Clinical Neurology and Neurosurgery 131 (2015) 21–25
Contents lists available at ScienceDirect
Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro
Patient outcomes for a minimally invasive approach to treat lumbar spinal canal stenosis: Is microendoscopic or microscopic decompressive laminotomy the less invasive surgery? Toru Fujimoto ∗ , Takuya Taniwaki, Shogo Tahata, Takayuki Nakamura, Hiroshi Mizuta Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Kumamoto, Kumamoto 860-8556, Japan
a r t i c l e
i n f o
Article history: Received 18 September 2014 Received in revised form 8 December 2014 Accepted 17 January 2015 Available online 24 January 2015 Keywords: Lumbar spinal canal stenosis Microscopic decompressive laminotomy Microendoscopic decompressive laminotomy Unilateral approach Minimally invasive surgery
a b s t r a c t Objective: We performed a study to compare the severity of surgical stress between microscopic and microendoscopic decompressive laminotomy performed via a unilateral approach in patients with lumbar spinal canal stenosis (LSCS). Materials and methods: A total of 41 patients received decompressive laminotomy for lumbar spinal stenosis. Twenty patients received microscopic decompressive laminotomy (MDL), and 21 patients received microendoscopic decompressive laminotomy (MEDL). The pre- and postoperative Japanese Orthopaedic Association (JOA), and Visual Analogue Scale (VAS) lower leg pain scores were evaluated. The other variables studied were the length of the operation, blood loss, length of hospital stay, the reaction of the CRP and WBC levels, the dosage of non-steroidal anti-inflammatory drugs (NSAIDs) used and surgical complications. Results: The clinical analyses of the surgical outcomes were evaluated after a minimum two-year followup. The pre-and postoperative JOA scores and VAS in the MDL and MEDL groups were statistically similar. There were statistically significant differences found between the lengths of the operation time, blood loss, length of hospital stay, the reaction of CRP, and the pain indicated by the dosage of NSAIDs. The length of the operation time was longer in the MEDL group, and the other variables were greater in the MDL group. Conclusions: The MEDL procedure is less invasive and safer than the MDL procedure. Hence, MEDL is an effective technique for treating symptomatic LSCS patients. © 2015 Elsevier B.V. All rights reserved.
1. Introduction The treatment of lumbar spinal canal stenosis (LSCS) has become an important issue, especially in older people. The aim of surgery for LSCS is to relieve lower leg pain, and regain the walking capacity by decompressing the canal stenosis. Usually, the classic operation was a dissection of the paraspinal muscles, and the posterior elements such as the spinous process and interspinous ligaments were removed during the procedure [1–3]. Such an operation is regarded to be highly aggressive, especially for elderly people. Early recoveries to normal activities are very important for such patients. Recently, microscopic and microendoscopic decompressive laminotomy via a unilateral approach have been performed as minimally invasive surgeries. Their advantages include the
∗ Corresponding author. Tel.: +81 96 373 5226; fax: +81 96 373 5228. E-mail address: [email protected] (T. Fujimoto). http://dx.doi.org/10.1016/j.clineuro.2015.01.014 0303-8467/© 2015 Elsevier B.V. All rights reserved.
preservation of facet joints, the midline ligament complex and paravertebral muscles to prevent postoperative spinal instability. Microscopic bilateral decompressive laminotomy via a unilateral approach was first described by Poletti [4]. This procedure is very useful for preservation of the spinous process and interspinous ligaments. For these reasons, microscopic decompressive laminotomy (MDL) via a unilateral approach has been indicated for lumbar spinal stenosis at our institution since April 2007. Microendoscopic discectomy (MED) is one of the minimally invasive procedures reported by Foley and Smith [5]. The reported clinical results obtained with MED have been similar to those obtained using open discectomy [6]. Furthermore, MED techniques have been applied for the treatment of lumbar spinal stenosis [7,8]. Microendoscopic bilateral decompressive laminotomy shows advantages over conventional procedures, such as gentle muscle dissection, and also provides good visualization. Since March 2009, microendoscopic decompressive laminotomy (MEDL) via a unilateral approach has also been indicated for lumbar spinal stenosis at our institution.
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T. Fujimoto et al. / Clinical Neurology and Neurosurgery 131 (2015) 21–25
These two techniques are both useful for the treatment of spinal canal stenosis as minimally invasive surgery; however, the studies performed to compare the two techniques have been limited. The objective of the current study was to compare the outcomes of patients with lumbar spinal stenosis treated with either microscopic or microendoscopic decompressive laminotomy, focusing on the surgical invasiveness and the results of the patient’s clinical evaluations. 2. Materials and methods 2.1. Patient population The following inclusion criteria were applied: neurological claudication or radicular leg pain resulting from spinal canal stenosis; severe canal stenosis evaluated on MR imaging and leg pain refractory to conservative treatment lasting for at least 3 months. The exclusion criteria were: foraminal stenosis; disc herniation; degenerative spondylolisthesis more than Meyerding Grade I; prior surgery in the same segment and inflammatory disease. Twenty consecutive patients undergoing MDL for LSCS between April 2007 and March 2009, and 21 consecutive patients undergoing MEDL for LSCS after April 2009 were enrolled in this study. These patients were informed that the data from the case would be submitted for publication, and all gave their consent. 2.2. Surgical procedures MDL via a unilateral approach was performed based on the previously reported method [4]. A 20-mm skin incision was made on the left side. After the subperiosteal dissection of the multifidus muscle, a Caspar-type retractor was used to retract the muscle. First, the inferior edge of the cranial lamina, and the medial edge of the facet joint, were removed using a high-speed pneumatic burr with diamond heads in a trumpeted manner. The ipsilateral side was resected, the ligamentum flavum was removed, and the dural sac was decompressed from the cranial border of the disc space down to the traversing nerve root. Tilting the operation table 20◦ away from the surgeon, along with resection of the deep portion of the basement of the spinous process, provided an oblique view of the contralateral side. Then, the contralateral lamina was undercut with a high-speed pneumatic burr, leaving the ligamentum flavum in place as protection for the dural sac and the nerve root. After the contralateral side lamina was resected, the ligamentum flavum was removed using the Kerrison rongeurs and curettes. The adequacy of decompression was determined by observing the pulsation of the dural sac and probing the traversing nerve roots to confirm their mobility (Fig. 1A). A 30-mm skin incision was made when performing two-level decompression. Two-level decompression was carried out via one skin incision with multiple separate muscular portals for each level. MEDL via a unilateral approach was performed based on a method reported previously, as described by Pao et al. [8]. Serial dilators were inserted through a 16-mm skin incision and lumbar paraspinal muscles to create an endoscopic tunnel. A 16-mm tubular retractor was then passed over the dilators. The METRx Microendoscopic Discectomy System (Medtronic Sofamor Danek, Memphis, TN) was mounted on the working channel via a connecting ring. Decompression was performed using the 25◦ endoscope and the tubular retraction system. The inferior edge of the cranial lamina, the superior edge of the caudal lamina and the bilateral medial edge of the facet joint were removed using a curved high-speed pneumatic burr with diamond heads. The degenerative ligamentum flavum was completely exposed. We then tilted the retractor tube to decompress the central canal, and the center of
the ligamentum flavum was divided to confirm the presence of the dural sac. We performed the flavectomy to decompress the central canal and bilateral lateral recesses. This process was performed by gently pressing down the dural sac, and excising the ligamentum flavum with straight and curved Kerrison rongeurs. The adequacy of decompression was determined by observing the pulsation of the dural sac and probing the traversing nerve roots to confirm their mobility (Fig. 1B). When performing two-level decompression, the skin incision was centered at the midpoint between the selected intervertebral disc levels. The skin incision was mobilized one level below after releasing the underlying connective tissue. Therefore, two-level decompression was carried out via one skin incision with multiple separate muscular portals for each level. 2.3. Surgical analysis The pre- and postoperative clinical evaluations were conducted using the Japanese Orthopaedic Association (JOA) score for the clinical symptoms and the Visual Analogue Scale (VAS) for leg pain during walking (LPW). The range of JOA scores was −3 to 29 points, with a higher score corresponding to a better result [7,9]. The VAS scores the intensity of pain from 0 (absence of pain) to 10 (worst pain ever experienced). The rate of improvement in the JOA score (RIS) was defined according to the following formula: [(postoperative score–preoperative score)/(29-preoperative score)] × 100% (Hirabayashi’s method.) The overall result was classified as excellent for an RIS of more than 75% of the preoperative score, with good for 50–74%, fair for 25–49% and poor for 0–24% or less, as previously described [10]. All 41 patients were included in the analyses of the surgical outcomes evaluated after a minimum two-year follow-up. In addition, the length of the operation, intra- and postoperative blood loss by day 2, changes in the laboratory data, including white blood cell (WBC) and C-reactive protein (CRP) levels, the duration of fever after surgery, the suppository administration of NSAIDs for surgical site pain, the duration of hospital stay and the presence of complications were also studied to evaluate tissue trauma and morbidity. 2.4. Statistical analysis Statistical correlations between the two groups were examined using the unpaired Student’s t-test, and qualitative data were evaluated using the Chi-square test. Probability values 5 years) are thus required. 5. Conclusions The MEDL procedure results in less pain at the surgical site, with the earlier resumption of normal activities and a shorter hospital stay, compared to the MDL procedure. MEDL is a safe technique that can be selected as the first surgical option in elderly symptomatic LSCS patients. References [1] Herno A, Airaksinen O, Saari T. Long-term results of surgical treatment of lumbar spinal stenosis. Spine 1993;18:1471–4. [2] Iguchi T, Kurihara A, Nakayama J, Sato K, Kurosaka M, Yamasaki K. Minimum 10year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine 2000;25:1754–9. [3] Johnsson KE, Willner S, Johnsson KJ. Postoperative instability after decompression for lumbar spinal stenosis. Spine 1986;11:107–10. [4] Poletti CE. Central lumbar stenosis caused by ligamentum flavum: unilateral laminotomy for bilateral ligamentectomy: preliminary report of two cases. Neurosurgery 1995;37:343–7.
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[5] Foley KT, Smith MM. Microendoscopic discectomy. Tech Neurosurg 1997;3:301–7. [6] Righesso O, Falavigna A, Avanzi O. Comparison of open discectomy with microendoscopic discectomy in lumbar disc herniations: results of randomized controlled trial. Neurosurgery 2007;61:545–9. [7] Ikuta K, Arima J, Tanaka T, Oga M, Nakano S, Oga M, et al. Short-term results of microendoscopic posterior decompression for lumbar spinal stenosis. J Neurosurg Spine 2005;2:624–33. [8] Pao JL, Chen WC, Chen PQ. Clinical outcomes of microendoscopic decompressive laminotomy for degenerative lumbar spinal stenosis. Eur Spine J 2009;18:672–8. [9] Toyoda H, Nakamura H, Konishi S, Dohzono S, Kato M, Matsuda H. Clinical outcome of microsurgical bilateral decompression via unilateral approach for lumbar canal stenosis: minimum five-year follow-up. Spine 2011;36:410–5. [10] Yone K, Sakou T, Kawauchi Y, Yamaguchi M, Yanase M. Indication of fusion for lumbar spinal stenosis in elderly patients and its significance. Spine 1996;21:242–8. [11] Postacchini F, Cinotti G. Bone regrowth after surgical decompression for lumbar spinal stenosis. J Bone Joint Surg Br 1992;74:862–9. [12] McCulloch JA. Microsurgical spinal laminotomies. In: Frymoyer JW, editor. The adult spine: principles and practice. New York: Raven Press; 1991. p. 1821–31. [13] Oertel MF, Ryang YM, Korinth MC, Gilsbach JM, Rohde V. Long-term results of microsurgical treatment of lumbar spinal stenosis by unilateral laminotomy for bilateral decompression. Neurosurgery 2006;59:1264–9. [14] Costa F, Sassi M, Cardia A, Ortolina A, Santis AD, Luccarell G, et al. Degenerative lumbar spinal stenosis: analysis of results in a series of 374 patients treated with unilateral laminotomy for bilateral microdecompression. J Neurosurg Spine 2007;7:579–86. [15] Morgalla MH, Noak N, Merkle M, Tatagiba MS. Lumbar spinal stenosis in elderly patients: is a unilateral microsurgical approach sufficient for decompression. J Neurosurg Spine 2011;14:305–12. [16] Minamide A, Yoshida M, Yamada H, Nakagawa Y, Kawai M, Maio K, et al. Endoscope-assisted spinal decompression surgery for lumbar spinal stenosis. J Neurosurg Spine 2013;19:664–71. [17] Cavusogle H, Kaya RA, Türkmenoglu ON, Tuncer C, Colak I, Aydin Y. Midterm outcome after unilateral approach for bilateral decompression of lumbar spinal stenosis: 5-year prospective study. Eur Spine J 2007;16:2133–42. [18] Mobbs RJ, Li J, Sivabalan P, Raley D, Rao PJ. Outcomes after decompressive laminectomy for lumbar spinal stenosis: comparison between minimally invasive unilateral laminectomy for bilateral decompression and open laminectomy. J Neurosurg Spine 2014;21:176–86. [19] Paravero L, Thiel M, Fritzsche C, Fritzsche E, Kunze C, Westphal M, et al. Lumbar spinal stenosis: prognostic factors for bilateral microsurgical decompression using a unilateral approach. Neurosurgery 2009;65:182–7. [20] Muramatsu K, Hachiya Y, Morita C. Postoperative magnetic resonance imaging of lumbar disc herniation: comparison of microendoscopic discectomy and Love’s method. Spine 2001;26:1599–605. [21] Mannion RJ, Guilfoyle MR, Efendy J, Nowitzke AM, Laing RJ, Wood MJ. Minimally invasive lumbar decompression-long-term outcome, morbidity, and the learning curve from the first 50 cases. J Spinal Disord Tech 2012;25:47–51.
Contents lists available at ScienceDirect
Clinical Neurology and Neurosurgery journal homepage: www.elsevier.com/locate/clineuro
Patient outcomes for a minimally invasive approach to treat lumbar spinal canal stenosis: Is microendoscopic or microscopic decompressive laminotomy the less invasive surgery? Toru Fujimoto ∗ , Takuya Taniwaki, Shogo Tahata, Takayuki Nakamura, Hiroshi Mizuta Department of Orthopaedic Surgery, Faculty of Life Sciences, Kumamoto University, 1-1-1 Honjyo, Kumamoto, Kumamoto 860-8556, Japan
a r t i c l e
i n f o
Article history: Received 18 September 2014 Received in revised form 8 December 2014 Accepted 17 January 2015 Available online 24 January 2015 Keywords: Lumbar spinal canal stenosis Microscopic decompressive laminotomy Microendoscopic decompressive laminotomy Unilateral approach Minimally invasive surgery
a b s t r a c t Objective: We performed a study to compare the severity of surgical stress between microscopic and microendoscopic decompressive laminotomy performed via a unilateral approach in patients with lumbar spinal canal stenosis (LSCS). Materials and methods: A total of 41 patients received decompressive laminotomy for lumbar spinal stenosis. Twenty patients received microscopic decompressive laminotomy (MDL), and 21 patients received microendoscopic decompressive laminotomy (MEDL). The pre- and postoperative Japanese Orthopaedic Association (JOA), and Visual Analogue Scale (VAS) lower leg pain scores were evaluated. The other variables studied were the length of the operation, blood loss, length of hospital stay, the reaction of the CRP and WBC levels, the dosage of non-steroidal anti-inflammatory drugs (NSAIDs) used and surgical complications. Results: The clinical analyses of the surgical outcomes were evaluated after a minimum two-year followup. The pre-and postoperative JOA scores and VAS in the MDL and MEDL groups were statistically similar. There were statistically significant differences found between the lengths of the operation time, blood loss, length of hospital stay, the reaction of CRP, and the pain indicated by the dosage of NSAIDs. The length of the operation time was longer in the MEDL group, and the other variables were greater in the MDL group. Conclusions: The MEDL procedure is less invasive and safer than the MDL procedure. Hence, MEDL is an effective technique for treating symptomatic LSCS patients. © 2015 Elsevier B.V. All rights reserved.
1. Introduction The treatment of lumbar spinal canal stenosis (LSCS) has become an important issue, especially in older people. The aim of surgery for LSCS is to relieve lower leg pain, and regain the walking capacity by decompressing the canal stenosis. Usually, the classic operation was a dissection of the paraspinal muscles, and the posterior elements such as the spinous process and interspinous ligaments were removed during the procedure [1–3]. Such an operation is regarded to be highly aggressive, especially for elderly people. Early recoveries to normal activities are very important for such patients. Recently, microscopic and microendoscopic decompressive laminotomy via a unilateral approach have been performed as minimally invasive surgeries. Their advantages include the
∗ Corresponding author. Tel.: +81 96 373 5226; fax: +81 96 373 5228. E-mail address: [email protected] (T. Fujimoto). http://dx.doi.org/10.1016/j.clineuro.2015.01.014 0303-8467/© 2015 Elsevier B.V. All rights reserved.
preservation of facet joints, the midline ligament complex and paravertebral muscles to prevent postoperative spinal instability. Microscopic bilateral decompressive laminotomy via a unilateral approach was first described by Poletti [4]. This procedure is very useful for preservation of the spinous process and interspinous ligaments. For these reasons, microscopic decompressive laminotomy (MDL) via a unilateral approach has been indicated for lumbar spinal stenosis at our institution since April 2007. Microendoscopic discectomy (MED) is one of the minimally invasive procedures reported by Foley and Smith [5]. The reported clinical results obtained with MED have been similar to those obtained using open discectomy [6]. Furthermore, MED techniques have been applied for the treatment of lumbar spinal stenosis [7,8]. Microendoscopic bilateral decompressive laminotomy shows advantages over conventional procedures, such as gentle muscle dissection, and also provides good visualization. Since March 2009, microendoscopic decompressive laminotomy (MEDL) via a unilateral approach has also been indicated for lumbar spinal stenosis at our institution.
22
T. Fujimoto et al. / Clinical Neurology and Neurosurgery 131 (2015) 21–25
These two techniques are both useful for the treatment of spinal canal stenosis as minimally invasive surgery; however, the studies performed to compare the two techniques have been limited. The objective of the current study was to compare the outcomes of patients with lumbar spinal stenosis treated with either microscopic or microendoscopic decompressive laminotomy, focusing on the surgical invasiveness and the results of the patient’s clinical evaluations. 2. Materials and methods 2.1. Patient population The following inclusion criteria were applied: neurological claudication or radicular leg pain resulting from spinal canal stenosis; severe canal stenosis evaluated on MR imaging and leg pain refractory to conservative treatment lasting for at least 3 months. The exclusion criteria were: foraminal stenosis; disc herniation; degenerative spondylolisthesis more than Meyerding Grade I; prior surgery in the same segment and inflammatory disease. Twenty consecutive patients undergoing MDL for LSCS between April 2007 and March 2009, and 21 consecutive patients undergoing MEDL for LSCS after April 2009 were enrolled in this study. These patients were informed that the data from the case would be submitted for publication, and all gave their consent. 2.2. Surgical procedures MDL via a unilateral approach was performed based on the previously reported method [4]. A 20-mm skin incision was made on the left side. After the subperiosteal dissection of the multifidus muscle, a Caspar-type retractor was used to retract the muscle. First, the inferior edge of the cranial lamina, and the medial edge of the facet joint, were removed using a high-speed pneumatic burr with diamond heads in a trumpeted manner. The ipsilateral side was resected, the ligamentum flavum was removed, and the dural sac was decompressed from the cranial border of the disc space down to the traversing nerve root. Tilting the operation table 20◦ away from the surgeon, along with resection of the deep portion of the basement of the spinous process, provided an oblique view of the contralateral side. Then, the contralateral lamina was undercut with a high-speed pneumatic burr, leaving the ligamentum flavum in place as protection for the dural sac and the nerve root. After the contralateral side lamina was resected, the ligamentum flavum was removed using the Kerrison rongeurs and curettes. The adequacy of decompression was determined by observing the pulsation of the dural sac and probing the traversing nerve roots to confirm their mobility (Fig. 1A). A 30-mm skin incision was made when performing two-level decompression. Two-level decompression was carried out via one skin incision with multiple separate muscular portals for each level. MEDL via a unilateral approach was performed based on a method reported previously, as described by Pao et al. [8]. Serial dilators were inserted through a 16-mm skin incision and lumbar paraspinal muscles to create an endoscopic tunnel. A 16-mm tubular retractor was then passed over the dilators. The METRx Microendoscopic Discectomy System (Medtronic Sofamor Danek, Memphis, TN) was mounted on the working channel via a connecting ring. Decompression was performed using the 25◦ endoscope and the tubular retraction system. The inferior edge of the cranial lamina, the superior edge of the caudal lamina and the bilateral medial edge of the facet joint were removed using a curved high-speed pneumatic burr with diamond heads. The degenerative ligamentum flavum was completely exposed. We then tilted the retractor tube to decompress the central canal, and the center of
the ligamentum flavum was divided to confirm the presence of the dural sac. We performed the flavectomy to decompress the central canal and bilateral lateral recesses. This process was performed by gently pressing down the dural sac, and excising the ligamentum flavum with straight and curved Kerrison rongeurs. The adequacy of decompression was determined by observing the pulsation of the dural sac and probing the traversing nerve roots to confirm their mobility (Fig. 1B). When performing two-level decompression, the skin incision was centered at the midpoint between the selected intervertebral disc levels. The skin incision was mobilized one level below after releasing the underlying connective tissue. Therefore, two-level decompression was carried out via one skin incision with multiple separate muscular portals for each level. 2.3. Surgical analysis The pre- and postoperative clinical evaluations were conducted using the Japanese Orthopaedic Association (JOA) score for the clinical symptoms and the Visual Analogue Scale (VAS) for leg pain during walking (LPW). The range of JOA scores was −3 to 29 points, with a higher score corresponding to a better result [7,9]. The VAS scores the intensity of pain from 0 (absence of pain) to 10 (worst pain ever experienced). The rate of improvement in the JOA score (RIS) was defined according to the following formula: [(postoperative score–preoperative score)/(29-preoperative score)] × 100% (Hirabayashi’s method.) The overall result was classified as excellent for an RIS of more than 75% of the preoperative score, with good for 50–74%, fair for 25–49% and poor for 0–24% or less, as previously described [10]. All 41 patients were included in the analyses of the surgical outcomes evaluated after a minimum two-year follow-up. In addition, the length of the operation, intra- and postoperative blood loss by day 2, changes in the laboratory data, including white blood cell (WBC) and C-reactive protein (CRP) levels, the duration of fever after surgery, the suppository administration of NSAIDs for surgical site pain, the duration of hospital stay and the presence of complications were also studied to evaluate tissue trauma and morbidity. 2.4. Statistical analysis Statistical correlations between the two groups were examined using the unpaired Student’s t-test, and qualitative data were evaluated using the Chi-square test. Probability values 5 years) are thus required. 5. Conclusions The MEDL procedure results in less pain at the surgical site, with the earlier resumption of normal activities and a shorter hospital stay, compared to the MDL procedure. MEDL is a safe technique that can be selected as the first surgical option in elderly symptomatic LSCS patients. References [1] Herno A, Airaksinen O, Saari T. Long-term results of surgical treatment of lumbar spinal stenosis. Spine 1993;18:1471–4. [2] Iguchi T, Kurihara A, Nakayama J, Sato K, Kurosaka M, Yamasaki K. Minimum 10year outcome of decompressive laminectomy for degenerative lumbar spinal stenosis. Spine 2000;25:1754–9. [3] Johnsson KE, Willner S, Johnsson KJ. Postoperative instability after decompression for lumbar spinal stenosis. Spine 1986;11:107–10. [4] Poletti CE. Central lumbar stenosis caused by ligamentum flavum: unilateral laminotomy for bilateral ligamentectomy: preliminary report of two cases. Neurosurgery 1995;37:343–7.
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[5] Foley KT, Smith MM. Microendoscopic discectomy. Tech Neurosurg 1997;3:301–7. [6] Righesso O, Falavigna A, Avanzi O. Comparison of open discectomy with microendoscopic discectomy in lumbar disc herniations: results of randomized controlled trial. Neurosurgery 2007;61:545–9. [7] Ikuta K, Arima J, Tanaka T, Oga M, Nakano S, Oga M, et al. Short-term results of microendoscopic posterior decompression for lumbar spinal stenosis. J Neurosurg Spine 2005;2:624–33. [8] Pao JL, Chen WC, Chen PQ. Clinical outcomes of microendoscopic decompressive laminotomy for degenerative lumbar spinal stenosis. Eur Spine J 2009;18:672–8. [9] Toyoda H, Nakamura H, Konishi S, Dohzono S, Kato M, Matsuda H. Clinical outcome of microsurgical bilateral decompression via unilateral approach for lumbar canal stenosis: minimum five-year follow-up. Spine 2011;36:410–5. [10] Yone K, Sakou T, Kawauchi Y, Yamaguchi M, Yanase M. Indication of fusion for lumbar spinal stenosis in elderly patients and its significance. Spine 1996;21:242–8. [11] Postacchini F, Cinotti G. Bone regrowth after surgical decompression for lumbar spinal stenosis. J Bone Joint Surg Br 1992;74:862–9. [12] McCulloch JA. Microsurgical spinal laminotomies. In: Frymoyer JW, editor. The adult spine: principles and practice. New York: Raven Press; 1991. p. 1821–31. [13] Oertel MF, Ryang YM, Korinth MC, Gilsbach JM, Rohde V. Long-term results of microsurgical treatment of lumbar spinal stenosis by unilateral laminotomy for bilateral decompression. Neurosurgery 2006;59:1264–9. [14] Costa F, Sassi M, Cardia A, Ortolina A, Santis AD, Luccarell G, et al. Degenerative lumbar spinal stenosis: analysis of results in a series of 374 patients treated with unilateral laminotomy for bilateral microdecompression. J Neurosurg Spine 2007;7:579–86. [15] Morgalla MH, Noak N, Merkle M, Tatagiba MS. Lumbar spinal stenosis in elderly patients: is a unilateral microsurgical approach sufficient for decompression. J Neurosurg Spine 2011;14:305–12. [16] Minamide A, Yoshida M, Yamada H, Nakagawa Y, Kawai M, Maio K, et al. Endoscope-assisted spinal decompression surgery for lumbar spinal stenosis. J Neurosurg Spine 2013;19:664–71. [17] Cavusogle H, Kaya RA, Türkmenoglu ON, Tuncer C, Colak I, Aydin Y. Midterm outcome after unilateral approach for bilateral decompression of lumbar spinal stenosis: 5-year prospective study. Eur Spine J 2007;16:2133–42. [18] Mobbs RJ, Li J, Sivabalan P, Raley D, Rao PJ. Outcomes after decompressive laminectomy for lumbar spinal stenosis: comparison between minimally invasive unilateral laminectomy for bilateral decompression and open laminectomy. J Neurosurg Spine 2014;21:176–86. [19] Paravero L, Thiel M, Fritzsche C, Fritzsche E, Kunze C, Westphal M, et al. Lumbar spinal stenosis: prognostic factors for bilateral microsurgical decompression using a unilateral approach. Neurosurgery 2009;65:182–7. [20] Muramatsu K, Hachiya Y, Morita C. Postoperative magnetic resonance imaging of lumbar disc herniation: comparison of microendoscopic discectomy and Love’s method. Spine 2001;26:1599–605. [21] Mannion RJ, Guilfoyle MR, Efendy J, Nowitzke AM, Laing RJ, Wood MJ. Minimally invasive lumbar decompression-long-term outcome, morbidity, and the learning curve from the first 50 cases. J Spinal Disord Tech 2012;25:47–51.
