Nerve compression at the level of the thoracic vertebrae, or thoracic radiculopathy, is less common than in the cervical radiculopathy or lumbar nerve compression because of the lower amount of pressure and movement that the thoracic vertebrae are subjected to. However a pinched nerve at the thoracic level may cause symptoms that just as severe, usually presenting as pain, tingling, and numbness in the arms, chest, abdomen or pelvis.
Anatomy of the Thoracic Spine
The parts of the spine at the mid-back region is made up of 12 thoracic vertebrae, each being separated, as in other regions, by an intervertebral disc which acts as a cushion between the vertebrae and also allow movement and flexibility of the spine. Symptoms of nerve compression or entrapment neuropathy may occur when a nerve is compressed or pinched as it traverses a closed space, such as the spinal cord through the spinal canal, and depending upon the site of compression, varying symptoms may be produced. The mid-back or thoracic region is not involved with much bending or flexing movements, hence spinal problems at this level is comparatively rare, resulting in less chance of nerve compression.
Types of Nerve Compression in the Thoracic or Mid Back Region
1. Herniated thoracic intervertebral disc
A herniation or bulging disc occurs when there is a rupture of the outer layer of the disc causing the inner disc contends to protrude and impinge on the nerves within the spinal canal or exiting the canal.
2. Degenerative thoracic intervertebral disc
The intervertebral disc has a hard outer covering supporting a soft gelatinous center and due to gradual wear and tear as a result of age, the outer layer of the disc degenerates. This allows the soft inner portion to protrude out and may put pressure on a nerve root, causing pain, tingling and numbness. This phenomenon is rare in the thoracic region and when it does occur, it is a slowly progressing condition that takes years to develop.
3. Trauma to the thoracic region of the back
A traumatic injury to the thoracic region of the back may give rise to herniated intervertebral disc as a result of the sudden severe force to the mid back.
4. Thoracic outlet syndrome
Nerves or blood vessels may become compressed in the thoracic outlet, the space between the clavicle (collar bone) and first rib, giving rise to symptoms such as pain and numbness in the shoulders, neck and fingers.
Causes of Thoracic Outlet Syndrome
- Trauma due to car accident injuries or severe falls.
- Job related repetitive injuries, like carrying heavy loads.
- Repetitive injuries due to sports related activities or old injuries.
- Idiopathic meaning that the cause is unknown.
- Congenital defect, such as cervical rib, where an extra rib occurs above the first rib.
- Poor posture.
Symptoms of Thoracic Outlet Syndrome
The symptoms due to nerve compression, or neurogenic thoracic outlet syndrome, are caused by compression of the brachial plexus, a bundle of nerves that come out from the spinal cord. The brachial plexus controls muscle movements and sensation of the shoulder, arm and hand, hence the symptoms produced on compression of the brachial plexus may be associated with its innervation. These include :
- Neck and shoulder pain
- Tingling or numbness in the fingers
- Aches or pains in the arm or hand
- Muscle weakness often noticed as a weakening grip.
Apart from the case history and clinical findings upon the physical examination of the patient, certain tests may be done to confirm the diagnosis, such as :
- X-ray – cervical rib can be seen on x-ray
- Magnetic resonance imaging or MRI scan
- Electromyography or EMG
- Nerve conduction study or nerve conduction velocity test
Conservative management is the treatment of choice and may include :
- Exercises to strengthen the shoulder muscles
- Relaxation techniques
- Maintaining good posture
In more severe cases, with persistent symptoms, other therapeutic measures may have to be considered.
- Medications to relieve pain and reduce inflammation, such as ibuprofen, and muscle relaxants are helpful.
- Surgery may be considered if conservative treatment is not effective in giving relief from symptoms or if there is significant nerve damage, although there remains a risk of injury to the brachial plexus during the operation.
5. Spinal Stenosis
Narrowing of the spinal canal, as a result of degenerative changes associated with normal wear and tear due to aging, may cause compression on the spinal cord and nerves, but this condition is rare in the thoracic region.
6. Long Thoracic Nerve Compression
Compression of the long thoracic nerve may occur as a result of carrying heavy packs, such as in army recruits or backpackers, or the nerve may be stretched following heavy labor. Pain is negligible, but there may be impairment of movement in overhead arm extension and winging of the scapula or shoulder blade. This condition may resolve spontaneously in six to twelve months if further compression of the nerve is avoided, such as carrying a heavy object or bag across the shoulder. Exercises to strengthen the muscles are recommended, with surgery being the last option for treatment.