Differential Diagnosis for Shoulder and Arm Pain

The patient presents with pain on pressing down on the left shoulder head while in a neutral position, producing pain in the neck and left arm. Applying an axle load with forward neck flexion does not produce shock-like paresthesia. Based on these symptoms, the following differential diagnoses are considered:

• Single Most Likely Diagnosis

  • Cervical Radiculopathy: This condition involves compression or irritation of the nerve roots in the cervical spine, which can cause pain in the neck and arm. The pain pattern and the fact that applying an axle load with forward neck flexion does not produce shock-like paresthesia suggest a mechanical issue that could be related to nerve root compression.

• Other Likely Diagnoses

  • Thoracic Outlet Syndrome (TOS): TOS involves compression of the nerves and/or blood vessels that pass into the thoracic outlet (the space between your collarbone and first rib). This could explain the pain in the neck and arm, especially if the compression is affecting the brachial plexus.
  • Subacromial Impingement Syndrome: This condition occurs when the shoulder blade puts pressure on the underlying soft tissues when you lift your arm away from your body. It could cause pain in the shoulder that radiates to the arm, especially if there's an associated cervical component.
  • Cervical Spondylosis: This is a type of arthritis that affects the joints and discs in the neck. It can cause pain and stiffness in the neck and can radiate to the arm if nerve roots are involved.

• Do Not Miss Diagnoses

  • Cervical Spinal Cord Compression: Although less likely, this is a critical diagnosis not to miss. Conditions such as cervical spondylotic myelopathy or a spinal tumor could cause these symptoms, and missing them could lead to significant and potentially irreversible neurological damage.
  • Acute Coronary Syndrome: While the presentation is atypical, chest pain or arm pain can sometimes be referred from cardiac issues. Given the potential severity of missing a cardiac condition, it's essential to consider this in the differential diagnosis.

• Rare Diagnoses

  • Pancoast Tumor: A rare type of lung cancer that can cause shoulder and arm pain due to its location at the top of the lung, where it can compress nerves.
  • Brachial Plexitis (Neuralgic Amyotrophy): An inflammatory condition that affects the nerves of the brachial plexus, causing severe pain and potentially leading to muscle weakness.

Each of these diagnoses has a different set of implications for treatment and prognosis, highlighting the importance of a thorough diagnostic workup to determine the underlying cause of the patient's symptoms.