Thoracic spinal stenosis

Thoracic Spinal Stenosis

Thoracic spinal stenosis is narrowing of the spinal canal in the middle portion of the spine. The thoracic spine consists of 12 vertebrae, labeled T1 through T12, and extends from the base of the neck to the upper lower back.

Unlike the lumbar spine, the thoracic spinal canal contains the spinal cord. Because of this, significant thoracic spinal stenosis can affect not only local nerves but also the spinal cord itself. When spinal cord compression causes neurologic problems, the condition is called thoracic myelopathy.

Thoracic spinal stenosis is less common than cervical or lumbar spinal stenosis, but it can cause significant problems with walking, balance, strength, and sensation when the spinal cord becomes compressed.

What Causes Thoracic Spinal Stenosis?

Thoracic spinal stenosis can develop from several different conditions.

Common causes include:

  • Degenerative arthritis
  • Bone spurs
  • Thickening of the ligamentum flavum
  • Ossification of the ligamentum flavum
  • Ossification of the posterior longitudinal ligament (OPLL)
  • Thoracic disc herniation
  • Enlarged facet joints
  • Congenitally narrow spinal canal
  • Previous spine surgery
  • Spinal deformity
  • Fracture
  • Tumor or other lesions within or near the spinal canal

More than one abnormality may contribute to narrowing in the same patient.

Symptoms of Thoracic Spinal Stenosis

Symptoms depend on the location and severity of the narrowing.

Some patients have significant narrowing on imaging but few symptoms. Others develop progressive neurologic problems as pressure on the spinal cord increases.

Possible symptoms include:

  • Mid-back pain
  • Numbness or tingling around the chest or abdomen
  • Numbness or tingling in the legs
  • Leg weakness
  • Heaviness of the legs
  • Leg stiffness
  • Difficulty walking
  • Poor balance
  • Frequent falls
  • Loss of coordination
  • Abnormal sensation below the level of compression

Severe spinal cord compression may eventually affect bowel or bladder function.

Pain is not always the main symptom. Some patients primarily notice that their legs feel weak, stiff, heavy, or difficult to control.

Thoracic Myelopathy

Myelopathy means abnormal function of the spinal cord.

Thoracic spinal stenosis can gradually compress the spinal cord and produce thoracic myelopathy.

Signs and symptoms may include:

  • Difficulty walking
  • A stiff or unsteady gait
  • Leg weakness
  • Leg numbness
  • Increased muscle tone
  • Poor balance
  • Abnormal reflexes
  • Difficulty coordinating leg movements
  • Bowel or bladder dysfunction in advanced cases

Unlike compression of a single nerve root, spinal cord compression may affect both legs and multiple neurologic functions at the same time.

Progressive myelopathy should be evaluated promptly.

What Is Ossification of the Ligamentum Flavum?

The ligamentum flavum is a ligament located along the back portion of the spinal canal.

In some patients, this ligament becomes progressively thickened, calcified, and eventually replaced by bone. This is called ossification of the ligamentum flavum, or OLF.

OLF has a strong tendency to occur in the thoracic spine and is an important cause of thoracic spinal stenosis and myelopathy.

The newly formed bone grows inward from the back of the spinal canal and can gradually compress the spinal cord.

OLF is often most prominent in the lower thoracic spine near the transition between the thoracic and lumbar regions.

What Is OPLL?

The posterior longitudinal ligament runs along the back surface of the vertebral bodies inside the spinal canal.

Ossification of the posterior longitudinal ligament, or OPLL, occurs when portions of this ligament become thickened and replaced by bone.

OPLL is more commonly associated with the cervical spine, but it can also occur in the thoracic spine.

Unlike ossification of the ligamentum flavum, which compresses the spinal cord from behind, thoracic OPLL usually produces compression from the front of the spinal cord.

Thoracic OPLL can be particularly challenging because the spinal cord may become compressed between ossified structures in front of the spinal cord and the posterior elements behind it.

How Is Thoracic Spinal Stenosis Diagnosed?

Diagnosis usually begins with a detailed history and neurologic examination.

The physician may evaluate:

  • Leg strength
  • Sensation
  • Reflexes
  • Balance
  • Walking pattern
  • Coordination
  • Signs of spinal cord dysfunction

Imaging is then used to determine the source and severity of the compression.

MRI

MRI is usually the most important initial imaging study.

MRI can demonstrate:

  • The spinal cord
  • Degree of spinal canal narrowing
  • Disc herniations
  • Ligament thickening
  • Spinal cord compression
  • Tumors or other soft-tissue abnormalities

MRI may also show abnormal signal within the spinal cord, which can indicate injury or stress caused by chronic compression.

CT Scan

CT provides excellent detail of bone and calcified structures.

It is particularly valuable when thoracic stenosis may be caused by:

  • Ossification of the ligamentum flavum
  • OPLL
  • Bone spurs
  • Facet joint enlargement
  • Fractures
  • Previous spinal instrumentation

CT can also help determine how extensively an ossified ligament has become attached to the dura surrounding the spinal cord.

X-rays

Standing X-rays may be useful for evaluating:

  • Spinal alignment
  • Kyphosis
  • Scoliosis
  • Previous spinal fusion
  • Instability
  • Fractures

In complex cases, several different imaging studies may be necessary before deciding on treatment.

Nonsurgical Treatment

Not every patient with thoracic spinal stenosis requires surgery.

Patients with mild symptoms and no significant spinal cord dysfunction may sometimes be treated with observation and nonsurgical care.

Treatment may include:

  • Activity modification
  • Physical therapy
  • Anti-inflammatory medications
  • Pain medications
  • Treatment of osteoporosis when appropriate
  • Periodic neurologic examinations
  • Follow-up imaging

Nonsurgical treatments may help control pain, but they generally cannot physically enlarge a spinal canal that has become severely narrowed by bone or ossified ligaments.

For this reason, patients with progressive spinal cord symptoms are treated differently from patients who have pain alone.

When Is Surgery Recommended?

Surgery is more likely to be recommended when thoracic spinal stenosis causes significant spinal cord compression or progressive neurologic problems.

Indications may include:

  • Progressive difficulty walking
  • Leg weakness
  • Worsening balance
  • Frequent falls
  • Progressive numbness
  • Thoracic myelopathy
  • Significant spinal cord compression
  • Neurologic deterioration
  • Bowel or bladder dysfunction related to spinal cord compression

The purpose of surgery is to create more space for the spinal cord and prevent additional neurologic injury.

The amount of neurologic recovery after surgery varies. In general, surgery is often intended both to improve symptoms when possible and to prevent further deterioration.

Thoracic Laminectomy

A thoracic laminectomy is one of the most common operations used to treat thoracic spinal stenosis.

The lamina forms the back portion of the spinal canal.

During a laminectomy, part or all of the lamina is removed to create additional space for the spinal cord.

If thickened or ossified ligamentum flavum is contributing to the stenosis, it may also be carefully removed during the procedure.

Removal of Ossified Ligamentum Flavum

When OLF is causing thoracic stenosis, decompression may require careful removal of the abnormal bone behind the spinal cord.

This can be more technically demanding than a routine laminectomy because the ossified ligament may become firmly attached to the dura, which is the protective covering around the spinal cord.

In some cases, the ligament and dura may become partially fused together.

Careful surgical planning is therefore important.

Is Spinal Fusion Always Necessary?

No.

Some patients can undergo thoracic decompression without spinal fusion.

Fusion may be recommended when there is concern that decompression could create or worsen instability.

Factors that may favor fusion include:

  • Preexisting spinal instability
  • Significant spinal deformity
  • Extensive removal of the facet joints
  • Multilevel decompression
  • Previous spine surgery
  • Progressive kyphosis
  • Need for extensive bone removal

When fusion is required, screws and rods are typically used to stabilize the spine while bone grows between the vertebrae.

Surgery for Thoracic OPLL

Thoracic OPLL can be more difficult to treat because the compression is located in front of the spinal cord.

Depending on the location and severity of the disease, surgical options may include:

  • Posterior decompression
  • Posterior decompression and fusion
  • More extensive circumferential decompression
  • Direct removal or treatment of the ossified ligament in selected patients

The optimal treatment depends on spinal alignment, the number of affected levels, the amount of spinal cord compression, and the location and shape of the OPLL.

Risks of Thoracic Decompression Surgery

Because surgery is performed around the spinal cord, thoracic decompression requires careful technique.

Potential risks include:

  • Neurologic injury
  • Weakness or paralysis
  • Dural tear
  • Cerebrospinal fluid leak
  • Infection
  • Bleeding
  • Blood clot
  • Failure to completely relieve symptoms
  • Spinal instability
  • Need for additional surgery

The individual risk varies considerably depending on the cause and severity of the stenosis.

Recovery After Thoracic Stenosis Surgery

Recovery depends on the extent of surgery and the severity of the neurologic problems present before treatment.

Patients are typically encouraged to begin walking relatively soon after surgery.

Physical therapy may be used to improve:

  • Strength
  • Balance
  • Walking
  • Coordination
  • Endurance

Recovery of spinal cord function may occur gradually over several months.

Patients who have had severe or long-standing myelopathy may have some permanent neurologic symptoms even after the spinal cord has been successfully decompressed.

For this reason, progressive weakness or walking difficulty should generally not be ignored.

When Should Thoracic Spinal Stenosis Be Evaluated Urgently?

Patients should seek prompt medical evaluation when symptoms suggest worsening spinal cord dysfunction.

Concerning symptoms include:

  • New or progressive leg weakness
  • Rapidly worsening difficulty walking
  • Frequent falls
  • Increasing numbness in both legs
  • Loss of coordination
  • New bowel or bladder dysfunction

These symptoms may indicate significant spinal cord compression.

Outlook

Thoracic spinal stenosis is uncommon, but it can become a serious condition when it begins to interfere with spinal cord function.

The goal of treatment is not simply to address what is seen on an MRI or CT scan. Treatment should be based on the combination of:

  • Symptoms
  • Neurologic examination
  • Severity of spinal cord compression
  • Spinal alignment
  • Underlying cause of the stenosis
  • Progression over time

Patients with mild, stable disease may sometimes be monitored. Patients with progressive thoracic myelopathy often benefit from surgical decompression before severe spinal cord dysfunction becomes permanent.

Related Topics

  • Thoracic Myelopathy
  • Ossification of the Ligamentum Flavum
  • OPLL
  • Thoracic Disc Herniation
  • Thoracic Foraminal Stenosis
  • Thoracic Spinal Instability
  • Thoracic Laminectomy
  • Thoracic Spinal Fusion
  • Thoracic Pedicle Screw Instrumentation