Natural Evolution and Conservative Treatment of Adult Spondylolisthesis



Natural Evolution and Conservative Treatment of Adult Spondylolisthesis


Michel Benoist

Raphael Vialle



Isthmic spondylolisthesis results from separation of the pars after a stress fracture or from elongation of the pars without separation. These lesions leave the posterior elements in normal position and allow forward slippage of the lumbar spine. Most cases of isthmic spondylolisthesis develop in schoolchildren. New cases may appear in adolescents or adults engaged in strenuous athletics or heavy work. Meyerding’s classification is generally used to describe the degree of slippage: Grade 1 = 0-25% of slip; Grade 2 = 25%-50% of slip; Grade 3 = 50%-75% of slip; Grade 4 = over 75% of slip and spondyloptosis.

Most cases treated in adulthood are predominantly low or moderate (Grade 1 or 2) painful spondylolisthesis. High-grade listhesis is usually detected in childhood or adolescence. However high-grade lesions may have to be treated in adulthood if no major significant symptoms have necessitated surgery in adolescence. The purpose of this chapter is to discuss the natural evolution of lytic spondylolisthesis in adults, including progression of the slip and correlation of the clinical symptoms with the grading and progression of the slip. An overview of conservative treatment is also presented.


EVOLUTION OF SPONDYLOLYSIS INTO SPONDYLOLISTHESIS

Newly developed slippage in adults with spondylolysis is rare but may occur with no evidence of trauma. Such cases have been reported by some authors (1,2,3,4), as listed in Table 13.1.


PROGRESSION OF SLIPPAGE IN ADULT ISTHMIC SPONDYLOLISTHESIS

Adult progression of slippage is unusual, and many cases of spondylolisthesis remain stable for the entire adulthood. Studies on progression of the slip in adults are few, often combining adolescents and adults. Progression is even doubted by some investigators. Wiltse and Rothman (5), summarizing the natural history of isthmic spondylolisthesis, state that “significant increases in olisthesis after adulthood are sufficiently uncommon that they are not considered a substantial problem.” However, there are a few reports in the literature indicating that progression of the slip does happen and may generate clinical symptoms.

In the majority of these studies, progression of slippage is described in pain-selected populations. There is, however, one study describing the natural history in subjects
unselected for pain (6). This study by Beutler et al. was started in the early 1950s. Radiographs were obtained in 500 six-year-old schoolchildren. Twenty-two subjects (4.4%) had a spondylolysis. By adulthood, a lytic defect of the pars developed in eight more individuals. These 30 subjects were followed up for 45 years. At the last follow-up, assessment included radiographs, magnetic resonance imaging, a questionnaire on back pain, and 36-Item Short Form Health Survey (SF-36) survey. No subject was lost to follow-up evaluation once a lesion was identified. Conclusions of that report provide valuable information. First, healing of a unilateral pars defect was observed in three subjects. Second, a marked slowing of slip progression was observed in the adult decades to the age of 50 years, and in no subject did the slippage reach 40%. Most patients with bilateral pars defect and slippage followed a clinical course similar to the general population. However, the small number of subjects studied prohibits any generalization of the results.








TABLE 13.1. Evolution of spondylolysis into spondylolysis in adulthood


















Authors


Number of Cases


Postacchini (1)


5


Heggeness et al. (2)


2


Virta et al. (3)


1


Ohmori et al. (4)


6


Progression of slippage has also been reported in studies of patients selected for pain. Recently, Floman (7) has reported a clinical and radiographic review of adult patients with progressive olisthesis. Eighteen patients with low back pain and sciatica were followed during a period of 2 to 20 years (mean: 6-8 years). Slip progression started after the third decade of life, ranging from 9% to 30% (mean: 14.6%).

Marked progression of the slip (>10%) in an adult population with spondylolisthesis and back pain was documented by Virta and Osterman (8). A group of 40 nonoperated patients with Grade 1 or Grade 2 L5 spondylolisthesis was followed up for an average of 17 years. Mean progression of the slip during the observation time was 6.1%.

A clinical and radiologic follow-up study with at least 20 years of observation was published by Saraste (9) in 1987. Vertebral slippage was calculated as the distance in millimeters from the posteroinferior limit of the spondylolytic vertebra to a line through the posterior border of the vertebra below. The mean progression of slippage in 144 adults was 5 mm. Ohmori et al. (4) have followed a group of 22 patients with spondylolysis for an average of 10 years. Four patients with L5 spondylolisthesis at the first visit (mean degree of slip: 15.5 + 13.6) showed progression of the slip. The degree of slip at the second visit was 21.5+/−5).

Danielson et al. (10) have studied the radiologic progression of the slip in a group of 311 patients younger than 30 years at admission. The mean observation time was 3.8 years. A true progression (i.e., an increase >20% from admission) was found in only 3% of the patients. When progression of the slip was related to the different ages, a peak of increase of slippage was observed at age 20-25 years. Similarly, Seitsalo et al. (11), in a long-term evaluation of 272 patients, found that slippage increased in only 4% of adult patients during an observation time of 10 years. Progression of slippage in pain-selected populations is summarized in Table 13.2.









TABLE 13.2. Progression of vertebral slippage in pain-selected populations (adults)































Authors


Mean Progression


Observation Time in Years


Saraste H. (9)


5 mm


20


Danielson et al. (10)


3%


3,8


Seitsalo et al. Spine 1992


4%


10


Virta and Osterman (8)


6%


17


Ohmori et al. (4)


5%


10


Floman (7)


14,6


6,8



RADIOLOGIC VARIABLES ASSOCIATED WITH FURTHER SLIPPAGE

Predictive factors have been searched and discussed in studies dealing with radiologic progression of the listhesis. However, as emphasized by Beutler et al. (12), radiographic parameters vary from study to study. Radiographic positioning is not standardized and different measurements are used. For these reasons, predictive radiologic variables are difficult to identify.

The degree of slip, as well as other parameters, among them slip angle, lumbar index, cranial convexity of S , and disc height, are often difficult to evaluate especially in Grade 3 or 4. Moreover, studies are retrospective, often mixing children, adolescents, and adults. They also lack inter- and intraobserver rating. In spite of these shortcomings and conflicting results, a few common predictive or etiologic factors of progression have been formulated by investigators.

Disc degeneration is correlated with slip progression in most studies. In this regard, the study by Floman (7) is strongly documented as disc degeneration was assessed at the slip level not only by plain radiographs but also by computed tomography or by magnetic resonance imaging. Disc narrowing was also graded according to the presence of osteophytes and of vacuum phenomenon. In all 18 cases described in Floman’s study, slip increase was associated with marked disc degeneration at the slip level.

Relation between slip progression and disc degeneration is reported in other studies, including that of Beutler et al. (6). Natural history of the same group of patients had been assessed in 1990. Disc degeneration had already been disclosed as facilitating progression of the slip (13). In Saraste’s study, progression of the listhesis was also correlated with disc degeneration, especially in the group with L4 spondylolisthesis. Starting in adult life, disc degeneration appears to be the key factor of slip progression. As stated by Farfan et al. (14), “Disc degeneration occurs below the pars because of rotatory and anteriorly shear forces acting on the disc.” An intact disc is the only resistant structure to slip progression. However, as mentioned by Floman (7), progression of slippage and disc degeneration may be concomitant and not related.

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Sep 22, 2016 | Posted by in NEUROSURGERY | Comments Off on Natural Evolution and Conservative Treatment of Adult Spondylolisthesis

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