Spinal Disorders: Fundamentals of Diagnosis and Treatment Part 55 doc

ab cd Figure 6. Surgical decompression of a spinal stenosis a A midline approach exposes the interlaminar windows L3/4 and L4/5 as well as the facet joints to decompress a spinal stenosis at these levels. b The supra- and interspinous ligaments are resected under the preservation of the spinous pro- cess. The interlaminar window is opened with a Kerrison rongeur and the compressing bone and hypertrophied flavum are removed. c It is important to realize that the narrowest part of the stenosis is always under the lamina. Therefore, the lamina has to be resected (laminotomy) in the caudal third or half. The remaining part needs to be undercut from the superior and inferior sides, respectively. d In some cases, the undercutting of the lamina does not suffice for an adequate decompression and the lamina needs to be resected. riorate in longer follow-up [45, 49, 89]. Clinical results of decompression on open (50–90%) [6, 80, 95] or microsurgical [53, 96] laminotomy are quite similar to those achieved by laminectomy. Although it is generally assumed that laminec- tomy may increase or cause vertebral instability [31, 35], no difference in clinical outcomes or spondylolisthesis progression between the two treatment methods was seen in two studies [95, 96], especially not when the motion segments were 528 Section Degenerative Disorders fully stable preoperatively and were not made unstable by a total laminectomy [29, 80]. Decompression and Spinal Fusion The addition of fusion with or without instrumentation to surgical decompres- sion is generally recommended when segmental instability is assumed. However, the radiologic assessment of segmental instability remains a matter of debate. Decompression and fusion are considered by many spine surgeons in case of: segmental instability (degenerative spondylolisthesis and scoliosis) concomitant moderate to severe back pain necessity for a wide decompression recurrent spinal stenosis Instrumented fusion provides higher fusion rates and better long term outcome The best fusion technique (Case Introduction, Case Study 2)isstillcontroversial, and the evidence in the literature favoring one technique over the other is still sparse [27, 28, 63]. Most information relates to cases in which degenerative spon- dylolisthesis is associated with spinal stenosis. Herkowitz et al. [31] prospectively compared decompression alone versus decompression and non-instrumented fusion in 50 patients who had spinal stenosis and degenerative spondylolisthesis. The authors concluded that in the patients who had had a concomitant fusion, the results were significantly better with respect to relief of pain in the back and lower limbs. In a subsequent study, Fishgrund et al. [24] prospectively random- a b c de Case Study 2 A 71-year-old female presented with buttock and posterior thigh pain only while walking. She was asymp- tomatic while sitting, lying and riding a bicycle. The painfree walking distance was limited to about 200 m. The standard lateral radiograph ( a) exhibited a degenerative spondylo- listhesis at the level of L4/5. A T2W image ( b) confirmed the suspected diagnosis of a concomitant spinal stenosis at this level (arrow). Note the hypertrophied flavum (arrow- heads) and degenerative changes of the facet joints (arrows)( c). Since the patient did not report any back pain, a lamina preserving decompression was performed. The degenerative spondylolisthesis was addressed by a non-instrumented fusion to improve long term outcome. At 2 years postoperatively the fusion was solid (arrows)( d, e). The patient was pain free and able to perform all her desired activities. Lumbar Spinal Stenosis Chapter 19 529 ized 67 patients comparing instrumented (pedicle screw fixation) versus non- instrumented fusion. Clinical outcome was excellent or good in 76% of the instrumented and 85% of the non-instrumented cases. This difference was not statistically significant. However,successful fusion was significantly higher in the instrumented group (82 vs. 45%). The authors concluded that the use of pedicle screws may lead to a higher fusion rate, but clinical outcome shows no improve- ment in pain in the back and lower limbs. However, Kornblum et al. [57] demon- strated the long term (5–14 years) benefits of a successful fusion over non-union with respect to back and lower limb symptoms in patients with degenerative spondylolisthesis and spinal stenosis. The need for an additional interbody fusion is not supported by the literature There is no evidence in the literature that an additional interbody fusion by an anterior (ALIF) or posterior (PLIF, TLIF) approach improves outcome. Newer techniques such as interspinous spacer stabilization are still evolving and conclu- sions on clinical effectiveness are premature [105]. Operative Risks and Complications Reoperation rates for decompressive laminectomy vary from 7% to 23% [32, 35, 40, 49]. In a cohort study [64], the cumulative incidence of reoperation among patients who underwent surgery for spinal stenosis was slightly higher following initial fusion (19.9%) than decompression alone (16.8%). Reoperation among patients initially presenting with spondylolisthesis was lower with fusion (17.1%) than with decompression alone (28%). These findings are supported by controlled trials indicating better outcome for fusion than decompression alone when spondylolisthesis is present [24, 31]. Interestingly, this data suggests that over 60% of reoperations following fusion are associated with device complica- tions or non-union, rather than new levels of disease or disease progression. In a population based study of reoperation after back surgery [37], the sub- group spinal stenosis showed a complication rate for laminectomy alone and decompression with fusion of 4.6% and 7.7%, respectively. Reoperation after laminectomy was seen in 10% of the cases, which was equal to the 10.2% after decompression with fusion. Patients with spinal stenosis often present with significant comorbidities which influence the surgical strategy The morbidity associated with surgical treatment of lumbar stenosis in the elderly is an important aspect as those patients often present with a number of preexisting cardiovascular, pulmonary, or metabolic comorbidities [15, 18, 47, 49]. Advanced age does not increase the morbidity, nor does it decrease patient satisfaction or lengthen the return to activity [25, 81]. An increased complication rate has also been shown to be associated with spinal fusion performed for lum- bar stenosis in elderly patients [15, 18, 94]. Therefore less invasive surgical approaches may be of particular interest. Mortality rate has been found to be approximately 0.6–0.8% [18, 92]. 530 Section Degenerative Disorders Recapitulation Epidemiology. Spinal stenosis can be found in up to 80 % of individuals aged over 70 years. However, about 20% of asymptomatic individuals demon- strate signs of spinal stenosis on MRI indicating that there is no strong correlation with the imaging find- ings. The rate of spinal surgery for spinal stenosis is about 10 per 100000 individuals per year. Pathogenesis. The pathomechanism of central spinal stenosis is predominantly related to a hyper- trophy of the yellow ligament which is a result of a compensatory mechanism to restabilize a segmen- tal hypermobility. Furthermore, bony canal com- promise is caused by the occurrence of facet joint enlargement (osteoarthrosis), osteophyte forma- tion,anddegenerative spondylolisthesis.Thisfi- nally results in a progressive compression of the cauda equina. A congenitally narrow spinal canal is a rare cause of spinal stenosis. Claudication symp- toms can be explained by the neurogenic compres- sion and/or the vascular compression theory.Itis assumed that both mechanisms play a role. Me- chanical nerve root compression resultsinde- creased nutrition, microvascular changes, edema and fibrosis. The vascular compression theory sug- gests that spinal stenosis has pathologic effects on the blood supply of the cauda equina. It is assumed that venous congestion within the nerve root(s) between the levels of stenosis leads to a compro- mised nutrition and results in clinical symptoms. Clinical presentation. The prevailing symptom of spinal stenosis is neurogenic claudication,which can be described as numbness, weakness and dis- comfort in the legs while walking or prolonged standing. In contrast to vascular claudication, symptoms improve by forward bending. Objective neurological deficits are rarely present during rest. These symptoms may or may not be associated with back pain but usually patients suffer much more from the claudication symptoms while they can live with the back pain. Radicular claudication is caused by a lateral recess or foraminal stenosis and results in nerve root pain while walking and prolonged standing. Diagnostic work-up. The imaging modality of choice is MRI, which allows a precise depiction of the pathoanatomy in terms of the central and fo- raminal stenosis. Standing radiographs are useful to diagnose a concomitant degenerative spondylolis- thesis or scoliosis. Radiographs may also indicate a congenitally narrow spinal canal. Neurophysiologic studies are indicated to confirm the significance of a mild to moderate spinal stenosis with equivocal symptoms. They are also helpful in confirming a radi- culopathy in case of a lateral recess or foraminal ste- nosis. In elderly patients, peripheral neuropathy is frequent, which can be detected by electrophysiolo- gy. The most important differential diagnosis is pe- ripheral vascular disease, which has to be ruled out by vascular status and in some cases angiography. Non-operative treatment. Conservative measures cannot influence the natural history of spinal steno- sis, which is a progressive degenerative disease leading to an increasing immobilization of the pa- tient. However, non-operative treatment may be considered in cases with only mild to moderate ste- nosis and only minimal interference with lifestyle. Treatment options consist of medication (analge- sics, NSAIDs, muscle relaxants), administration of calcitonin, postural education, physical therapy and epidural injections. There is only sparse scientific evidence in support of the clinical effectiveness of any such measures compared to the natural history. Operative treatment. The treatment of choice is spinal decompression. In the early years, laminec- tomy was considered the standard surgical treat- ment and is still indicated in severe stenosis. How- ever, reports on increasing segmental instability have resulted in a shift to a more conservative ap- proach preserving the posterior elements as much as possible. Today, laminotomy is the preferred treatment in cases presenting without additional deformity or putative segmental instability. This ap- proach can even be performed by minimal access surgery under microscopic guidance. When degen- erative spondylolisthesis or scoliosis or significant concomitant back pain due to facet joint osteoar- thritis is present, fusion is considered an important adjunct to decompression. Instrumented fusion re- sults in a higher fusion rate and a better long term outcome than non-instrumented fusion. Many spine surgeons therefore favor instrumented fusion although the scientific evidence for this approach is still weak. Lumbar Spinal Stenosis Chapter 19 531 Key Articles Ve rbiest H (1954) A radicular syndrome from developmental narrowing of the lumbar vertebral canal. J Bone Joint Surg Br 36-B:230 – 7 Classic article on the clinical presentation of neurogenic claudication as a result of spinal stenosis. Amundsen T, Weber H, Nordal HJ, Magnaes B, Abdelnoor M, Lilleas F (2000)Lumbar spinal stenosis: conservative or surgical management? A prospective 10-year study. Spine 25(11):1424 – 35 A cohort of 100 patients with symptomatic lumbar spinal stenosis were given surgical or conservative treatment and followed for 10 years. Nineteen patients with severe symp- toms were selected for surgical treatment and 50 patients with moderate symptoms for conservative treatment, whereas 31 patients were randomized between the conservative (n=18) and surgical (n=13) treatment groups. After a period of 4 years, excellent or fair results were found in half of the patients selected for conservative treatment, and in four- fifths of the patients selected for surgery. Patients with an unsatisfactory result from con- servative treatment were offered delayed surgery after 3–27 months. The treatment result of delayed surgery was essentially similar to that of the initial group. The treatment result for the patients randomized for surgical treatment was considerably better than for the patients randomized for conservative treatment. Clinically significant deterioration of symptoms during the final 6 years of the follow-up period was not observed. Patients with multilevel afflictions, surgically treated or not, did not have a poorer outcome than those with single-level afflictions. The authors concluded that the outcome was most favorable forsurgicaltreatment.However,aninitialconservativeapproachseemsadvisablefor many patients because those with an unsatisfactory result can be treated surgically later withagoodoutcome. Grob D, Humke T, Dv orak J (1995) Degenerative lumbar spinal stenosis. Decompression with and without arthrodesis. J Bone Joint Surg Am 77:1036 – 41 The authors prospectively evaluated the results of decompression of the spine, with and without spinal fusion, for the treatment of lumbar spinal stenosis without instability in 45 patients. The patients were randomly assigned to one of three treatment groups: Group I was treated with decompression with laminotomy and medial facetectomy; Group II, with decompression and arthrodesis of the most stenotic segment; and Group III, with decompression and spinal fusion of all decompressed vertebral segments. After 24–32 months, all three groups had a significant improvement in walking distance. With the numbers available, there were no significant differences in the results among the three groups with regard to the relief of pain. The authors concluded that spinal fusion is not necessary in patients presenting with spinal stenosis in the absence of segmental instabil- ity. Herkowitz HN, Kurz LT (1991) Degenerative lumbar spondylolisthesis with spinal ste- nosis. A prospective study comparing decompression with decompr ession and inter- transverse p rocess arthrodesis. J Bone Joint Surg Am 73:802 – 8 In a prospective study, 50 patients who had spinal stenosis associated with degenerative lumbar spondylolisthesis were prospectively studied to determine if concomitant inter- transverse-process arthrodesis provided better results than decompressive laminectomy alone. After 2–4 years, patients with concomitant fusion had the significantly better results with respect to relief of pain in the back and lower limbs. FischgrundJS,MackayM,HerkowitzHN,BrowerR,MontgomeryDM,KurzLT(1997) Degenerative lumbar spondylolisthesis with spinal stenosis: a prospective, randomized study comparing decompressive laminectomy and arthrodesis with and without spinal instrumentation. Spine 22(24):2807 – 12 In this prospective study patients with degenerative spondylolisthesis and spinal stenosis were randomized into groups with and without pedicle screw instrumentation as an adjunct to decompression and posterolateral fusion. After a 2-year follow-up, clinical outcome was excellent or good in 76% of the patients with instrumentation and in 85% without instrumentation. Successful fusion occurred in 82% of the instrumented cases versus 45% of the non-instrumented cases (p<0.0015). However, successful fusion did not influence patient outcome (p =0.435). The authors concluded that the use of pedicle screws may lead to a higher fusion rate, but clinical outcome shows no improvement regardingpaininthebackandlowerlimbs. 532 Section Degenerative Disorders Key Articles Kornblum MB, Fischgrund JS, Herkowitz HN, Abraham DA, Berkower DL, Ditkoff JS (2004) Degenerative lumbar spondylolisthesis with spinal stenosis: a prospective long term study comparing fusion and pseudarthrosis. Spine 29:726 – 33 A longer term follow-up (5–14 years) of the previous study indicated that clinical out- come was excellent to good in 86% of patients with a solid fusion and in 56% of patients with a non-union (p<0.01). The solid fusion group performed significantly better in the symptom severity and physical function categories on the self-administered question- naire. The authors concluded that in patients undergoing single-level decompression and posterolateral arthrodesis for spinal stenosis and concurrent spondylolisthesis, a solid fusion improves long-term clinical outcome. Weinstein JN, Tosteson TD, Lurie JD, Tosteson AN, Blood E, Hanscom B, Herkowitz H, Cammisa F, Albert T, Boden SD, Hilibrand A, Goldberg H, Berven S, An H (2008)Surgi- cal versus nonsurgical therapy for lumbar spinal stenosis. N Engl J Med 358:794 – 810 In this very recent landmark study, study patients with a history of at least 12 weeks of symptoms and spinal stenosis without spondylolisthesis were enrolled in either a ran- domized cohort (n=289) or an observational cohort (n=365) at 13 U.S. spine clinics. Treatment consisted either of decompressive surgery or usual non-surgical care. At 2 years, 67% of patients who were randomly assigned to surgery had undergone surgery, whereas 43% of those who were randomly assigned to receive non-surgical care had also undergone surgery. Despite the high level of non-adherence, the intention-to-treat analy- sis of the randomized cohort showed a significant treatment effect favoring surgery on the SF-36 scale for bodily pain. However, there was no significant difference in scores on phys- ical function or on the Oswestry Disability Index. The as-treated analysis, which combined both cohorts and was adjusted for potential confounders, showed a significant advantage for surgery by 3 and 24 months postoperatively for all primary outcomes. In the combined as-treated analysis, patients who underwent surgery showed significantly more improve- ment in all primary outcomes than did patients who were treated non-surgically. References 1. 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Eur Spine J 13:22–31 Lumbar Spinal Stenosis Chapter 19 537 . spine, with and without spinal fusion, for the treatment of lumbar spinal stenosis without instability in 45 patients. The patients were randomly assigned to one of three treatment groups: Group. decompression with laminotomy and medial facetectomy; Group II, with decompression and arthrodesis of the most stenotic segment; and Group III, with decompression and spinal fusion of all decompressed. treatment, and in four- fifths of the patients selected for surgery. Patients with an unsatisfactory result from con- servative treatment were offered delayed surgery after 3–27 months. The treatment