Spinal Stenosis

Abstract

Spinal stenosis is a commonly encountered problem in the cervical and lumbar spine. It can be caused by a range of pathologies and can present in different ways depending on which area of the spine is stenotic and the degree of stenosis. For example, central stenosis is more likely to cause conditions like myelopathy or bladder dysfunction, whereas neuroforaminal stenosis is more likely to cause nerve root conditions like radiculopathy. Understanding the anatomy of the spinal cord and column is critical to understanding the effects and treatments for the different types of spinal stenosis.

Cervical Spinal Stenosis

Definition

• Central canal diameter <13 mm (normal is 17 mm)

Causes

• Congenital

• Traumatic arthritis

• Degenerative arthritis

Evaluation

History

• Often asymptomatic.

• Advanced stenosis may cause cervical myelopathy, ask about clumsiness with buttons and other hand dexterity tasks.

• May also cause radiculopathy.

Physical Exam

• Neurologic exam, with special attention to myelopathy

• Check for Hoffman’s sign

• Check all reflexes

• Observe for steady gait

Imaging

• AP, lateral, flexion, extension plain radiographs of the cervical spine may show canal narrowing.

  • Measure Torg-Pavlov ratio, which is the ratio of the width of the canal to the width of the vertebral body (<0.8 is abnormal).

• MRI.

Treatment

• If asymptomatic, may observe.

• If myelopathy, perform decompression +/− fusion.

• If radiculopathy, consider injection vs. decompression +/− fusion.

• Athletes – may not participate in sports if history of neurologic symptoms, even if transient

  • Interpretation of Torg ratio is controversial.

Lumbar Spinal Stenosis

Types

• Central stenosis <100 mm² on CT scan

• Lateral recess stenosis, narrowing lateral to the dura, and medial to the pedicle

  • Usually compresses the traversing root, which is the lower nerve root, e.g., L5 at the L4–L5 level.

• Foraminal stenosis

  • Usually compresses the exiting root, which is upper root in the lumbar spine, e.g., L4 at the L4–L5 level.

Causes

• All types may be caused by bulging or herniated discs, depending on where the disc presses on the neurologic structures.

• Central stenosis may be caused by ligamentum flavum hypertrophy or degenerative spondylolisthesis.

• Lateral recess and foraminal stenosis may be caused by degenerative spondylolisthesis or arthritic facets, which can hypertrophy or form synovial cysts.

Evaluation

History

• Patients complain of “pressure” and pain in their buttocks and lower extremities.

• Neurogenic claudication – pain and weakness in the lower extremities that is worst in lumbar extension and relieved by lumbar flexion, which opens the central canal.

• May have bladder dysfunction.

Physical Examination

• Neurologic exam.

• Phalen test – extend back for 1 min, then flex forward. Exacerbation and relief of symptoms is a positive test.

• Kemp sign – radicular pain worsened by extension.

Imaging

• AP, lateral, flexion, extension plain radiographs may show degenerative disease or spondylolisthesis.

  • May see instability in flexion/extension

• MRI, though may note stenosis in asymptomatic patients.

Treatment

• Anti-inflammatories, physical therapy, and cortisone injections may improve symptoms.

• Decompression alone should be performed for persistent symptoms if conservative therapy fails or for neurologic deficits.

• Decompression and fusion should be performed if there is evidence of instability, such as in some cases of degenerative dynamic spondylolisthesis.