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 Table of Contents  
ORIGINAL ARTICLE
Year : 2022  |  Volume : 9  |  Issue : 1  |  Page : 32-36

Clinico-Radiological assesment of lumbar spinal canal stenosis and evaluation of its surgical treatment


1 Department of Orthopaedics, Post Graduate Institute of Medical Education and Research, Chandigarh, India
2 Department of spine surgery, Spine Surgery, Medanta The Medicity, Gurugram, Haryana, India
3 Department of Orthopaedics, SLBSGMC, Mandi, Himachal Pradesh, India

Date of Submission07-Oct-2021
Date of Acceptance06-Nov-2021
Date of Web Publication9-Mar-2022

Correspondence Address:
Sarvdeep Singh Dhatt
Department of Orthopaedics, Post Graduate Institute of Medical Education and Research, Chandigarh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/joss.joss_8_21

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  Abstract 


Objective: This study aimed to predict the absolute criteria for surgical intervention and study the outcome of surgical intervention.
Materials and Methods: A prospective study was conducted from June 2002 to July 2003. A total of 35 patients were included in the study. Pre- and postoperative Oswestry Disability Index (ODI) scores were evaluated for all the patients. All patients underwent magnetic resonance imaging (MRI). The surgical indications were disabling backache with radicular pain, limited walking capacity, and neurological deficits leading to a poor ODI score. Surgical procedures done were discectomy and laminectomy with or without fixation with pedicle screws on a case-to-case basis. Follow-up was done for up to 1 year at three-monthly intervals. The final ODI score was taken at the last follow-up and was compared with preoperative scores.
Results: A 50 ± 10 years was the average age of patients included in the study. The average walking capacity was 40 m; the average duration of symptoms was 41 months. ODI improved from average score of 71% ± 4% preoperatively to 22% ± 6% postoperatively. L4–L5 was the level most severely narrowed, with a mean cross-sectional area of 75 mm2. The most common surgical interventions done were discectomy and laminectomy, which were performed in 54% of the cases. We had good-to-excellent results in all our cases. None of the cases deteriorated after surgery.
Conclusion: The findings in this study have important implications in clinical practice. The radiological findings in the MRI correlated well with the clinical signs and symptoms of the patients, i.e., patients with significant findings in the MRI had profound clinical symptoms and neurological deficits.
Clinical Significance: Lumbar canal stenosis is a clinicoradiological diagnosis. ODI score is related to canal narrowing on MRI. Clinical improvement is related to preoperative disability and canal narrowing on MRI.

Keywords: Lumbar canal stenosis, magnetic resonance imaging, Oswestry Disability Index


How to cite this article:
Dhatt SS, Kumar V, Dagar A, Salaria AK, Neradi D. Clinico-Radiological assesment of lumbar spinal canal stenosis and evaluation of its surgical treatment. J Spinal Surg 2022;9:32-6

How to cite this URL:
Dhatt SS, Kumar V, Dagar A, Salaria AK, Neradi D. Clinico-Radiological assesment of lumbar spinal canal stenosis and evaluation of its surgical treatment. J Spinal Surg [serial online] 2022 [cited 2022 May 27];9:32-6. Available from: http://www.jossworld.org/text.asp?2022/9/1/32/339278


  Introduction Top


Lumbar canal stenosis (LCS) is a clinicoradiological diagnosis. The normal canal cross-sectional area of the lumbar spine is about 180 mm2 (± 50 mm2). Term relative canal stenosis is used when the canal cross-section area is 100 mm2 or less. Absolute stenosis exists when the area becomes 75 mm2 or less.[1] LCS results from a chronic pathological process arising out of multifactorial etiologies summating to cause canal narrowing.[2],[3] Involvement can be at a single level or multiple levels. Etiological causes include disc degeneration causing reduced disc space height, disc bulge, segmental instability causing ligamentous hypertrophy, degenerative facet capsular hypertrophy/cyst, and spondylolisthesis. The outcome is reduced space for the dural sac, which, combined with vascular engorgement on mobilization, causes symptomatology.[4]

Mere, the presence of narrowing of the lumbar canal on radiology does not diagnose LCS. It is the presence of clinical features as neurological claudication, more tolerance in walking on an inclined plane compared to flat or decline plane, back pain, and their correlation with findings on magnetic resonance imaging (MRI) images that seals the diagnosis.[5] Although terms relative and absolute canal stenosis are frequently used in literature and are used as a threshold for surgery, no one can deny the presence of a subset of patients who have lower than threshold canal area on radiology without corresponding symptoms.[2] The theoretical reason for such cases is individual/subjective pain tolerance, adaptability of neural structures because of chronicity of pathology, and low demand age group of patients involved. On the other hand, there is more than 100 mm2 area in the canal but with symptoms tempting enough to decompression. The proposed explanation for these cases is that MRI at most centers of the world (particularly in the developing world) is done with patients lying supine. MRI picture thus presented does not consider the presence of dynamic dural compression and change in mechanics on standing and walking.[6],[7],[8],[9] In this study, we assessed the clinicoradiological correlation and evaluated decompression results alone in our subset of patients.


  Materials and Methods Top


A prospective study was conducted from June 2002 to July 2003. A total of 35 patients with LCS were included in the study. Inclusion criteria were any case with age over 18 years, clinical symptoms pertaining to neurogenic claudication with or without motor weakness, sensory deficit, and absent reflexes. Exclusion criteria included failed back syndrome, spondylolisthesis, spinal trauma, and congenital canal stenosis.

At admission, a detailed clinical examination of the patient was done. Patients were interrogated about the duration of their symptoms, both of low backache and leg pain/tingling/numbness. The functional disability of patients was measured using the Oswestry Disability Index (ODI) questionnaire. The walking capacity of the patient was measured by dividing the corridor of the hospital with markings at every100 m. After thorough clinical evaluation, radiological investigations, including roentograms and MRI, were done. Stenotic pathological levels were identified and correlated with neurological levels identified on clinical examination. The pathological findings on MRI were disc bulge, ligamentum flavum hypertrophy, facet hypertrophy. The cross-sectional area of the canal was taken on axial T1-weighted images using the UNIX software by a single senior radiologist. The MRI used at our institute was a 1.5 Tesla Siemens Magnetom design. The dural sac was outlined, and then the cross-sectional area was measured [Figure 1]. The reference value for the cross-sectional areas of the dural sac taken was as follows:
Figure 1: Cross-sectional area measurement

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  1. Normal range – 180 ± 50 mm2
  2. Relative stenosis – 100–75 mm2
  3. Absolute stenosis – <75 mm2.


These values were then compared with the respective neurological deficit and clinical symptoms and disability of the patients.

The surgical indications were disabling backache with radicular pain, limited walking capacity, and neurological deficits leading to a poor ODI score. The level of the decompression was decided by correlating clinical features with radiological findings. Surgery was planned depending on the number of levels involved in the pathological process. Single-level procedures were performed in 9% of the cases. About 71% of the patients had decompression at two levels, and 17% cases had at three levels, while 3% had a four-level decompression. Surgical procedures done were discectomy and laminectomy with or without fixation with pedicle screws on a case-to-case basis.

Follow-up was done up to 1 year at three-monthly intervals. The final ODI score was taken at the last follow-up and was compared with preoperative scores. Those cases that improved only between 0% and 25% were categorized as poor, those between 26% and 50% were categorized as fair, those between 51% and 75% were categorized as good, and those between 76% and 100% were categorized as excellent.


  Results Top


A total of 35 cases were included in the study. The age group of the patients ranged from young adults to geriatric (25 to 70 years) with an average age of 50 ± 10 years [Figure 2]. The maximum number of patients were in the age group of 41 to 50 years (40% cases). However, 83% of the cases were above 41 years. Males outnumbered female patients with a ratio of 2.9:1. Smoking emerged as a common habit, with 43% of the cases being smokers.
Figure 2: Age distribution

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The duration of localized backache ranged from 2 months to 180 months, with the average duration being 41 months [Figure 3]. Duration of leg pain/neurological claudication ranged from 15 days to 180 months, with the average being 19 months [Figure 4]. About 77% of cases were in the 0–20 months range. The average walking capacity was 40 m, ranging from 10 to 80 m. The majority (83%) of the cases had a walking capacity of <50 m [Figure 5]. On examination, 91% of the patients had sensory and 80% had a motor deficit.
Figure 3: Duration of backache in Years

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Figure 4: Duration of leg pain in years

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Figure 5: Walking capacity in meters

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The L4–L5 was the most common level, with 86% of the cases having stenosis at this level. The average area was 74.6 mm2, and the least affected level was L1-L2, with just 5% of the patients having features of stenosis with the average area being 168 mm2 [Figure 6]. Preoperatively and 1 year after surgery, the Oswestry Disability Questionnaire was asked from the patients, which showed an improvement in all the cases [Figure 7]. Preoperatively, the index values ranged from 62 to 78%, with the mean being 71% ± 4%. Postoperatively, the index ranged from 10 to 37%, with the mean being 22% ± 6%. In 14% of cases, pain killers gave moderate relief from pain and 23% of cases got complete relief from pain preoperatively. The walking section of the Oswestry Index showed that preoperatively 14% of patients could not walk and had to crawl to the toilet literally, 17% of the cases could walk with sticks, and 69% of the cases could not walk more than ¼ mile. At 1-year follow-up, only 9% of the cases had to use sticks to walk, 14% of the patients could walk up to ½ mile, 31% of the cases could walk up to 1 mile, and 37% of the cases could walk any distance. All cases had a good or excellent result. About 74% of cases had a good result and 26% of the cases had an excellent result. None of the patients had a poor or fair outcome.
Figure 6: Cross-sectional area on MRI

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Figure 7: ODI score comparison: preoperative to 1-year follow-up

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  Discussion Top


There has been a steady rise in cases of LCS mainly because of increased age expectancy, awareness among masses, and availability of health infrastructure for all. Due to multifactorial etiogenesis, multilevel involvement, variability of symptomatology, and dynamic mechanical compression, it is essential to define a threshold for surgical intervention for LCS.[10]

The mean age of the patients in our study was 50 ± 10 years, which is comparable to other studies.[11] Majority of patients in our study were male, which is in line with other series.[12] Smoking is an independent risk factor for LCS, as suggested by finding that most patients were smokers.

A significant predictor of disability was a decrease in the walking capacity of patients with LCS. Difficulty in walking around was one of the most common complaints of patients and the main hindrance to daily activities. The average walking capacity was 40 m in our study. The majority (83%) of the cases had a walking capacity of less than 50 m. However, interestingly, the walking capacity of the patients did not correlate well with the neurological deficit of the patient or to the dural sac area on MRI. This could probably be explained by individual pain tolerance, psychological aspects of back pain and dynamic compression in LCS; because of this reason, it must be emphasized again that LCS is clinicoradiological diagnosis.[13],[14],[15],[16]

The cross-sectional area in mm2 was taken on T1-weighted MRI images. In this study, 86% of cases had stenosis at L4-L5 level with mean area of cross section being 74.6mm2. L1-L2 level was least common to be stenosed with only 5% of cases and mean area of cross section being 168mm2. Our study found that all cases that had area below 100 mm2, even at one level, had features of claudication, although there was no significant correlation between cross-sectional area and claudication distance. Involvement of multiple levels is found to be more disabling. According to studies by Porter and Ward[17] and Hamanishi et al.,[18] clinicoradiological correlation is more obvious in multilevel involvement compared to a single level.[19] While correlating the MRI area with the neurological deficit, we could observe that in all patients, in whom the area was less than 100 mm2, there was a neurological deficit, but we could not delineate the amount of deficit associated.

Several papers have reported good results following surgery for LCS in the literature.[20] Postacchini et al.[21] reported that clinical long-term results were excellent or good in 43 patients (67%) in the study of 64 patients with 8-year follow-up. A meta-analysis showed that 64% of surgically treated LSS patients had good-to-excellent outcomes.[22] Katz et al.[23] reported that in a follow-up of cohort of 88 patients, 55 responded to questions. Twenty patients (23%) had undergone reoperation by 7- to 10-year follow-up. Thirty-three percent of the respondents had severe back pain at follow-up, 53% were unable to walk two blocks. In our study, preoperatively, the Oswestry Index values ranged from 62% to 78%, with the mean being 71% ± 4%. Postoperatively, the index ranged from 10% to 37%, with the mean being 22% ± 6%. The satisfaction levels at 1-year follow-up based on the Oswestry Disability Questionnaire were also calculated. All cases had a good or excellent result. About 74% of the cases had a good result and 26% of the cases had an excellent result. Among surgical options, a randomized controlled study demonstrated no difference between decompression-only group or decompression with fusion group.[24] Studies also demonstrated causes of reoperation as inadequate decompression, instability, smoking, and diabetes.[25]


  Conclusion Top


The findings in this study have important implications in clinical practice. The radiological findings in the MRI correlated well with the clinical signs and symptoms of the patients, i.e., patients with significant findings in the MRI had profound clinical symptoms and neurological deficits. All patients with severe stenosis on MRI had excellent results in the postoperative period.

Clinical significance

LCS is a clinicoradiological diagnosis. ODI score is related to canal narrowing on MRI. Clinical improvement is related to preoperative disability and canal narrowing on MRI.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Menon VK, Raniga SB, Al Busaidi AQ. MRI morphology of surgically treated lumbar canal stenosis: A retrospective study. J Spinal Disord Tech 2015;28:12-8.  Back to cited text no. 9
    
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Schönström N, Lindahl S, Willén J, Hansson T. Dynamic changes in the dimensions of the lumbar spinal canal: An experimental study in vitro. J Orthop Res 1989;7:115-21.  Back to cited text no. 15
    
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Boden SD, Davis DO, Dina TS, Patronas NJ, Wiesel SW. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. J Bone Joint Surg Am 1990;72:403-8.  Back to cited text no. 16
    
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Porter RW, Ward D. Cauda equina dysfunction. The significance of two-level pathology. Spine (Phila Pa 1976) 1992;17:9-15.  Back to cited text no. 17
    
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Hamanishi C, Matukura N, Fujita M, Tomihara M, Tanaka S. Cross-sectional area of the stenotic lumbar dural tube measured from the transverse views of magnetic resonance imaging. J Spinal Disord 1994;7:388-93.  Back to cited text no. 18
    
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Sirvanci M, Bhatia M, Ganiyusufoglu KA, Duran C, Tezer M, Ozturk C, et al. Degenerative lumbar spinal stenosis: Correlation with Oswestry Disability Index and MR imaging. Eur Spine J 2008;17:679-85.  Back to cited text no. 19
    
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Postacchini F, Cinotti G, Gumina S, Perugia D. Long-term results of surgery in lumbar stenosis. 8-year review of 64 patients. Acta Orthop Scand Suppl 1993;251:78-80.  Back to cited text no. 21
    
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