Spinal pain is a well recognised condition associated with significant personal and community burdens. The most common spinal regions studied are the lumbar and cervical spine, probably because of their strong and well-established associations with pain conditions, work-related injuries, intervertebral disc degenerative conditions, headaches and psychosocial disturbances. Compared to the lumbar and cervical spine, the thoracic spine has received less attention in terms of clinical, genetic and epidemiologic research, yet pain experienced in the thoracic spine can be equally disabling, imposing similar burdens on the individual, community and workforce.
Thoracic back pain has been historically problematic with extensive differential diagnoses. Detailed history and thorough physical examination along with diagnostic tests play a pivotal role in detecting the underlying pathology. An appropriate multidisciplinary approach should be implemented for the management of thoracic back pain patients. Physical therapy is imperative in the long-term management of these patients. In addition to pharmacological and interventional treatments, psychological aspects of chronic pain and functional loss should be addressed as well. Timely interventions may be warranted to prevent further clinical sequelae and functional disability resulting from inadequate pain control.
Thoracic back pain is a term commonly used to describe mid or upper-back pain. Thoracic back pain is much less common than neck or low back pain; therefore, the diagnosis of pain originating from thoracic region has been challenging. Frequently, thoracic back pain has a benign musculoskeletal origin, but it may indicate a more serious underlying problem. The neural complexity of the thoracic spine, along with referred visceral pain, leads to poor pain source localization.
Although the incidence of spinal pain has been reported as 54–80% of the general population, the number of patients suffering from chronic upper or mid-back pain secondary to thoracic disorders is rather small, ranging from 3% to 22% of outpatient pain population.
The thoracic area of the spine consists of 12 vertebrae (10 of which connect to ribs with costovertebral joints), intervertebral discs, supporting soft tissue, and 12 thoracic nerves. Thoracic vertebrae are considerably larger and stronger than cervical vertebrae. The spinous processes of T1 and T2 are long, laterally flattened, and directed inferiorly. On the other hand, the spinous processes of T11 and T12 are shorter, wider, and directed more posteriorly. In general, thoracic vertebrae have longer and larger transverse processes when compared to cervical vertebrae. Movements of the thoracic region are limited by the attachment of the ribs to the sternum. From a structural viewpoint, the 12 thoracic vertebrae have three separate shapes, with the smaller upper four thoracic vertebrae sharing some characteristics with the cervical vertebra and the larger lower four thoracic vertebrae sharing similar features with the lumbar vertebrae. The middle four thoracic vertebrae share characteristics with both the cervical and lumbar regions. The spinal canal has a similar diameter in the thoracic and lumbar area, but the space around the thoracic spine is narrower than lumbar spine. Thus, spinal cord compression from a herniated thoracic disc is more likely at the thoracic level. The upper thoracic vertebral interspaces from T1 to T2 and the lower thoracic vertebral interspaces from T10 to T12 are functionally equivalent to the cervical and lumbar interspaces, respectively, which facilitates placement of the epidural block in a similar fashion to the cervical and lumbar approaches. The thoracic vertebral interspaces between T3 and T9 are functionally unique because of the acute downward angle of the spinous processes. Epidural blockade of these middle thoracic interspaces requires use of the paramedian approach to the thoracic epidural space.
The thoracic facet joints are paired synovial joints formed by the articulation of the superior and inferior articular facets of adjacent vertebrae. They are true joints in that they are lined with synovium and possess a true joint capsule that is richly innervated and so can become a pain generator. The poor localization of facet joint pain is explained in part by the pattern of overlapping of the sensory innervation of these joints and their close proximity to one another. The posterior rami of a nerve root diverge from the spine at the intervertebral foramen and pass dorsally and caudally through the intertransverse ligament where they divide into medial, lateral, and intermediate branches. The medial branch crosses over the top of the transverse process at a variable point lateral to the point at which the transverse process meets the vertebra. The nerve then travels medially and inferiorly across the surface of the transverse process to innervate the facet joint. The medial branch supplies the lower pole of the facet joint at its own level and the upper pole of the facet joint below. Therefore each facet joint receives its innervation from a medial branch nerve of two posterior primary rami. One branch arises from the nerve at the same level as the joint, and the other from the segmental level above. This explains why the dorsal nerve from the vertebra above the affected level must often also be blocked to provide complete pain relief.
Thoracic back pain can originate from different areas of thorax including surrounding soft tissues of the spine, intervertebral discs, facet joints, the spinal cord and nerve roots, or the body of the vertebra, or it can be referred pain. The pain may be the outcome of different pathological process including degenerative changes, autoimmune diseases, trauma, osteoporosis, infection, or malignancy.
Myofascial pain is generally related to a combination of muscle and ligament sprain and inflammatory response. Poor posture and excessive sitting most usually cause thoracic back strain. Poor posture may be due to development of osteoporosis in elderly patients, which often results in excessive drooping of the neck and shoulders and decreased lumbar lordosis.
Compression of a spinal nerve root may lead to radiculopathy. Thoracic radicular pain can frequently be the result of thoracic spine degenerative changes, a neoplastic process, or trauma. The natural kyphosis of the thoracic spine places the spinal cord in close proximity to the back of the intervertebral discs, vertebral bodies, and ligaments, thus making the thoracic spinal cord more susceptible to compression from those structures. Postherpetic neuralgia may present with neuropathic pain along the affected dermatomes. Entrapment of the intercostal nerves may lead to intercostal neuralgia. Diabetes mellitus is the most common metabolic cause of radiculopathy.
Ankylosing spondylitis often affects the entire spine with initial restriction of lumbar and chest motion and later involves the cervical spine. In those patients, pain originates from costovertebral joints, in which, prevalently, the 11th and 12th ribs and the 6th through 8th ribs are involved.
Thoracic spine compression fractures commonly take place in patients with osteoporosis, but they are usually stable. Pathologic fractures can occur due to metastatic cancer from the lung, prostate, or breast. A major trauma with high energy is usually required to cause a thoracic compression fracture in a healthy vertebra. The latter is usually associated with spinal cord injury. Characteristically in osteoporotic fractures, the anterior aspects of vertebrae are affected, and compound fractures may lead to kyphosis.
Thoracic intervertebral discs could be a potential pain generator as a result of degenerative changes or infectious processes. Pain is usually the presenting symptom in nearly 60% of cases. Muscle spasms or pain radiating to the front of the chest/abdomen may also be experienced.
Thoracic facet pain accounts for 42% of patients presenting with thoracic back pain . Thoracic spondylosis is the result of abnormal wear and tear that causes gradual narrowing of the disc space and deformed bone growth that can lead to increased pressure on adjacent tissue and nerves, causing pain and possibly neurological symptoms. Thus, patients with thoracic facetogenic pain are generally older, whereas patients with discogenic pain are younger. Thoracic facet joint syndrome results from a sudden twisting motion, twisting when lifting overhead, or an unguarded rotating motion of the thoracic spine. The resultant pain may be mild, dull, and aching, with radiation encircling the chest, or it may be sharp pleuritic-type pain that can affect lung functional vital capacity and overwhelm the patient. There is usually decreased motion in the portion of the spine involved. Examination of the patient may reveal a loss of the thoracic curve or muscle spasms, causing localized scoliosis.
Non spinal causes of thoracic pain and possibly emergent causes that should be kept in mind including vascular disease (e.g., thoracic aortic dissection, thoracic aneurysms, acute coronary syndrome, and pulmonary embolism), thoracic cavity pathology (e.g., pleuritis, pericarditis, pneumonia, lung malignancy), and abdominal pathology whether intraperitoneal or retroperitoneal (e.g., peptic ulcer disease, pancreatitis, hepatobiliary disease). Furthermore, the differential diagnosis for thoracic pain can include major surgeries like coronary bypass, mastectomy, and thoracotomy. Diffuse thoracic pain prevalently may result from visceral diseases like achalasia, pancreatic diseases, and esophageal cancer.
Plain radiographs, computed tomography (CT), MRI and isotope bone scan are the main imaging modalities that can help reach a precise diagnosis. Thoracic back pain is considered as a red flag and imaging studies should be ordered earlier in thoracic back pain of unknown etiology due to the lower incidence of radiculopathy and higher incidence of tumour involvement in this region. MRI is the main imaging modality for assessment of disc degenerative disease; furthermore, one might consider short T1 inversion recovery (STIR) views when the index of suspicion for vertebral body fracture is high.
It is important to rule out non spinal and serious causes of thoracic pain before considering pain treatments.
Non pharmacological treatments like TENS machine and acupuncture should be considered in all patients.
Medication management includes simple analgesics like paracetamol, anti inflammatories and codeine based preparations. Anti neuropathic agents should be considered in patients presenting with nerve pain secondary to disc prolapse or intercostal neuralgia.
There is no known anatomical, imaging, or histopathological standard for identifying a painful facet joint. One must clinically evaluate patients with suspected facet-related pain, select those with symptomatic facets, and then decide at which levels to make the injections. Facet-induce pain is currently a diagnosis of exclusion supported by abolition of pain after injection of local anaesthetic into the joint or onto the two medial branch nerves supplying the joint.
The major indications for facet joint injection include the following.
Nerve root blocks are offered to patients presenting with radicular pain affecting the chest wall. Pulsed radiofrequency ablation of the dorsal root ganglion (DRG) or intercostal nerves can be offered to patients who respond positively to the initial nerve blocks. Successful results have been reported in utilizing pulsed RF treatment in thoracic radicular back pain management Stolker et al. showed significant pain relief after pulsed RF treatment in more than 70% of patients for 13–46 months.
Thoracic medial branch blocks are useful in the diagnosis of pain mediated by thoracic medial braches, usually arising from facet joints. A prognostic medial branch block is useful for predicting whether radiofrequency lesioning of the affected joint(s) may provide long-lasting relief of pain originating from the facet joints. Pain relief from radiofrequency treatment can last between 6 months to 2 years, though this may not always be the case.
Variable medial branch paths in the thoracic region make the clinical outcomes of conventional RF ablation inconsistent. COOLIEF thoracic cooled RF uses revolutionary cooling technology for thoracic medial branch neurotomy. Unlike conventional RF, COOLIEF Cooled RF enables placement of a large volume, spherical, repeatable lesion that is optimised in size and position to compensate for the variable nerve course, which increases the probability of capturing the target medial branch nerve.
Clinical studies of COOLIEF Cooled RF addressing other sources of pain have demonstrated up to 24 months pain relief with improved physical function and a reduction in paid medication usage.