Introduction
Lumbar spinal stenosis (LSS) stands as a prevalent degenerative condition affecting older adults, characterized by a clinical picture of buttock or lower extremity pain, potentially accompanied by low back discomfort, and confirmed through imaging as a narrowing of spaces surrounding neural and vascular structures within the lumbar spine (1–3). This narrowing can arise from various factors, including intervertebral disc herniation, ligamentum flavum hypertrophy, facet joint hypertrophy, spondylolisthesis, osteophytes, and ectopic fat tissue (Figures 1, 2). Accurate Ame Medical Diagnosis is crucial for effective management of this condition.
Figure 1 Key causes of lumbar spinal stenosis illustrated: intervertebral disc herniation, hypertrophy of the ligamentum flavum, and facet joint hypertrophy contributing to spinal canal narrowing.
Figure 2 Spondylolisthesis and its role in lumbar spinal stenosis: forward slippage of the upper vertebra over the lower vertebra leading to lumbar spinal canal constriction.
Epidemiology
The precise prevalence of LSS remains undetermined, yet estimates suggest over 200,000 adults in the United States are affected (2), with projections indicating a rise to 64 million elderly adults by 2025 (4). The Framingham Study (5) highlighted the prevalence of congenital relative LSS at 4.7% and absolute LSS at 2.6%, while acquired relative and absolute LSS were found to be 22.5% and 7.3%, respectively, in the 60–69 age group. For individuals aged 70–79, these figures escalated to 47.2% and 19.4% for relative and absolute LSS, respectively. A population-based study conducted in Japan (6) demonstrated an age-related increase in LSS incidence, ranging from 1.7–2.2% in the 40–49 age group to 10.3%–11.2% in the 70–79 age group. Another study reported the incidence of symptomatic LSS at approximately 10% (7). LSS is the primary indication for spinal surgery among patients older than 65 years (8). Between 2002 and 2007, the rate of lumbar stenosis surgery among Medicare beneficiaries ranged from 135.5–137.5 per 100,000 individuals. The average hospital charges for decompression alone were about $23,724, and for procedures combined with fusion, they reached $80,888. In 2009, hospital expenses for LSS among Medicare beneficiaries totaled $1.65 billion (9), underscoring the substantial socioeconomic impact of this condition and the importance of accurate ame medical diagnosis to manage healthcare costs.
History and Symptoms
Neurogenic claudication stands as the most frequently reported symptom by LSS patients. Individuals describe pain or discomfort radiating into the buttock, thigh, and lower leg following a certain distance of walking (10, 11), leading to functional impairment and reduced walking capacity (12, 13). In cases involving dynamic components of LSS, pain symptoms often find relief in seated positions or lumbar flexion (such as when using a shopping cart or bicycle) and are exacerbated by lumbar extension, which further constricts the lumbar spinal canal area (14–17). Patients with lumbar stenosis complicated by spondylolisthesis frequently experience low back pain (18, 19, along with other symptoms like leg numbness, balance disturbances, and lower extremity weakness (12, 20). A detailed patient history is a cornerstone of ame medical diagnosis for LSS.
Physical Examination
The physical examination for LSS involves several key assessments, including gait analysis (observing for normal or wide-based gait), the modified Romberg maneuver (assessing balance with feet together and eyes closed for approximately 10 seconds), pain response to flexion, strength evaluation of knee flexors and extensors, ankle dorsiflexors and plantar flexors, pinprick sensation testing, and Achilles reflex assessment. While the specificity of a wide-based gait and abnormal Romberg test results exceeds 90%, their sensitivity remains below 50%. The “No pain with flexion” sign exhibits a sensitivity of 79% but a specificity of only 44% (16). Notably, no single physical examination finding demonstrates high sensitivity and specificity concurrently, highlighting the need for a comprehensive approach to ame medical diagnosis.
Radiographic Images
Plain Radiography
Plain radiographic images can reveal spondylolisthesis, although not all instances of spondylolisthesis result in LSS. Additional radiographic signs suggestive of LSS include narrowing of the intervertebral foramina and intervertebral disc space, small interlaminar windows, facet joint hypertrophy, short pedicles, thick lamina, and a deep posterior concavity of vertebral bodies (21). However, plain radiography is most useful in cases of obvious stenosis or spondylolisthesis and may not detect subtle narrowing. While not definitive for ame medical diagnosis, plain radiography can provide initial clues.
CT and MRI
Magnetic Resonance Imaging (MRI) is the preferred imaging modality for confirming LSS. Renowned for its superior visualization of soft tissues, MRI is widely recommended for LSS diagnosis (22–24). Computed Tomography (CT) is utilized in cases where ossification is suspected, MRI is contraindicated, or MRI is unavailable. Both CT and MRI play vital roles in achieving an accurate ame medical diagnosis.
Although a universally accepted gold standard of quantitative MRI criteria for LSS diagnosis is lacking, several parameters are clinically employed. For central LSS, the most common parameters include anteroposterior canal diameter and cross-sectional area. In lateral LSS, the height and depth of the lateral recess and the lateral recess angle are frequently assessed. For foraminal stenosis, foraminal diameter and height, hypertrophic facet joint degeneration, and foraminal nerve root impingement are key indicators (25, 26). Anteroposterior canal diameter thresholds ranging from 10 to 12 mm and cross-sectional area thresholds from 70 to 100 mm² have been reported as cut-off values for defining central stenosis (27–37) (Figure 3, Table 1). Lateral recess height/depth ≤2–5 mm and lateral recess angle ≤30–38° have been suggested for lateral stenosis (38–40) (Figure 4, Table 2). These quantitative measures significantly enhance the precision of ame medical diagnosis using imaging.
Figure 3 Measuring spinal canal dimensions for LSS diagnosis: (Left) Anteroposterior canal diameter measurement (red arrow); (Right) Cross-sectional area measurement (red hatched area) illustrating key MRI parameters.
Table 1
Cut-off Values for Anteroposterior Canal Diameter and Cross-Sectional Area in CT and MRI for Central Stenosis Diagnosis Based on Literature Review
| Literatures | Anteroposterior canal diameter (mm) | Cross sectional area (mm2) |
|---|---|---|
| CT | ||
| Ullrich (32) | ≤10 | – |
| Haig (27) | ≤11.95 | – |
| Bolender (33) | ≤10 (severe stenosis); 10–13 (moderate stenosis); 13-16 (mild stenosis) | – |
| Lee (34) | – | ≤70 (severe stenosis); 70–100 (moderate stenosis) |
| Verbiest (35) | ≤10 | – |
| Schönström (36) | ≤10 | – |
| Schönström (37) | – | 75–100 (moderate); ≤75 (severe) |
| MRI | ||
| Fukusaki (28) | ≤12 | ≤100 |
| Koc (29) | ≤10 | ≤70 |
| Mariconda (31) | ≤10 | – |
| Hamanishi (30) | ≤12 | ≤100 |
Figure 4 Measuring lateral recess dimensions for lateral stenosis diagnosis: Height/depth measurement (red arrow) and lateral recess angle measurement (yellow angle) on CT scan.
Table 2
Cut-off Values for Height/Depth and Angle of Lateral Recess in CT for Lateral Stenosis Diagnosis Based on Literature Review
| Literatures | Height/depth of lateral recess (mm) | Angle of lateral recess |
|---|---|---|
| Strojnik (38) | ≤3.6 | ≤30° |
| Ciric (39) | >5 (normal); ≤3 (highly indicative); ≤2 (diagnostic) | – |
| Mikhael (40) | 3–5 (suggestive); ≤3 (definitive) | ≤38° |
A large-scale MRI study (41) employing standardized measurements for developmental LSS suggested that developmental LSS can be diagnosed if the anteroposterior canal diameter at L1 is ≤14 mm, at L2 is ≤15 mm, at L3 is ≤16 mm, at L4 is ≤17 mm, and at L5 is ≤18 mm.
Another significant radiographic sign, the “sedimentation sign”—defined as the absence of nerve root sedimentation to the dorsal aspect of the dural sac (positive sedimentation sign) on MRI—is recognized as a reliable indicator of LSS (42–45). A meta-analysis (46) encompassing seven studies reported a sensitivity of 0.80 (95% CI: 0.77–0.83) and specificity of 0.96 (95% CI: 0.94–0.98) for the sedimentation sign. In severe morphological LSS cases, the sedimentation sign exhibited even higher sensitivity (0.899, 95% CI: 0.87–0.92) and specificity (0.99, 95% CI: 0.98–1.00). A positive sedimentation sign may also predict greater surgical treatment efficacy and inform treatment decisions regarding surgery for LSS (47, 48). Reversibility of a preoperative positive sedimentation sign post-surgery correlates with improved clinical outcomes, whereas a persistent postoperative positive sedimentation sign may indicate incomplete decompression or surgical complications (49). These advanced imaging techniques and signs enhance the accuracy of ame medical diagnosis and treatment planning.
Myelography
Myelography has been shown to have slightly superior diagnostic accuracy for LSS compared to CT (33). Bell et al. reported myelography accuracy at 93% versus 89% for CT (50). MRI and myelography may offer similar accuracy in diagnosing lumbar canal stenosis (51). A study by Bischoff et al. (52) found myelography to be the most specific diagnostic method (88.9% specificity) when compared to myelo-CT and MRI for lumbar canal stenosis diagnosis. However, due to its invasive nature and associated side effects, myelography is not routinely used in clinical practice. Despite its accuracy, the invasiveness of myelography limits its role in routine ame medical diagnosis.
Additional Investigations
Electromyography (EMG) is not routinely employed in LSS diagnosis. However, in specific clinical scenarios where radiographic findings do not fully explain patient symptoms, in cases of unilateral symptoms with bilateral pathology (53), or when differentiating LSS from peripheral neuropathy is necessary (54, EMG can be valuable. Caution is advised when LSS and peripheral neuropathy coexist. Paraspinal mapping, a quantitative EMG technique, may aid in LSS diagnosis and better reflect nerve root physiology compared to limb EMG (55). Selective lumbar nerve root blocks can identify the responsible level in patients with multilevel anatomic LSS, potentially reducing the extent of surgical intervention (56, 57). These additional investigations, while not primary, can refine ame medical diagnosis in complex cases.
Other techniques such as magnetic stimulation caudal motor conduction time (58 and dermatomal somatosensory-evoked potentials (59, 60 are infrequently used, and their diagnostic accuracy remains uncertain.
Diagnosis and Differential Diagnosis
A universally accepted gold standard diagnostic criterion for LSS is still lacking (22, 61). Therefore, LSS diagnosis necessitates a comprehensive evaluation encompassing patient history, physical examination findings, and radiographic images. Key diagnostic elements include patient age, neurogenic claudication, radiating buttock or leg pain exacerbated by lumbar extension and relieved by sitting or lumbar flexion, wide-based gait, and radiographic evidence of spinal canal narrowing. In some instances, EMG and nerve root block results are also considered. A holistic approach is essential for accurate ame medical diagnosis of LSS.
Differential diagnoses for LSS include vascular claudication, peripheral neuropathy, hip osteoarthritis, and trochanteric bursitis. The presence of a shopping cart sign, symptoms located above the knees, symptom onset with standing, and relief with sitting strongly correlate with neurogenic claudication. Conversely, calf symptoms relieved by standing are more indicative of vascular claudication (62). Peripheral neuropathy patients may have a history of diabetes mellitus (63). EMG can be helpful in differential diagnosis (64, 65). Hip osteoarthritis and trochanteric bursitis are also common in older adults; selective anesthetic and corticosteroid injections into the hip joint or trochanteric bursa can aid in differentiation. However, these conditions can coexist with LSS, complicating the differential diagnosis process. Precise ame medical diagnosis is crucial to distinguish LSS from these overlapping conditions.
Classification
Numerous classifications for LSS have been proposed, but a universally accepted system is absent. One of the most widely recognized classifications is the Arnoldi classification (66), which categorizes LSS into congenital and acquired forms. Congenital LSS includes idiopathic and achondroplastic types, while acquired LSS encompasses degenerative, combined, spondylolisthetic, iatrogenic, post-traumatic, and miscellaneous types. The Arnoldi classification provides a structured framework for understanding the diverse etiologies of LSS and aids in ame medical diagnosis and management strategies.
Figure 5 The Arnoldi Classification System for Lumbar Spinal Stenosis: outlining congenital and acquired categories, including degenerative, spondylolisthetic, and iatrogenic subtypes.
Treatment
Non-operative Management
Various non-operative treatment options are available for LSS patients, including lifestyle modifications, medications, physiotherapy, multidisciplinary rehabilitation, epidural injections, and complementary medicine. High-quality randomized controlled trials supporting the efficacy of non-operative methods remain limited (67, 68). Lifestyle adjustments such as weight loss and smoking cessation may reduce low back pain incidence (69 and improve walking capacity and quality of life (70. Over-the-counter (OTC) medications like gabapentin, vitamin B1, and prostaglandins, as well as non-steroidal anti-inflammatory drugs (NSAIDs), may provide symptomatic relief. Recent systematic reviews (71, 72) indicate that oral NSAIDs are more effective than placebo and acetaminophen for persistent low back pain, and intramuscular NSAIDs show similar outcomes to combined manipulation and soft tissue therapy. Evidence does not support the use of calcitonin for pain relief or walking distance improvement in LSS patients (73, 74. Opioids may be prescribed for severe pain, but long-term opioid use carries significant risks, potentially making operative options more suitable (75). Non-operative treatments aim to manage symptoms identified through ame medical diagnosis.
Physiotherapy encompasses a wide range of treatments, including massage, manipulation, exercises (strengthening and flexibility), balance training, braces or corsets, pain management with heat, ice, electrical stimulation, lifestyle modifications, and complementary medicine (acupuncture) (76). Exercises may offer short-term benefits for leg pain and function compared to no treatment, but the evidence quality is low (68). Currently, no evidence suggests the superiority of one physiotherapy approach over others (77).
Epidural injections, involving local anesthetic with or without steroids, may provide short-term radicular pain relief (78–80. Improvements in pain and functional parameters are similar between epidural injections and physical therapy (29. Studies also indicate that epidural injections combining anesthetic and steroids offer no additional benefit compared to anesthetic injection alone (28, 81). Moreover, epidural injections do not significantly impact long-term functional impairment, surgery risk, or long-term pain relief (78–80). Non-operative treatments are often the first line of defense following ame medical diagnosis.
Operative Management
Surgical intervention is recommended when symptoms persist despite non-operative treatments. Operative techniques include decompression alone, interspinous spacers, and spinal arthrodesis. Surgical options are considered after a thorough ame medical diagnosis and failed conservative management.
Decompression
Decompression surgery aims to relieve spinal canal and foraminal narrowing, remove pressure factors, and release nerve roots. Decompression approaches include conventional laminectomy, bilateral laminotomy, unilateral laminotomy with contralateral recess decompression via a transmedia approach (Figure 6), partial facetectomy, and split-spinous process laminotomy/laminoplasty (82–86). Decompression effectively alleviates claudication and radicular leg pain, improving physical function in LSS patients (87, 88). A 10-year prospective study comparing surgical decompression with conservative treatment showed excellent or fair outcomes in half of conservatively treated patients and four-fifths of surgically decompressed patients after 4 years, with significantly better results in the surgical group (89). Accurate ame medical diagnosis is paramount to determine the necessity and type of surgical decompression.
Figure 6 Unilateral laminotomy for bilateral decompression in LSS: (A) Preoperative MRI showing bilateral ligamentum flavum hypertrophy causing LSS; (B) Postoperative illustration of unilateral laminotomy with contralateral recess decompression, effectively relieving nerve compression.
A randomized controlled trial (RCT) (90) involving 94 patients (50 operative, 44 nonoperative) demonstrated pain and Oswestry Disability Index (ODI) improvements in both groups, but surgical management showed a mean difference favoring surgery of 11.3 in disability, 1.7 in leg pain, and 2.3 in back pain at one-year follow-up, and 7.8 in disability, 1.5 in leg pain, and 2.1 in back pain at two-year follow-up. Walking ability did not significantly differ between treatment groups. Another clinical trial including randomized and non-randomized patients showed significant surgical benefit on the SF-36 bodily pain scale and no significant ODI difference in randomized patients. Combining both groups, surgical patients demonstrated greater improvement in pain scores and ODI compared to non-operative patients (87).
A Cochrane systematic review found that bilateral laminotomy may offer better perceived recovery than conventional laminectomy. Unilateral laminotomy for bilateral decompression and bilateral laminotomy may reduce iatrogenic instability risk, and bilateral laminotomy and split-spinous process laminotomy may lessen postoperative low back pain severity (84). These surgical techniques are refined based on advancements in ame medical diagnosis and surgical outcomes research.
Interspinous Spacer
Considering the dynamic component theory in LSS, where pain is relieved in flexion and exacerbated in extension (14–16, interspinous spacers (e.g., X-stop, coflex, DIAM, Aperius devices) have been developed and clinically applied (91–93). Biomechanical studies (94) show that interspinous spacers significantly increase the canal area (18%), subarticular diameter (50%), canal diameter (10%), foraminal area (25%), and foraminal width (41%) in extension. Interspinous spacers offer an alternative LSS treatment option (95, insertable percutaneously alone or combined with decompression. Percutaneous stand-alone spacer implantation is minimally invasive (96, 97 but may carry a higher risk of unsatisfactory back pain, leg pain, quality of life, and implantation failure (98. Combining interspinous spacers with decompression yields similar pain and functional outcomes to decompression alone (99, 100. Meta-analyses (101) indicate that interspinous spacers are costly, associated with high reoperation rates, and do not provide significantly greater benefit than decompression alone, thus lacking strong evidence to support their widespread use for LSS. The decision to use interspinous spacers should be carefully considered within the context of ame medical diagnosis and individual patient needs.
Lumbar Fusion
The optimal surgical approach for LSS—decompression alone versus decompression with fusion—remains a long-standing debate (102–106). Various lumbar fusion techniques using different approaches exist, including posterior/posterolateral lumbar fusion, posterior lumbar interbody fusion, transforaminal lumbar interbody fusion (TLIF), and oblique lumbar interbody fusion (OLIF) (107–109) (Figure 7). The rate of decompression plus fusion for lumbar stenosis has increased, while decompression alone has decreased (110, 111).
Figure 7 Lumbar fusion for spondylolisthesis-related LSS: (A, B) Preoperative MRI and radiography showing L4–5 spondylolisthesis; (C, D) Postoperative radiography demonstrating slip reduction and fusion after laminectomy and posterior lumbar interbody fusion, resulting in symptom resolution.
However, research suggests limited or no additional benefit of decompression with fusion for most LSS patients (112, 113). A recent RCT indicated that instrumented fusion might reduce spondylolisthesis progression. In a 5-year RCT comparing decompression plus fusion to decompression alone for LSS with and without spondylolisthesis, Försth et al. (114) found no significant clinical outcome differences between the two groups. Ghogawal et al. (115) reported in another RCT that decompression plus fusion resulted in statistically significant improvement in overall physical health-related quality of life compared to decompression alone (score change from baseline: 14.1 vs. 7.4, P=0.02) at 4-year follow-up for degenerative grade I spondylolisthesis patients. Both RCTs (114, 115) showed that decompression plus fusion was associated with greater blood loss, longer operative time, and longer hospital stay.
Fusion is a more complex procedure than decompression alone, potentially increasing perioperative complications, mortality, and costs (9). Given the limited evidence supporting fusion advantages, its application should be restricted to patients with spinal instability, deformities, vertebral destruction from trauma, tumors, or infections, or neuroforaminal stenosis with compressed exiting nerves due to postsurgical disc collapse (102, 104). The decision for fusion versus decompression is guided by a precise ame medical diagnosis and assessment of spinal stability.
Minimally Invasive Trends
Some surgeons employ posterior microdecompression techniques for LSS treatment, minimizing tissue disruption with micro-endoscopy assistance (116). Percutaneous endoscopic interlaminar and transforaminal decompression techniques have also been developed and utilized for LSS (117–121).
TLIF techniques have evolved into minimally invasive TLIF (MI-TLIF) (122–124. Meta-analyses indicate that MI-TLIF offers similar clinical outcomes to traditional TLIF with less trauma for LSS with or without grade I–II spondylolisthesis (125–127).
Minimally invasive lateral lumbar interbody fusion (LLIF) and OLIF (128–130) are also reported as indirect decompression options for LSS. The efficacy and safety of indirect decompression are still debated. Unlike direct decompression, indirect decompression may alleviate radiculopathy and neurogenic claudication by restoring intervertebral and foraminal heights and correcting spinal alignment (131), favored by some surgeons for LSS patients with degenerative scoliosis (132). However, indirect decompression is contraindicated in patients with bony lumbar stenosis, congenital stenosis, and/or locked facets (133, 134). Minimally invasive techniques represent advancements in surgical approaches informed by ame medical diagnosis and patient-specific factors.
The use of minimally invasive techniques in spine surgery has rapidly increased with advanced image guidance systems (135). However, these techniques have limitations, including longer learning curves, risks of specific complications (136, 137, specific and limited indications, and variable clinical outcomes across surgeons. Thus, minimally invasive techniques for lumbar stenosis treatment are still evolving, and their safety and efficacy require further high-quality studies. Ongoing research and refinement of these techniques aim to improve patient outcomes following ame medical diagnosis of LSS.
Summary and Key Points
- LSS exhibits high prevalence in older populations and is the most common reason for spinal surgery in elderly patients.
- No gold standard diagnostic criteria exist for LSS; diagnosis requires comprehensive assessment of patient history, physical examination, radiographic images (CT or MRI), and sometimes EMG or nerve root blocks.
- Various non-operative options are available for primary LSS, but no single approach is definitively superior.
- Operative treatment is recommended for persistent symptoms. Decompression alone or with fusion remains debated, with increasing evidence favoring fusion for limited indications, and cautious use of interspinous spacers.
- Minimally invasive techniques are emerging in spine surgery, but their indications, safety, and efficacy require further high-quality evidence.
Accurate ame medical diagnosis is the cornerstone of effective LSS management, guiding treatment strategies from conservative measures to advanced surgical interventions.
Acknowledgements
Funding: This work was supported by the National Natural Science Foundation of China (81501933), Zhejiang science and technology innovation project (2016R413061), and Wenzhou Science and Technology Project (Y20160369). The funders had no role in study design, execution, or writing.
Footnote
Conflicts of Interest: Dr. Wu serves as an unpaid Section Editor of AME Medical Journal. The other authors declare no conflicts of interest.
Ethical Statement: The authors are accountable for all aspects of the work, ensuring that questions related to the accuracy or integrity of any part are appropriately addressed.
Open Access Statement: This is an Open Access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), permitting non-commercial replication and distribution with proper citation and no modifications. See: https://creativecommons.org/licenses/by-nc-nd/4.0/.
References
doi: 10.21037/amj.2017.04.13Cite this article as: Wu AM, Zou F, Cao Y, Xia DD, He W, Zhu B, Chen D, Ni WF, Wang XY, Kwan K. Lumbar spinal stenosis: an update on the epidemiology, diagnosis and treatment. AME Med J 2017;2:63.
