Clinical and Functional Outcome of Multiple Laminotomy Technique in the Treatment of Lumbar Spinal Stenosis 

 George.W. Boghdady*,Wael. A. El-Adl*,Mohammed. M. Wahba**

Abstract:

Purpose

Lumbar spinal stenosis is the narrowing of the osteoligamentous vertebral canal causing compression of the neural elements within the spinal canal, the lateral recesses, or intervertebral foramina. Surgery aims to decompress the nervous structures, particularly the nerve roots, without compromising vertebral stability. Different surgical modalities have been implicated with different success rates. The purpose of this study is to assess the clinical and functional outcome after multiple laminotomy in treatment of lumbar spinal stenosis.

Methods

Fifty-six patients with lumbar canal stenosis were operated on using the multiple laminotomy technique after adequate unsuccessful conservative treatment. Far lateral superior and inferior laminotomies limited to one half of the superior lamina and one quarter of the inferior lamina together with the intervening ligamentum flavum were performed. Attention was given to lateral recess and root canal decompression. In 8 patients multiple laminotomies failed to achieve adequate decompression due to absolute stenosis, and were excluded from the results. Patients were followed up for a mean period of 27.63 ± 10.56 months and assessed according to the Japanese Orthopaedic association (JOA) score.

Results

Satisfactory (excellent and good) results were obtained in 87.5% of the patients with mean recovery rate of JOA score of 65% (P < 0.000). Six minor dural tears without residual neurological signs were recorded. Permanent neurological (root) injury was recorded in only 2 patients.

Conclusion

Results of the present study proved multiple laminotomy technique to be the procedure of choice for mild to moderate developmental and degenerative stenosis.

keywords:

Lumbar spinal stenosis; Interlaminar decompression; Multiple laminotomy

J.Orthopaedics 2007;4(4)e14
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Introduction:

Lumbar spinal stenosis (LSS) is the narrowing of the osteoligamentous vertebral canal causing compression of the neural elements within the spinal canal, the lateral recesses, or intervertebral foramina. ^1,2,3 The narrowing may be limited to a single motion segment or more diffuse, spanning two or more segments.⁴ LSS can be classified in several ways based on the anatomic location of the narrowing or on the aetiology.^5,6 Degenerative spinal stenosis is the most common subtype found in patients seeking medical care.⁶ Developmental stenosis, on the other hand, presents earlier in age with similar clinical findings but with multilevel involvement and fewer degenerative changes.⁷ The clinical hallmark finding of lumbar stenosis is neurogenic claudication presenting as intermittent pain or parasthesia in the legs brought on by spinal extension, and classically relieved by flexion.^4,7 Several studies have confirmed the effectiveness of both non surgical treatment and surgical decompression for the management of LSS but there is also a general agreement that the more severe the stenotic symptoms and signs, the greater the role of surgery.^2,4,8-10 Traditionally surgical treatment of spinal stenosis is carried out through a decompressive laminectomy with a limited facetectomy. Some authors recommend a less invasive approach using unilateral laminotomy, bilateral laminotomy (fenestration), bilateral partial laminectomy, a unilateral approach for bilateral decompression, and interspinous process decompression.^2,9,11-14 These limited approaches were designed to decrease patient morbidity with faster rehabilitation; limit surgery to the pathologic area only; decrease postoperative spinal instability; and potentially avoid the need for fusion.¹³ The aim of the present study was to assess the clinical and functional outcome of multiple laminotomy technique in the treatment of LSS.

Material and Methods :

Fifty-six patients with symptomatic LSS were the subject of this prospective study between January 2003 and June 2005. There were 34 males and 22 females ranging in age from 21 to 68 years with a mean of 58.61 ± 10.56 years. All patients had a previous unsuccessful adequate conservative treatment. Patients with obvious spinal instability or any previous spinal surgery were excluded from this study. Detailed history taking, with standardized general and neurological assessment of the patients were performed. Patients were clinically evaluated using the score rating system of the Japanese Orthopaedic Association (JOA Score) shown in table 1¹⁰. Patients were radiologically investigated using plain X-ray, CT scan, and MRI. The central canal was considered relatively stenotic when the mid-sagittal diameter was between 10 – 12 mm or when the cross sectional area of the dural sac was 80 – 130 mm². Absolute stenosis was considered when the mid-sagittal diameter was less than 10 mm or the cross sectional area of the dural sac less than 80 mm². The root canal was considered stenotic when its diameter was less than 3 mm.¹⁹

All patients were subjected to surgical decompression using multiple laminotomy technique without spinal fusion through the standard posterior approach with the patient in the flexed prone position. The bone from the inferior aspect of the cranial lamina and, to a minimal degree, from the superior aspect of the subjacent lamina was resected, and subsequent flavectomy was performed to expose the spinal canal. The medial aspect of the facet joint was resected to decompress the lateral recess. The spinous process, the supra- and interspinous ligaments, and a substantial portion of the lamina were preserved.^9,13,15

Intraoperatively, multiple laminotomy procedure failed to adequately decompress the neural elements due to tight (absolute) canal stenosis in 8 out of the 56 patients included in the present study. Hence, in the same operative sittings, the decompression was extended to total laminectomy, and these patients were excluded from the study.

Forty-eight patients were followed up for a mean period of 27.63 ± 10.56 (11-45), and the final clinical and functional results were calculated by the formula (Postoperative JOA Score – Preoperative JOA Score / (Total Score – Preoperative JOA Score) x 100¹⁰. The result was rated as excellent when JOA score ranged between 100% - 81%, good when score ranged between 80% - 66%, Fair when score ranged between 65% - 50% and poor when the score was below 50%. Excellent and good results were considered a satisfactory result while fair and poor results were considered unsatisfactory. Data were statistically analyzed by the SPSS data processing program for windows using the Student’s t-test. 

Results :

Forty-eight patients with LSS were subjected to spinal decompression using multiple laminotomy technique. There were 30 males and 18 females (1.7:1) with a mean age of 61.96 ± 5.29 (47 – 68) years. They were followed up for a mean period of 27.63 ± 10.56 (11-45) months. The clinical symptoms and signs of LSS among patients are summarized in table 2. All patients underwent CT and/or MRI imaging evaluation for the spinal stenosis. Twenty-four patients (50%) had spinal stenosis at the L3–L4 level, 18 patients (37.5%) at L4–L5 level, and 6 patient (12.5%) at L2–L3 level. Forty patients had one level and 6 patients had two levels of segmental involvement. Three-segmental involvement was noted in 2 patients. Evidence of disc herniation was present in 40 patients mostly at L3-4 and L4-5 levels. Pathologically, there were 16 patients with developmental stenosis, 18 with degenerative stenosis, and 14 with combined stenosis.

Intraoperative findings are summarized in table 3. Fourteen patients (29.2%) underwent bilateral laminotomy alone. Ten patients (20.8%) had discectomy in addition to laminotomy, 8 patients (16.7%) had a combination of laminotomy and facetectomy, and 16 patients (33.3%) had a combination of laminotomy, discectomy and facetectomy. Twelve minor operative complications were recorded (25%) and included superficial wound infection in 2 patients, urinary tract infection in 2 patients, and dural tears without residual neurological signs in 8 patients. Major complications were noted in only 2 patients with permanent neurological (root) injury. No deep wound infections or thrombo-embolic complications occurred in the present study.

The mean JOA score was 7.5 ± 0.8 preoperatively and 12.3 ± 0.9 at the last follow up, with mean recovery rate of 65% (P < 0.000). The overall obtained satisfactory results were 87.5% (37.5% “18 patients” excellent, and 50% “24patients” good), while there were 12.5% unsatisfactory results (8.33% “4 patients” fair, and 4.17% “2 patients” poor).

Clinical cases 

Case № (1)

A male patient aged 47 years presented with low back pain; referred bilateral legs pain and intermittent neurogenic claudication limiting his working activity for one-year duration. Pain increased by walking and standing in extension and relieved by sitting. Neurological studies revealed positive straight leg raising test on the right side at 60^o, there were hyposthesia and motor weakness of L5 dermatome. The claudication distance was 300 meters. The pre-operative JOA Score was 19 points.

            Radiological studies revealed moderate central canal stenosis at L4 level (mid-sagittal diameter of 11.5 mm), right postero-lateral L4 –L5 disc prolapse compressing the right L5 nerve root and thickened ligamentum flavum (Fig. 1 A, B, C & D).

The operative procedure for decompression was L4 laminotomy and L4 – L5 discectomy. Intra-operative findings revealed thick sclerosed laminae, narrow interlaminer space, stenosis of central spinal canal at L4 level, prolapse of L4-L5 intervertebral disc, sparsity of epidural fat and absent dural pulsation. There were no intra-operative or post-operative complications.

The duration of follow up was 25 months. Neurogenic claudication and leg pain was completely relived. The final JOA score was 28 point. The overall improvement rate was 90% (excellent outcome).

Figure 1: Preoperative (A, B & C) and postoperative (D) radiographs of case N^o 1.

Case № (2)

A housewife aged 50 years, presented with low back pain, referred right leg pain and neurognic intermittent claudication of 2 years duration. Leg pain increased by walking and prolonged standing with back extension and relieved by sitting. Claudication distance was 500 meters. Neurological examination was unremarkable. The pre-operative JOA score was 17 points.

Radiological studies revealed multilevel moderate central canal stenosis at L3, L4 and L5 level (mid-sagittal diameter 11.5 mm), thickened ligamentum flavum and disc bulge at L4-5 and L5-S1 level. (Fig. 2 A, B, C, D & E)

The operative procedure for decompression was multiple laminotomy at L3, L4 and L5 levels. The intra-operative findings were thick sclerosed laminae, narrow interlaminar space, sparsity of epidural fat, thickened ligamentum flavum, absent dural pulsation and stenosis of central spinal canal. There were multilevel disc bulge at L3-4, L4-5 and L5-S1. Post-operative superficial wound infection occurred and resolved by systemic antibiotics.

The duration of follow up was 24 months. The final assessment revealed marked improvement of symptom and work ability. The final JOA score was 26 points. The overall improvement rate was 75% (good outcome).

Figure 2: Preoperative (A, B, C & D) and postoperative (E) radiographs of case N^o 2.

Discussion:

Forty-eight patients suffering from stenosis of the lumbar spinal canal were the subjects of this study. All patients were subjected to previous unsuccessful conservative treatment. Patients with obvious spinal instability or any previous spinal surgery were excluded from this study. At the end of follow up period, the surgical outcome was evaluated both clinically by JOA scoring system and radiologically.

Patients of this study were 30 males and 18 females, with male to female ratio 1.7:1 respectively with a mean age of 48.2 ± 11.094 years. This is in consistence with the findings of Fahy and Nixon¹, Fritz et al⁴, and Benoist⁸. The paucity of females suffering from lumbar canal stenosis can be attributed to less abuse of their spines; their canals may be generally wider, variation in the vascular anatomy of the female pelvis, or hormonal factors⁸. Almost all authors agree that lumbar canal stenosis occurs in middle and old age when degenerative changes supervene, reaching their maximum prevalence in the 5th and 6th decades of life and account for the late onset of symptoms in most patients; they believed that the so-called developmental stenosis remains asymptomatic until the critical reserve space for the enclosed neural elements becomes compromised by structural changes associated with aging and trauma^1,3-5,8.

All patients included in this study were suffering from low back pain and unilateral or bilateral neurogenic claudication at the onset of presentation. These results are consistent with those of Fahy and Nixon¹, Spivak³, Fritz et al.⁴, Benoist⁸, Postacchini et al.⁹, and Eule et al.¹¹, who reported an incidence of 85 – 100 % of different types of complaints. On the contrary, Thome et al.¹³, reported an incidence of 6-19% of complaints.

Neurogenic claudication was present in all of our patients. Mixed sensory deficit (numbness and hyposthesia) and motor weakness were the commonest claudication symptom experienced by our patients. Motor weakness alone was not experienced by any of our patients. These results are not consistent with the findings of Thome et al¹³ where claudication leg pain occurred in 93% of their patients while sensory deficit occurred in 63% and motor weakness in 43%. Results of the present study are also in contrast with those of Postacchini et al⁹ where motor weakness was the commonest claudication symptom (80.5%) followed by leg pain (47.4%), and sensory deficit was the least frequent (45.3%).

Intraoperatively, the narrowing of the lumbar canal was found to be due to combinations of ligamentum flavum hypertrophy (100%), thickening of the lamina (86.5%), and facetal hypertrophy (37.5%). Concomitant disc prolapse contributed to narrowing of the lumbar canal in 83.33% of patients. These findings are in accordance with findings of different studies^{1,2,8,10,11,13} who found that degenerative changes in the facet joints and intervertebral discs, as well encroachment upon the canal by hypertrophied ligamenta flava were the commonest abnormalities encountered with in their patients.

All patients had central stenosis, 37.5% had associated root canal stenosis and 12.5 % had associated lateral recess stenosis. This coincides with findings of Benoist⁸, Thome et al.,¹³ and Yamazaki et al.,¹⁵ who found that central canal stenosis is rarely an isolated occurrence, and usually, a variable degree of lateral canal narrowing coexists with central stenosis and that the nerve root canals should be the area of primary surgical interest.

During operation, the highest incidence of stenosis was found to be at L4 and L3 levels (about 50% of cases), followed by L4-5 level (18 pattients), and L2-3 level in 6 patients. These findings coincide with those of different studies^2,9,11,13,15 Decompression at a single level was done for 83.33% of cases, while two level decompressions were done for 12.5% of cases. Three level decompressions were done for 4.17% of case. These findings are not consistent with those of Shabat et al.⁵, Postacchini⁹, Taniguchi et la.¹⁰, Eule¹¹, and Thome et al.¹³, who performed two or three level decompressions in 37 – 45 % of their patients.

Complications in the present study were represented intraoperatively by dural tears (16.7%) and postoperatively by superficial wound infection in 4.17% of cases and urinary tract infection in 4.17% of cases. In other studies the dural tears range between 0.3% -13%^2,11,13. However, these tears didn’t affect the postoperative result. Benoist⁸ declared that one of the surgical problems in lumbar canal stenosis is adherence of the dura along the deep medial portions of the facets at the areas of greatest compression.

The postoperative assessment of relief using JOA score revealed overall 87.5% satisfactory results (37.5% excellent and 50% good). The overall unsatisfactory results were 12.5% (8.33% fair and 4.17% poor). These results are in accordance with those of Haba et al.², Eule et al.¹¹, and Thome et al.¹³, who achieved satisfactory results in 78-84% of their patients. The present study showed a significant improvement in the unrestricted walking distance at the latest follow up examination compared with per-operative distance (claudication distance) in all patients. This finding coincides with that of Eule et al.¹³.

Satisfactory results were obtained in younger age group and in patients with short duration of back pain and claudication symptoms when compared with unsatisfactory results. These findings are consistent with those of Fritz et al.⁴ and Eule et al.¹¹, who found that long-standing compression on the nerve roots would result in irreversible damage to the nervous tissue and worsen the expected post-operative outcome. In accordance with Fritz et al.⁴, the association of disc prolapse with stenosis had a higher proportion of excellent results than those with stenosis alone, and the group of patients with preoperative neurological deficits had better results than the groups without deficits.

Conclusion:

Of the 48 patients included in this study, satisfactory results were obtained in 87.5% of cases. The best results were in the younger age group. Claudication symptoms predicted more satisfactory results. The longer the claudication distance, and the shorter the duration of symptoms, the better was the prognosis. Disc prolapse and discectomy was consistent with more satisfactory results. Claudication pain, and claudication weakness were the commonest symptoms to be improved postoperatively, while low back pain was the least. These results indicate that multiple laminotomy is an effective method and the treatment of choice for developmental, degenerative, or combined lumbar canal stenosis with preservation of vertebral stability.

Reference :

1. Fahy D, Nixon JE. Lumbar Spinal Stenosis. Current Orthopaedics 2001; 15: 91-100.
2. Haba K, Ikeda M, Soma M, Yamashima T. Bilateral Decompression of Multilevel Lumbar Spinal Stenosis Through a Unilateral Approach. Journal of Clinical Neuroscience 2005; 12: 169-71.
3. Spivak JM. Current Concepts Review. Degenerative Lumbar Spinal Stenosis. The Journal of Bone and Joint Surgery (Am) 1998; 88-A: 1053-66.
4. Fritz JM, Delitto A, Welch WC, Erhard RE. Lumbar Spinal Stenosis: A review of Current Concepts in Evaluation, Management, and Outcome Measurements. Arch Phys Med Rehabil 1998; 79: 700-8.
5. Shabat S, Leitner Y, Nyska M, Berner Y, Fredman B, Gepstein R. Surgical Treatment of Lumbar Spinal Stenosis in Patients Aged 65 Years and Older. Archives of Gerontology and Geriatrics 2002; 35: 143-52.
6. Vo AN, Kamen LB, Shih VC, Bitar AA, Stitik TP, Kaplan RJ. Rheabilitation of Orthopedic and Rheumatologic Disorders. 5. Lumbar Spinal Stenosis. Arch Phys Med Rehabil 2005; 86: 69-76.
7. Singh K, Samartzis D, Vaccaro AR, Nassr A, Andersson GB, Yoon ST, et al. Congenital Lumbar Stenosis: A Prospective Control-Matched, Cohort Radiographic Analysis. The Spine Journal 2005; 5: 615-22.
8. Benoist M. The Natural History of Lumbar Degenerative Spinal Stenosis. Joint Bone Spine 2002; 69: 450-7.
9. Postacchini F, Cintti G. The Surgical Treatment of Central Lumbar Stenosis: Multiple Laminotomy Compared with Total Laminectomy. The Journal of Bone and Joint Surgery (Br) 75-B 1993; 385-92.
10. Taniguchi S, Yamamoto H. Decompression Surgery for Lumbar Spinal Stenosis. Current Orthopaedics 1999; 13: 184-90.
11. Eule JM, Breeze R, Kindt GW. Bilateral Partial Laminectomy: A Treatment for Lumbar Spinal Stenosis and Midline Disc Herniation. Spine 1999; 52: 329-38.
12. Rao RD, Wang M, Singhal P, McGrady LM, Rao S. Intradiscal Pressure and Kinematic Behavior of Lumbar Spine After Bilateral Laminotomy and Laminectomy. The Spine Journal 2002; 2: 320-6.
13. Thome C, Zevgaridis D, Leheta O, Bazner H, Pockler-Schoniger C, Wohler J, et al. Outcome After Less-Invasive Decompression of Lumbar Spinal Stenosis: A Randomized Comparison of Unilateral Laminotomy, Bilateral Laminotomy, and Laminectomy. J Neurosurg: Spine 2005; 3: 129-41.
14. Zucherman JF, Hsu JY, Hartjen CA, Mehalic TF, Implicito DA, Martin MJ, et al. A Multicenter, Prospective, Randomized Trial Evaluating the X STOP Interspinous Process Decompression System for the Treatment of Neurogenic Intermittent Claudication. Spine 2005; 30: 1351-8.
15. Yamazaki K, Yoshida S, Ito T, et al. Postoperative Outcome of Lumbar Spinal Canal Stenosis After Fenestration: Correlation With Changes in Intradural and Extrdural Tube on Magnetic Resonance Imaging. Journal of Orthopaedic Surgery 2002; 10: 136-43.

This is a peer reviewed paper 

Please cite as : George.W. Boghdady : Clinical and Functional Outcome of Multiple Laminotomy Technique in the Treatment of Lumbar Spinal Stenosis 

J.Orthopaedics 2007;4(4)e14

URL: http://www.jortho.org/2007/4/4/e14

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