J Neurosurg 77:669-676. 1992
Long-term evaluation of decompressive surgery for degenerative lumbar stenosis ANI'IIONY J. CAPtJTY, M.D., AND ALFRED J. LUESSENIIOP, M.D.
Departmenl cf A2"m'osur.r
Georg,elown Unive,:s'it), Medical Center. Washington, D.C.
u- One-hundred patients who had undergone decompressive surgery for lumbar stenosis between 1980 and 1985 were evaluated as to their long-term outcome. Four patients with postfusion stenosis were included. A 5year follow-up period was achieved in 88 patients. The mean age was 67 years, and 80% were over 60 years of age. There was a high incidence of coexisting medical diseases, but the principal disability was lumbar stenosis with neurological involvement. Results were categorized as either a surgical success or a failure, depending upon the achievement of preset goals within the context of lifestyle and needs. There were no perioperative complications. Initially there was a high incidence of success, but recurrence of neurological involvement and persistence of low-back pain led to an increasing number of failures. By 5 years this number had reached 27% of the available population pool, suggesting that the failure rate could reach 50% within the projected life expectancies of most patients. Of the 26 failures, 16 were secondary to renewed neurological involvement, which occurred at new levels of stenosis in eight and recurrence of stenosis at operative levels in eight. Reoperation was successful in 12 of these 16 patients, but two required a third operation. The incidence of spondylolisthesis at 5 years was higher in the surgical failures (12 of 26 patients) than in the surgical successes (16 of 64). Spondylolisthetic stenosis tended to recur within a few years following decompression. To forestall recurrences, it is suggested that stabilization be carried out at levels of spondylolisthetic stenosis and the initial decompression include adjacent levels of threatening symptomatic stenosis. However, the heterogenicity of this patient population, with varying patterns and levels of symptomatic stenosis, precludes application of rigid surgical protocols. KEY WORDS spinal fusion
9
laminectomy 9 lumbar spine spondylolisthesis
p
REVIOUS reports have described the short-term outcome for patients undergoing decompressive surgery for neurologically symptomatic lumbar stenosis, a~'7-~~ However, there is very. little information regarding the interval incidences of recurrences and causes for surgical failures in long-term follow-up studies. To assess this situation, we studied the outcomes for 100 patients operated on by one of us between 1980 and 1985. This group offers the potential of at least 5 years of follow-up evaluation and as long as 10 years for some. Also, patients undergoing reoperation a second or third time during this interval could be followed for an extended period. All patients in this series conformed to the definition of degenerative spinal stenosis with varying degrees of laminar thickening, ligamentous hypertrophy, facet hypertrophy, and anular bulging, with or without spondylolisthesis or scoliotic angulation, leading in various combinations to symptomatic crowding of adjacent nerve roots and the cauda equina. Excluded from this group were 20 patients who had undergone surgery for
J. NetlrosttQ,,. / Volume 77/November. i992
9 stenosis
9
radiculopathy
stenosis following discectomy at the same spinal level and stenosis following fusions for spinal fractures, scoliosis, spondylolisthesis secondary to spondylolysis, and instability secondary, to spinal tumors. We elected to include four patients with postfusion stenosis whose initial surgery elsewhere had been for discectomies at a lower level. These four will be considered separately, leaving 96 patients for full consideration. Clinical Material and Methods
A retrospective analysis was undertaken of 100 patients who underwent surgery for symptoms of degenerative lumbar spinal stenosis at Georgetown University Hospital from 1980 to 1985. There was a 5- to 10-year follow-up period. Fourteen of the 100 patients were lost to follow-up review; however, 10 of these 14 bad a documented follow-up period greater than 5 years. Six patients died in the follow-up period. All patients underwent myelography. To prevent bias, the data analysts were independent of the surgeon. 669
A. J. Caputy and A. J. Luessenhop
FIG. 2. Graph showingpatients' age at time of referral.
FIG. 1. Chain of referral of 100 surgical patients. F/U = follow-up period.
Case Material The patients were referred by internists, rheumatologists, orthopedic surgeons, neurologists, and other practitioners and had been managed for periods ranging from 1 month to 12 years (mean 6 months) with various medications, physiotherapy, corsets, exercise programs, and epidural steroids until these methods had become ineffective. Most were referred when acquired neurological symptoms dominated pre-existing complaints of low-back pain. Some patients were not referred because coexisting medical disease presented too great a surgical risk; however, once referred, no patient who was severely symptomatic was rejected for surgery because of age or complicating medical disease. Some patients were denied surgery because they were not severely symptomatic, and a few declined surgery, but the number of these was not ascertained (Fig. 1). This chain of referral prevents this surgical group from being fully representative of the clinical problem as it may emerge in a given population, but it is likely that the full spectrum of the clinical problem is represented. Patient Characteristics Patient age at the time of referral ranged from 43 to 84 years (mean 67 years) (Fig. 2); 80% were aged 60 years or over. The male:female ratio was 46:54. Aside 670
from varying degrees of associated low-back pain, all of the patients had combinations of radicular and cauda equina symptoms. For the latter we use the term "caudopathy" as more appropriate than "neurological claudication" or "claudicant symptoms." Forty-seven percent of the patients presented with a caudopathy and 63% had various combinations of radiculopathy. Seventy-six percent of those with radicular symptoms had multiple roots affected, and 24% had single-root pathology. The median length of preoperative symptoms was 6 months (range 1 month to 12 years). All patients underwent myelography. Based on preoperative imaging, the posterior elements were implicated as having the most significant pathology in all cases. The significant coexisting medical problems are shown in Table I. Many of the patients were at least mildly symptomatic from degenerative joint disease elsewhere, and this was a severe problem in 10 patients who had undergone hip or knee replacement surgery. Also symptomatic cervical spondylosis, requiring interbody fusions in some cases, was present in at least 13 patients and necessitated concomitant conservative management. Retrospectively, we could not assign a percentage incidence for reactive or senile depression with loss of initiative or patterns of illness behavior, but this was an important clinical accompaniment in some. Many of the patients have been reduced to a lifestyle of at least partial dependency. Diagnostic Testing Although many of the patients had undergone computerized tomography and/or magnetic resonance (MR) imaging prior to referral, all subsequently underwent myelography, which we considered essential for full evaluation. Correlation of foci of symptomatic neural involvement with the characteristics of the subjective complaints, objective examination, and myelographic findings was very accurate. Although MR imaging alone depicts a wider range of pathological changes, correlation with neurological symptoms is less certain. Electrodiagnostic testing had been carried out J. Neurosurg. / Vohtme 77/November, 1992
Decompressive surgery for degenerative lumbar stenosis in many, but we did not find the results of this uniformly useful and, at present, it is used only selectively.
TA B LE 1
Coexisting medical diseases in lO0 patients treatedJbr lumbar slenosis
Surgical Technique The objective of the surgery was complete anatomical decompression of all symptomatically involved neural elements as diagnostically correlated. This led to full laminectomies and partial facetectomies of one or more levels in 85% of the patients. Unilateral hemilaminectomies of adjacent vertebrae with partial facetectomies for lateral stenosis were undertaken in the remaining 15%. In 14% of the patients it was judged, at the time of surgery, that anular bulging was playing a significant role and discectomy was added. Overall, the removal of adjacent laminae at a single level occurred in 21% of cases; laminectomies extended to two or three levels in 65% and to more than three levels in 14%. The greatest number of laminae removed was four. In most cases partial facetectomies were restricted to symptomatic roots. In no case were the facets fully removed or obviously fractured. No simultaneous fusions were undertaken.
Postsurgical Complications There were no immediate or delayed postoperative complications in the 100 primary operations and 16 reoperations. We regard this as fortuitous for, in subsequent years, we have encountered instances of cerebrospinal fluid leaks, nonfatal pulmonary emboli, superficial wound infections, and recently death in an elderly, moderately senile patient who had become overmedicated to the point of respiratory depression from a morphine infusion pump used for postoperative analgesia.
Evaluation of Surgical Results The postsurgery evaluations were obtained from serial patient examinations as well as initial and subsequent hospital records, and were updated by telephone interviews with patients and/or family members. The operating surgeon did not play a role in these evaluations or participate in the final classification of patients' outcomes as to either the success or failure at a given postsurgery interval. For evaluation of surgical results we deviated from the more commonly employed categories, such as excellent, good, fair, or poor, because we believed these categories, however rigidly defined, are subjective and not altogether pertinent to this older population with its high incidence of coexisting disabling medical problems. Rather, we utilized only two categories, namely success and failure, because they related to individualized goals proposed by the surgeon, requested by the patient, and agreed upon by both the patient and his/ her family. Such a scheme may create, in certain instances, a strikingly different result from a method relying on excellent to poor categories. For example, we cite the case of a 71-year-old retiree who, while
J. Neurosurg. / Vohtme 77/November, 1992
Disease
No. of Cases
symptomaticcervicalspondylosis advanced osteoarthritis hip replacement knee replacement other diabetes (insulin) neuropathy cardiopulmonary peripheral-vascular hypertension hypothyroidism
13 14 6 4 4 9 2 19 6 29 11
Parkinson's disease cancer dementia depression*
2 5 3 ?
* For descriptionsee text.
training for senior Olympic competition, acquired a severe and incapacitating L-4 radiculopathy with quadriceps atrophy secondary to L3-4 lateral stenosis. The goal was to allow him to continue his training and to compete. Following surgery this goal was reached; he competed and achieved his lifelong ambition of setting the world record for his age group in the 80-m high hurdles. If the surgery had restored him to a status of near-complete comfort for usual activities but was insufficient for strenuous athletic activities, his case would have been a surgical failure by our scheme, but by the other criteria he would have had a good or excellent result. At the other extreme, restoring a mostly dependent patient to a status of more complete self-care, including the capacity for independent grocery shopping, household management, and desired social activities would be considered a success but, by the excellent to poor categories, persistence of a certain degree of low-back pain and discomfort would result in a fair category. Results
Immediate Postoperative Results All of the patients showed initial improvement during their hospitalization and for a few months thereafter. This was ascribed to the placebo effects of the surgery, improved medication for pain management and depression, and more appropriate physiotherapy. This too may be considered fortuitous because, since 1985, we have encountered instances of immediate failure with persistence of radiculopathy requiring reoperation during the same hospitalization and worsening of low-back pain for some months after surgery. Most of the patients experienced significant improvement of spinal pain, as well as alleviation of neurological symptoms, but this was not predictable for each patient. 671
A. J. Caputy and A. J. Luessenhop
FIG. 3. Graph and chart showing the decline in the number of patients followed.
FIG. 4. Graph showing the percentage of patients reverting to the surgical failure category.
Late Postoperative Results The number of patients followed was steadily reduced by death from other causes and patients lost to review so that, by 5 years, the total number of patients had fallen from 96 to 88 and thereafter declined more rapidly; by 10 years, only seven were still being followed (Fig. 3). By 4 months postsurgery, failure of patients to attain their goal began to appear and steadily accumulated thereafter; 26 patients, still followed, ultimately reverted to the failure category (Fig. 4). On clinical grounds these failures fell into two groups: those secondary to back pain alone and those with renewed neurological involvement with varying degrees of back pain. Most failures in the back-pain category were evident within the first 3 years and thereafter their number increased only slightly; however, the number of failures with neurological involvement increased steadily. After 5 years, the size of the patient pool declined rapidly so the percentage incidence of failures became progressively less accurate. Each of these failure categories will be considered separately.
myelegraphically. At sites ofrestenosis there was partial laminar regeneration and dense scar. There were no postoperative complications in this group of patients followed for 8 months to 9 years (mean 3.8 years). Two patients suffered neurological involvement, 10 months and 3 years later; both again acquired stenosis, and underwent a third procedure for nerve root decompression. Both were ultimately relieved of their neurological symptoms and thereafter remained in the success category after 2 and 7 years of follow-up monitoring (Table 2). Four patients ultimately became failures because of persistent or worsening low-back pain; these four patients had sport-
Recurrence of Neurological Symptoms and Reoperation The 16 patients with recurrent neural involvement (Table 2) became failures because of renewed radiculopathy in 13 and renewed caudopathy in three. The neurological involvement was secondary to new levels of stenosis (above the previous surgery in three and below in five) and secondary to re-formation of stenosis at previously decompressed levels in eight (Figs. 5 and 6). In one of these eight, renewed radiculopathy was on the opposite side and a partial facetectomy had not been performed there. In five patients, the renewed stenosis was at a spondylolisthetic level (Figs. 7 and 8). Comparison with previous myelograms showed instances of moderate but nonsymptomatic pre-existing stenosis, which had subsequently progressed to a neurologically symptomatic stage. All of these 16 patients underwent reoperation directed at the sites of renewed and recurrent stenosis, as these correlated clinically and 672
TABLE 2 Reoperation for recurrent neural involvement in 16 patients Case No.
Age at 1st Site of Outcome/ Surgery(yrs), Restenosis* Follow-Up Sex Period~ with spondylolisthesis 1 57, M below success/lyr 2 70, F below reop/3 yrs 3 59, M same success/8mos 4 69, F same failure, LBP/7 yrs 5 71, F same failure, LBP/1 yr 6 68, M same failure, LBP/5 yrs 7 69, F same failure, LBP/4 yrs no spondylolisthesis 8 71, M below reop/10mos 9 64, M below success/5yrs 10 67, M below success/3yrs 11 62, M opposite success/4yrs I2 70, M same success/lyr 13 68, F same success/3yrs 14 70, M above success/2yrs 15 66, M above success/8mos 16 59, M above success/9yrs 3rd surgery 2 70, F opposite success/7yrs 8 71, M same:~ success/2yrs * Site of recurrence in relation to previoussurgery. t LBP = low-backpain. This patient acquired a spondylolisthesis.
J. Neurosurg. / Volume 77 / November. 1992
Decompressive surgery for degenerative lumbar stenosis
FIG. 7. Myelogram of a 7 l-year-old woman with caudopathy secondary to spondylolisthetic stenosis. FIG. 5. Myelogram of a 71-year-old man showing an L-4 radiculopathy secondary to lateral stenosis at L3-4.
dylolisthetic stenosis and, although the degrees of spondylolisthesis had not increased, a stenosis recurred at these levels. Neurological involvement was relieved by the second operation, but this did not suffice for overall surgical success.
Persisting or Worsening of Low-Back Pain Of the 10 patients with persistent or worsening lowback pain, five had pre-existing or newly acquired spondylolisthesis. These 10 surgical failures averaged 68 years of age at the time of surgery, and their subsequent courses were complicated by dementia, litigation, can-
cer, congestive heart disease, rheumatoid arthritis, and severe osteoarthritis involving both knees and hips. Five patients without pre-existing spondylolisthesis fell into the surgical failure category within months following the surgery, whereas the five with spondylolisthesis tended to have a longer interval of success before again becoming disabled with low-back pain. In two of these patients the spondylolisthesis increased.
Postfusion Stenosis The 100 patients studied included four who had previously undergone decompressive laminectomies of L-4 and L-5 and fusions of L-4 to S-1 with subsequent development of a symptomatic segment of stenosis above the levels fused. All had been operated on elsewhere. Decompressive laminectomies and partial facetectomies directed at the site of stenosis were carried out in all four patients, and they remained in the success category for 6, 7, 7, and 9 years postoperatively. The Incidence of Spondylolisthesis Because degenerative spondylolisthesis is implicated as a structural basis for low-back pain and may be the
FIG. 6. Myelogram of the patient depicted in Fig. 5 showing a new level of stenosis below the level of decompressive surgery performed 3 years earlier.
J. Neurosurg. / Volume 77~November, 1992
FIG. 8. Myelogram of the patient depicted in Fig. 7 showing renewed lateral stenosis causing radiculopathy 5 years following decompression. The degree of spondylolisthesis is unchanged.
673
A. J. C a p u t y a n d A. J. L u e s s e n h o p TABLE 3 Outcomes with lamineclom3' and partialjacetectomy
Authors & Year
No. of Cases
Age (yrs)
Outcome
Follow-Up Period
Getty, 1980 Johnsson, et al., 1981 Weir & De Leo, 1981 Hall, et al., 1985 Ganz, 1990
20 22 81 68 33
mean52 (18-75) mean63 (48-80) 64% > 50 mean63 (32-83) mean57 (21-84)
good55%, fair 25%, poor 20%, reop 20% (50% good) excellent& good 59%, unchanged & poor 41% good 95%, unchanged 3%, worse 1%, unknown 1%, reop 7% excellent& good 84% good82%, poor 18%
mean 3.5 yrs (1-10 yrs) mean 22 mos (3-79 mos) 3 mos-12 yrs mean 4 yrs (2.4-5.4 yrs) 1-6 yrs
primary factor contributing to a segment of stenosis, its incidence and possible significance in the 96 patients and subsequent surgical failures were evaluated. Although many of the 96 patients had mild degrees of either antero- or retro-olisthesis, significant spondylolisthesis of grades I and II was present in 28 (29%). In 12 patients, this disorder was associated with a single level of neurologically symptomatic spondylolisthetic stenosis, whereas in the remaining 16, it was more or less incidental with sites of symptomatic stenosis at multiple levels. Spondylolisthesis was at the L4-5 level in 20 patients, the L3-4 level in six, and involving multiple levels to some degree in addition to these two levels in two patients. According to standard classification, it was graded I in 12 patients, I to II in 13 patients, and II in three patients. Of the 64 patients remaining in the surgical success category at the end of 5 years, 17 had had spondylolisthesis at one level or more at the time of their initial surgery. Possible progression of this or the acquisition of new levels of spondylolisthesis was not determined in this group. In contrast, there was a disproportionately greater incidence of spondylolisthesis among the surgical failures (12 of 26 patients). Newly acquired spondylolisthesis was noted in five, two of whom had undergone a discectomy. Of the 16 surgical failures due to renewed neurological involvement, stenosis bad recurred at the original level of spondylolisthesis in five of the seven with previous spondylolisthetic stenosis; one of the two patients who underwent a third operation had a newly acquired spondylolisthetic stenosis. Also, the four failures of reoperation had recurrent spondylolisthetic stenosis (Table 2). Of the 1O surgical failures due to low-back pain, pre-existing or newly acquired spondylolisthesis was present in five. Degenerative spondylolisthetic stenosis tended to recur within a few years with renewed neurological involvement despite initially effective decompression, and the olisthesis itself had a high incidence in the patients with back-pain failure (nine of 14 patients). Discussion Literature R e v i e w
Since the earlier studies by Verbiest, 2~ Weinstein, 2~ Epstein, el al., 4 and others, ~7 19.23 there have been a succession of reports describing the results of decom674
pressive surgery alone in smaller groups of patients followed for shorter intervals. 2'5"7-~o.t4,~6,22The most pertinent of these are summarized in Table 3. It is likely that the categories of excellent and good correspond to our category of surgical success. Rather than differences in surgical technique, the most likely factors leading to variable results are patient selection, varying follow-up intervals, mean age of the patients, and differences in analyzing outcome. In the recent literature there has been a tendency to ascribe poor results to persistence of levels of instability and increased instability caused by the surgery: for example, discectomy leading to spondylolisthesis, damaging or removal of facets, and laminar removal over multiple segments. 13.~5,22Because of the difficulties in correlating complaints of pain with unstable structural abnormalities, the overall importance of these is not uniformly recognized. The necessity for spinal fusion following lumbar decompression for stenosis is controversial. Wiltse, et al., 23 recommended that a wide decompression including facet removal be performed to achieve satisfactory decompression. They advocated discectomy as needed to achieve this same satisfactory decompression. However, they did recommend fusion in patients less than 60 years of age with various combinations of radical facetectomies, discectomies, and spondylolisthesis. Verbiest, 2~ in his review paper published in 1977, stated that in spite of a decompression there was only a slight tendency for forward slippage of the decompressed vertebral segments except when the spondylolisthesis was present. In 1989, Herkowitz and Garfin j~ found a less favorable long-term outcome in patients with spondylolisthesis when compared to a similar group of patients undergoing decompressions who did not have spondylolisthesis. However, Tile, et al., t9 found that in six cases of existing spondylolisthesis and two cases of new spondylolisthesis there were no symptoms referable to that finding. Hopp and Tsou, 13 in their 1988 article, reported a 17% reoperation rate for instability related to spondylolisthesis in their decompressive laminectomies and found that preoperative indicators of potential instability were the presence of degenerating disc as evidenced by traction spurs, diminished disc height, the presence of a lysthesis, and scoliosis or asymmetry in the narrowed disc. They also found that surgical procedures involving total facetectomy and destabilization of the pars interarticularis resulted in an increased risk J. Neurosurg. / Vohtme 77 / November, 1992
Decompressive surgery for degenerative lumbar stenosis of instability as well. It was recommended that the posterior elements be spared to avoid instability after the decompression, and an intraoperative fusion at the primary surgery was recommended when these preoperative risk factors were present. ~a Feffer, et at.,6 described 19 patients treated with and without fusion following lumbar decompression. The surgery was undertaken to treat symptoms of spinal stenosis directly referable to spondylolisthesis. They found that five of eight patients in the group with fusion rated their results as good, whereas five of 19 patients in the group without fusion rated their results as good. They recommended simultaneous decompression and fusion in patients with spondylolistbesis. Herkowitz and Kurz 12 concluded that spinal stenosis associated with degenerative spondylolisthesis should undergo fusion following decompression. They noted that among 53 patients with single-level spinal stenosis associated with degenerative spondylolisthesis, 69% of those who underwent decompression alone had an excellent-to-good result whereas 92% of those undergoing decompression and fusion had an excellent-to-good result. Surgical Failures A primary purpose in assessing these patients was to determine the causes and interval incidence of surgical failures against a background of progressive degenerative spinal changes. We found that the incidence of surgical failure increased steadily so that, by the end of 5 years, it included approximately 25% of the patients. If this rate of failure continued, perhaps 50% or more of the patients would be in this category within 10 to 15 years, which would be the anticipated longevity of a 60- to 70-year age group in which a majority of the patients fall. Furthermore, we found that the majority of the surgical failures ( 16 of 26 patients) were secondary to a renewed neurological involvement rather than increasing degrees of low-back pain possibly secondary to increased instability resulting from the surgery. For this reason, second and third operations were mostly successful in restoring patients to a surgical success category (12 of 16 patients). Treatment Recommendations The population of patients seen suggests that lumbar spondylosis is in general satisfactorily managed conservatively, and in most cases it is only after neurological involvement intervenes that symptoms become severe enough for surgical consideration. Experience with this group of patients has led us to modify our surgical approach in two ways, hopefully to extend the duration of surgical success. The first modification relates to the limitations at the time of the initial surgery. We found that segments of moderate but asymptomatic stenosis both above and below decompressed levels subsequently became symptomatic, and nerve roots not symptomatically involved but within the segments decompressed subsequently led to new radiculopathy. We now include partial facetecJ. Neurosurg. / Volume 77 / November, 1992
tomies for all nerve roots, symptomatic or not, at the levels of laminar decompression and partial laminectomies of adjacent levels to decompress threatening stenosis. The second modification relates to the need to stabilize levels of degenerative spondylolisthesis at the time of the initial surgery. There have been conflicting reports regarding this procedure, but the more recent reports suggest a better short-term outcome with stabilization.3.6.~.12.~9,22We found a higher incidence of spondylolisthesis in both of the surgical failure categories. Of the 16 patients who became neurological failures, six had renewed stenosis at the level of spondylolisthesis and one other (with newly acquired spondylolisthesis) had a corresponding segment of stenosis. Since initialing this study, we have subjected all patients with spondylolisthetic stenosis to spinal stabilization, both at the initial surgery and at reoperation. However, we are stabilizing only very selectively those levels of spondylolisthesis without neurologically significant stenosis because of the likelihood of postfusion stenosis. ~ Retrospectively, the overall need for stabilization should include about 15% of the patients. The prospective study of Herkowitz and Kurz ~2 suggests results favoring this. Whether or not improvement in short-term results will ultimately be offset by postfusion stenosis at adjacent levels remains to be determined. Overall for the age group involved, the background for disabling pain is multifactorial, and rigid protocols for surgical management may not be uniformly applicable. Surgical judgments should be tailored to meet individual clinical circumstances. Conclusions
Based on our study, we conclude as follows. I. Decompressive surgery for lumbar stenosis with neurological involvement can be carried out with very low risk, despite the advanced age of most of the patients and a high incidence of complicating medical diseases. 2. Surgical decompression restricted to levels of symptomatic neurological involvement results in a high level of surgical success initially but in time the symptomatic neurological involvement recurs, and a small group with disabling low-back pain persists so that within the anticipated longevity of most of the patients approximately one-half will become disabled again. 3. Most of the late surgical failures are due to renewed neurological involvement secondary to either restenosis at decompressed levels or progression of stenosis at adjacent levels. Reoperation results in a high level of surgical success. 4. Spondylolisthetic stenosis tends to recur following decompression, and there is a higher incidence of spondylolisthesis of grades I to II in patients with surgical failure secondary to persisting low-back pain. 5. It is recommended that sites of spondylolisthetic stenosis be stabilized at the time of decompressive 675
A. J. Caputy and A. J. Luessenhop surgery. This should include about 15% of neurologically symptomatic patients. References 1. Brodsky A: Post-laminectomy and post-fusion stenosis of the lumbar spine. Clin Orthop 115:130-139, 1976 2. Cauchoix J, Chassaing V, Benoist M, et al: Lumbar spinal stenosis, in Wackenheim A, Babin E (eds): The Narrow Lumbar Canal. Radiologieal Signs and Surgery. Berlin: Springer-Verlag, 1980, pp 9 i - 104 3. Conley FK, Cady CT, Lieberson RE: Decompression of lumbar spinal stenosis and stabilization with Knodt rods in the elderly patient. Neurosurgery 26:758-763, 1990 4. Epstein JA, Epstein BS, Lavine L: Nerve root compression associated with narrowing of the lumbar spinal canal. J Neurol Neurosurg Psychiatry 25:165-176, 1962 5. Fast A, Robin GC, Floman Y: Surgical treatment of lumbar spinal stenosis in the elderly. Arch Phys Med Rehabil 66:149-151, 1985 6. Feffer HL, Wiesel SW, Cuckler JM, et al: Degenerative spondylolisthesis. To fuse of not to fuse. Spine 10: 287-289, 1985 7. Ganz JC: Lumbar spinal stenosis: postoperative results in terms of preoperative posture-related pain. J Neurosurg 72:71-74, 1990 8. Getty CJM: Lumbar spinal stenosis: the clinical spectrum and the results of operation. J Bone Joint Surg (Br) 62: 481-485, 1980 9. Grabias S: The treatment of spinal stenosis. J Bone Joint Surg (Am) 62:308-313, 1980 10. Hall S, Bartleson JD, Onofrio BM, et al: Lumbar spinal stenosis. Clinical features, diagnostic procedures, and results of surgical treatment in 68 patients. Ann Intern Med 103:271-275, 1985 1l. Herkowilz HN, Garfin SR: Decompressive surgery for spinal stenosis. Semin Spine Surg 1:163-167, 1989 12. Herkowitz HN, Kurz LT: Degenerative lumbar spondylolisthesis with spinal stenosis: a prospective study corn-
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13. 14. 15.
16. 17. 18. 19. 20.
21. 22. 23.
paring decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg (Am) 73: 802-808, 1991 Hopp E, Tsou PM: Postdecompression lumbar instability. Clin Orthop 227:143-150, 1988 Johnsson KE, Willner S, Pettersson H: Analysis of operated cases with lumbar spinal stenosis. Aeta Orthop Scand 52:427-433, 1981 Kaneda K, Kazama H, Satoh S, et al: Follow-up study of medial facetectomies and posterolateral fusion with instrumentation in unstable degenerative spondylolisthesis. Clin Orthop 203:159-167, 1986 Kirkaldy-Willis WH, Wedge JH, Yong-Hing K, et al: Lumbar spinal nerve lateral entrapment. Clin Orthop 169: 171-178, 1982 Paine KWE: Results of decompression for lumbar spinal stenosis. Clin Orthop 115:96-100, 1976 Russin LA, Sheldon J: Spinal stenosis; report of series and long term follow-up. Clin Orthop 115:101-103, 1976 Tile M, McNeil SR, Zarins RK, et al: Spinal stenosis. Results of treatment. Clin Orthop 115:104-108, 1976 Verbiest H: The results of surgical treatment of idiopathic developmental stenosis of the lumbar vertebral canal. A review of twenty-seven years' experience. J Bone Joint Surg (Br) 59:181-188, 1977 Weinstein PR, Ehni G, Wilson CB: Lumbar Spondylosis. Diagnosis, Management and Surgical Treatment. Chicago: Year Book Medical, 1977, p 203 Weir B, De Leo R: Lumbar stenosis: analysis of factors affecting outcome in 81 surgical cases. Can J Neurol Sei 8:295-298, 1981 Wiltse LL, Kirkaldy-WillisWH, McIvor GWD: The treatment of spinal stenosis. Clin Orthop 115:83-91, 1976
Manuscript received November 22, 1991. Accepted in final form May 6, 1992. Address reprint requests to: Anthony J. Caputy, M.D., Division of Neurosurgery, Georgetown University Hospital, 3800 Reservoir Road NW, Washington, DC 20007.
J. Neurosurg. / Volume 77 / November. 1992
Long-term evaluation of decompressive surgery for degenerative lumbar stenosis ANI'IIONY J. CAPtJTY, M.D., AND ALFRED J. LUESSENIIOP, M.D.
Departmenl cf A2"m'osur.r
Georg,elown Unive,:s'it), Medical Center. Washington, D.C.
u- One-hundred patients who had undergone decompressive surgery for lumbar stenosis between 1980 and 1985 were evaluated as to their long-term outcome. Four patients with postfusion stenosis were included. A 5year follow-up period was achieved in 88 patients. The mean age was 67 years, and 80% were over 60 years of age. There was a high incidence of coexisting medical diseases, but the principal disability was lumbar stenosis with neurological involvement. Results were categorized as either a surgical success or a failure, depending upon the achievement of preset goals within the context of lifestyle and needs. There were no perioperative complications. Initially there was a high incidence of success, but recurrence of neurological involvement and persistence of low-back pain led to an increasing number of failures. By 5 years this number had reached 27% of the available population pool, suggesting that the failure rate could reach 50% within the projected life expectancies of most patients. Of the 26 failures, 16 were secondary to renewed neurological involvement, which occurred at new levels of stenosis in eight and recurrence of stenosis at operative levels in eight. Reoperation was successful in 12 of these 16 patients, but two required a third operation. The incidence of spondylolisthesis at 5 years was higher in the surgical failures (12 of 26 patients) than in the surgical successes (16 of 64). Spondylolisthetic stenosis tended to recur within a few years following decompression. To forestall recurrences, it is suggested that stabilization be carried out at levels of spondylolisthetic stenosis and the initial decompression include adjacent levels of threatening symptomatic stenosis. However, the heterogenicity of this patient population, with varying patterns and levels of symptomatic stenosis, precludes application of rigid surgical protocols. KEY WORDS spinal fusion
9
laminectomy 9 lumbar spine spondylolisthesis
p
REVIOUS reports have described the short-term outcome for patients undergoing decompressive surgery for neurologically symptomatic lumbar stenosis, a~'7-~~ However, there is very. little information regarding the interval incidences of recurrences and causes for surgical failures in long-term follow-up studies. To assess this situation, we studied the outcomes for 100 patients operated on by one of us between 1980 and 1985. This group offers the potential of at least 5 years of follow-up evaluation and as long as 10 years for some. Also, patients undergoing reoperation a second or third time during this interval could be followed for an extended period. All patients in this series conformed to the definition of degenerative spinal stenosis with varying degrees of laminar thickening, ligamentous hypertrophy, facet hypertrophy, and anular bulging, with or without spondylolisthesis or scoliotic angulation, leading in various combinations to symptomatic crowding of adjacent nerve roots and the cauda equina. Excluded from this group were 20 patients who had undergone surgery for
J. NetlrosttQ,,. / Volume 77/November. i992
9 stenosis
9
radiculopathy
stenosis following discectomy at the same spinal level and stenosis following fusions for spinal fractures, scoliosis, spondylolisthesis secondary to spondylolysis, and instability secondary, to spinal tumors. We elected to include four patients with postfusion stenosis whose initial surgery elsewhere had been for discectomies at a lower level. These four will be considered separately, leaving 96 patients for full consideration. Clinical Material and Methods
A retrospective analysis was undertaken of 100 patients who underwent surgery for symptoms of degenerative lumbar spinal stenosis at Georgetown University Hospital from 1980 to 1985. There was a 5- to 10-year follow-up period. Fourteen of the 100 patients were lost to follow-up review; however, 10 of these 14 bad a documented follow-up period greater than 5 years. Six patients died in the follow-up period. All patients underwent myelography. To prevent bias, the data analysts were independent of the surgeon. 669
A. J. Caputy and A. J. Luessenhop
FIG. 2. Graph showingpatients' age at time of referral.
FIG. 1. Chain of referral of 100 surgical patients. F/U = follow-up period.
Case Material The patients were referred by internists, rheumatologists, orthopedic surgeons, neurologists, and other practitioners and had been managed for periods ranging from 1 month to 12 years (mean 6 months) with various medications, physiotherapy, corsets, exercise programs, and epidural steroids until these methods had become ineffective. Most were referred when acquired neurological symptoms dominated pre-existing complaints of low-back pain. Some patients were not referred because coexisting medical disease presented too great a surgical risk; however, once referred, no patient who was severely symptomatic was rejected for surgery because of age or complicating medical disease. Some patients were denied surgery because they were not severely symptomatic, and a few declined surgery, but the number of these was not ascertained (Fig. 1). This chain of referral prevents this surgical group from being fully representative of the clinical problem as it may emerge in a given population, but it is likely that the full spectrum of the clinical problem is represented. Patient Characteristics Patient age at the time of referral ranged from 43 to 84 years (mean 67 years) (Fig. 2); 80% were aged 60 years or over. The male:female ratio was 46:54. Aside 670
from varying degrees of associated low-back pain, all of the patients had combinations of radicular and cauda equina symptoms. For the latter we use the term "caudopathy" as more appropriate than "neurological claudication" or "claudicant symptoms." Forty-seven percent of the patients presented with a caudopathy and 63% had various combinations of radiculopathy. Seventy-six percent of those with radicular symptoms had multiple roots affected, and 24% had single-root pathology. The median length of preoperative symptoms was 6 months (range 1 month to 12 years). All patients underwent myelography. Based on preoperative imaging, the posterior elements were implicated as having the most significant pathology in all cases. The significant coexisting medical problems are shown in Table I. Many of the patients were at least mildly symptomatic from degenerative joint disease elsewhere, and this was a severe problem in 10 patients who had undergone hip or knee replacement surgery. Also symptomatic cervical spondylosis, requiring interbody fusions in some cases, was present in at least 13 patients and necessitated concomitant conservative management. Retrospectively, we could not assign a percentage incidence for reactive or senile depression with loss of initiative or patterns of illness behavior, but this was an important clinical accompaniment in some. Many of the patients have been reduced to a lifestyle of at least partial dependency. Diagnostic Testing Although many of the patients had undergone computerized tomography and/or magnetic resonance (MR) imaging prior to referral, all subsequently underwent myelography, which we considered essential for full evaluation. Correlation of foci of symptomatic neural involvement with the characteristics of the subjective complaints, objective examination, and myelographic findings was very accurate. Although MR imaging alone depicts a wider range of pathological changes, correlation with neurological symptoms is less certain. Electrodiagnostic testing had been carried out J. Neurosurg. / Vohtme 77/November, 1992
Decompressive surgery for degenerative lumbar stenosis in many, but we did not find the results of this uniformly useful and, at present, it is used only selectively.
TA B LE 1
Coexisting medical diseases in lO0 patients treatedJbr lumbar slenosis
Surgical Technique The objective of the surgery was complete anatomical decompression of all symptomatically involved neural elements as diagnostically correlated. This led to full laminectomies and partial facetectomies of one or more levels in 85% of the patients. Unilateral hemilaminectomies of adjacent vertebrae with partial facetectomies for lateral stenosis were undertaken in the remaining 15%. In 14% of the patients it was judged, at the time of surgery, that anular bulging was playing a significant role and discectomy was added. Overall, the removal of adjacent laminae at a single level occurred in 21% of cases; laminectomies extended to two or three levels in 65% and to more than three levels in 14%. The greatest number of laminae removed was four. In most cases partial facetectomies were restricted to symptomatic roots. In no case were the facets fully removed or obviously fractured. No simultaneous fusions were undertaken.
Postsurgical Complications There were no immediate or delayed postoperative complications in the 100 primary operations and 16 reoperations. We regard this as fortuitous for, in subsequent years, we have encountered instances of cerebrospinal fluid leaks, nonfatal pulmonary emboli, superficial wound infections, and recently death in an elderly, moderately senile patient who had become overmedicated to the point of respiratory depression from a morphine infusion pump used for postoperative analgesia.
Evaluation of Surgical Results The postsurgery evaluations were obtained from serial patient examinations as well as initial and subsequent hospital records, and were updated by telephone interviews with patients and/or family members. The operating surgeon did not play a role in these evaluations or participate in the final classification of patients' outcomes as to either the success or failure at a given postsurgery interval. For evaluation of surgical results we deviated from the more commonly employed categories, such as excellent, good, fair, or poor, because we believed these categories, however rigidly defined, are subjective and not altogether pertinent to this older population with its high incidence of coexisting disabling medical problems. Rather, we utilized only two categories, namely success and failure, because they related to individualized goals proposed by the surgeon, requested by the patient, and agreed upon by both the patient and his/ her family. Such a scheme may create, in certain instances, a strikingly different result from a method relying on excellent to poor categories. For example, we cite the case of a 71-year-old retiree who, while
J. Neurosurg. / Vohtme 77/November, 1992
Disease
No. of Cases
symptomaticcervicalspondylosis advanced osteoarthritis hip replacement knee replacement other diabetes (insulin) neuropathy cardiopulmonary peripheral-vascular hypertension hypothyroidism
13 14 6 4 4 9 2 19 6 29 11
Parkinson's disease cancer dementia depression*
2 5 3 ?
* For descriptionsee text.
training for senior Olympic competition, acquired a severe and incapacitating L-4 radiculopathy with quadriceps atrophy secondary to L3-4 lateral stenosis. The goal was to allow him to continue his training and to compete. Following surgery this goal was reached; he competed and achieved his lifelong ambition of setting the world record for his age group in the 80-m high hurdles. If the surgery had restored him to a status of near-complete comfort for usual activities but was insufficient for strenuous athletic activities, his case would have been a surgical failure by our scheme, but by the other criteria he would have had a good or excellent result. At the other extreme, restoring a mostly dependent patient to a status of more complete self-care, including the capacity for independent grocery shopping, household management, and desired social activities would be considered a success but, by the excellent to poor categories, persistence of a certain degree of low-back pain and discomfort would result in a fair category. Results
Immediate Postoperative Results All of the patients showed initial improvement during their hospitalization and for a few months thereafter. This was ascribed to the placebo effects of the surgery, improved medication for pain management and depression, and more appropriate physiotherapy. This too may be considered fortuitous because, since 1985, we have encountered instances of immediate failure with persistence of radiculopathy requiring reoperation during the same hospitalization and worsening of low-back pain for some months after surgery. Most of the patients experienced significant improvement of spinal pain, as well as alleviation of neurological symptoms, but this was not predictable for each patient. 671
A. J. Caputy and A. J. Luessenhop
FIG. 3. Graph and chart showing the decline in the number of patients followed.
FIG. 4. Graph showing the percentage of patients reverting to the surgical failure category.
Late Postoperative Results The number of patients followed was steadily reduced by death from other causes and patients lost to review so that, by 5 years, the total number of patients had fallen from 96 to 88 and thereafter declined more rapidly; by 10 years, only seven were still being followed (Fig. 3). By 4 months postsurgery, failure of patients to attain their goal began to appear and steadily accumulated thereafter; 26 patients, still followed, ultimately reverted to the failure category (Fig. 4). On clinical grounds these failures fell into two groups: those secondary to back pain alone and those with renewed neurological involvement with varying degrees of back pain. Most failures in the back-pain category were evident within the first 3 years and thereafter their number increased only slightly; however, the number of failures with neurological involvement increased steadily. After 5 years, the size of the patient pool declined rapidly so the percentage incidence of failures became progressively less accurate. Each of these failure categories will be considered separately.
myelegraphically. At sites ofrestenosis there was partial laminar regeneration and dense scar. There were no postoperative complications in this group of patients followed for 8 months to 9 years (mean 3.8 years). Two patients suffered neurological involvement, 10 months and 3 years later; both again acquired stenosis, and underwent a third procedure for nerve root decompression. Both were ultimately relieved of their neurological symptoms and thereafter remained in the success category after 2 and 7 years of follow-up monitoring (Table 2). Four patients ultimately became failures because of persistent or worsening low-back pain; these four patients had sport-
Recurrence of Neurological Symptoms and Reoperation The 16 patients with recurrent neural involvement (Table 2) became failures because of renewed radiculopathy in 13 and renewed caudopathy in three. The neurological involvement was secondary to new levels of stenosis (above the previous surgery in three and below in five) and secondary to re-formation of stenosis at previously decompressed levels in eight (Figs. 5 and 6). In one of these eight, renewed radiculopathy was on the opposite side and a partial facetectomy had not been performed there. In five patients, the renewed stenosis was at a spondylolisthetic level (Figs. 7 and 8). Comparison with previous myelograms showed instances of moderate but nonsymptomatic pre-existing stenosis, which had subsequently progressed to a neurologically symptomatic stage. All of these 16 patients underwent reoperation directed at the sites of renewed and recurrent stenosis, as these correlated clinically and 672
TABLE 2 Reoperation for recurrent neural involvement in 16 patients Case No.
Age at 1st Site of Outcome/ Surgery(yrs), Restenosis* Follow-Up Sex Period~ with spondylolisthesis 1 57, M below success/lyr 2 70, F below reop/3 yrs 3 59, M same success/8mos 4 69, F same failure, LBP/7 yrs 5 71, F same failure, LBP/1 yr 6 68, M same failure, LBP/5 yrs 7 69, F same failure, LBP/4 yrs no spondylolisthesis 8 71, M below reop/10mos 9 64, M below success/5yrs 10 67, M below success/3yrs 11 62, M opposite success/4yrs I2 70, M same success/lyr 13 68, F same success/3yrs 14 70, M above success/2yrs 15 66, M above success/8mos 16 59, M above success/9yrs 3rd surgery 2 70, F opposite success/7yrs 8 71, M same:~ success/2yrs * Site of recurrence in relation to previoussurgery. t LBP = low-backpain. This patient acquired a spondylolisthesis.
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Decompressive surgery for degenerative lumbar stenosis
FIG. 7. Myelogram of a 7 l-year-old woman with caudopathy secondary to spondylolisthetic stenosis. FIG. 5. Myelogram of a 71-year-old man showing an L-4 radiculopathy secondary to lateral stenosis at L3-4.
dylolisthetic stenosis and, although the degrees of spondylolisthesis had not increased, a stenosis recurred at these levels. Neurological involvement was relieved by the second operation, but this did not suffice for overall surgical success.
Persisting or Worsening of Low-Back Pain Of the 10 patients with persistent or worsening lowback pain, five had pre-existing or newly acquired spondylolisthesis. These 10 surgical failures averaged 68 years of age at the time of surgery, and their subsequent courses were complicated by dementia, litigation, can-
cer, congestive heart disease, rheumatoid arthritis, and severe osteoarthritis involving both knees and hips. Five patients without pre-existing spondylolisthesis fell into the surgical failure category within months following the surgery, whereas the five with spondylolisthesis tended to have a longer interval of success before again becoming disabled with low-back pain. In two of these patients the spondylolisthesis increased.
Postfusion Stenosis The 100 patients studied included four who had previously undergone decompressive laminectomies of L-4 and L-5 and fusions of L-4 to S-1 with subsequent development of a symptomatic segment of stenosis above the levels fused. All had been operated on elsewhere. Decompressive laminectomies and partial facetectomies directed at the site of stenosis were carried out in all four patients, and they remained in the success category for 6, 7, 7, and 9 years postoperatively. The Incidence of Spondylolisthesis Because degenerative spondylolisthesis is implicated as a structural basis for low-back pain and may be the
FIG. 6. Myelogram of the patient depicted in Fig. 5 showing a new level of stenosis below the level of decompressive surgery performed 3 years earlier.
J. Neurosurg. / Volume 77~November, 1992
FIG. 8. Myelogram of the patient depicted in Fig. 7 showing renewed lateral stenosis causing radiculopathy 5 years following decompression. The degree of spondylolisthesis is unchanged.
673
A. J. C a p u t y a n d A. J. L u e s s e n h o p TABLE 3 Outcomes with lamineclom3' and partialjacetectomy
Authors & Year
No. of Cases
Age (yrs)
Outcome
Follow-Up Period
Getty, 1980 Johnsson, et al., 1981 Weir & De Leo, 1981 Hall, et al., 1985 Ganz, 1990
20 22 81 68 33
mean52 (18-75) mean63 (48-80) 64% > 50 mean63 (32-83) mean57 (21-84)
good55%, fair 25%, poor 20%, reop 20% (50% good) excellent& good 59%, unchanged & poor 41% good 95%, unchanged 3%, worse 1%, unknown 1%, reop 7% excellent& good 84% good82%, poor 18%
mean 3.5 yrs (1-10 yrs) mean 22 mos (3-79 mos) 3 mos-12 yrs mean 4 yrs (2.4-5.4 yrs) 1-6 yrs
primary factor contributing to a segment of stenosis, its incidence and possible significance in the 96 patients and subsequent surgical failures were evaluated. Although many of the 96 patients had mild degrees of either antero- or retro-olisthesis, significant spondylolisthesis of grades I and II was present in 28 (29%). In 12 patients, this disorder was associated with a single level of neurologically symptomatic spondylolisthetic stenosis, whereas in the remaining 16, it was more or less incidental with sites of symptomatic stenosis at multiple levels. Spondylolisthesis was at the L4-5 level in 20 patients, the L3-4 level in six, and involving multiple levels to some degree in addition to these two levels in two patients. According to standard classification, it was graded I in 12 patients, I to II in 13 patients, and II in three patients. Of the 64 patients remaining in the surgical success category at the end of 5 years, 17 had had spondylolisthesis at one level or more at the time of their initial surgery. Possible progression of this or the acquisition of new levels of spondylolisthesis was not determined in this group. In contrast, there was a disproportionately greater incidence of spondylolisthesis among the surgical failures (12 of 26 patients). Newly acquired spondylolisthesis was noted in five, two of whom had undergone a discectomy. Of the 16 surgical failures due to renewed neurological involvement, stenosis bad recurred at the original level of spondylolisthesis in five of the seven with previous spondylolisthetic stenosis; one of the two patients who underwent a third operation had a newly acquired spondylolisthetic stenosis. Also, the four failures of reoperation had recurrent spondylolisthetic stenosis (Table 2). Of the 1O surgical failures due to low-back pain, pre-existing or newly acquired spondylolisthesis was present in five. Degenerative spondylolisthetic stenosis tended to recur within a few years with renewed neurological involvement despite initially effective decompression, and the olisthesis itself had a high incidence in the patients with back-pain failure (nine of 14 patients). Discussion Literature R e v i e w
Since the earlier studies by Verbiest, 2~ Weinstein, 2~ Epstein, el al., 4 and others, ~7 19.23 there have been a succession of reports describing the results of decom674
pressive surgery alone in smaller groups of patients followed for shorter intervals. 2'5"7-~o.t4,~6,22The most pertinent of these are summarized in Table 3. It is likely that the categories of excellent and good correspond to our category of surgical success. Rather than differences in surgical technique, the most likely factors leading to variable results are patient selection, varying follow-up intervals, mean age of the patients, and differences in analyzing outcome. In the recent literature there has been a tendency to ascribe poor results to persistence of levels of instability and increased instability caused by the surgery: for example, discectomy leading to spondylolisthesis, damaging or removal of facets, and laminar removal over multiple segments. 13.~5,22Because of the difficulties in correlating complaints of pain with unstable structural abnormalities, the overall importance of these is not uniformly recognized. The necessity for spinal fusion following lumbar decompression for stenosis is controversial. Wiltse, et al., 23 recommended that a wide decompression including facet removal be performed to achieve satisfactory decompression. They advocated discectomy as needed to achieve this same satisfactory decompression. However, they did recommend fusion in patients less than 60 years of age with various combinations of radical facetectomies, discectomies, and spondylolisthesis. Verbiest, 2~ in his review paper published in 1977, stated that in spite of a decompression there was only a slight tendency for forward slippage of the decompressed vertebral segments except when the spondylolisthesis was present. In 1989, Herkowitz and Garfin j~ found a less favorable long-term outcome in patients with spondylolisthesis when compared to a similar group of patients undergoing decompressions who did not have spondylolisthesis. However, Tile, et al., t9 found that in six cases of existing spondylolisthesis and two cases of new spondylolisthesis there were no symptoms referable to that finding. Hopp and Tsou, 13 in their 1988 article, reported a 17% reoperation rate for instability related to spondylolisthesis in their decompressive laminectomies and found that preoperative indicators of potential instability were the presence of degenerating disc as evidenced by traction spurs, diminished disc height, the presence of a lysthesis, and scoliosis or asymmetry in the narrowed disc. They also found that surgical procedures involving total facetectomy and destabilization of the pars interarticularis resulted in an increased risk J. Neurosurg. / Vohtme 77 / November, 1992
Decompressive surgery for degenerative lumbar stenosis of instability as well. It was recommended that the posterior elements be spared to avoid instability after the decompression, and an intraoperative fusion at the primary surgery was recommended when these preoperative risk factors were present. ~a Feffer, et at.,6 described 19 patients treated with and without fusion following lumbar decompression. The surgery was undertaken to treat symptoms of spinal stenosis directly referable to spondylolisthesis. They found that five of eight patients in the group with fusion rated their results as good, whereas five of 19 patients in the group without fusion rated their results as good. They recommended simultaneous decompression and fusion in patients with spondylolistbesis. Herkowitz and Kurz 12 concluded that spinal stenosis associated with degenerative spondylolisthesis should undergo fusion following decompression. They noted that among 53 patients with single-level spinal stenosis associated with degenerative spondylolisthesis, 69% of those who underwent decompression alone had an excellent-to-good result whereas 92% of those undergoing decompression and fusion had an excellent-to-good result. Surgical Failures A primary purpose in assessing these patients was to determine the causes and interval incidence of surgical failures against a background of progressive degenerative spinal changes. We found that the incidence of surgical failure increased steadily so that, by the end of 5 years, it included approximately 25% of the patients. If this rate of failure continued, perhaps 50% or more of the patients would be in this category within 10 to 15 years, which would be the anticipated longevity of a 60- to 70-year age group in which a majority of the patients fall. Furthermore, we found that the majority of the surgical failures ( 16 of 26 patients) were secondary to a renewed neurological involvement rather than increasing degrees of low-back pain possibly secondary to increased instability resulting from the surgery. For this reason, second and third operations were mostly successful in restoring patients to a surgical success category (12 of 16 patients). Treatment Recommendations The population of patients seen suggests that lumbar spondylosis is in general satisfactorily managed conservatively, and in most cases it is only after neurological involvement intervenes that symptoms become severe enough for surgical consideration. Experience with this group of patients has led us to modify our surgical approach in two ways, hopefully to extend the duration of surgical success. The first modification relates to the limitations at the time of the initial surgery. We found that segments of moderate but asymptomatic stenosis both above and below decompressed levels subsequently became symptomatic, and nerve roots not symptomatically involved but within the segments decompressed subsequently led to new radiculopathy. We now include partial facetecJ. Neurosurg. / Volume 77 / November, 1992
tomies for all nerve roots, symptomatic or not, at the levels of laminar decompression and partial laminectomies of adjacent levels to decompress threatening stenosis. The second modification relates to the need to stabilize levels of degenerative spondylolisthesis at the time of the initial surgery. There have been conflicting reports regarding this procedure, but the more recent reports suggest a better short-term outcome with stabilization.3.6.~.12.~9,22We found a higher incidence of spondylolisthesis in both of the surgical failure categories. Of the 16 patients who became neurological failures, six had renewed stenosis at the level of spondylolisthesis and one other (with newly acquired spondylolisthesis) had a corresponding segment of stenosis. Since initialing this study, we have subjected all patients with spondylolisthetic stenosis to spinal stabilization, both at the initial surgery and at reoperation. However, we are stabilizing only very selectively those levels of spondylolisthesis without neurologically significant stenosis because of the likelihood of postfusion stenosis. ~ Retrospectively, the overall need for stabilization should include about 15% of the patients. The prospective study of Herkowitz and Kurz ~2 suggests results favoring this. Whether or not improvement in short-term results will ultimately be offset by postfusion stenosis at adjacent levels remains to be determined. Overall for the age group involved, the background for disabling pain is multifactorial, and rigid protocols for surgical management may not be uniformly applicable. Surgical judgments should be tailored to meet individual clinical circumstances. Conclusions
Based on our study, we conclude as follows. I. Decompressive surgery for lumbar stenosis with neurological involvement can be carried out with very low risk, despite the advanced age of most of the patients and a high incidence of complicating medical diseases. 2. Surgical decompression restricted to levels of symptomatic neurological involvement results in a high level of surgical success initially but in time the symptomatic neurological involvement recurs, and a small group with disabling low-back pain persists so that within the anticipated longevity of most of the patients approximately one-half will become disabled again. 3. Most of the late surgical failures are due to renewed neurological involvement secondary to either restenosis at decompressed levels or progression of stenosis at adjacent levels. Reoperation results in a high level of surgical success. 4. Spondylolisthetic stenosis tends to recur following decompression, and there is a higher incidence of spondylolisthesis of grades I to II in patients with surgical failure secondary to persisting low-back pain. 5. It is recommended that sites of spondylolisthetic stenosis be stabilized at the time of decompressive 675
A. J. Caputy and A. J. Luessenhop surgery. This should include about 15% of neurologically symptomatic patients. References 1. Brodsky A: Post-laminectomy and post-fusion stenosis of the lumbar spine. Clin Orthop 115:130-139, 1976 2. Cauchoix J, Chassaing V, Benoist M, et al: Lumbar spinal stenosis, in Wackenheim A, Babin E (eds): The Narrow Lumbar Canal. Radiologieal Signs and Surgery. Berlin: Springer-Verlag, 1980, pp 9 i - 104 3. Conley FK, Cady CT, Lieberson RE: Decompression of lumbar spinal stenosis and stabilization with Knodt rods in the elderly patient. Neurosurgery 26:758-763, 1990 4. Epstein JA, Epstein BS, Lavine L: Nerve root compression associated with narrowing of the lumbar spinal canal. J Neurol Neurosurg Psychiatry 25:165-176, 1962 5. Fast A, Robin GC, Floman Y: Surgical treatment of lumbar spinal stenosis in the elderly. Arch Phys Med Rehabil 66:149-151, 1985 6. Feffer HL, Wiesel SW, Cuckler JM, et al: Degenerative spondylolisthesis. To fuse of not to fuse. Spine 10: 287-289, 1985 7. Ganz JC: Lumbar spinal stenosis: postoperative results in terms of preoperative posture-related pain. J Neurosurg 72:71-74, 1990 8. Getty CJM: Lumbar spinal stenosis: the clinical spectrum and the results of operation. J Bone Joint Surg (Br) 62: 481-485, 1980 9. Grabias S: The treatment of spinal stenosis. J Bone Joint Surg (Am) 62:308-313, 1980 10. Hall S, Bartleson JD, Onofrio BM, et al: Lumbar spinal stenosis. Clinical features, diagnostic procedures, and results of surgical treatment in 68 patients. Ann Intern Med 103:271-275, 1985 1l. Herkowilz HN, Garfin SR: Decompressive surgery for spinal stenosis. Semin Spine Surg 1:163-167, 1989 12. Herkowitz HN, Kurz LT: Degenerative lumbar spondylolisthesis with spinal stenosis: a prospective study corn-
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13. 14. 15.
16. 17. 18. 19. 20.
21. 22. 23.
paring decompression with decompression and intertransverse process arthrodesis. J Bone Joint Surg (Am) 73: 802-808, 1991 Hopp E, Tsou PM: Postdecompression lumbar instability. Clin Orthop 227:143-150, 1988 Johnsson KE, Willner S, Pettersson H: Analysis of operated cases with lumbar spinal stenosis. Aeta Orthop Scand 52:427-433, 1981 Kaneda K, Kazama H, Satoh S, et al: Follow-up study of medial facetectomies and posterolateral fusion with instrumentation in unstable degenerative spondylolisthesis. Clin Orthop 203:159-167, 1986 Kirkaldy-Willis WH, Wedge JH, Yong-Hing K, et al: Lumbar spinal nerve lateral entrapment. Clin Orthop 169: 171-178, 1982 Paine KWE: Results of decompression for lumbar spinal stenosis. Clin Orthop 115:96-100, 1976 Russin LA, Sheldon J: Spinal stenosis; report of series and long term follow-up. Clin Orthop 115:101-103, 1976 Tile M, McNeil SR, Zarins RK, et al: Spinal stenosis. Results of treatment. Clin Orthop 115:104-108, 1976 Verbiest H: The results of surgical treatment of idiopathic developmental stenosis of the lumbar vertebral canal. A review of twenty-seven years' experience. J Bone Joint Surg (Br) 59:181-188, 1977 Weinstein PR, Ehni G, Wilson CB: Lumbar Spondylosis. Diagnosis, Management and Surgical Treatment. Chicago: Year Book Medical, 1977, p 203 Weir B, De Leo R: Lumbar stenosis: analysis of factors affecting outcome in 81 surgical cases. Can J Neurol Sei 8:295-298, 1981 Wiltse LL, Kirkaldy-WillisWH, McIvor GWD: The treatment of spinal stenosis. Clin Orthop 115:83-91, 1976
Manuscript received November 22, 1991. Accepted in final form May 6, 1992. Address reprint requests to: Anthony J. Caputy, M.D., Division of Neurosurgery, Georgetown University Hospital, 3800 Reservoir Road NW, Washington, DC 20007.
J. Neurosurg. / Volume 77 / November. 1992
