Patients who have spondylolisthesis of any kind are at risk for developing pain related to neurologic encroachment. At the level of the cauda equina, the pain can be categorized as either radiculopathy or neurogenic claudication. Low-grade isthmic spondylolisthesis generally causes a radiculopathy of the exiting nerve root [6, 7], whereas high-grade isthmic spondylolisthesis can also cause central stenosis, leading to a radiculopathy of the traversing nerve or neurogenic claudication. For lumbar degenerative spondylolisthesis, the most commonly affected neurologic structure is the traversing nerve root in the subarticular zone, but these patients may also have central stenosis that leads to neurogenic claudication. Spine care providers must have a thorough knowledge of the specific areas of neurologic impingement in order to effectively guide operative or nonoperative treatment for patients with spondylolisthesis.

Spinal cord level spondylolisthesis is most often found in the cervical spine. These patients can have radicular symptoms but also may have myelopathy from compression of the spinal cord in a static or dynamic fashion (Fig. 3.2). The pain from a radiculopathy in these patients can be very debilitating, whereas the pain arising from compression of the spinal cord and myelopathy may be less severe. Pain from myelopathy can manifest as upper extremity dysesthesia. Although this can be bothersome, this type of pain generated from compression of the spinal cord is not nearly as dangerous as the dysdiadochokinesia, ataxia, and bladder/bowel incontinence that can arise from myelopathy. Figure 3.3 demonstrates how spondylolisthesis in the cervical spine can lead to spinal cord compression and myelopathy. In summary, pain or symptomatology arising from neurologic compression can occur in all types of spondylolisthesis and must be addressed in any treatment algorithm.

Patients with spondylolisthesis in the cervical and lumbar spine can have multiple pain generators. The intervertebral disc, facet joints, or neurologic compression are common pain sources for patients with spondylolisthesis. These pain sources can also be present in other spinal pathologies. Providers must consider all potential pain generators in patients with spondylolisthesis in order to effectively guide treatment.

For patients with isthmic spondylolisthesis, pars interarticularis pathology can be a source of pain. It is generally accepted that there are nerve endings at the site of the defect in the pars interarticularis. These nerve endings transmit painful stimuli when there is abnormal motion or stress at the site of the defect. For the patient with an isthmic spondylolisthesis, pain from a pars interarticularis defect (a type of fracture nonunion) may manifest as pain in the paravertebral area and be associated primarily with extension [8]. Because of its proximity to the facet joint, the symptoms from a painful pars interarticularis defect may overlap with the symptoms from a painful facet joint.

The peer-reviewed evidence for the pars interarticularis as a pain generator is sparse. The best evidence in the current literature that supports the pars as a pain generator comes from clinical series in which patients had a positive diagnostic bupivacaine injection and were then treated with a pars repair. Wu et al. [9] reported on a retrospective series on 93 patients who had positive diagnostic injections with bupivacaine. After direct repair of the pars defect, 85 patients had good or excellent results [9]. A more recent, smaller series by Karatas et al. [10] reported on 16 patients who were treated with 2 different pars repair techniques. All patients received diagnostic bupivacaine injections. There were 14/16 patients who achieved good or excellent results following pars repair [10]. Successful outcome following repair of a pars defect after using a positive diagnostic injection as a criteria gives this diagnostic test some credibility. Furthermore, these studies prove that the pars interarticularis can be an isolated pain generator in isthmic spondylolisthesis in those patients without significant anterolisthesis or disc degeneration. While others have purported the use of corticosteroid and bupivacaine injections into the pars interarticularis [8], there is no strong literature to date that supports this treatment modality.

In the last 10 years, a large body of literature has demonstrated the importance of lumbopelvic parameters in the treatment of pediatric and adult scoliosis patients. The concept of lumbopelvic balance has also been applied to patients with spondylolisthesis. In contradistinction to scoliosis, the sagittal malalignment in spondylolisthesis originates from a more focal pathology, typically at one level. Spinopelvic alignment is most relevant to those with isthmic spondylolisthesis, but emerging theory has purported a greater impact in patients with degenerative spondylolisthesis. Indeed, any anterolisthesis can lead to positive sagittal balance. Those patients with dysplastic and spondylolytic spondylolisthesis are more prone to develop a higher-grade slip and hence are more at risk for developing significant sagittal imbalance.

Patients with sagittal imbalance often suffer from axial pain that directly relates to their spinopelvic mismatch. The mismatch forces them to consume more energy in order to maintain an upright posture because of the increased activity of the paraspinal musculature. In the spinal deformity literature, multiple studies have demonstrated a positive correlation between worsening sagittal imbalance and more severe clinical symptoms as well as health related quality of life (HRQOL) [11–13].

The principle of spinopelvic alignment has also been applied to patients with spondylolisthesis. In one of the earliest studies to examine pelvic parameters in spondylolisthesis, Hanson et al. [14] investigated the degree of pelvic incidence in patients with both low and high-grade isthmic spondylolisthesis. They demonstrated that both adult and pediatric patients with isthmic spondylolisthesis had a higher mean pelvic incidence than matched controls. Another more recent study linked the presence of greater sagittal imbalance in isthmic spondylolisthesis with patients’ symptoms. Harroud et al. [15] analyzed the sagittal alignment parameters in 149 pediatric and adolescent patients with isthmic spondylolisthesis and correlated them with HRQOL based on SRS-22 scores. They demonstrated worse SRS-22 scores in patients with greater sagittal imbalance. The sagittal imbalance and the HRQOL scores were most significant for the patients with high-grade spondylolisthesis [15].