Practice Essentials
Thoracic disc injury, first described in 1838, is an uncommon site of injury owing to the stabilizing effect of the rib cage. [1] The similarity of symptoms to lumbar disc herniation makes the diagnosis of a thoracic disc injury difficult, [2, 3, 4, 5, 6] but the process tends to be self-limiting and rarely requires surgical intervention. [4]
The progressive wear and tear that is noted with degenerative disc disease increases the risk of injury via trauma. Contributing factors to disc injury include the following:
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Age
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Trauma
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Smoking
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Obesity
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Sedentary lifestyle
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Poor physical fitness
(See also the articles Disk Herniation and Thoracic Spine, Trauma [in the Radiology section], Thoracic Discogenic Pain Syndrome [in the Sports Medicine section], Lumbar Disc Disease [in the Neurosurgery section], and Herniated Nucleus Pulposus [in the Orthopedic Surgery section], as well as Return to Contact Sports After Spinal Surgery and Thoracoscopic Spine Surgery for Decompression and Stabilization of the Anterolateral Thoracic and Lumbar Spine on Medscape.)
For patient education resources from eMedicineHealth, see Upper Back Pain and the Pain Management Center.
Epidemiology
United States statistics
The incidence of thoracic disc injuries is 1 in 1 million persons per year, and these injuries account for 0.25-0.75% of all disc herniations. [7]
Functional Anatomy
The thoracic discs are unusually stable compared with the cervical and lumbar discs. The stability of the thoracic discs is secondary to the surrounding rib cage, with the stabilizing effect of the rib articulations. However, the blood supply of the thoracic spine is more tenuous than the cervical and lumbar spine, especially at the T4-T9 watershed area, which is more prone to ischemic injury.
Sport-Specific Biomechanics
The facet orientation in the thoracic spine is vertical, with a slight medial angulation. This orientation allows for easier lateral bending and rotation versus pure bending. Biomechanical studies have shown that intervertebral discs are at the highest risk of injury when combined with bending and torsional forces. Therefore, the thoracic spine discs are at a decreased risk of injury because of the decreased bending potential in this segment of the spine.
The spinal cord-to-canal ratio (the ratio of the cross-sectional area of the cord to the cross-sectional area of the spinal canal) is 40% in the thoracic spine versus 25% in the cervical spine. The thoracic spine is also naturally kyphotic. These 2 facts make the thoracic spine more sensitive to cord compression from disc herniation.
Prognosis
Thoracic disc disease is usually self-limiting; return to play depends on the success of conservative management in controlling the pain/radiculopathy that is associated with the disc herniation.
Salazar et al reported the case of an older man who had a spontaneous resolution of a calcified thoracic disc herniation. [8]
Complications
The most serious but rare complication of thoracic disc disease is myelopathy. Myelopathic features, including hyperreflexia, weakness, and bowel/bladder dysfunction, may not improve after surgical decompression. Worsening myelopathic findings are an absolute indication for surgical decompression.
