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 Table of Contents  
ORIGINAL ARTICLE
Year : 2013  |  Volume : 27  |  Issue : 3  |  Page : 159-164

The efficacy of lumbar sympathetic nerve block for neurogenic intermittent claudication in lumbar spinal stenosis


Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo, Japan

Date of Web Publication7-Jan-2014

Correspondence Address:
Masataka Ifuku
Department of Anesthesiology and Pain Medicine, Juntendo University School of Medicine, Tokyo
Japan
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-5333.124601

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  Abstract 

Background: The symptoms of LSS include radicular symptoms (RS) and IMC. IMC is thought to be caused by circulatory disturbances in the cauda equina nerves and does not often resolve naturally. There are reports of increased cauda equina nerve blood flow in canine spinal stenosis models as a result of lumbar sympathetic resection. Thus, we believed that improvement of IMC in LSS may be achieved by performing a LSNB to produce a medium-term effect. Materials and Methods: Patients with LSS suffering from IMC in both legs were enrolled in this study. Those with IMC symptoms alone were classified as cauda equina-type (CE group), while those who also suffered from RS were classified as mixed-type (M group). LSNB was performed on both sides using a neurolysis in both groups. Evaluation was using the Zurich claudication questionnaire (ZCQ). Results: Twenty-six subjects were completed the six-month observation period. In contrast to the CE group who, throughout the observation period, experienced significant improvements in Symptom Severity (SS) and Physical Function (PF) scores compared with those before treatment, no such significant differences were observed in the M group throughout the observation period. In addition, a significant decrease in the SS scores of the CE group one-month after treatment and in the PF and Patient Satisfaction (PS) scores both one-month and two-months after treatment was observed in comparison with the M group. Conclusion: Our results show that LSNB for LSS is more effective in improving neurogenic intermittent claudication than radicular symptoms, and this suggests that LSNB could become an effective treatment for cauda equina-type lumbar spinal stenosis that is resistant to other conservative treatment.

Keywords: Lumbar sympathetic nerve block, lumbar spinal stenosis, neurogenic intermittent claudication


How to cite this article:
Ifuku M, Iseki M, Hasegawa R, Morita Y, Komatsu S, Inada E. The efficacy of lumbar sympathetic nerve block for neurogenic intermittent claudication in lumbar spinal stenosis. Indian J Pain 2013;27:159-64

How to cite this URL:
Ifuku M, Iseki M, Hasegawa R, Morita Y, Komatsu S, Inada E. The efficacy of lumbar sympathetic nerve block for neurogenic intermittent claudication in lumbar spinal stenosis. Indian J Pain [serial online] 2013 [cited 2019 Nov 21];27:159-64. Available from: http://www.indianjpain.org/text.asp?2013/27/3/159/124601


  Introduction Top


Lumbar spinal stenosis (LSS) is a condition is caused by senescent, degenerative changes of the lumbar vertebrae, which result in spinal canal narrowing. The cauda equina nerves and nerve roots are compressed as a consequence of spinal stenosis, resulting in numbness and lower limb pain. The symptoms of LSS are divided into three types: Radicular pain, claudication, and a mixture of these two symptomatic types. [1],[2] Radicular pain arises from the compression of nerve roots at the intervertebral foramen and the lateral recess of the ventral lumbar facet joint and sciatic leg pain, which is usually unilateral, accompanies the resulting inflammation. On the other hand, the chief complaint with neurogenic LSS is intermittent claudication (IMC), where bilateral lower limb pain and numbness are experienced with continued walking and standing. This is thought to be caused by a deficiency of oxygen supply or blood flow disturbances in the cauda equina nerves and nerve roots resulting from the compression of intervertebral discs and ligament a flava. [3],[4] Since radicular symptoms (RS) are caused by inflammatory neural changes, they respond well to conservative treatment such as epidural and nerve root blocks, and spontaneous remission can be expected. [5] By contrast, neurogenic IMC is caused by anatomical compression, being thus resistant to conservative treatment and rendering spontaneous remission unlikely. Accordingly, surgical treatment is considered as the first choice in cases with severe symptoms. [6],[7]

A prostaglandin E 1 derivative (PGE 1 ) increases cauda equina neuronal blood flow. [8] In a comparative study of patients with LSS exhibiting neurogenic symptoms, who were randomly divided into a PGE 1 group and a nonsteroidal anti-inflammatory drugs (NSAIDs) group, the PGE 1 group showed significant improvement in numbness while walking as well as in the walking distance. [9] These results appear to indicate that if this PGE 1 treatment increased cauda equina blood flow, it could provide a conservative treatment option for neurogenic LSS in conjunction with the surgical and mechanical compression release.

Onda et al., [10] reported increased neuronal blood flow in a canine chronic cauda equina nerve compression model after sympathetic nerve resection. These findings suggest that lumbar sympathetic nerve blocking (LSNB) could also become a clinical treatment for neurogenic LSS. Until date, there have only been reports of LSNB being used in the treatment of ischemic pain such as arteriosclerosis obliterans (ASO) of lower extremities and CRPS. [10] The therapeutic effect derived from neurolytic blocks was found to be sustained for at least a few months following each of the treatments described in the above reports, [11],[12] leading us to believe that a similar long-term sustained effect could be expected in terms of cauda equina nerve blood flow improvement. There is a difference, however, between the pathology of pure neurogenic LSS and mixed-type LSS. The former shows no difference in symptoms between the left and right sides, while the latter is accompanied by unilateral radicular pain. Thus, individual observation and comparison of the effect of blocks on both types of LSS is required. In this study, lumbar sympathetic nerve blocks using a neurolytic agent were performed on subjects suffering from spinal stenosis with cauda equina claudication. We then observed the resulting effects of the block in improving IMC symptoms over an extended period of time. In addition, both neurogenic and mixed-type LSS patients were compared to determine which condition the lumbar sympathetic nerve blocks are effective in treating.

[TAG:2]Materials and Methods [/TAG:2]

Subjects

The criteria for LSS patients with neurogenic symptoms were as follows:

Inclusion criteria

1) Magnetic resonance imaging: Spinal canal narrowing, the planimetrically assessed cross-sectional dural area being less than 100 mm 2 . [13] 2) Bilateral IMC symptoms classified as neurogenic claudication based on a LSS questionnaire [14] (this questionnaire could not distinguish between neurogenic LSS and mixed-type LSS accompanied by RS). 3) A duration of symptoms and signs of more than 6 months. 4) Symptoms which did not improve or remained the same with PGE 1 and NSAID administration. 5) Symptoms that did not improve or remained the same with lumbar epidural steroid injection (epidural steroid injection via the translaminar or transforaminal route).

Exclusion criteria

1) Patients with an ankle-brachial index (ABI) of 1.0 or less on either side as well as those in whom the possibility of vascular IMC resulting from ASO could not be excluded. [15] 2) Patients with a history of other diseases that affect walking and pain such as osteoarthritis of the knee and Parkinson's disease. 3) Patients for whom surgical treatment that causes bladder and rectal disturbance or lower limb motor neuropathy was required as soon as possible. 4) Patients determined to be affected by other conditions such as mental illness by a physician.

Study protocol

Study design is a comparative prospective study. This study was approved by the hospital ethics committee, and informed consent for the use of the resulting data was obtained from each individual subject.

The subjects were divided into a cauda equina-type group (CE group), which exhibited pure neurogenic IMC symptoms with no symptomatic difference between sides, and an mixed-type group (M group), which exhibited neurogenic IMC symptoms bilaterally, accompanied by unilateral RS. Lumbar sympathetic nerve blocks using a neurolytic agent were performed on all subjects after admission to hospital. A block was performed on one side of the subjects' back on one day and on the opposite side on the following day. Complete nerve block was declared upon observation of a rise in foot skin temperature, used as an objective evaluation index, during the following day's observation. Evaluation was conducted before treatment and 1, 2, and 6 months after treatment. There were no changes in the drugs administered to the subjects in either group over the 6-month observation period. The M-group subjects in whom RS remained severe at follow-up evaluation following LSNB were administered lumbar epidural steroid injections as required.

Procedure

  1. The block was performed using an X-ray fluoroscopy-guided paravertebral approach, with the subject in the dorsal position, and the side to be blocked lying dorsally. The lumbar sympathetic nerves are present in a compartment anterolateral to the vertebral body surrounded by the anterior longitudinal ligament, parietal peritoneum, and psoas major muscle anterior fascia. The needle tip was guided to this site.
  2. One milliliter of contrast agent (iohexol) was injected fluoroscopically, after which a check for leakage to the lumbar arteries and veins in the middle vertebral body and the psoas major muscle on the dorsal side was performed [Figure 1]. One milliliter of mepivacaine (2%) was then injected, and the subject was observed for 15 min.
  3. After 15 min, 1 mL of anhydrous ethanol was injected following confirmation of a rise in skin temperature on the blocked side compared with that on the non-blocked side and normal sensation in the genitofemoral nerve region. The subject was then left to rest for 2 h in the same decubitus position.
  4. It is recommended that lumbar sympathetic nerve blocks be performed at the second and third lumbar vertebral level. [16] If the approach was made at the L2 or L3 vertebral body and an increase in skin temperature was not observed in that region following injection of a local anesthetic, another approach was made at the level of a different vertebral body.
Figure 1: Fluoroscopic injection of 1 mL of the contrast agent during lumbar sympathetic nerve block. Left: Lateral image; Right: Anterior image

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Evaluation items

Evaluation was conducted using the Japanese version of the self-administered Zurich claudication questionnaire (ZCQ). [17] An intergroup comparison of symptom severity (SS), Physical Function (PF), and Patient Satisfaction (PS) in the CE and M group before and after treatment as well as a comparison between the two groups at each stage was conducted.

Statistical analysis

After confirming the normal distribution of each ZCQ score using the Shapiro-Wilk test, multiple comparisons within the groups were conducted at four stages: Before treatment and 1, 2, and 6 months after treatment using one-way analysis of variance (ANOVA). In addition, the comparison of average age, condition duration, MRI dural tube area, and ZCQ scores between groups was conducted using a two-sample t-test where the data followed a normal distribution as an independent sample and using the Mann-Whitney test where the data were not normally distributed. Statistical significance was set at P < 0.05.


  Results Top


Twenty-eight subjects were enrolled in this study between April 2010 and November 2011. Lumbar sympathetic nerve blocks were performed on 14 CE group subjects and 14 M group subjects. Two M-group subjects were unable to attend hospital during the follow-up period because of other conditions and withdrew from this study leaving a total of 26 subjects who completed the 6-month posttreatment observation period [Figure 2]. The average age of these 26 subjects was 72.4 years (range 53-85 years); average morbidity duration was 4.2 years (range 0.5-20 years); average MRI dural tube area was 48.4 mm 2 (range, 25.5-78.1 mm 2 ), and 16 of the 26 subjects (61.5%) had lumbar spondylolisthesis complications. Hyposensitivity of the genitofemoral nerve area was observed in one M-group subject as a complication following treatment, although this did not cause pain; recovery of sensation was observed subsequently at the 6-month follow-up. No other complications were observed during the study period. There was no significant difference between the two groups with regard to age, dural tube area, condition duration, or frequency of lumbar slippage [Table 1].
Table 1: Baseline characteristics of 26 patients with spinal stenosis

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Figure 2: Flow of the patients through each stage of the study

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A significant reduction in the posttreatment SS and PF ZCQ scores of the CE group in comparison to pretreatment scores was observed at all stages (1, 2, and 6 months following treatment) (P < 0.05). On the other hand, no significant difference in pretreatment and posttreatment ZCQ scores was observed in the M group at any stage (P > 0.05) [Figure 3].
Figure 3: ZCQ scores before and after lumbar sympathetic nerve blocks by functional classification

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In a comparison of ZCQ scores between groups, a significant decrease in the SS scores of the CE group 1 month after treatment and in the PF and PS scores both 1 and 2 months after treatment was observed in comparison to the M group [Table 2].
Table 2: Primary efficacy outcomes

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  Discussion Top


Severe neurogenic Langerhans cells (lumbar spinal stenosis) is usually treated with surgery, although the incidence of complications (including minor complications) in spinal surgery performed on the elderly is as high as 40%. [18],[19],[20] In addition, an increased rate of postoperative infection has been reported in cases where lumbar spinal fusion is performed in comparison to when only laminectomy is performed. [21] The subjects in this study were relatively elderly with an average age of 72 years, and 60% of these subjects had lumbar spondylolisthesis complications requiring fixation. Considering the risk of systemic complications and complications associated with surgery, some patients were already been deemed unfit for surgery. As this condition often follows a chronic course, conservative treatment is generally the first choice. Surgical treatment is only considered necessary in rare cases [22] where a patient exhibits progressive paralysis or bladder or rectal dysfunction. In addition, failure of conservative treatment does not significantly impact postoperative results; thus, it is thought that conservative treatment should be the starting point. [23] Accordingly, we believed that LSNB can offer an effective treatment option for neurogenic LSS that is resistant to other forms of conservative treatment.

The validity of ZCQ as an evaluator of LCS treatment has only been examined in cases of laminectomy, [24] although it is considered to be the most accurate questionnaire in terms of LCS evaluation items. [25] ZCQ is also used to evaluate the outcome of conservative treatment of LCS where cauda equina symptoms are present [26] as well as the outcomes of minimally invasive surgery such as decompressive surgery. [27] Accordingly, we concluded that ZCQ was the most appropriate scale to evaluate the treatment performed in this study.

One reason for no significant difference in SS was observed between the CE and M groups from 2 months posttreatment and in PF and PS 6 months posttreatment may be that some of the CE group subjects experienced symptom relapse. Relapse of symptoms may have caused them to generate higher scores. This is believed to be because there were cases where the sustained sympathetic nerve block effects following the use of a neurolytic agent disappeared after 2-6 months. In addition, epidural steroid injections were administered to M group subjects for their RS, which complicated their cauda equina symptoms. In other words, the CE group subjects received additional treatment, which may have contributed to preventing the deterioration of their posttreatment ZCQ scores. However, while acute RS improved 60-80% within 12 weeks, some subjects are believed to experience chronic symptoms, [28] and the M-group subjects in this study suffering from RS had experienced chronic pain for 6 months or more. The long-term effects of epidural steroid injection for chronic radiculopathy have not been investigated so far, [29],[30] and it is also difficult to achieve a long-term effect with a single blocking treatment. Although it is suggested that nerve root blood flow is increased, similar to the effect exhibited on the cauda equina by blocking the lumbar sympathetic nerves in canine nerve root stenosis models, [31] the main cause of RS is cauda equina inflammation; therefore, the effect of LSNB on M group subjects suffering from RS in this study was thought to be low.

While high frequency heat coagulation may be preferable, as it lowers the risk of complications in neurolytic surgery when compared with the use of neurolytic agents such as anhydrous ethanol and phenol, [11] neurolytic agents clearly have a long-lasting effects, [12] which led to the selection of anhydrous ethanol for use in this study. Although treatment-related safety procedures were complied with for all patients in this study, unilateral hyposensitivity of the genitofemoral nerve area was observed in one subject following treatment. A possible cause of this is that the needle tip may have moved to the psoas major muscle attachment of the vertebral body during the observation period following injection of local anesthetic. As anhydrous ethanol has a low viscosity in comparison to the contrast agent and local anesthetic, some ethanol may have thus leaked to the psoas major muscle. As a result of this, we believe it is necessary to carefully reaffirm the position of the needle tip before neurolytic agent injection during LSNB and to use the same or a lesser amount than the local anesthetic.

The comparison in this study was performed between a group exhibiting pure cauda equina claudication symptoms and a group exhibiting cauda equina claudication symptoms accompanied by unilateral RS; no comparison with a control group was conducted. Therefore, we believe it is necessary to further examine the efficacy of LSNB in the future in a study that incorporates comparison with a non-blocking group.


  Conclusion Top


We conducted LSNB using neurolytic agents in cases of LSS, and the results suggested efficacy in the improvement of neurogenic IMC, although not in improving RS. Compared with RS, the symptoms of cauda equina cannot be expected to resolve naturally. Therefore, LSNB is believed to be a treatment worth trying in cases where surgery absolutely cannot be performed and for patients such as the elderly where surgery carries a high risk because of the patient's general condition. In addition, a large multicenter study is needed to confirm our results.

 
  References Top

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27.Zucherman JF, Hsu KY, 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: Two-year follow-up results. Spine 2005;30:1351-8.  Back to cited text no. 27
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