Lumbar spinal stenosis (LSS) is a common syndrome induced by cauda equina nerve or nerve root compression of the spinal canal, neural tube, or intervertebral foramen. Clinically, LSS is characterized by lumbosacral radicular pain, intermittent claudication, numbness along with gait disturbance, and even urinary dysfunction, which greatly influence the patients’ daily activities and quality of life.¹

Folder patients over 70 years of age Lumbar Spinal Canal Stenosis [LCS] is among the most common surgical conditions. Although immediate surgical intervention is necessary when accompanied by acute lower limb paralysis or bladder or rectal disorders, in the absence of such "red flags", the effectiveness of surgical treatment is controversial.

LSS symptoms and signs are often inconsistent with the imaging examination, which can be asymptomatic in some patients. The lumbar spine degenerative process is reported to be the main pathogenesis of LSS.

It is estimated that the prevalence of LSS is 47.2% and increases with age.²

Non-operative treatment comprises rest, muscle relaxants, non-steroidal anti-inflammatory drugs, and physical therapy. Selective nerve root block (SNRB) is an option when symptoms persist or when patients are not suitable for surgery. The therapeutic value of SNRB for lumbar spinal stenosis is accepted [1,3]. 

SNRB can be performed at multiple sites, including the cervical, thoracic and lumbar spine, and can reduce pain in patients with severe pain. However, there are scattered reports of adverse events occurring with SNRB [7]. There are also reports of higher complication rates in patients who have received several injections compared with those who have received only one injection⁴, and to the best of our knowledge, there have been no reports of the efficacy of repeated SNRBs.

The present study was conducted in the department of Orthopedics, RDJM Medical college, Muzaffarpur Turki, Bihar. A total of 50 patients who visited our hospital between 2022 and 2024 with LCS and who underwent SNRB were included in this study. LCS was diagnosed on the basis of clinical symptoms and imaging findings. Patients with acute-onset lumbar disc herniation, trauma, cauda equina syndrome, pain due to other factors, such as polymyalgia rheumatica, peripheral vascular circulatory disorders, and psychological factors, and patients who could not be followed up owing to non-attendance or transfer of doctor after SNRB were excluded. After excluding these patients, 42 patients were included in the study. The mean age of the patients was 82 years (range: 70-92 years); 20 were men and 22 were women.

We clarified the presence or absence of surgery, number of blocks performed, block effect, magnetic resonance images, presence or absence of complications, and disease duration by clinical records, retrospectively. The magnetic resonance images were examined for the area of the spinal canal at the responsible level and for the presence or absence of herniation. The area of the spinal canal was calculated as the average of three measurements at the same level. For patients with visual analog scale (VAS) records, those whose scores decreased over time were defined as those with pain reduction; for those without VAS records, pain reduction was evaluated based on patient statements and their activities of daily living (ADL) improvements noted in the patient's medical record at the next visit. Of the nonoperative patients, those who achieved pain relief with SNRB were defined as the effective group, excluding those who did not wish to undergo surgery owing to advanced age, those who were ineligible for surgery owing to comorbidities and poor general condition, and those who declined surgery for family reasons. Of the patients who underwent surgery, the ineffective group comprised those who underwent surgery owing to inadequate efficacy of SNRB, excluding those who strongly desired surgery to improve their ADL even though SNRB had some efficacy, and those who strongly desired surgery at their visit. We compared the results of each investigated item between the effective group and the ineffective group.

Technique

SNRB was performed by the same surgeon. The patient was placed in the prone position under fluoroscopy and received an injection of 0.25% bupivacaine and Methylprednisolone. Although pain reproduction was not always confirmed, the drug was injected after confirming that the needle tip was in the optimal position using fluoroscopy The procedure was performed maximum 3 times in all patients. We performed SNRB at 4-6 weeks intervals, depending on the patient's symptoms.

Statistical test was done using SPSS version 23.

Of the 50 patients who underwent SNRB, 42 met the inclusion criteria; 32 patients were nonoperative, and 10 patients were operative. Of the non-operative cases, 30 patients comprised the effective group, and of the surgically treated cases, 9 patients comprised the ineffective group. Of the 42 evaluable patients, 30 patients comprised the effective group and 61% were able to avoid surgery, with SNRB. The mean age was 82.0 years in the effective group and 83.2 years in the ineffective group.

Comparing each category, the spinal canal area at the responsible level was 110.25 mm2 in the effective group and 79.33 mm2 in the ineffective group, and the ineffective group had a significantly narrower spinal canal area than the effective group (p=0.005) (Table 1). The duration of disease, number of blocks, and lumbar disc herniation rate were 9.2 months/16.2 months (p=0.1), 2.03 times/3.24 times (p=0.11), and 37.1%/48.6% (p=0.59), in the effective/ineffective groups, respectively, with no significant difference.

Table 1: Results of each category between the effective and ineffective groups

Although one of the patients in the effective group had a symptom relapse six months after the initial symptom relief, the SNRB again relieved the symptoms. Thereafter, no symptom recurrence was observed. Of the ineffective group, three patients relapsed two to six months after symptom relief with SNRB.

This study examined the effectiveness of selective nerve root block (SNRB) as a conservative treatment for lumbar canal stenosis (LCS) in patients over 70 years old. SNRB has been frequently reported as a viable non-surgical option [5]. Kannan et al. evaluated its efficacy in patients with radiculopathy who continued to experience high Visual Analog Scale (VAS) scores despite medication [1]. Among the 76 patients who underwent SNRB, 35 eventually required surgery, while 54% were able to avoid it. In our study, 61% of patients successfully avoided surgery, demonstrating a comparable effectiveness of SNRB⁶ in managing LCS.

In this study, there was no significant difference in disease duration between the effective and ineffective groups. However, the p-value was relatively low (0.1), with disease durations of 9.2 months and 19.05 months, respectively. While not statistically significant, the substantial difference in duration suggests that longer disease duration may reduce the success of non-operative therapy. As the sample size increases, this difference may become statistically significant.

Our study found that the spinal canal area at the affected level was significantly narrower in the ineffective group. Similarly, Tadokoro et al. examined the outcomes of conservative treatment in older patients and identified factors influencing its success [8]. Their study reported that patients with complete contrast blockage at the affected level on myelography showed lower improvement in activities of daily living (ADL) with conservative treatment. Consistent with our findings, these results suggest that conservative therapy is less effective in cases with severe spinal canal narrowing, indicating potential limitations in its therapeutic effectiveness.

In this study, there was no significant difference in disease duration between the effective and ineffective groups. However, the p-value was relatively low (0.112), with disease durations of 8.43 months and 18.95 months, respectively. Although not statistically significant, the substantial difference suggests that longer disease duration may reduce the success of non-operative therapy. A larger sample size may reveal a significant association between disease duration and treatment effectiveness.

Mallinson et al. reported that 69.1% of patients experienced pain relief within seven days of SNRB [3]. In contrast, Ko et al. examined VAS scores over time and found that pain reduction peaked at two weeks post-SNRB before gradually declining [10]. In our study, SNRB was performed an average of three times, with an efficacy rate of 61%. Since pain relief has been shown to diminish two weeks after a single nerve root block, multiple SNRBs may provide greater symptom relief. However, there are no existing studies on the effects of repeated nerve root blocks, and our study did not determine the optimal frequency for treatment.

Adverse events following SNRB have been reported in the literature. Manchikanti et al. documented minor complications, including focal hemorrhage and nerve root irritation, in 3,162 of 15,645 patients who underwent SNRB [11]. Similarly, Stalcup et al. reported minor complications in 98 of 1,777 patients [4]. These adverse effects were generally mild and included transient lower extremity weakness, dizziness, and persistent pain, with a higher incidence observed in patients receiving multiple nerve root blocks. While repeated SNRBs may increase the risk of perineural adhesions and associated complications, no adverse events were observed in this study, despite all patients being over 80 years old. These findings suggest that SNRB can be performed with relative safety, even in elderly patients.

This study has several limitations. First, the sample size was relatively small. As previously discussed, a larger cohort may help identify significant differences between the effective and ineffective groups, warranting further investigation. Second, pain improvement measures, such as the Visual Analog Scale (VAS), could not be assessed in some cases. Given that the study population consisted of elderly patients, accurately correlating VAS scores with verbal pain descriptions was challenging, making it difficult to ensure consistency in pain assessment. However, symptom progression was effectively monitored through patient and family reports documented in medical records. Lastly, the follow-up rate was low. Not all patients who experienced improvement were followed up, which may be attributed to factors such as worsening comorbidities or reduced medical visits during the COVID-19 pandemic. To mitigate this limitation, future studies could consider conducting follow-up assessments via telephone surveys.

In this study, SNRB was effective in over 60% of elderly patients with LCS. However, its therapeutic efficacy may be lower in cases of advanced LCS and prolonged disease duration. Given its relatively favorable safety profile, SNRB may serve as a viable treatment option for older patients with significant perioperative risks.

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