Eur J Orthop Surg Traumatol DOI 10.1007/s00590-014-1532-y
ORIGINAL ARTICLE
Clinical results of microsurgical bilateral decompression via unilateral approach for lumbar canal stenosis with multiple-level involvement Nobuhiro Tanaka • Kazuyoshi Nakanishi • Naosuke Kamei Risako Yamamoto • Toshio Nakamae • Bunichiro Izumi • Ryo Ohta • Yuki Fujioka • Mitsuo Ochi
•
Received: 27 February 2014 / Accepted: 14 August 2014 Ó Springer-Verlag France 2014
Abstract Object Microsurgical decompression of the lumbar spine is a beneficial approach for selected patients of lumbar spinal stenosis (LSS). The purpose of this prospective study was to describe the clinical results of surgical treatment for microsurgical bilateral decompression via unilateral approach on patients with LSS with multiple-level involvement. Materials and methods Seventy-three consecutive patients who had microsurgical bilateral decompression via unilateral approach of more than two spinal levels were included in this study. Seventy-seven patients who had surgery at a single level over the same time periods were compared as a single-level LSS group. Results The preoperative Japanese Orthopaedic Association scores averaged 11.7 points, and the postoperative scores averaged 21.2 points with an average recovery rate (RR) of 56 % in the multiple-level LSS group. There was no significant difference in the RR between the groups. There were no major complications related to the surgery in the both groups. Conclusion Microsurgical bilateral decompression via unilateral approach was a useful and safe operative procedure for LSS patients. Sufficient clinical results that were comparable to single-level LSS patients were obtained even in the patients with multiple-level LSS, if the patient were correctly selected and the microsurgical decompression surgery were carefully performed.
N. Tanaka (&) K. Nakanishi N. Kamei R. Yamamoto T. Nakamae B. Izumi R. Ohta Y. Fujioka M. Ochi Department of Orthopaedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551, Japan e-mail: [email protected]
Keywords Lumbar spine Canal stenosis Microsurgical decompression Surgical outcomes Multiple level
Introduction With the rapid growth of the elderly population in recent decades, physicians are confronted with increased cases of degenerative spine diseases. Lumbar spinal canal stenosis (LSS) is a common disease of the lumbar spine and occurs frequently in the elderly population [1]. This chronic sickness may result in severe morbidity with low-back pain, pain and/or numbness of legs, gait difficulties due to neurogenic claudications, and even to paralysis of the lower extremities or urinary dysfunction [2]. Frequently, there exists multiple spondylotic changes in the spinal column in the elderly population; therefore, there may be more frequent multiple-level spinal compressions of the LSS in this generation compared to younger generations. Posterior decompression with laminectomy is a standard operative therapy for this disease, and decompression surgery has been shown to bring measurable results for patients [3, 4]. Recent innovations of microsurgical technique enable surgeons to perform less invasive therapies for this degenerative condition [5–9]. In particular, bilateral decompression via a unilateral approach has been reported as a less invasive technique [10–12]. Preserving the facet joint is important in order to maintaining postoperative spinal stability for the lumbar spine [13]. However, there are few reports of clinical results of multiple-level compression of LSS patients [14, 15], and the clinical results of microsurgical procedures for these conditions are not fully examined. We carefully determine the decompression levels for surgical operations to restrict the spinal levels, which is
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responsible to the clinical symptoms based on the physiological and radiological findings. In the current study, we performed a prospective study of surgical treatment for microsurgical bilateral decompression via unilateral approach in patients with LSS with multiple-level involvement. The purpose of this study was to evaluate the clinical results of microsurgical surgical procedures for LSS patients with multiple-level spinal compressions.
Methods One hundred fifty consecutive patients with LSS who were scheduled to undergo microsurgical lumbar decompression were included for the study. The patient inclusion criteria included radiculopathy and/or cauda equina syndrome rather than low-back pain with no previous back surgery and unsuccessful conservative treatment for 3 months. The patients with no or tolerable lower extremity symptoms were treated conservatively. The patients with significant low-back pain due to preexistent spinal instabilities or deformities were excluded from this study and indicated to spinal fusions. Apparent congenital spinal stenosis or spinal stenosis based on achondroplasia was also excluded from the study. The decompression levels for surgical operations were carefully determined based on the clinical findings and limited to one spinal level as much as possible. Based on the number of operation sites, the patients were divided into two groups: the multiple-level canal stenosis group and the single-level canal stenosis group. The multiple-level stenosis group consisted of 73 patients (36 men and 37 women), and the mean age at the time of operation was 73 years (range 41–93 years). All of the patients in this group had multiple-level canal stenosis of more than two spinal levels, and 21 patients (29 %) showed degenerative spondylolisthesis of the lumbar spine. The single-level canal stenosis group consisted of 77 patients (47 men and 30 women) who had decompression surgery at a single spinal level during the same time period. The mean age at the time of surgery of this group was 70 years (range 39–86 years). Thirty patients (39 %) of this group showed degenerative spondylolisthesis. All of the patients in this series had microsurgical bilateral decompression via unilateral approach without spinal fusion using a surgical microscope. The posterior elements were preserved as much as possible to prevent postoperative instabilities or slippages, while sufficient decompressions were confirmed under the surgical microscope. The levels for decompression were carefully determined to restrict spinal levels, which is responsible to the symptoms by radiographic evaluation and clinical physiological examinations: the area of hypesthesia, sensory
123
losses, muscle weaknesses, and decreases in deep tendon reflexes. Morphological deformities of the dural sac or the nerve roots on preoperative MRIs, myelograms, and CT myelograms due to compression or impingement were considered significant when judging the level of radiographic abnormalities. Neurologic deficits before and after surgery were assessed using a scoring system proposed by the Japanese Orthopaedic Association (JOA score) (Table 1). Functional improvement of the JOA score was expressed by the recovery rate (RR) [16]. The RR for each patient was classified into four grades: the RR greater than 75 % categorized as excellent of activity of daily living, 50–74 % good, 25–49 % fair, and \24 % as poor, respectively. The mean follow-up period was 23 months (range 12–66 months) for the multiple-level group and 24 months (range 12–54 months) for the single-level group. This study was reviewed and approved by the institutional review board, and all patients provided informed consent prior to the initiation of the study. Statistical analysis was performed using the Mann–Whitney U test. P \ 0.05 was considered statistically significant.
Results Microsurgical decompressions were performed for all patients and included 2 spinal levels for 65 patients and 3 spinal levels for 8 patients in the multiple-level group. In this group, the preoperative JOA scores averaged 11.7 points (range -3 to 21) and the postoperative scores averaged 21.2 points (range 3–28). The JOA scores significantly improved after surgery (P \ 0.05), and the recovery rate (RR) at the follow-up period averaged 56 % (range 0–95 %). Excellent result was obtained by 19 patients (26 %), good results by 28 patients (38 %), fair results by 17 patients (23 %), and poor results by 9 patients (12 %). The mean operation time was 119 min (range 70–265 min), and the mean blood loss was 65 mls (range 10–280 mls). There were no major complications in these patients, and only 2 cases of wound infections, 1 case of dural tear, and 1 case of wrong-level surgery were reported. There were no cases of clinical deteriorations due to the recurrences of stenosis at the same spinal levels; however, 4 cases require additional operations during the follow-up period; 2 cases of discectomy for lumbar disc herniation at the adjacent levels, 1 case of spinal fusion for progressive degenerative scoliosis, and 1 case of cervical laminoplasty for cervical spondylotic myelopathy. In the single-level group, the preoperative JOA scores averaged 13.3 points (range 3–22) and the postoperative scores averaged 22.4 points (range 4–29) with significant improvement. The RR averaged 59 % (range -19 to
Eur J Orthop Surg Traumatol Table 1 Criteria for low-back pain diseases of the Japanese Orthopaedic Association score (full score 29) Symptoms and signs
Evaluation and score
1. Subjective symptoms Lower back pain None
3
Occasional mild pain
2
Occasional severe pain
1
Continuous severe pain
0
Leg pain and/or tingling None
3
Occasional slight symptoms
2
Occasional severe symptoms
1
Continuous severe symptoms
0
Gait Normal
3
Able to walk farther than 500 m
2
Although it results in symptoms Unable to walk farther than 500 m
1
Unable to walk farther than 100 m
0
2. Clinical signs Straight-leg-raising test Normal 30°–70° \30° Sensory disturbance None
2 1 0
and the mean blood loss was 39 mls (range 5–270 mls). There were also no major complications in this group. However, one patient had a postoperative recurrence of the symptoms within 5 months and required additional posterior decompression at the same spinal level. Two cases require additional operations during the follow-up period: 1 case of posterior decompression for LSS at the adjacent levels and 1 case of posterior decompression for foraminal stenosis at the adjacent levels. There were no significant differences in age between the multiple-level patients group and the single-level group. The pre- and postoperative JOA scores of the multiplelevel patients group were significantly lower than those of the single-level group; however, there was no significant difference in the RR between the groups (P \ 0.05). Excellent or good results in the RR were obtained in 47 patients (64 %) of the multiple-level patients group and 55 patients (71 %) in the single-level group, respectively. The operation times were significantly longer in the multiplelevel group than those in the single-level group; however, those of each operation level in the multiple-level group were significantly shorter than the single-level group (P \ 0.05). The blood losses were also significantly larger in the multiple-level group than those in the single-level group, but there was no significant difference in the blood losses/operation level between the groups (P \ 0.05) (Table 2).
2
Slight disturbance (not subjective)
1
Marked disturbance
0
Case presentation
Motor disturbance Normal
2
Slight weakness (MMT 4)
1
Marked weakness (MMT 3–0)
0
3. Activities of daily living
Severe
Moderate
None
Turn over while lying
0
1
2
Standing
0
1
2
Washing
0
1
2
Leaning forward
0
1
2
Sitting (about 1 h)
0
1
2
Lifting or holding heavy object Walking 4. Urinary bladder function
0
1
2
0
1
2
Normal
0
Mild dysuria
-3
Severe dysuria
-6
100 %), and excellent result was obtained by 23 patients (30 %), good results by 32 patients (42 %), fair results by 10 patients (13 %), and poor results by 12 patients (16 %). The mean operation time was 95 min (range 48–245 min),
A 71-year-old woman had a significant gait disturbance for 1 year. She had severe pain and numbness in both lower extremities, and these symptoms increased while walking. Her symptoms suggested the existence of LSS with Table 2 Comparison between the multiple-level patients group and the single-level patient group Multiple-level (n = 73)
Single-level (n = 77)
Significancea
Age (years)
73
70
NS
Preoperative JOA score
11.7
13.3
P \ 0.05
Postoperative JOA score
21.2
22.4
P \ 0.05
Recovery rate (%)
61
59
NS
Operation time (min)
119
95
P \ 0.05
Operation time/ operation level (min)
58
95
P \ 0.05
Blood loss (ml)
65
39
P \ 0.05
Blood loss/operation level (ml)
31
39
NS
JOA Japanese Orthopaedic Association, NS not significant a
Mann–Whitney U test
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neurogenic claudication. Preoperative myelogram showed a severe LSS at 3–4 and L4–5 with mild degenerative spondylolisthesis of the L4 vertebra (Figs. 1, 2). The preoperative JOA score was 11 points. A microsurgical bilateral decompression via unilateral approach was performed. The operation time was 123 min, and the blood loss was 65 ml. There were no complications related to the surgery. At 5 years postoperatively, her gait disturbance was resolved and the JOA score had improved to 24 with an RR of 72 %. Plane X–p imaging at the latest follow-up showed a well-maintained alignment of the lumbar spine
(Fig. 3). Postoperative CT scans demonstrated sufficient decompressions, while preserving facet joints to avoid postoperative instability (Fig. 4).
Discussion Degenerative changes in the intervertebral discs and facet joints cause narrowing of the spinal canal and neural foramina, and these conditions in the lumbar spine result in LSS, especially in the elderly population [1]. The patients
Fig. 1 Images obtained from a 71-year-old woman. Preoperative AP and lateral plane X-ps (a, b) and lateral myelogram (c) show severe spinal canal stenosis at L3–4 and L4–5 with mild degenerative spondylolisthesis of the L4 vertebra
Fig. 2 Preoperative CT myelogram at L3–4 and L4–5 (a, b) shows severe spinal canal stenosis
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Fig. 3 Postoperative plane X-ps (a, b) shows well-maintained alignments of the lumbar spine
Fig. 4 Postoperative CT scans at L3–4 and L4–5 (a, b) show sufficient decompressions while preserving facet joints
usually suffer disabling back and lower extremity pain. Nonoperative management includes the restriction of aggravating activities, physical therapy, and anti-inflammatory medications for the patients with mild clinical symptoms. Surgical treatment may be appropriate for patients who showed no improvement after nonoperative
treatment or showed more severe clinical symptoms. Because of the recent increase in the elderly population, there are more frequent cases of multiple-level involvement of degenerative lumbar spine disease. However, few reports have described the clinical results of multiple-level compression of LSS patients [14, 15], and the therapeutic
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results for these conditions have not been examined fully. In the current study, the clinical results of microsurgical bilateral decompression via unilateral approach in patients with LSS with multiple spinal level involvement and in patients with single spinal level involvement were obtained. Usually, surgical indication for this disease includes intolerable pain in average daily living, progressively worsening or a significant degree of motor weakness, and sphincter dysfunction [17]. The extent of surgical decompression was determined by clinical evaluation, imagery examination, and the type of disease process exhibited. Satisfactory results from operative treatment can be expected only after adequate and thorough decompression of the neural elements. Because the most common cause of unsatisfactory results is inadequate decompression of the spinal contents [20], surgeons require sufficient decompression to resolve the symptoms. Therefore, the surgical decision for LSS patients with multiple spinal level involvement should be carefully planned. We determined the surgical operation sites through radiographic evaluation and physiological examinations. In the current series, 73 of 150 patients (49 %) were diagnosed as multiple-level involvements, and sufficient clinical results were obtained after surgery. Imaging features of the spinal involvement, facet joint arthrosis, ligament flavum hypertrophy, disc protrusion, and nerve root impingement should be assessed for exact diagnosis, and MRI and CT have been used for the clinical assessment of LSS [18, 19]. Sato and Kikuchi reported the clinical analysis of two spinal level compression in LSS patients [15]. They reported that the responsible level should be determined based on the neurologic findings after a gait load test and a selective nerve root block, because it is uncommon for both stenotic levels to be symptomatic even in patients with two spinal level stenosis. Obviously, there must be asymptomatic abnormalities on MRI [20]; therefore, physicians should correlate imagery abnormalities and clinical signs and symptoms before operative treatment is contemplated. Although the majority of LSS patients may show a single spinal level involvement, there must be numerous LSS patients with multiple spinal level involvement due to the recent rapid growth of the elderly population. There may be considerable complications even in decompression surgery, especially in elderly or multiply operated patients [21, 22]. Minimally invasive surgery should be attempted to reduce operative complications. The pathology of LSS has not been characterized fully, whereas the degenerated ligament of flavum had been reported to be important in the induction of neurologic symptoms [23]. Microsurgical decompression of the spinal canal is one of the optimal treatments for this disease, and
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many authors have reported its advantages and effectiveness [5, 7–9, 11, 24]. These procedures are accompanied by less blood loss and surgical morbidity. In addition, the microsurgical procedures preserve facet joints and laminae, which preserve postoperative spinal stabilities [25]. Papavero et al. [24] also reported that microsurgical bilateral decompression using unilateral laminotomy is an effective surgical option for LSS, even in high-risk patients with multilevel stenosis. In the current study, we performed microsurgical bilateral decompression via unilateral approach on all the patients, and the blood losses were significantly larger in the multiple-level group than those in the single-level group. However, there was no significant difference in the blood losses/operation level between the groups. The operation times were significantly longer in the multiple-level group than those in the single-level group, and the operation time/operation level in the multiple-level group was significantly shorter than the single-level group. These results indicate that, with the aid of surgical microscope, a surgeon can perform a less invasive operation even for the multiple spinal level stenosis patient. Although bilateral decompression via unilateral approach is a useful minimally invasive procedure, this approach would be difficult and technically demanding in cases of decompression of the lateral recess and medial foraminal stenosis at the contralateral side. Depth and inclination of laminae at the surgical site may alter operative fields at the contralateral side. In such cases, this surgical technique may have potential risks such as incomplete decompression or neuromeningeal damage. Surgical microscopes enable clear visualization of the pathology of the region. The use of a surgical microscope is necessary for a safe procedure, and blind or rough manipulation of the dura or nerve roots should be avoided during microsurgical procedures. Meanwhile, surgeons should understand the microsurgical anatomy of the ligament of flavum and realize its biomechanical advantages to preserve spinal stabilities. Decompression should be performed to address all clinically relevant neural elements while maintaining spinal stability. Surgical success rates are sufficiently high for this disease; however, they may be compromised by inadequate decompression, inadequate stabilization, or medical comorbidities [26]. Lu et al. [27] reported that spinal motion was significantly increased in flexion after multilevel fenestrations and discectomies. Strict selection of patient for decompression surgery and restriction of the surgical levels should be needed to obtain good clinical results for multiple-level involved patient. Spinal fusions with instrumentation, which can resolve postoperative instabilities and achieve the restoration of spinal alignment, may address these issues of postoperative iatrogenic instabilities and insufficient clinical results. In
Eur J Orthop Surg Traumatol
the current study, we demonstrate equivalent clinical results in the RR between the single and multiple spinal level LSS patients after microsurgical decompressions. Of course, cautious decisions should be made to determine the decompression levels for surgical operation, and comparable clinical results were obtained in LSS patients with multiple-level involvement compared to patients with single-level compression. Although posterior decompression and fusions may be logical options for multiple spinal level involvement, decompression surgery with less invasive techniques may bring sufficient clinical results even in multiple spinal level LSS patients. Some latent limitations may exist in this study. The JOA score may not provide a wide-ranging assessment of the level of impairment in LSS patients [28]. In addition, there may be a false-positive clinical diagnosis based on the imaging studies, based mainly on MRIs [20]. New diagnostic tools to assess the nerve function, such as a diffusion tensor imaging [29], may be needed for exact diagnosis, especially in the elderly patients.
Conclusion According to the increase in the elderly population, physicians may encounter increased LSS patients with multiple spinal level involvement. Obviously, surgeons should determine the decompression levels with great care to reduce surgical morbidity. If the patient were correctly selected and the decompression surgery were carefully performed, sufficient clinical results that were comparable to single-level LSS patients were obtained even in the patients with multiple-level LSS. Conflict of interest
None.
References 1. Postacchini F, Gumina S, Cinotti G et al (1994) Ligamenta flava in lumbar disc herniation and spinal stenosis. Light and electron microscopic morphology. Spine 19(8):917–922 2. Jo¨nsson B, Annertz M, Sjo¨berg C et al (1997) A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part I: clinical features related to radiographic findings. Spine 22(24):2932–2937 3. Herno A, Airaksinen O, Saari T (1993) Long-term results of surgical treatment of lumbar spinal stenosis. Spine 18(11): 1471–1474 4. Jo¨nsson B, Annertz M, Sjo¨berg C et al (1997) A prospective and consecutive study of surgically treated lumbar spinal stenosis. Part II: five-year follow-up by an independent observer. Spine 22(24):2938–2944 5. Baba H, Uchida K, Maezawa Y et al (1996) Microsurgical nerve root canal widening without fusion for lumbosacral intervertebral foraminal stenosis: technical notes and early results. Spinal Cord 34(11):644–650
6. Ikuta K, Tono O, Oga M (2008) Clinical outcome of microendoscopic posterior decompression for spinal stenosis associated with degenerative spondylolisthesis–minimum 2-year outcome of 37 patients. Minim Invasive Neurosurg 51(5):267–271 Epub 2008 Oct 14 7. Mayer HM, Korge A (2009) Microsurgical decompression of degenerative lumbar spinal stenosis. Eur Spine J 18(12): 1989–1990 8. Schillberg B, Nystro¨m B (2000) Quality of life before and after microsurgical decompression in lumbar spinal stenosis. J Spinal Disord 13(3):237–241 9. Tsai RY, Yang RS, Bray RS Jr (1998) Microscopic laminotomies for degenerative lumbar spinal stenosis. J Spinal Disord 11(5): 389–394 10. Cavusoglu H, Kaya RA, Turkmenoglu ON et al (2007) Midterm outcome after unilateral approach for bilateral decompression of lumbar spinal stenosis: 5-year prospective study. Eur Spine J 16:2133–2142 11. Sasai K, Umeda M, Maruyama T et al (2008) Microsurgical bilateral decompression via a unilateral approach for lumbar spinal canal stenosis including degenerative spondylolisthesis. J Neurosurg Spine 9(6):554–559 12. Weiner BK, Walker M, Brower RS et al (1999) Microdecompression for lumbar spinal canal stenosis. Spine 24:2268–2272 13. Jo¨nsson B, Akesson M, Jo¨nsson K et al (1992) Low risk for vertebral slipping after decompression with facet joint preserving technique for lumbar spinal stenosis. Eur Spine J 1:100–104 14. Haba K, Ikeda M, Soma M et al (2005) Bilateral decompression of multilevel lumbar spinal stenosis through a unilateral approach. J Clin Neurosci 12(2):169–171 15. Sato K, Kikuchi S (1997) Clinical analysis of two-level compression of the cauda equina and the nerve roots in lumbar spinal canal stenosis. Spine 22(16):1898–1903 16. Hirabayashi K, Miyakawa J, Satomi K et al (1981) Operative results and postoperative progression of ossification among patients with ossification of cervical posterior longitudinal ligament. Spine 6(4):354–364 17. Lee CK, Hansen HT, Weiss AB (1978) Developmental lumbar spinal stenosis. Pathology and surgical treatment. Spine 3(3): 246–255 18. Drew R, Bhandari M, Kulkarni AV et al (2000) Reliability in grading the severity of lumbar spinal stenosis. J Spinal Disord 13(3):253–258 19. Lurie JD, Tosteson AN, Tosteson TD, Carragee E et al (2008) Reliability of readings of magnetic resonance imaging features of lumbar spinal stenosis. Spine 33(14):1605–1610 20. Boden SD, Davis DO, Dina TS et al (1990) Abnormal magneticresonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am 72(3):403–408 21. Carroll SE, Wiesel SW (1992) Neurologic complications and lumbar laminectomy. A standardized approach to the multiplyoperated lumbar spine. Clin Orthop Relat Res 284:14–23 22. Smith EB, Hanigan WC (1992) Surgical results and complications in elderly patients with benign lesions of the spinal canal. J Am Geriatr Soc 40(9):867–870 23. Okuda T, Fujimoto Y, Tanaka N et al (2005) Morphological changes of the ligamentum flavum as a cause of nerve root compression. Eur Spine J 14(3):277–286 Epub Oct 2, 2004 24. Papavero L, Thiel M, Fritzsche E, Kunze C, Westphal M, Kothe R (2009) Lumbar spinal stenosis: prognostic factors for bilateral microsurgical decompression using a unilateral approach. Neurosurgery 65(6 Suppl):182–187 25. Hamasaki T, Tanaka N, Kim J et al (2009) Biomechanical assessment of minimally invasive decompression for lumbar spinal canal stenosis: a cadaver study. J Spinal Disord Tech 22(7):486–491
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Eur J Orthop Surg Traumatol 26. Hilibrand AS, Rand N (1999) Degenerative lumbar stenosis: diagnosis and management. J Am Acad Orthop Surg 7(4):239–249 27. Lu WW, Luk KD, Ruan DK et al (1999) Stability of the whole lumbar spine after multilevel fenestration and discectomy. Spine 24(13):1277–1282 28. Nakamura M, Miyamoto K, Shimizu K (2009) Difference in evaluation of patients with low back pain using the Japanese
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Orthopaedic Association Score for Back Pain and the Japanese Version of the Roland-Morris Disability Questionnaire. J Orthop Sci 14(4):367–373 Epub 2009 Aug 7 29. Eguchi Y, Ohtori S, Orita S et al (2011) Quantitative evaluation and visualization of lumbar foraminal nerve root entrapment by using diffusion tensor imaging: preliminary results. AJNR Am J Neuroradiol 32(10):1824–1829 Epub 2011 Sep
ORIGINAL ARTICLE
Clinical results of microsurgical bilateral decompression via unilateral approach for lumbar canal stenosis with multiple-level involvement Nobuhiro Tanaka • Kazuyoshi Nakanishi • Naosuke Kamei Risako Yamamoto • Toshio Nakamae • Bunichiro Izumi • Ryo Ohta • Yuki Fujioka • Mitsuo Ochi
•
Received: 27 February 2014 / Accepted: 14 August 2014 Ó Springer-Verlag France 2014
Abstract Object Microsurgical decompression of the lumbar spine is a beneficial approach for selected patients of lumbar spinal stenosis (LSS). The purpose of this prospective study was to describe the clinical results of surgical treatment for microsurgical bilateral decompression via unilateral approach on patients with LSS with multiple-level involvement. Materials and methods Seventy-three consecutive patients who had microsurgical bilateral decompression via unilateral approach of more than two spinal levels were included in this study. Seventy-seven patients who had surgery at a single level over the same time periods were compared as a single-level LSS group. Results The preoperative Japanese Orthopaedic Association scores averaged 11.7 points, and the postoperative scores averaged 21.2 points with an average recovery rate (RR) of 56 % in the multiple-level LSS group. There was no significant difference in the RR between the groups. There were no major complications related to the surgery in the both groups. Conclusion Microsurgical bilateral decompression via unilateral approach was a useful and safe operative procedure for LSS patients. Sufficient clinical results that were comparable to single-level LSS patients were obtained even in the patients with multiple-level LSS, if the patient were correctly selected and the microsurgical decompression surgery were carefully performed.
N. Tanaka (&) K. Nakanishi N. Kamei R. Yamamoto T. Nakamae B. Izumi R. Ohta Y. Fujioka M. Ochi Department of Orthopaedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University, Kasumi 1-2-3, Minami-ku, Hiroshima 734-8551, Japan e-mail: [email protected]
Keywords Lumbar spine Canal stenosis Microsurgical decompression Surgical outcomes Multiple level
Introduction With the rapid growth of the elderly population in recent decades, physicians are confronted with increased cases of degenerative spine diseases. Lumbar spinal canal stenosis (LSS) is a common disease of the lumbar spine and occurs frequently in the elderly population [1]. This chronic sickness may result in severe morbidity with low-back pain, pain and/or numbness of legs, gait difficulties due to neurogenic claudications, and even to paralysis of the lower extremities or urinary dysfunction [2]. Frequently, there exists multiple spondylotic changes in the spinal column in the elderly population; therefore, there may be more frequent multiple-level spinal compressions of the LSS in this generation compared to younger generations. Posterior decompression with laminectomy is a standard operative therapy for this disease, and decompression surgery has been shown to bring measurable results for patients [3, 4]. Recent innovations of microsurgical technique enable surgeons to perform less invasive therapies for this degenerative condition [5–9]. In particular, bilateral decompression via a unilateral approach has been reported as a less invasive technique [10–12]. Preserving the facet joint is important in order to maintaining postoperative spinal stability for the lumbar spine [13]. However, there are few reports of clinical results of multiple-level compression of LSS patients [14, 15], and the clinical results of microsurgical procedures for these conditions are not fully examined. We carefully determine the decompression levels for surgical operations to restrict the spinal levels, which is
123
Eur J Orthop Surg Traumatol
responsible to the clinical symptoms based on the physiological and radiological findings. In the current study, we performed a prospective study of surgical treatment for microsurgical bilateral decompression via unilateral approach in patients with LSS with multiple-level involvement. The purpose of this study was to evaluate the clinical results of microsurgical surgical procedures for LSS patients with multiple-level spinal compressions.
Methods One hundred fifty consecutive patients with LSS who were scheduled to undergo microsurgical lumbar decompression were included for the study. The patient inclusion criteria included radiculopathy and/or cauda equina syndrome rather than low-back pain with no previous back surgery and unsuccessful conservative treatment for 3 months. The patients with no or tolerable lower extremity symptoms were treated conservatively. The patients with significant low-back pain due to preexistent spinal instabilities or deformities were excluded from this study and indicated to spinal fusions. Apparent congenital spinal stenosis or spinal stenosis based on achondroplasia was also excluded from the study. The decompression levels for surgical operations were carefully determined based on the clinical findings and limited to one spinal level as much as possible. Based on the number of operation sites, the patients were divided into two groups: the multiple-level canal stenosis group and the single-level canal stenosis group. The multiple-level stenosis group consisted of 73 patients (36 men and 37 women), and the mean age at the time of operation was 73 years (range 41–93 years). All of the patients in this group had multiple-level canal stenosis of more than two spinal levels, and 21 patients (29 %) showed degenerative spondylolisthesis of the lumbar spine. The single-level canal stenosis group consisted of 77 patients (47 men and 30 women) who had decompression surgery at a single spinal level during the same time period. The mean age at the time of surgery of this group was 70 years (range 39–86 years). Thirty patients (39 %) of this group showed degenerative spondylolisthesis. All of the patients in this series had microsurgical bilateral decompression via unilateral approach without spinal fusion using a surgical microscope. The posterior elements were preserved as much as possible to prevent postoperative instabilities or slippages, while sufficient decompressions were confirmed under the surgical microscope. The levels for decompression were carefully determined to restrict spinal levels, which is responsible to the symptoms by radiographic evaluation and clinical physiological examinations: the area of hypesthesia, sensory
123
losses, muscle weaknesses, and decreases in deep tendon reflexes. Morphological deformities of the dural sac or the nerve roots on preoperative MRIs, myelograms, and CT myelograms due to compression or impingement were considered significant when judging the level of radiographic abnormalities. Neurologic deficits before and after surgery were assessed using a scoring system proposed by the Japanese Orthopaedic Association (JOA score) (Table 1). Functional improvement of the JOA score was expressed by the recovery rate (RR) [16]. The RR for each patient was classified into four grades: the RR greater than 75 % categorized as excellent of activity of daily living, 50–74 % good, 25–49 % fair, and \24 % as poor, respectively. The mean follow-up period was 23 months (range 12–66 months) for the multiple-level group and 24 months (range 12–54 months) for the single-level group. This study was reviewed and approved by the institutional review board, and all patients provided informed consent prior to the initiation of the study. Statistical analysis was performed using the Mann–Whitney U test. P \ 0.05 was considered statistically significant.
Results Microsurgical decompressions were performed for all patients and included 2 spinal levels for 65 patients and 3 spinal levels for 8 patients in the multiple-level group. In this group, the preoperative JOA scores averaged 11.7 points (range -3 to 21) and the postoperative scores averaged 21.2 points (range 3–28). The JOA scores significantly improved after surgery (P \ 0.05), and the recovery rate (RR) at the follow-up period averaged 56 % (range 0–95 %). Excellent result was obtained by 19 patients (26 %), good results by 28 patients (38 %), fair results by 17 patients (23 %), and poor results by 9 patients (12 %). The mean operation time was 119 min (range 70–265 min), and the mean blood loss was 65 mls (range 10–280 mls). There were no major complications in these patients, and only 2 cases of wound infections, 1 case of dural tear, and 1 case of wrong-level surgery were reported. There were no cases of clinical deteriorations due to the recurrences of stenosis at the same spinal levels; however, 4 cases require additional operations during the follow-up period; 2 cases of discectomy for lumbar disc herniation at the adjacent levels, 1 case of spinal fusion for progressive degenerative scoliosis, and 1 case of cervical laminoplasty for cervical spondylotic myelopathy. In the single-level group, the preoperative JOA scores averaged 13.3 points (range 3–22) and the postoperative scores averaged 22.4 points (range 4–29) with significant improvement. The RR averaged 59 % (range -19 to
Eur J Orthop Surg Traumatol Table 1 Criteria for low-back pain diseases of the Japanese Orthopaedic Association score (full score 29) Symptoms and signs
Evaluation and score
1. Subjective symptoms Lower back pain None
3
Occasional mild pain
2
Occasional severe pain
1
Continuous severe pain
0
Leg pain and/or tingling None
3
Occasional slight symptoms
2
Occasional severe symptoms
1
Continuous severe symptoms
0
Gait Normal
3
Able to walk farther than 500 m
2
Although it results in symptoms Unable to walk farther than 500 m
1
Unable to walk farther than 100 m
0
2. Clinical signs Straight-leg-raising test Normal 30°–70° \30° Sensory disturbance None
2 1 0
and the mean blood loss was 39 mls (range 5–270 mls). There were also no major complications in this group. However, one patient had a postoperative recurrence of the symptoms within 5 months and required additional posterior decompression at the same spinal level. Two cases require additional operations during the follow-up period: 1 case of posterior decompression for LSS at the adjacent levels and 1 case of posterior decompression for foraminal stenosis at the adjacent levels. There were no significant differences in age between the multiple-level patients group and the single-level group. The pre- and postoperative JOA scores of the multiplelevel patients group were significantly lower than those of the single-level group; however, there was no significant difference in the RR between the groups (P \ 0.05). Excellent or good results in the RR were obtained in 47 patients (64 %) of the multiple-level patients group and 55 patients (71 %) in the single-level group, respectively. The operation times were significantly longer in the multiplelevel group than those in the single-level group; however, those of each operation level in the multiple-level group were significantly shorter than the single-level group (P \ 0.05). The blood losses were also significantly larger in the multiple-level group than those in the single-level group, but there was no significant difference in the blood losses/operation level between the groups (P \ 0.05) (Table 2).
2
Slight disturbance (not subjective)
1
Marked disturbance
0
Case presentation
Motor disturbance Normal
2
Slight weakness (MMT 4)
1
Marked weakness (MMT 3–0)
0
3. Activities of daily living
Severe
Moderate
None
Turn over while lying
0
1
2
Standing
0
1
2
Washing
0
1
2
Leaning forward
0
1
2
Sitting (about 1 h)
0
1
2
Lifting or holding heavy object Walking 4. Urinary bladder function
0
1
2
0
1
2
Normal
0
Mild dysuria
-3
Severe dysuria
-6
100 %), and excellent result was obtained by 23 patients (30 %), good results by 32 patients (42 %), fair results by 10 patients (13 %), and poor results by 12 patients (16 %). The mean operation time was 95 min (range 48–245 min),
A 71-year-old woman had a significant gait disturbance for 1 year. She had severe pain and numbness in both lower extremities, and these symptoms increased while walking. Her symptoms suggested the existence of LSS with Table 2 Comparison between the multiple-level patients group and the single-level patient group Multiple-level (n = 73)
Single-level (n = 77)
Significancea
Age (years)
73
70
NS
Preoperative JOA score
11.7
13.3
P \ 0.05
Postoperative JOA score
21.2
22.4
P \ 0.05
Recovery rate (%)
61
59
NS
Operation time (min)
119
95
P \ 0.05
Operation time/ operation level (min)
58
95
P \ 0.05
Blood loss (ml)
65
39
P \ 0.05
Blood loss/operation level (ml)
31
39
NS
JOA Japanese Orthopaedic Association, NS not significant a
Mann–Whitney U test
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neurogenic claudication. Preoperative myelogram showed a severe LSS at 3–4 and L4–5 with mild degenerative spondylolisthesis of the L4 vertebra (Figs. 1, 2). The preoperative JOA score was 11 points. A microsurgical bilateral decompression via unilateral approach was performed. The operation time was 123 min, and the blood loss was 65 ml. There were no complications related to the surgery. At 5 years postoperatively, her gait disturbance was resolved and the JOA score had improved to 24 with an RR of 72 %. Plane X–p imaging at the latest follow-up showed a well-maintained alignment of the lumbar spine
(Fig. 3). Postoperative CT scans demonstrated sufficient decompressions, while preserving facet joints to avoid postoperative instability (Fig. 4).
Discussion Degenerative changes in the intervertebral discs and facet joints cause narrowing of the spinal canal and neural foramina, and these conditions in the lumbar spine result in LSS, especially in the elderly population [1]. The patients
Fig. 1 Images obtained from a 71-year-old woman. Preoperative AP and lateral plane X-ps (a, b) and lateral myelogram (c) show severe spinal canal stenosis at L3–4 and L4–5 with mild degenerative spondylolisthesis of the L4 vertebra
Fig. 2 Preoperative CT myelogram at L3–4 and L4–5 (a, b) shows severe spinal canal stenosis
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Fig. 3 Postoperative plane X-ps (a, b) shows well-maintained alignments of the lumbar spine
Fig. 4 Postoperative CT scans at L3–4 and L4–5 (a, b) show sufficient decompressions while preserving facet joints
usually suffer disabling back and lower extremity pain. Nonoperative management includes the restriction of aggravating activities, physical therapy, and anti-inflammatory medications for the patients with mild clinical symptoms. Surgical treatment may be appropriate for patients who showed no improvement after nonoperative
treatment or showed more severe clinical symptoms. Because of the recent increase in the elderly population, there are more frequent cases of multiple-level involvement of degenerative lumbar spine disease. However, few reports have described the clinical results of multiple-level compression of LSS patients [14, 15], and the therapeutic
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results for these conditions have not been examined fully. In the current study, the clinical results of microsurgical bilateral decompression via unilateral approach in patients with LSS with multiple spinal level involvement and in patients with single spinal level involvement were obtained. Usually, surgical indication for this disease includes intolerable pain in average daily living, progressively worsening or a significant degree of motor weakness, and sphincter dysfunction [17]. The extent of surgical decompression was determined by clinical evaluation, imagery examination, and the type of disease process exhibited. Satisfactory results from operative treatment can be expected only after adequate and thorough decompression of the neural elements. Because the most common cause of unsatisfactory results is inadequate decompression of the spinal contents [20], surgeons require sufficient decompression to resolve the symptoms. Therefore, the surgical decision for LSS patients with multiple spinal level involvement should be carefully planned. We determined the surgical operation sites through radiographic evaluation and physiological examinations. In the current series, 73 of 150 patients (49 %) were diagnosed as multiple-level involvements, and sufficient clinical results were obtained after surgery. Imaging features of the spinal involvement, facet joint arthrosis, ligament flavum hypertrophy, disc protrusion, and nerve root impingement should be assessed for exact diagnosis, and MRI and CT have been used for the clinical assessment of LSS [18, 19]. Sato and Kikuchi reported the clinical analysis of two spinal level compression in LSS patients [15]. They reported that the responsible level should be determined based on the neurologic findings after a gait load test and a selective nerve root block, because it is uncommon for both stenotic levels to be symptomatic even in patients with two spinal level stenosis. Obviously, there must be asymptomatic abnormalities on MRI [20]; therefore, physicians should correlate imagery abnormalities and clinical signs and symptoms before operative treatment is contemplated. Although the majority of LSS patients may show a single spinal level involvement, there must be numerous LSS patients with multiple spinal level involvement due to the recent rapid growth of the elderly population. There may be considerable complications even in decompression surgery, especially in elderly or multiply operated patients [21, 22]. Minimally invasive surgery should be attempted to reduce operative complications. The pathology of LSS has not been characterized fully, whereas the degenerated ligament of flavum had been reported to be important in the induction of neurologic symptoms [23]. Microsurgical decompression of the spinal canal is one of the optimal treatments for this disease, and
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many authors have reported its advantages and effectiveness [5, 7–9, 11, 24]. These procedures are accompanied by less blood loss and surgical morbidity. In addition, the microsurgical procedures preserve facet joints and laminae, which preserve postoperative spinal stabilities [25]. Papavero et al. [24] also reported that microsurgical bilateral decompression using unilateral laminotomy is an effective surgical option for LSS, even in high-risk patients with multilevel stenosis. In the current study, we performed microsurgical bilateral decompression via unilateral approach on all the patients, and the blood losses were significantly larger in the multiple-level group than those in the single-level group. However, there was no significant difference in the blood losses/operation level between the groups. The operation times were significantly longer in the multiple-level group than those in the single-level group, and the operation time/operation level in the multiple-level group was significantly shorter than the single-level group. These results indicate that, with the aid of surgical microscope, a surgeon can perform a less invasive operation even for the multiple spinal level stenosis patient. Although bilateral decompression via unilateral approach is a useful minimally invasive procedure, this approach would be difficult and technically demanding in cases of decompression of the lateral recess and medial foraminal stenosis at the contralateral side. Depth and inclination of laminae at the surgical site may alter operative fields at the contralateral side. In such cases, this surgical technique may have potential risks such as incomplete decompression or neuromeningeal damage. Surgical microscopes enable clear visualization of the pathology of the region. The use of a surgical microscope is necessary for a safe procedure, and blind or rough manipulation of the dura or nerve roots should be avoided during microsurgical procedures. Meanwhile, surgeons should understand the microsurgical anatomy of the ligament of flavum and realize its biomechanical advantages to preserve spinal stabilities. Decompression should be performed to address all clinically relevant neural elements while maintaining spinal stability. Surgical success rates are sufficiently high for this disease; however, they may be compromised by inadequate decompression, inadequate stabilization, or medical comorbidities [26]. Lu et al. [27] reported that spinal motion was significantly increased in flexion after multilevel fenestrations and discectomies. Strict selection of patient for decompression surgery and restriction of the surgical levels should be needed to obtain good clinical results for multiple-level involved patient. Spinal fusions with instrumentation, which can resolve postoperative instabilities and achieve the restoration of spinal alignment, may address these issues of postoperative iatrogenic instabilities and insufficient clinical results. In
Eur J Orthop Surg Traumatol
the current study, we demonstrate equivalent clinical results in the RR between the single and multiple spinal level LSS patients after microsurgical decompressions. Of course, cautious decisions should be made to determine the decompression levels for surgical operation, and comparable clinical results were obtained in LSS patients with multiple-level involvement compared to patients with single-level compression. Although posterior decompression and fusions may be logical options for multiple spinal level involvement, decompression surgery with less invasive techniques may bring sufficient clinical results even in multiple spinal level LSS patients. Some latent limitations may exist in this study. The JOA score may not provide a wide-ranging assessment of the level of impairment in LSS patients [28]. In addition, there may be a false-positive clinical diagnosis based on the imaging studies, based mainly on MRIs [20]. New diagnostic tools to assess the nerve function, such as a diffusion tensor imaging [29], may be needed for exact diagnosis, especially in the elderly patients.
Conclusion According to the increase in the elderly population, physicians may encounter increased LSS patients with multiple spinal level involvement. Obviously, surgeons should determine the decompression levels with great care to reduce surgical morbidity. If the patient were correctly selected and the decompression surgery were carefully performed, sufficient clinical results that were comparable to single-level LSS patients were obtained even in the patients with multiple-level LSS. Conflict of interest
None.
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