause of arm pain but is critical to diagnose early due to its poor prognosis if left untreated.
- Acute coronary syndrome: Although less common, arm pain can be a presenting symptom of a heart attack, especially in women. The fact that pain occurs at night could be related to increased cardiac demand or decreased oxygen supply during sleep.
- Rare diagnoses
- Complex regional pain syndrome (CRPS): A condition characterized by chronic pain, inflammation, and hypersensitivity after an injury or trauma. The absence of trauma history and lack of other CRPS symptoms (like swelling, skin changes) makes this less likely.
- Brachial plexitis (neuralgic amyotrophy): An inflammatory condition of the brachial plexus that can cause severe arm pain, usually followed by weakness. The absence of weakness and paresthesias makes this diagnosis less likely, but it should be considered if the patient's symptoms evolve.