Spondylolisthesis

What is Spondylolisthesis

Spondylolisthesis is a degenerative disease of the lumbar spine that results in pain and functional disability. It occurs more commonly in women and is most often seen after age 40.

This disease is caused by one vertebral body slipping onto another as a result of degeneration of the facet joints and intervertebral disk. Usually, the upper vertebral body moves anteriorly relative to the vertebral body below it, which causes narrowing of the spinal canal.

This narrowing results in a relative spinal stenosis and back pain. Occasionally, the upper vertebral body slides posteriorly relative to the vertebral body below it, which compromises the neural foramina. Facet joint tropism may contribute to the development of spondylolisthesis

Spondylolisthesis occurs when the pars defect (spondylolysis) is bilateral allowing forward displacement (subluxation) of the rostral vertebra. Clinically significant spondylolisthesis (grade 2–4) is best identified on lateral radiographs, and instability can be documented during maximum flexion and extension views. It usually occurs at L5 to S1 level.

Clinically, a patient with spondylolisthesis reports back pain with lifting, twisting, or bending of the lumbar spine. Patients may state that they feel like they have “a catch in their back.” A disease of the fifth decade and beyond, patients with spondylolisthesis often report radicular pain of the lower extremity and often experience pseudoclaudication with walking. Rarely, the slippage of the vertebra is so extreme that myelopathy or cauda equina syndrome develops.

What are the Symptoms of Spondylolisthesis

Patients with spondylolisthesis report back pain with motion of the lumbar spine. Rising from a sitting to a standing position often reproduces the pain. Many patients with spondylolisthesis experience radicular symptoms that manifest on physical examination as weakness and sensory abnormality in the affected dermatomes. Often, more than one dermatome is affected. Occasionally, a patient with spondylolisthesis experiences compression of the lumbar spinal nerve roots and cauda equina, resulting in myelopathy or cauda equina syndrome. Lumbar myelopathy is most commonly due to midline herniated lumbar disk, spinal stenosis, tumor, or rarely, infection. Patients with lumbar myelopathy or cauda equina syndrome experience varying degrees of lower extremity weakness and bowel and bladder symptoms; this represents a neurosurgical emergency and should be treated as such.

How is Spondylolisthesis diagnosed?

Plain radiographs of the lumbar spine usually are sufficient to diagnose spondylolisthesis. The lateral view shows the slippage of one vertebra onto another. Magnetic resonance imaging (MRI) of the lumbar spine provides the best information regarding the contents of the lumbar spine.

MRI is highly accurate and helps identify abnormalities that may put the patient at risk of developing lumbar myelopathy, such as the trefoil spinal canal of congenital spinal stenosis. In patients who cannot undergo MRI, such as patients with pacemakers, computed tomography (CT) and myelography are reasonable second choices. Radionucleotide bone scanning and plain radiographs are indicated if fracture or bony abnormality, such as metastatic disease, is being considered.

Although this testing provides useful neuroanatomical information, electromyography and nerve conduction velocity testing provide neurophysiological information that can delineate the actual status of each individual nerve root and the lumbar plexus.

Screening laboratory tests, consisting of complete blood cell count, erythrocyte sedimentation rate, and automated blood chemistry testing, should be performed if the diagnosis of spondylolisthesis is in question.

Differential Diagnosis

Spondylolisthesis is a radiographic diagnosis that is supported by a combination of clinical history, physical examination, radiography, and MRI. Pain syndromes that may mimic spondylolisthesis include lumbar radiculopathy; low back strain; lumbar bursitis; lumbar fibromyositis; inflammatory arthritis; and disorders of the lumbar spinal cord, roots, plexus, and nerves. MRI of the lumbar spine should be performed in all patients thought to have spondylolisthesis. Screening laboratory tests consisting of complete blood cell count, erythrocyte sedimentation rate, antinuclear antibody testing, human leukocyte antigen (HLA), B-27 antigen screening, and automated blood chemistry testing should be performed if the diagnosis of spondylolisthesis is in question to help rule out other causes of pain.

Treatment

Spondylolisthesis is best treated with a multimodality approach. Physical therapy, including flexion exercises, heat modalities, and deep sedative massage, combined with nonsteroidal antiinflammatory drugs (NSAIDs) and skeletal muscle relaxants, represents a reasonable starting point. The addition of steroid epidural nerve blocks is a reasonable next step.

Caudal or lumbar epidural blocks with a local anesthetic and steroid have been shown to be extremely effective in the treatment of pain secondary to spondylolisthesis.

Underlying sleep disturbance and depression are best treated with a tricyclic antidepressant compound, such as nortriptyline, which can be started at a single bedtime dose of 25 mg.

Complications

Failure to diagnose spondylolisthesis accurately may put the patient at risk of developing lumbar myelopathy, which, if untreated, may progress to paraparesis or paraplegia.

Electromyography helps distinguish plexopathy from radiculopathy and helps identify coexistent entrapment neuropathy, such as tarsal tunnel syndrome, which can confuse the diagnosis.

Clinical Pearls

The diagnosis of spondylolisthesis should be considered in any patient reporting back pain, radicular pain, or both, or symptoms of pseudoclaudication.

Patients with symptoms of myelopathy should undergo MRI on an urgent basis. Physical therapy may help prevent recurrent episodes of pain, but, ultimately, surgical stabilization of the affected segments may be required.