Thoracic Disk Disease: Diagnosis and Treatment

Vanichkachorn, JS and Vaccaro, AR.  J Am Acad Orthop Surg 2000; 8: 159-169 

Abstracted by Kasey Miller PT, DPT, COMT Kansas City, Missouri – Fellowship Candidate, IAOM-US Fellowship Program & Jean-Michel Brismée, PT, ScD, Fellowship Director, IAOM-US Fellowship program 

Research:  The purpose of this article was to outline how to diagnose thoracic disk disease as well as discuss the associated treatments, whether that is conservative treatment or a surgical approach. 

Methods: The authors collected several articles about thoracic disk disease and summarized a few main points. They began discussing the anatomical differences between the thoracic spine versus the cervical and lumbar spine and then followed by the history of thoracic disk disease as well as the epidemiology and incidence of thoracic spine discogenic lesions. After the background information was discussed, the authors detailed the clinical presentation and the patterns of thoracic disk herniation. And lastly, they discussed the most successful nonoperative treatment techniques and when surgical treatment is necessary. 

Results: 

Anatomy and Biomechanics: The thoracic spine is a rigid structure between the mobile cervical and lumbar regions and its unique stability is the result of the surrounding thoracic ribcage.1 The facet of T1 through T10 vertebral bodies are generally oriented vertically, with slight medial angulation in the coronal plane, which provides stability during flexion and extension but allows greater movement in rotation. Due to the increased mobility allowed through the facet joints into rotation, the thoracic intervertebral disks are most at risk for injury during this rotation. The spinal cord is smallest in diameter in the thoracic region as the spinal cord-canal ratio is approximately 40% because of the small canal size, compared with 25% in the cervical region. Furthermore, the natural thoracic spine kyphosis causes the spinal cord to lie directly on the posterior longitudinal ligament and the posterior aspects of both the vertebral bodies and the disks.

Epidemiology: Out of 90 asymptomatic individual’s magnetic resonance images (MRI), 73% were found to display thoracic disk abnormalities. Of these individuals, 37% had herniations and 29% showed deformation of the cord. They also noted that small herniations (>10% of canal compromise) either remained unchanged or increased in size, while larger herniations (>20% canal compromise) tended to get smaller over time. They concluded that asymptomatic thoracic disk herniations exhibit relatively little change in size over time and rarely become symptomatic. It has been estimated that the incidence of symptomatic herniation is approximately 1 in 1 million persons per year.2 This represents approximately 0.25% to 0.75% of the total incidence of symptomatic spinal disc herniations each year. The occurrence of symptomatic thoracic disk disease is greatest between the fourth and sixth decades of age, with peak incidence in the fifth decade. Slightly more occurrence in males than female and between 33% and 50% of patients of patients report a history of trauma or significant physical exertion prior to the onset of symptoms.3

Clinical Presentation: Due to the thoracic spine being a very popular region for both spine-related and non-spine related conditions, the clinician should examine the entire patient to be able to rule out all other possible causes for symptoms before pursuing the diagnosis of thoracic disk lesion. Patients with symptomatic thoracic disk herniations can be divided into three groups: axial pain, radicular pain, myelopathy. 

Axial pain, is usually localized to the middle to lower thoracic region, but in some circumstances may radiate to the middle to lower lumbar spine. Patients in this category will characterize their pain as mild to moderate intensity. 

Radicular pain is often described as anterior-chest bandlike discomfort in a dermatomal distribution, and is the second type of presentation. The T10 dermatomal level is the most commonly reported distribution. Radicular pain is more common in upper thoracic and lateral disk herniations and is often reported in combination with some amount of axial pain. Patients in this category will display, more often sensory changes, such as parethesias in a dermatomal or radicular distribution. 

Myelopathy is the third category of thoracic disk lesions and is the most serious. In this category, patients will report muscle weakness along with paresthesia and axial pain. A positive Babinski sign, sustained clonus, wide-based gait, and spasticity are all signs of myelopathy and indicate marked thoracic cord compression. Bowel and bladder dysfunction, which are seen in approximately 15% to 20% of patients with symptomatic thoracic disk herniations can be reported.

High thoracic disc herniations (T2-5) may be rarer but can mimic cervical disk disease and present with symptoms of upper arm pain, radiculopathy, and paresthesia. It is important to differentiate between the cervical spine versus the thoracic spine. The cervical compression test (Figure 1) is more indicative of a cervical origin of the patient’s upper extremity symptoms than of thoracic herniation. When myelopathy is present as indicated by hyperreflexia in the lower extremities, but the Hoffman sign is negative, the source of patient’s symptoms is likely below the cervical spine. 

Differentiation between lumbar and thoracic causation requires further testing in a similar fashion than when trying to diagnose if the pain is coming from the thoracic or cervical spine when the patient has upper extremity symptoms. The Romberg sign, the inability to stand upright with eyes closed, is very useful for detecting subtle changes in proprioception and early myelopathy, which may be helpful in determining thoracic or lumbar origin. Posterior spinal elements palpation can also be helpful in differentiating between thoracic and lumbar involvement as you may be able to localize the pain or recreate the radicular symptoms. Examination of the muscles which are innervated by thoracic nerve roots such as having your patient perform a partial sit-up is also helpful. Asymmetric contraction of the innervated rectus abdominis muscle may indicate a disorder arising from the thoracic spinal cord. Testing of the superficial abdominal reflexes can indicate an upper-motor-neural lesion arising from this region. The superficial cremasteric reflex demonstrates the integrity of the efferent T12 and afferent L1-2 neurologic levels (Figure 2). And lastly, identification of the sensory level is extremely important in evaluating thoracic cord compression. The presence of dysesthesias in a radicular pattern should also be noted and can help identify the level of dysfunction whether in the thoracic or lumbar region. 

Nonoperative Treatment: Conservative treatment depends on which category the patient falls in. 

In patients with predominantly axial pain without significant radicular symptoms, treatment should consist of activity modification and non-steroidal anti-inflammatory drugs. 

In those with significant radicular symptoms on presentation, a regimen of nonoperative modalities such as corticosteroid injections or oral steroids should be considered. The steroid injection will be placed into the intercostal nerves and can help as a therapeutic as well as a diagnostic tool. 

Those who present with myelopathy or a progressive neurological deficit are immediately candidates for surgical intervention. However, a complete medical workup and careful preoperative planning is required before surgery is performed. If clinicians can help those with myelopathy within the first few weeks of treatment, surgery may be avoided but this needs to be closely observed. 

Within each category, this article emphasizes that physical therapy is vital for improvement. The authors go into more detail and report physical therapy in the acute pain stage should consist of primarily passive modalities such as heat, ice, manipulation, and ultrasound to provide patient comfort. Once the patient is no longer in the acute stage, therapy should progress and become more active and include range-of-motion, flexibility, and strengthening exercises. More specifically, hyperextension exercises are beneficial and should be emphasized by the therapist (Figure 3). After the resolution of the patient’s symptoms, a home therapy program that includes aerobic conditioning should be implemented for prevention of recurrent symptoms. 

Figure 3: Hyperextension exercises are used for thoracic disk categories to help with symptoms’ centralization, or reduction of radicular symptoms. However, the study does not give dosage of exercises to be performed.Surgical Approach: When the decision for surgical excision of a thoracic disk herniation has been made, there are a few ways this can be performed. The authors go into great detail about three specific approaches: anterior, posterior, and lateral. Anterior approaches include the more common transthoracic and the less common transsternal approaches. Posterior approaches include laminectomy and pediculofacetectomy. Lateral approaches include costotransversectomy and lateral extracavitary exposure. Each approach has its own particular advantages and disadvantages, which must be carefully considered when selecting the procedure to be performed. 

 

IAOM-US Comments:   The management of the herniated thoracic disc remains a difficult task due to the multiple internal structures that can refer pain into the thoracic region as well as the 70% incidence of bone metastases in patients with cancer.5 However, before the treatment approach that the IAOM-US uses for thoracic disk lesions is explained, clinicians need to understand how to properly diagnose if the thoracic disk is involved. The IAOM-US uses a specific order of tests, the basic clinical examination, to identify what structure in the body is causing pain.  But how do clinicians know if the disk is involved? Each structure that causes pain will present with a specific pattern throughout your basic clinical examination. So, what is the pattern for the disk? Before further explaining the specific pattern, that disc involvement follows in your clinical exam, it is important to specify there are different types of disk injuries. As this study recognizes the categories as axial pain, radiculopathy, and myelopathy, the IAOM-US recognizes the thoracic disk categories as internal disc disruption, protrusion, and prolapse. 

Those with thoracic spine internal disc disruption present with pain that can be midline, parasagittal, and even ventral. They will report pain with twisting but also with prolonged sitting and physical labor. The most painful movement is axial rotation and it can sometime be worse with added cervical flexion at the end of the thoracic rotation. Their pain will not worsen with added 3-Dimensional testing and imaging such as MRI will often be negative.6

The thoracic disc protrusion is similar to that of internal disc disruption but is more likely to display radiating pain. Therefore, if a patient presents with a protrusion the clinician will notice midline, band-form, parasagittal, or even ventral pain with radiating symptoms in a line around the thoracic wall and can travel under the pectoral muscle or breast. They, along with the internal disc disruption, will have pain with twisting that can increase with cervical flexion but they will also have a positive thoracic slump test. Their pain will not worsen with 3-Dimensional testing but an MRI may pick up a small protrusion in the thoracic spine.6

The third category of disk injuries, thoracic disk prolapse, may be the most severe but is also the least likely to occur. Reason being, the thoracic disks are very thin compared to that of the cervical and lumbar spine. The cervical disk to vertebral body ratio is 1:4, lumbar disk is 1:3, while the thoracic disk can vary from 1:5 to 1:7.7 Another reason why prolapses are less common is the natural abutment the disc has to the corresponding rib.6 This increases the stability of the disc and limits the ability of the disc material to migrate in a posterolateral direction. However, thoracic disk prolapses can occur and the clinician will notice similar findings to that of a thoracic disc protrusion but the patient will also report positive spinal cord signs. These signs can include L’Hermitte’s signs, spastic gait, cold feet, and hyperreflexia, the thoracic disc prolapse category can correlate with the myelopathy category that Vanichkachorn and Vaccaro described. 

Once clinicians have identified the thoracic disk is involved, they can create a more specific plan of care with disk related treatments. Several techniques that are very effective in the treatment of a thoracic disc lesion are soft tissue mobilization and axial separation. 

Soft tissue mobilization allows the clinician to relax the muscles surrounding the injured area, which will then allow more separation during axial separation. Some of the musculature that can be targeted to help relieve increased pressure to the thoracic disk are the rotatory muscles and erector spinae. Soft tissue techniques should always be pain free and can include the performance into flexion, extension and/or a pain free rotation (Figure 4). 

Axial separation is a great technique in order to allow decompression to the disk as well as tighten the annular fibers of the injured disk, which can help reduce the size of the protrusion that has occurred using a vacuum like phenomenon.8 Axial separation can be performed in two different ways: seated, or sidelying.  Seated axial separation is best suited for those patients that report increased pain with both right and left axial rotation. The clinician can preposition their patient into the position of comfort such as flexion, sidebending, and rotation prior to applying the separation in order to reduce their pain as much as possible. Once the clinician has the patient in the most comfortable position, he/she will then provide a traction force to help alleviate the disk irritation (Figure 5). If the patient only has pain while rotating a specific direction, sidelying axial separation is best suited. Depending on symptoms’ longevity, severity of symptoms, and size of patient, the clinician may perform the sidelying axial separation technique with one, two, or three people to achieve the goal of this technique which is to resolve all symptoms. Prior to performing the technique, clinicians ensure they place the patient with the painful side up and then rotate their thoracic spine into the direction that was not painful. For example, if the patient has pain on their right side and has pain with right rotation, the therapist will position the patient lying on their left side and rotate them into a left rotated position. It will be in this position of comfort that the therapist applies the separation (Figure 6). 

Once the thoracic disk irritation has calmed down, secondary or indirect treatments need to be implemented. One of the most prominent dysfunctions that are extremely common with thoracic disk irritation is rib pathology. However, prior to addressing rib dysfunction around the region of disk irritation, the clinician should ensure the disc has started its healing process and is not irritable. This is because of the natural abutment the disc has to the corresponding rib. If the clinician begins to mobilize the rib that is attached to a disk that is irritated, this rib can pull and tug at that injured disc, disrupting the healing environment and prolonging their recovery. 

While Vanichkachorn and Vaccaro did a very good job of categorizing the different disc pathologies, the outline of conservative treatment options was lacking. With the use of the IAOM-US treatment techniques and identifying the pain generator based off their specific pattern, the clinician should feel confident in treating any patient with a thoracic disk pathology. 

Figure 4: Pre-positioning during soft tissue mobilization can be helpful to reduce pressure caused by hypertonic muscles as well as prepare the patient for axial separation into a specific direction. The images above indicate neutral (left), flexed position (right), and extended position (bottom).

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