T4 syndrome -- a condition that affects the nerves exiting your spine at the fourth vertebra in your upper back -- may occur when vertebra in your upper and middle back are angled too far forward. This relatively rare condition may associated with injury to the joints between your vertebrae at this level of your spine.

Upper Back Stiffness and Joint Tenderness

T4 syndrome is characterized by upper back stiffness and tenderness over the T4 vertebra's joints. Although little evidence exists to explain the definitive cause or causes of T4 syndrome and its associated upper back stiffness and tenderness, it's believed that poor posture, too much movement at the affected joints and vertebra that are rotated may be contributory factors. It's also possible the T4 syndrome symptoms such as upper back stiffness and tenderness could arise due to excessive strain on the thoracic spine, especially with bending or twisting motions or heavy lifting. Sudden, unguarded spinal movements can cause significant back pain or discomfort. Pressing on the vertebra or muscles in your upper back may increase this pain.

Arm & Hand Pain or Numbness

Arm and hand pain and numbness is one of the most common symptoms associated with T4 syndrome. People with T4 syndrome will experience generalized pain throughout one or both arms, although pain in the upper arm is most common. And although both arms and hands may be affected, T4 syndrome-related arm and hand pain typically manifests on just one side of the body. The arm pain often is accompanied by numbness or tingling.

Headaches

Headaches are another common symptom associated with T4 syndrome. Joint manipulation of the involved spinal segments may alleviate these symptoms. T4 syndrome-related headaches manifest in the mid to upper back, and typically are felt on both sides of the head. People often describe a T4 syndrome-related headaches as a fuzzy or fluffy feeling, similar to cotton wool in the ears, or as a band around their head, which is similar to a tension headache.