|Year : 2016 | Volume
| Issue : 3 | Page : 171-175
Efficacy of stellate ganglion block in the management of CRPS-not otherwise specified
Ashok Jadon, Priyanka Jain, Amit Agrawal
Department of Anaesthesia and Pain Relief Service, Tata Motors Hospital, Jamshedpur, Jharkhand, India
|Date of Web Publication||10-Jan-2017|
Duplex-63, Vijaya Heritage Phase-6, Kadma, Jamshedpur - 831 005, Jharkhand
Source of Support: None, Conflict of Interest: None
Background: Stellate ganglion block (SGB) is a well-established treatment option for CRPS (complex regional pain syndrome) type I. However, no studies have been conducted to study its efficacy in patients with CRPS-not otherwise specified (NOS). We conducted a study to evaluate the efficacy of SGB in decreasing pain and improving the functional use of the upper limb in patients with CRPS-NOS. Materials and Methods: We performed SGB on 24 patients with a diagnosis of CRPS-NOS at weekly intervals until 50% relief in pain and functional activity of the limb was achieved. Pain and functional ability of the limb were assessed by visual analog scale (VAS) disabilities of the arm, shoulder, and hand (DASH) scores, respectively. VAS and DASH scores were recorded before and 1 week after the procedure and the results were compared using appropriate statistical tests. The number of blocks required to achieve the desired effect was also noted in all the patients. Results: All the patients in our study showed significant improvement in VAS (P = 0.001) and DASH scores (P < 0.001). It was noted that the number of blocks required to achieve the desired relief was lower in patients with shorter duration of symptoms (<12 weeks) than those with longer duration of symptoms (>12 weeks). This finding was statistically significant (P = 0.047). Conclusion: SGB used early in the course of disease improves pain and functional ability of the limb in patients with CRPS-NOS. We also presume that CRPS-NOS might be an initial stage of the full blown CRPS and hence can serve as a window period in identifying and treating patients early in the course of the disease. However, this finding needs to be substantiated by further studies.
Keywords: Chronic regional pain syndrome-not otherwise specified, disabilities of the arm, shoulder, and hand, stellate ganglion block, visual analog scale
|How to cite this article:|
Jadon A, Jain P, Agrawal A. Efficacy of stellate ganglion block in the management of CRPS-not otherwise specified. Indian J Pain 2016;30:171-5
| Introduction|| |
Complex regional pain syndrome (CRPS) is a chronic neuropathic pain syndrome characterized by spontaneous or stimulus-evoked pain that is disproportionate to the insult and is accompanied by a myriad of autonomic and motor disturbances in highly variable combinations.  Although a century and a half has passed since its first documentation,  its natural course and pathophysiology remain poorly understood. Furthermore, the therapeutic interventions remain controversial due to lack of high-quality research.  Sympathetic dysfunction is presumed to be an essential component in the pathogenesis of this syndrome,  and sympathetic blockade has been recommended to interrupt and reverse the process.  Sympathetic blockade of the upper limb can be achieved by stellate ganglion block (SGB). Although SGB has been well established as a treatment option of CRPS I, the supporting evidence is scarce for CRPS-not otherwise specified (NOS).  The purpose of this study was to evaluate the efficacy of SGB in decreasing pain and improving the functional use of the upper limb in CRPS-NOS.
| Materials and Methods|| |
The study consisted of 24 patients who presented to our center with the diagnosis of CRPS-NOS  and had consented for inclusion into the trial. The diagnosis was made based on the proposed new diagnostic criteria for CRPS.  Inclusion criteria were pain (pain was continuous burning sensation with occasionally needle and pricks sensation mainly in hand and arm) which was disproportionate to the inciting event and associated with either one or a combination of sensory, vasomotor, sudomotor, or motor symptoms and/or signs which could not be explained by an alternate diagnosis. Prior treatments with conservative therapies such as medications, physical therapy, and rehabilitation programs were not successful in these patients. Exclusion criteria were smoking or use of tobacco in any form of medicines such as beta-blockers and vasodilators that could affect sympathetic function, any infection, or anatomical abnormality in the neck (at probable injection site), known drug allergies, and coagulopathy.
In all the patients of our study, the identified cause of CRPS-I was fracture of the distal end of radius which is also one of the most common causes of this syndrome in the upper limb.  A detailed history and physical examination of the patients found that they all belonged to CRPS-NOS subtype.
A modified SGB under fluoroscopic guidance  was performed in all the patients. The patient was placed in the supine position with the neck slightly extended and the head rotated to the opposite side. The fluoroscopic beam was directed in an anteroposterior direction until the C6/7 disc was well visualized. Subsequently, the fluoroscopic beam was rotated obliquely, ipsilateral to the side where blockade was desired to allow adequate visualization of the neural foramina. Under real-time imaging, a single pass was made with a 25-gauge spinal needle  to contact the bone. Care was taken to avoid passage of the needle toward the neural foramina and the thecal sac (present posteriorly); the disc located cephalad; and the esophagus, which resides medial to the ultimate target point. At this point, the needle tip can be seen to contact and rest at the junction between the uncinate process and the vertebral body of C7. After removing the stylet and pulling out the needle about 2 mm, 1-2 ml of radio-opaque contrast was injected under live fluoroscopy to avoid injection within the muscle. Following this, negative aspiration of a test dose of 0.5 ml of 1% lidocaine was done to rule out intravascular injection into the vertebral artery. If safe and correct needle position was confirmed, a mixture of 1% lidocaine (6 ml) +40 mg methyl prednisolone (depot preparation) was injected at first procedure and 6 ml 1% lidocaine +20 mg methyl prednisolone (depot preparation) in subsequent blocks. Throughout the procedure, the patients were monitored for pulse, blood pressure, and SpO 2 . Temperature of affected and nonaffected limbs was taken before and 5 min after the block. Criteria for successful block were postblock rise of temperature >2°C and spread of contrast up to first thoracic vertebral level. Patients were observed in the postanesthesia care unit for 1 h before being discharged.
All the patients were assessed subjectively for pain and functional ability of the limb before and on follow-up 1 week after the block. Pain was assessed using visual analog scale (VAS) with "0" being no pain and "10" being the worst imaginable pain. The functional ability of the limb was assessed using the disabilities of the arm, shoulder, and hand (DASH)  score which consists of 30-item disability/symptom scale concerning the degree of difficulty in performing different physical activities (21 items), the severity of the symptoms (5 items) as well as the impact these problems have on the patient's activities (4 items). Each item has five response options and the scores for all items are then calculated by a computer to obtain a final scale score ranging from 0 (no disability) to 100 (most severe disability).  Questionnaires in vernacular language were provided to all the patients to assess the functional ability of the limb.  A reduction in 50% of VAS and DASH scores was considered significant relief and the number of blocks required to achieve this was noted. The target was to achieve >50% pain relief and a maximum of three blocks were attempted, each performed at a weekly interval. Any adverse event related to the block was also noted.
Statistical analysis was performed using the StatCalc® (Statistical Software, Version 5.4.3; 2004) AcaStat Software,554 Presido Park Pl Poinciana, Florida 34759 (USA). Paired t-test was used to compare VAS and DASH scores before and after the block in all the patients. Unpaired t-test was used for comparison of the number of blocks between the patients with duration <12 weeks and duration >12 weeks. A P < 0.05 was considered as statistically significant.
| Results|| |
All the patients showed ≥50% relief in pain and functional ability of the limb following SGB [Table 1]. The block produced a statistically significant difference in VAS (P = 0.001) and DASH (P < 0.001) scores in all the patients [Table 2]. It was also noted that the number of blocks required in patients with duration of symptoms <12 weeks (2.17 ± 0.72) was lower than the number of blocks required in patients with duration of symptoms >12 weeks (3 ± 1.0). This difference was statistically significant (P = 0.047) as can be seen in [Table 3]. No adverse events to the medications or the procedure were noted during the entire course of the study.
|Table 1: Patient demographics, visual analog scale, and disabilities of the arm, shoulder, and hand scores before and after stellate ganglion block|
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|Table 2: Mean visual analog scale and disabilities of the arm, shoulder, and hand scores before and after stellate ganglion block|
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|Table 3: Mean number of blocks in patients with duration <12 weeks and duration >12 weeks|
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| Discussion|| |
There is considerable evidence suggesting the involvement of the sympathetic nervous system in the pathophysiology of CRPS  and sympathetic blockade has been recognized as an important procedure both in the diagnosis and treatment of CRPS.  Blockade of the sympathetic nervous system of the upper limb can be accomplished at the level of the stellate ganglion. 
Our study evaluated the efficacy of SGB in 24 patients with CRPS-NOS following traumatic fracture of the distal end of radius. All the patients showed a statistically significant improvement in pain and functional ability as assessed by the VAS (P = 0.001) and DASH (P < 0.001) scores, respectively [Table 2]. However, it was noted that the number of blocks required to achieve the desired 50% reduction varied from patient to patient. On further analysis, we found that our group of patients was heterogeneous with regard to the duration of CRPS [Table 3]. It was also noted that the mean number of blocks required to achieve improvement in pain and functional ability was higher in the group with duration >12 weeks (2.17 ± 0.72) than those with duration <12 weeks (3 ± 1.0). This finding was statistically significant as suggested by a P = 0.047 [Table 3]. Our results, therefore, indicate that sympathetic blockade improves the symptoms and functional ability in patients with CRPS-NOS and intervention early in the course of the disease proves beneficial. Our results are supported by studies conducted by Yucel et al.  and Ackerman and Zhang.  However, both these studies evaluated the effect of SGB in CRPS-I while our trial studied the effect of the block in CRPS-NOS. We would also like to mention that no literature has been reported so far on the efficacy of this block in CRPS-NOS.
The proposed new diagnostic criteria for CRPS  define three subtypes of CRPS. CRPS I shows no evidence of major nerve damage while in CRPS II, evidence of nerve damage is seen. Those subsets of patients who partially meet the diagnostic criteria and whose symptoms cannot be explained by an alternate diagnosis were grouped into a third subtype named CRPS-NOS [Table 1].
All the patients in our study were followed closely right from the time of presentation and conservative therapies in the form of medications and physical therapy was tried for 4-6 weeks before SGB was attempted. As per the proposed new diagnostic criteria for CRPS,  we found that our study patients did not meet the criteria for CRPS I or II and had to be labeled as CRPS-NOS. Since the disease was progressive as suggested by the failure of improvement of symptoms by conservative therapies, we presume that CRPS-NOS might probably be an initial stage of CRPS (CRPS-I) in this context as all the patients of our study had fractured distal end of radius as the initial event. We assume that CRPS-I might actually be in continuum with CRPS-NOS where the symptoms/signs have not yet progressed to meet the diagnostic criteria. This can be important as identifying patients with CRPS-NOS would actually mean identifying and treating CRPS early in the course of the disease. However, since the sample size was small and the study was not randomized, it would be too early to comment and further trials are needed to substantiate this finding.
An oblique fluoroscopic approach targeting the junction between the uncinate process and the vertebral body at the C7 level was used to block the stellate ganglion effectively and avoiding vascular injury. We routinely use this modified technique to perform SGB and no untoward events have been reported so far. Performed at the level of C7 vertebra, it increases the efficacy of sympathetic block as the ganglion lies in proximity at this level. Other advantages of this technique include less volume of the local anesthetic agent required, decreased the risk of complications (vascular injury, injury to the disc, esophageal perforation, recurrent laryngeal nerve injury), and the simplicity and ease with which it can be performed. ,
However, the role of sympathetic block has been called into question as there is no consensus on clinical assessment of a "successful block" and many "clinically successful blocks" provide varying degree of sympatholysis.  This is supported by the fact that the number of blocks required achieving a set desired 50% reduction of symptoms varied from patient to patient. A systematic review published by Cepeda et al. in 2002 concluded that the efficacy of sympathetic blockade in the treatment of CRPS is questionable as the efficacy was based mainly on case series.  Later in 2005, another review published by Cepeda et al. stated that it was not possible to determine the effect of sympathetic blockade on long-term pain relief as the published evidence was scarce. 
Another significant confounding factor is the lack of consensus in defining the criterion of a successful sympathetic block. Malmqvist et al. defined strict criteria for the definition of a successful sympathetic block in an observational study. They considered Horner's syndrome, increased in skin temperature >34°C, increased skin blood flow >50% by laser Doppler, abolished skin resistance response ulnar, and abolished skin resistance response radial as indicators of sympathetic block and 4 out of the 5 criteria implied a successful SGB. Only 15 out of 54 blocks met 4 out of the 5 criteria of a successful block and they concluded that it was difficult to achieve a block that met all the five established criteria.  A study conducted by Schürmann et al. also highlighted the clinical difficulty in identifying a successful sympathetic block. They clearly stated that even in the case of significant limb temperature elevation, sympatholysis may be incomplete with the same holding true for Horner's syndrome. Therefore, they concluded that clinical investigation is not reliable in the assessment of SGB.  Even though we have used 80 mg of Depo-Medrol as maximum dose during whole treatment; however, side effects of depot steroid cannot be undermined.  Frequent injection at short interval to be avoided. Continuous monitoring is warranted to detect and manages the side effect at earliest.
As the available literature is scarce, it is difficult to draw a conclusion regarding the effectiveness of this procedure and further randomized clinical trials are needed to evaluate the efficacy of SGB in the treatment of CRPS-NOS. Until then, SGB can be considered as an important treatment option on an individualized basis and can serve as a bridge to rehabilitation techniques in patients with CRPS.
Since pain and functional disability were both assessed subjectively, unintentional individual bias may have crept into the study. Our study was also limited by a small sample size and the lack of assessment of the long-term effect of SGB on the symptoms of CRPS.
| Conclusion|| |
We would like to conclude that SGB reduces pain and improves functional ability of the limb in patients with CRPS. The duration of the disease serves as an important factor in the success of treatment and SGB should be considered as early as possible once other treatment modalities fail. We also presume that CRPS-NOS is an initial stage of the disease in which symptoms/signs have not yet progressed to meet the diagnostic criteria of CRPS though this needs to be further substantiated. This would also mean that identifying patients with CRPS-NOS can provide an opportunity for treating patients early in the course of the disease. However, our study has limitations of a small number of patients and possibility of observational bias; we suggest that more studies are required before the beneficial role of SGB in CRPS-NOS is accepted in clinical practice.
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Conflicts of interest
There are no conflicts of interest.
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