Thoracic Myelopathy

Overview

Thoracic myelopathy is a clinical syndrome caused by dysfunction of the spinal cord within the thoracic spine, the segment running from T1 to T12. Unlike the more mobile cervical and lumbar regions, the thoracic spine is relatively rigid, which partly explains why myelopathy here is less common than in the neck. However, the anatomy is unforgiving: the thoracic spinal canal is comparatively narrow, the cord fills a large proportion of the available space, and the segmental blood supply is sparse, leaving a vascular watershed zone in the mid-thoracic region that is especially vulnerable to compression.

When something compresses the thoracic cord, it disrupts both the long ascending sensory tracts and the descending corticospinal pathways. The result is an upper motor neuron syndrome affecting the lower body, meaning the legs, not the arms, are involved, which helps distinguish a thoracic problem from a cervical one. Thoracic myelopathy typically presents in middle-aged and older adults, though the specific cause shapes the demographic pattern.

What causes it

Several structural problems can compress or injure the thoracic cord. The most common are:

• Thoracic disc herniation: often involving a calcified disc, occurring most frequently in the lower thoracic segments and sometimes linked to disc degeneration or prior trauma.
• Ossification of the ligamentum flavum: a hardening of the ligament at the back of the spinal canal, encountered more often in East Asian populations and typically affecting patients in their fifties and sixties.
• Ossification of the posterior longitudinal ligament: bone formation along the front of the spinal canal, also more prevalent in East Asian populations.
• Degenerative spondylosis with canal stenosis: progressive narrowing from disc-space collapse, bone spurs, and thickened ligament.
• Space-occupying lesions: tumors, epidural abscess, or epidural hematoma that physically displace the cord.

Less frequently, intrinsic cord pathology, such as demyelinating disease, spinal cord infarction, or transverse myelitis, can produce a similar clinical picture without external compression. Additional risk factors include diffuse idiopathic skeletal hyperostosis, systemic conditions predisposing to infection or metastatic disease, anticoagulation (which raises the risk of spontaneous epidural hematoma), and prior spinal surgery or radiation.

Symptoms and warning signs

Patients with thoracic myelopathy most commonly report a gradual worsening of gait, lower limb weakness, stiffness, and a sense of imbalance. A band-like tightness, pressure, or dysesthesia encircling the chest or abdomen (the "girdle sign") is characteristic and corresponds to the sensory level at the site of compression. On examination, spasticity, overactive reflexes, clonus, and an upgoing plantar response (Babinski sign) in the legs are typical findings; upper limb function is generally preserved, which helps localize the lesion to the thoracic cord rather than the cervical cord.

As the condition advances, bowel dysfunction, bladder dysfunction, and sexual dysfunction may emerge. The natural history is often one of stepwise or gradual deterioration, though acute worsening can occur.

Certain presentations require urgent evaluation and should not be managed with a "wait and see" approach:

• Rapidly progressive myelopathy or acute neurologic deterioration
• New bowel or bladder dysfunction: this represents a potential surgical emergency requiring immediate imaging
• Fever with severe localized back pain and elevated inflammatory markers, suggesting spinal epidural abscess
• Constitutional symptoms, night pain, or known primary cancer, suggesting spinal malignancy

How it's diagnosed

Diagnosis depends on correlating the clinical syndrome with imaging. MRI of the entire thoracic spine is the investigation of choice. It shows the site and degree of cord compression, intrinsic cord signal changes, and any associated soft-tissue pathology. Increased signal on T2-weighted images within the cord indicates edema, gliosis, or myelomalacia, which often reflects more established injury. Because the thoracic cord can be difficult to localize clinically, imaging the full spine is prudent, and cervical pathology should be excluded when the picture is ambiguous.

CT scanning complements MRI by characterizing calcified disc herniations and ossified ligaments in detail and guides surgical planning. Plain radiographs assess overall spinal alignment, deformity, and instability.

When infection or malignancy is suspected, contrast-enhanced imaging, inflammatory markers, blood cultures, and biopsy where appropriate are added to the evaluation. As with all spinal imaging, findings must be interpreted alongside the clinical history and examination. Asymptomatic compression is not uncommon, and intrinsic cord disorders can mimic compressive disease.

Treatment options

Management is guided by the underlying cause, the severity of deficit, and whether symptoms are stable or progressing.

Observation and conservative care may be appropriate for mild or non-progressive symptoms in early degenerative disease. This typically includes activity modification, physical therapy focused on gait and strength, and close monitoring for any change in neurologic status. There are no medications that reverse cord compression, but management of spasticity and pain can improve quality of life.

Infectious causes require urgent surgical decompression and drainage combined with targeted antibiotic therapy. Malignant cord compression is managed through a combination of surgery, radiation, and oncologic treatment guided by tumor type and overall prognosis.

For most patients with established compressive myelopathy and significant deficits, conservative measures are unlikely to restore cord function. Surgical decompression is generally necessary to halt deterioration.

When surgery is considered

Surgery is typically recommended when compressive thoracic myelopathy has produced significant neurologic deficits, or when symptoms are clearly progressive. Because conservative care cannot reverse existing cord dysfunction, delaying surgery in the setting of worsening deficits risks permanent neurologic injury. Outcomes are best when decompression is performed before severe or long-standing deficits have developed.

The surgical approach is individualized to the anatomy and cause of compression:

• Posterior decompression (with or without instrumented fusion) is used for ossified ligamentum flavum and other dorsal compressive lesions, where the cord can be safely decompressed from behind.
• Anterior (transthoracic) or posterolateral (costotransversectomy/lateral extracavitary) approaches are favored for calcified central disc herniations and ventral ossification of the posterior longitudinal ligament, where working from behind would require retracting the spinal cord.

Emergency presentation (acute cord compression, spinal epidural abscess, or rapidly deteriorating neurologic function) requires immediate surgical evaluation without delay.