Typical physical changes that occur in an individual with spondylolisthesis will be a general stiffening of the back and a tightening of the hamstrings, with a resulting change in both posture and gait. The posture will typically give the appearance that the individual leans forward slightly and/or that they are suffering from lordosis. In more advanced cases, the gait of the individual may change to give the appearance of more of a "waddle" than a walk, where the individual rotates the pelvis more due to the decreased mobility in the hamstrings. A result of the change in gait is often a noticeable atrophy in the gluteal muscles due to lack of use.
An individual suffering from spondylolisthesis will typically experience generalized pain in the lower back, along with intermittent shocks of shooting pain beginning in the buttock traveling downward into the back of the thigh and/or lower leg. Sciatica that extends below the knee and may be felt in the feet. Sometimes symptoms include tingling and numbness. Sitting and trying to stand up may be painful and difficult. Coughing and sneezing can intensify the pain. The individual may also note a "slipping sensation" when moving into an upright position. An increase in activity level, for an individual experiencing pain of this type, will likely cause the individual to experience an increase in pain levels in the day(s) following the activity due to inflammation of the soft tissues, which is alleviated with reduced activity and/or rest.
Low-Grade Isthmic Spondylolisthesis
Patients with symptomatic low-grade (<50% slippage) isthmic spondylolisthesis typically present with activity related back pain and often with radicular symptoms as well, but despite the large number of individuals with radiographic evidence of isthmic spondylolisthesis, few of them become symptomatic or require treatment.
Additionally, the cause of pain in patients with isthmic spondylolisthesis remains unclear. The first theory of pain production was segmental instability with excessive forward translation during flexion. This notion was logical from the mechanical standpoint as the pars defect eliminated the vertebral body’s primary restraint to forward translation, the inferior facet joint. This theory has now been evaluated by multiple radiographic studies, none of which were able to demonstrate excessive forward translation as a common feature of isthmic spondylolisthesis. A more contemporary theory of pain generation is excessive tension on the annulus of the inferior disc and foraminal stenosis at the level of the slip. Excessive annular tension is also mechanically logical as without the restraint of the inferior facet joints; the disc has to both resist shear forces from the slip and compressive forces from the body’s mass. However, this theory does not explain why some patients have symptoms while so many others do not, since the inferior discs of all patients with isthmic spondylolisthesis are subjected to similar forces. Foraminal stenosis is also thought to play a role, but long-term studies on surgical outcome have shown that many patients have poor results following decompression alone. Since the mid-1950s, surgeons have been advocating the combination of decompression and fusion. A recent biomechanical study of flexion-extension X-rays in patients with isthmic spondylolisthesis and normal controls found paradoxical motion at the level of the slip in 46% of patients and 0% of controls without back pain. Paradoxical motion has not been previously reported in cases of spondylolisthesis, but its role in the symptomatic and asymptomatic patient is unclear.
High-Grade Isthmic Spondylolisthesis
High-grade isthmic spondylolisthesis and dysplastic spondylolisthesis are regarded as separate clinical entities from low-grade isthmic slips. High-grade slips are defined as those with greater than 50% forward displacement. These slips are also accompanied by a significant amount of lumbosacral kyphosis, which is forward bending of the L5 vertebral body over the sacral promontory. Rounding of the sacral body and trapezoidal deformation of L5 are also common features. High-grade slips are much rarer than low-grade slips, representing less than 10% of all isthmic slips, and the vast majority present during adolescence, most during the early teenage years.
Unlike low-grade slips, many patients present without pain. Instead symptoms like bodily deformity, neurologic abnormalities, tight hamstrings, and abnormal gait are often the reason for consultation. The natural history of high-grade spondylolisthesis is also quite different from those with low-grade slips. The majority of low-grade slips are asymptomatic and do not progress past a patient’s initial presentation. Prospective studies on children with low-grade slips have demonstrated that once a slip occurs, it rarely worsens, even after 40+ years of follow-up. However, high-grade slips do continue to progress in many cases and are much more likely to cause pain. One natural history study by a Swedish researcher, Saraste, found that roughly 60% of patients with slips greater than 15 mm (which is roughly a Meyerding grade 2 or greater) had persistent daily symptoms, including both back pain and radiculopathy. The low-grade slips in Saraste's study were symptomatic in only 10% of patients.
Some cases do eventually progress to complete spondyloptosis and prevention of progression is the primary focus of surgery for high-grade slips. Why low-grade slips tend not to progress and why certain slips ultimately become severe is not known. There have been few long-term follow-up studies on patients with high-grade spondylolisthesis who did not undergo surgery. Harris and Weinstein reported on eleven patients after a mean follow-up of 18 years, all of which had greater than 50% slip and did not have surgery. Thirty-six percent of patients were asymptomatic, 55% of patients had relatively mild symptoms, and only one (9%) was disabled. The patients with mild symptoms were all able to work and participate in recreational activities, although they did need to make modifications to their lifestyle. No patient developed fulminant cauda equina syndrome, severe neurologic symptoms, or incontinence. Forty-five percent of patients had some neurologic abnormalities on exam, including weakness, paresthesias, and diminished deep tendon reflexes. Patient symptoms were primarily related to mild to moderate neurologic symptoms, muscle weakness, especially abdominal muscles, inactivity/deconditioning, obesity, lack of spinal mobility, and the late development of degenerative scoliosis with lateral listhesis (a deformity associated with advanced osteoarthritis of the lumbar spine). The patients in this study were a group of 21 patients who had undergone classic posterior interlaminar fusion from L4 to S1 for their severe slip with. The surgically treated patients were less symptomatic with 57% reporting no symptoms and no limitations, 36% reporting mild symptoms, and 5% reporting severe symptoms12. It should also be noted that the outcomes of posterior interlaminar fusions were poorer than newer posterolateral and circumferential techniques now utilized. Patients with posterior-only fusions tend to have more progression of their spondylolisthesis following surgery and more pain as well.
Degenerative spondylolisthesis
Unlike isthmic spondylolisthesis, degenerative spondylolisthesis is not associated with a neural arch defect, meaning that the forward translation of the vertebral body also causes narrowing of the central spinal canal at the level of the slip. In contrast, patients with isthmic spondyolisthesis almost universally have widening of the central spinal canal at the level of the slip. This narrowing of the canal in degenerative spondylolisthesis has been termed the "napkin ring effect", an illustrative description as one imagines the spinal canal as a series of napkin rings with one of the rings slid forward in comparison to the others. The classic symptomology of patients with symptomatic degenerative spondylolisthesis are similar to those with symptomatic lumbar spinal stenosis; which can be either neuorgenic claudication or radiculopathy (either unilateral or bilateral radiculopathy) with or without low back pain.
Neurogenic claudication is thought to result from central canal narrowing that is exacerbated by the listhesis (forward slip). The classic symptoms of neurogenic claudication are bilateral (both legs) posterior leg pain that worsens with activity, but is relieved by sitting or forward bending.
Further Reading
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