Thoracic Spinal Pain
Definitions
Topography
Thoracic spinal pain is pain perceived anywhere in the region bounded superiorly by a transverse line through the tip of the spinous process of T1, inferiorly by a transverse line through the tip of the spinous process of T12, and laterally by vertical lines tangential to the most lateral borders of the erector spinae muscles.
This area may be subdivided into upper, middle and lower thirds. Pain felt lateral to this area constitutes posterior chest wall pain and not thoracic spinal pain
IASP Taxonomy
Thoracic discogenic pain: Appropriate response to selective anaesthetisation of the putatively symptomatic disc or to provocation discography
Thoracic zygapophysial joint pain: Complete relief of pain on selective radiologically controlled intra-articular anaesthesia of the targeted joint followed by validation procedures to exclude false positive results
Costotransverse joint pain: Complete relief on selective radiologically controlled intra-articular anaesthesia of the targeted joint followed by validation procedures to exclude false positive results
Thoracic trigger point syndrome: Presence of a palpable tender, firm, fusiform nodule or band in a specified muscle which produces the patient’s pain and/or referred pain on palpation. Elimination of the trigger point by stretching, dry needling or local anaesthesia relieves the patient’s pain
Thoracic segmental dysfunction: Aggravation of a patient’s pain by selectively stressing the specified affected segment. Stressing the neighbouring segments does not reproduce the pain.
Thoracic spinal pain of unknown origin: No other cause for the pain can be found or attributed
Thoracic muscle strain: Pain in a specific muscle with a history of activities consistent with a strain of that muscle. Tenderness on palpation and aggravation on stretching or relief of pain with selective anaesthetisation
Somatic thoracic spinal pain: acknowledges that the pain arises from one of the tissues that can not be specifically identified and removes the inference that the pain may be psychogenic
Other Terms
Spondylogenic or non-radicular pain: Pain which originates from any of the components of the vertebrae including joints, discs, ligaments and muscle attachments
Somatic dysfunction: Impaired or altered function of related components of the somatic system; skeletal arthrodial and myofascial structures; and related vascular, lymphatic and neural elements
Painful minor intervertebral dysfunction: Reversible, benign, painful, segmental vertebral dysfunction of mechanical and reflex origin
Hyper/hypo-mobility lesion of the mobile intervertebral joint complex: Increased or decreased range of inter-vertebral joint movement and associated accessory movements
Intervertebral derangement: Disturbance of the normal resting position of the articular surfaces of two adjacent vertebrae as a result of a change of the position of the fluid in the nucleus
Epidemiology
There are no formal population studies on the incidence or prevalence of thoracic spinal pain as an entity. Estimates from pain clinics suggests 16% as a presenting complaint and a prevalence of 12%. There are no data from general practice describing the incidence of thoracic spinal pain as a presenting complaint
The natural history is unknown.
For risk factors there is only one study among male infantry recruits which found that an increased lumbar lordosis was the only predictive factor.
Aetiology
Compared to neck pain and low back pain, there has been little progress in understanding the causes and sources of thoracic spinal pain. The aetiology in most cases is unknown. The strongest evidence supports the zygapophysial joints, thoracic discs, interspinous ligaments, and potentially the costovertebral joints.
Complicating matters, pain can be referred from cervical structures (zygapophysial joints, cervical muscles, cervical discs) to the thoracic spine. (see Cervical Pain Maps)
Uncommon Causes
Disc Protrusion: This condition is distinct from discogenic pain and should only really be considered in the presence of neurological signs. It is rare with 0.5-1.8% of all surgical discs. The M:F incidence is equal, and the peak prevalence is in the 4th to 6th decades. 75% occur below T8, with the peak being T11-12. Central protrusions are more common than lateral protrusions. The prevalence of asymptomatic disc bulging is as high as 37% using MRI.
Fracture: Osteoporotic fracture has a prevalence of 0.4-0.6%. The peak sites of T7-8, T11, and L1. Normal bone densitometry and radiographs are not completely reliable. Greater deformity is correlated with more pain. Fracture should be considered in those over the age of 60.
Infection: The pre-test probability is less than 0.01% but it may persist for a long time
Malignancy: Spinal metastases are reported as being most common in the thoracic spine (T4, T11), however they are still rare. The higher rate of thoracic involvement may be due to greater number of vertebrae. Study suggests pretest probability of 0.63% similar to lumbar data. The predictive power of clinical features not available but may be similar to the lumbar spine
Inflammatory Arthritis: It is unusual to present with just thoracic pain.
Clinical Features
Pain History
Just as somatic sources of cervical spine pain can be referred to the thoracic spine, there can be somatic referred pain from thoracic spine structures to the posterior and anterior chest wall and upper limbs. The lower thoracic segments may refer to the lumbar spine and gluteal region (see Superior Cluneal Nerve Entrapment).
The pain is deep, aching and poorly localised. The spread is 0.5 segments superior to 2.5 segments inferior, which can help predict the level. It doesn't radiate further than the posterior axillary line. It also hasn't been reproduced in the arm below T1.
The so-called "T4 syndrome" with arm pain is not corroborated.
Musculoskeletal Exam
There are few data on reliability or validity. Tradition dictates using look, feel, and move. All signs are liable to errors of reliability and validity. The critical objective is to exclude red flags but examination does not do this. Specificity may be very good for trauma.
There is no causal association established between posture and pain (i.e. questionable validity). There is poor evidence for an association between posture and interscapular pain. One reliability study produced good kappa scores.
For palpation most studies indicate poor reliability and poor validity. Studies on asymptomatic patients have shown that "clinical" findings are common.
There is no research dealing with the reliability or validity of gross or segmental movement.
A negative clinical exam makes fracture unlikely.
Neurological Exam
Patients with a malignant cause do not usually have neurological deficits. In infection neuromotor deficit is a late sign.Central disc protrusion may cause spinal stenosis and compression with myelopathy. This can result in leg weakness, spasticity, ataxia, numbness, or bowel or bladder disturbance. Central disc herniation at T12-2 can cause conus medullaris syndrome which is a combination of both upper and lower motor neuron deficits.
Lateral disc protrusions may cause radicular pain and radiculopathy, for example lower quadrant pain with T12 nerve root irritation, which can mimic appendicitis or diverticulitis.
Investigations
In the presence of red flags, plain films and inflammatory markers are the first screening tests.
Plain Radiographs in the Absence of Trauma
Plain films should only be done in the setting of red flags: age >50, trauma, neurologic deficit, weight loss, suspect ankylosing spondylitis, drugs or alcohol, history of cancer, corticosteroid use, fever, no improvement after one month, and seeking compensation. Disc space narrowing is common from the 3rd decade on with equal prevalence. Zygapophysial joint degeneration is most common at C7-T1 and T11-T12. Disc calcification has a LR of 18.8 for disc protrusion. Costovertebral joint osteoarthritis has a 60% prevalence in those aged over 40. Adolescents with scheuermann's disease may or may not have pain.
Plain Radiographs following Trauma
Trauma recommendations for xray are: spinal pain or tenderness, severity score >15, fall >3m, ejection from MVA >80km/hr, altered sensorium, neurologic deficit, major injuries, age >60.
Treatment
Physical and manual therapy is based on provisional diagnosis of pain arising from particular structure or segment. It relies on the unproven hypothesis that relieving stiffness or muscle spasm will relieve pain. The therapist must reliably and validly diagnose stiffness or spasm. The evidence for effectiveness is patchy compared to the neck and low back.
Overall there is no good evidence either supporting or refuting any particular form of treatment.
If injections are being considered there are several limitations. For targeted injections, how does one reliably distinguish between pain coming from a facet joint versus a costotransverse joint versus a costovertebral joint versus a disc versus a ligament. Furthermore the joints are very small and so cannot take up much corticosteroid limiting their possible duration of action.
For medial branch blocks and medial branch radiofrequency neurotomy, the medial branches vary in their course, limiting the ability for target specificity.
