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On-line version ISSN 1806-907X
Rev. Bras. Anestesiol. vol.55 no.6 Campinas Nov./Dec. 2005
Is superior hypogastric plexus block effective for treatment of chronic pelvic pain?*
¿El bloqueo del plexo hipogástrico superior es eficaz en el tratamiento del dolor pélvico crónico?
André P Schmidt, M.D.I; Sérgio R G Schmidt, TSA, M.D.II; Sady M Ribeiro, M.D.III
IEspecialista em Anestesiologia.
Médico Preceptor da Disciplina de Anestesiologia da Faculdade de Medicina
da Universidade de São Paulo e Doutorando em Ciências Biológicas
pelo Departamento de Bioquímica da Universidade Federal do Rio Grande do
Sul, RS, Brasil
IIMembro Fundador do Centro de Alívio da Dor do Hospital Mãe de Deus e Fundador do Serviço de Dor e Cuidados Paliativos do Hospital Nossa Senhora da Conceição, RS, Brasil
IIIEspecialista em Dor pela American Pain Board of Medicine. Department of Neurobiology, University of Texas, Houston, TX, USA
BACKGROUND AND OBJECTIVES:
Hypograstric plexus block has been considered a safe and effective alternative
for treat patients with chronic pelvic pain. Published studies available at
MedLine on the subject were included and evaluated in this review.
CONTENTS: Some studies have documented superior hypogastric plexus block effectiveness in relieving pain and decreasing opioid consumption, mainly in cancer patients. However, studies had failures in method or design.
CONCLUSIONS: New prospective and better-designed studies are still needed to confirm the effectiveness of hypogastric plexus block in relieving pelvic pain. These studies shall have stricter inclusion criteria, longer follow-up, and evaluation of other symptoms and quality of life before and after the procedure. Superior hypogastric plexus block should be recommended as alternative and not as primary therapy.
Key words: ANESTHETIC TECHNIQUES, Regional: hypogastric plexus block; PAIN, Chronic: pelvic, oncologic; SCIENTIFIC METHODOLOGY: evidence-based Medicine
JUSTIFICATIVA Y OBJETIVOS:
El bloqueo del plexo hipogástrico ha sido presentado como una alternativa
segura y eficaz en el tratamiento de pacientes portadores de dolor pélvico
crónico. Los estudios publicados y disponibles en el MedLine, abordando
este tema, fueron incluidos y analizados en esta revisión.
CONTENIDO: Algunos estudios documentaron la eficacia del bloqueo del plexo hipogástrico superior en reducir la intensidad del dolor y el consumo de opioides, principalmente en pacientes con cáncer. Sin embargo, los estudios presentan fallas en sus métodos o dibujos.
CONCLUSIONES: Aún son necesarios nuevos estudios prospectivos y mejor conducidos, para poder ratificar la efectividad del bloqueo del plexo hipogástrico en el alivio de condiciones dolorosas pélvicas. Esos estudios deben poseer criterios de inclusión más rigurosos, seguimiento más prolongado, evaluación de otros síntomas y de la calidad de vida antes y después del procedimiento. El bloqueo del plexo hipogástrico superior debe ser recomendado como una alternativa y no como terapéutica principal.
The blockade of nervous transmission trough sympathetic nervous system have been proposed to treat chronic pain of different origins 1,2. Classically, stellate ganglion blockade (C6-T1) has been used to treat upper limb, face and cervical pain; celiac plexus (T12-L1) block to relieve upper abdominal pain; and lumbar sympathetic chain block to treat lower limb pain 1,2. Several anesthetic or neurolitic techniques to block sympathetic ganglia have been described and evaluated in the last decades with prospective studies. Celiac plexus block is probably the most widely investigated method to treat pancreatic neoplastic pain 1,2.
However, the blockade of other plexuses, such as superior hypogastric plexus, has received minor attention and few studies were carried out on the subject. Superior hypogastric plexus is a retroperitoneal structure bilaterally located in L5 lower third and S1 upper third, close to the sacral promontory and common iliac veins bifurcation 3. Superior hypogastric plexus transmits visceral painful stimulations from right colon, uterus, cervix, tubes, upper vagina and bladder 3,4. Pre-sacral neurectomy is primarily used to treat non-oncologic painful conditions, such as endometriosis. Pre-sacral plexus (superior and inferior hypogastric plexus) may be approached by laparotomy or laparoscopy and has been evaluated by several studies 5-7.
Superior hypogastric anesthetic or neurolitic block has been proposed as an effective alternative to treat different pain syndromes, such as oncologic pelvic pain (visceral pain), chronic non-oncologic pelvic pain (endometriosis) and refractory penile pain, among others 1,2. Several techniques have been described to block superior hypogastric plexus sympathetic nervous system, such as clinical response to local anesthetic injection using external anatomic references, those guided by fluoroscopy or CT-scan 8-13.
Chronic non-oncologic pelvic pain is a prevalent and severe gynecologic problem. Causes are many but are in general categorized by the physician. In 1999, Zodervan et al. 14 have shown that chronic pelvic pain has an annual prevalence of 38.3/1000 individuals, similar to migraine, chronic lumbar pain and asthma, when evaluated in primary care. In 1996, Mathias et al. 15 have studied the prevalence of chronic pelvic pain and have concluded that it is under-diagnosed, in spite of affecting approximately one out of seven women, and have suggested that further understanding of costs and impact on quality of life is critical to improve medical attention to this chronic disease.
Patients with neoplasias and extensive pelvic involvement are also affected by severe chronic pain, often refractory to oral and parenteral drugs. Oncologic pelvic pain is a chronic condition related to visceral involvement by the tumor (visceral pain), to the impairment of pelvic muscular structures (somatic pain) and/or to the involvement of nervous structures (neuropathic pain) 16. Approximately 75% of patients with any type of cancer will present pain during the course of the disease, often with gradual worsening of the presentation. From these, 50% will have moderate to severe pain and up to 30% will describe pain as very severe 17,18. Notwithstanding, epidemiologic studies on pelvic painful syndromes related to neoplasias are scarce in the literature and little attention has been given to the subject.
Some studies emphasize that anesthetic or neurolitic superior hypogastric plexus block is effective to relief chronic pelvic cancer pain 4,13,16,19,20 and non-oncologic chronic pain 8,10,21.
This study aimed at reviewing available literature on superior hypogastric plexus block to treat chronic oncologic and non-oncologic pelvic pain and at evaluating its efficacy and effectiveness.
All studies on superior hypogastric plexus block to treat chronic pelvic pain published and available at PubMed/MedLine until December 2004 were included, reviewed and critically evaluated in this study. Comparisons were also performed between studies and evidence-based analysis.
A total of 20 references were found pointing to the efficacy of superior hypogastric plexus block to treat pelvic pain, between the years 1990-2004. Only five were prospective studies 4,13,16,22,23 and only one had significant sample size 16. Six studies described plexus approach techniques 9-11,24-26, four described isolated cases 8,12,27,28, three reviewed available literature on the subject 19,20,29 and two letters discussed the selection of patients submitted to such procedure 30,31.
Most studies have defined superior hypogastric plexus block as safe and effective to treat oncologic visceral pelvic pain. However, only one prospective controlled study was found in this review (Table I). Five longitudinal studies were performed with this technique. All studies aimed at evaluating superior hypogastric plexus block efficacy and safety to relief chronic pelvic cancer pain (Table II).
In 1990, Plancarte et al. 13 have described 28 pelvic cancer patients submitted to superior hypogastric plexus block for pain relief. The study aimed at evaluating pain relief by a pain visual analog scale. Authors have observed mean 70% pain improvement after blockade. However, they have not clearly presented the objective of the study and the follow-up of patients. Patients sample was heterogeneous and two thirds of patients were also submitted to concomitant epidural lidocaine injection, which could have influenced analgesia. Authors have not described the therapeutic strategy previously used by patients, important prognostic factor for the success of the procedure, and have not compared analgesic consumption before and after the intervention.
In 1993, de Leon-Casasola et al. 4 has evaluated 26 advanced gynecologic, colorectal or genito-urinary cancer patients suffering from disabling chronic pelvic pain. These patients have developed intolerance to oral opioids or presented excessive sedation with traditional therapy. Blockade effectiveness was evaluated by comparing opioid consumption decrease before and two weeks after the neurolitic procedure. Patients were followed up for six months. Eighteen patients (69%) had satisfactory pain relief and three patients (12%) needed a second procedure for pain relief. Remaining patients had moderate pain relief after two blockades although both groups had significant decrease in oral opioid consumption. There were no complications and authors have concluded that superior hypogastric plexus block is effective and safe for pain relief in selected patients. However there are major questions about this study: sample size is too small and heterogeneous, pain characteristics were not described, authors have used just one pharmacological alternative before the procedure and it was not clear whether adjuvant or other opioids could be more effective and safer as compared to blockade.
In 1997, Plancarte et al. 16 has performed the largest longitudinal multicenter study on superior hypogastric plexus block. The study aimed at evaluating continuous efficacy and safety of this blockade in advanced cancer patients. A total of 227 patients with gynecologic, colorectal or genitourinary neoplasias with poorly controlled pelvic pain or intolerable side effects of pharmacological treatment were included in this study. Blockade effectiveness was evaluated by comparing decrease in pain intensity and the use of opioids before and three weeks after neurolitic procedure. All patients were followed up for six months. Authors have observed that 79% of patients had positive response to diagnostic anesthetic blockade and were selected for neurolitic procedure. From these, 72% had satisfactory pain relief (62% after one blockade and 10% after two blockades), with a 95% confidence interval of 0.65-0.79. Remaining patients were submitted to other therapeutic strategies. Authors have also shown that both groups presented significant decrease in opioid consumption after blockade. Based on these results, authors have suggested that superior hypogastric plexus block is an effective adjuvant to control chronic oncologic pelvic pain. This study has used a more adequate method as compared to already discussed studies. Some questions, however, are to be considered. Only half the patients included in the study presented some of the benefits desired by the authors. The study has evaluated a large sample, which however, was heterogeneous. There were major differences among medical centers participating in the study, which may have influenced results. For example, oral morphine was not available for patients evaluated in the National Cancer Institute of Mexico. Two out of three drugs prescribed in Mexico to replace morphine (propoxifen and buprenorphine) are not indicated to treat moderate to severe oncologic pain due to their adverse effects and low efficacy 18. Again, it was impossible to know the therapeutic strategies and analgesic doses before blockade and the definition of what was considered therapeutic failure with oral opioids. It is not certain if other conservative measures could present similar results.
In 2002, Mercadante et al. 22 have evaluated pain mechanisms in pancreatic or pelvis cancer patients and the possible indication of celiac and superior hypogastric plexus block, respectively. This study has included 22 patients with pelvic cancer and 14 patients with pancreatic cancer. Authors have concluded that sympathetic blocks, especially superior hypogastric plexus block, should be considered adjuvant techniques and not primary therapy, especially due to multiple pain mechanisms involved in neoplasia progression. Pancreatic pain seems to maintain visceral characteristics, better responding to sympathetic block as compared to chronic pelvic pain.
In 2004, de Oliveira et al. 23 have studied 60 patients with history of chronic oncologic pelvic pain, especially visceral pain, secondary to inoperable cancer or metastases. The study has evaluated as major outcomes pain intensity by visual analog scale, quality of life by standardized questionnaire, adverse effects and opioid consumption before and after treatment. Patients were followed up for eight weeks. All patients received at admission the combination of paracetamol and weak opioid to treat pain. Then, patients were treated with oral analgesics according to World Health Organization (WHO) consensus and were randomly distributed in three groups: I - early neurolitic blockade; II - late neurolitic blockade; III - pharmacological treatment. De Oliveira et al. 23 has shown that there is no difference in major outcomes as compared to the first two groups. However, early or late neurolitic blocks were better than the pharmacological treatment in terms of quality of life, pain intensity, opioid consumption and adverse effects, proving to be safe and effective procedures. This study has the best design to evaluate the role of neurolitic blockers to treat pain, because it is a clinical trial with randomized and controlled distribution. In addition, patients were treated according to WHO guidelines before being submitted to invasive treatment such as neurolitic block. However, the study has several limitations, especially with regard to superior hypogastric plexus block. Due to loss of patients follow up or exclusion criteria, only 44 patients were included in the final analysis and there is no demonstration of sample calculation and study power analysis. Sample was very heterogeneous, including patients with different types of pain, with only 16 pelvic pain patients. Only 10 patients were allocated to superior hypogastric plexus block and were compared to six patients with pharmacological treatment. This has impaired the adequate analysis of the real efficacy of neurolitic block since different types of blockade for different pain locations were jointly analyzed. Follow up period was also short (eight weeks), maybe related to the advanced stage of the disease in most patients. Authors have also concluded that neurolitic blocks should be considered earlier, which is in disagreement with their results, which have not shown significant differences between earlier or later approaches.
Traditionally, superior hypogastric plexus block is guided by fluoroscopy with bilateral needles 13. Six studies9-11,24-26 have described alternative techniques to approach superior hypogastric plexus, such as anterior approach with single needle guided by CT-scan 24-26 or fluoroscopy 10, coaxial technique 9 and technique guided by microlaparoscopy 11. These studies, however, are purely descriptive and there is no comparison among different techniques.
The four case reports found in this review had no adequate power to support the use of superior hypogastric plexus block. In a letter, Chan et al. 27 have described a case of blockade guided by CT-scan to treat chronic oncologic perineal pain in a patient with severe kyphoscoliosis. Two weeks after the procedure, patient was under 60 mg.day-1 oral morphine with satisfactory pain relief. Authors have concluded that blockade is effective based in just one case with two-weeks follow up. Additionally, authors recommend caution in performing this procedure in patients with severe lumbo-sacral deformities and the use of lower neurolitic agent volume to prevent complications.
In 1998, Rosemberg et al. 12 have presented a case of anesthetic block associated to steroids, guided by fluoroscopy in patient with severe penile pain after transurethral prostate resection. Authors have described total pain relief with eight months follow-up. However, adjuvant drugs prescribed after the procedure were totally different than those used before the procedure and this may have played a major role in long-term pain relief. In 1995, Wechsler et al. 8 have evaluated CT-scan-guided superior hypogastric plexus block in endometriosis and chronic pelvic pain patients. Authors have concluded, based on just five patients, that this is an easy procedure. However, no patient had total pain relief after the procedure, two procedures were repeated (40%), there has been complication in one patient, patients had different profiles with regard to painful syndromes, authors have not described drugs used in each case and pain characteristics before and after the procedure, and three different techniques were used. In 2001, Yeo et al. 28 have published a case report describing a patient with severe disabling pain due to metastatic cervical cancer in spite of high oral opioid doses and adjuvant drugs. Pain and opioid consumption were significantly decreased after ganglion impar and superior hypogastric plexus neurolitic block. Authors have concluded that neurolitic block may be an adequate therapeutic option for selected patients.
Two letters were published discussing some aspects of the procedure addressed in previous study 4. Both discussed aspects such as definition of oncologic pelvic pain, definition of terminal disease, retroperitoneal advance of neoplasias, usefulness of diagnostic blockades and use of cordotomy 30,31.
Based on these studies, three reviews were undertaken addressing superior hypogastric plexus block. These reviews have emphasized blockade as well accepted, effective and safe technique to treat chronic pelvic pain 19,20,29. However, no review has critically evaluated such studies (Table III).
Other superior hypogastric plexus approaches, such as pre-sacral neurectomy, have been described 21,32,33, especially in non-oncologic conditions, but again prospective and controlled studies are needed to recommend such procedure 33.
Pelvic pain neurophysiology, especially in non-oncologic conditions, is still poorly known and controversial 3,33. Most reviewed articles emphasize visceral pain as major component of both oncologic and non-oncologic chronic pelvic pain. However, other components, such as somatic and neuropathic pain may play a critical role in some patients 3,22. Further studies carefully evaluating each pain characteristic presented by patients and, as a consequence, blockade efficacy for each type of pain, are needed.
To date, major therapy to relief chronic pelvic pain is pharmacological, but may include surgical and psychotherapeutic approaches. Due to the lack of evidence on invasive procedures such as superior hypogastric plexus block, different pharmacological alternatives are recommended. Rotation and individualization of opioid doses and adjuvant drugs may decrease toxicity and adverse effects, improving treatment efficacy and effectiveness 34,35.
Currently, there is a new paradigm in the medical practice. Evidence-based medicine denies the use of intuition, non-systematic clinical experience and pathophysiological reasoning as adequate to determine clinical decisions. Evidence-based medicine requires new medical skills, including critical review of available medical literature 36. However, adequate practice of evidence-based medicine basically depends on the quality of available evidence and on the context in which it is going to be applied (patient and health system) 37. From evidence-based medicine viewpoint, superior hypogastric plexus block to treat chronic pelvic pain has not yet been adequately evaluated by controlled studies even to treat oncologic pain.
Although mentioned studies emphasize superior hypogastric plexus block safety and efficacy in treating chronic pelvic pain, most of them have inadequate method to confirm this hypothesis. According to these data, one may conclude that new prospective studies with random distribution of patients are needed to ratify the real efficacy of superior hypogastric plexus block to treat chronic pelvic pain.
These studies shall include a larger and more homogeneous sample size associated to longer follow up period. Additionally, researchers should evaluate other outcomes such as pain-related functional capacity, anxiety, depressive symptoms and quality of life. These outcomes should be evaluated by previously validated specific tools. A multiprofessional approach should be encouraged aiming at identifying and treating socio-environmental and psychological problems involved with the painful syndrome presented by the patient.
To date, due to the lack of adequate studies, it is impossible to conclude that superior hypogastric plexus block is a safe and effective therapeutic strategy.
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Dr. André P. Schmidt
Address: Rua Oscar Freire 1799/504 Cerqueira César
ZIP: 05409-011 City: São Paulo, SP
Submitted for publication
March 15, 2005
Accepted for publication August 22, 2005
* Recebido do Received from Centro de Alívio da Dor do Hospital Mãe de Deus, Porto Alegre, RS