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Original Article J. St. Marianna Univ. Vol. 5, pp. 17–21, 2014

Effi cacy of Nerve Blocks in Patients with Cancer Pain: A Retrospective Study

Osamu Nishikido1, Takeshi Tateda1, Saori Tanigawa1, Yuki Kobayashi1, and Mami Hirakawa2

(Received for Publication: March 25, 2014)

AbstractPain is one of the most common sy mptoms in cancer patients, and it signifi cantly impairs their quality of

life. Although standard pharmacological methods are effective in 85–90% of patients with cancer pain, it is very diffi cult to control cancer pain refractory to standard pharmacological management. For these patients, nerve blocks may be an effective alternative. The purpose of this study was to evaluate the effi cacy and com-plications of nerve blocks administered to control cancer pain. This retrospective study analyzed the data ob-tained for 38 consecutive patients with cancer (43 interventions) who received nerve blocks between December 2009 and November 2013. In this study, we compared pain intensity, performance status, opioid consumption, and adverse effects before and a week after the procedure. Pain intensity decreased, and performance status improved signifi cantly after the nerve blocks, without any unpredictable, serious side effects. There were no signifi cant differences in the changes in opioid consumption after intervention. Epidural blocks decreased pain intensity, and performance status improved signifi cantly. However, intrathecal nerve blocks and peripheral nerve blocks signifi cantly lowered pain intensity, but did not improve performance status. Thus, the epidural block may be a more effective method for cancer pain than the intrathecal nerve block and the peripheral nerve block. The nerve blocks also infl uenced the effects of other therapies, including systemic analgesia, radio-therapy, and chemotherapy. A prospective study is expected to identify the treatment effi cacy of each type of nerve block used in palliative care for cancer patients.

Key WordsCancer pain, Nerve block, Palliative care

1 Department of Anesthesiology, St. Marianna University School of Medicine2 Department of Clinical Oncology, St. Marianna University School of Medicine

Introduction

Pain is one of the most common symptoms of cancer, and it signifi cantly impairs the patient’s qual-ity of life. Currently, cancer pain is managed by standard pharmacological methods, which can con-trol this pain in 85–90% of patients1); however, it is very diffi cult to control cancer pain refractory to standard pharmacological methods. For these pa-tients, nerve blocks may be an effective alternative. But though Japanese multicenter studies have re-vealed the effi cacy of nerve blocks in cancer pain management refractory to standard pharmacological treatment, the use of nerve blocks varies among dif-ferent institutions2). The purpose of this study was to evaluate the effi cacy and complications of nerve

blocks administered to control cancer pain in patients at St. Marianna University Hospital.

Patients and Methods

Between December 2009 and November 2013, 302 patients were introduced to a palliative care team (PCT) at St. Marianna University Hospital. Thirty-eight patients (12.6%) who received nerve blocks were included in this retrospective study. A total of 43 nerve blocks were administered; fi ve patients un-derwent two procedures. We compared pain intensity, performance status, opioid consumption, and adverse effects before and a week after the procedure for all patients. The degree of pain was evaluated using the Japanese version of the Support Team Assessment Schedule (STAS-J)3), the reliability and validity of

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which have been confi rmed. Using this scale, pain was scored as 0 (no pain), 1 (mild pain; the patient performs usual activities and is not bothered by pain), 2 (moderate pain; some activities are limited by pain), 3 (severe pain; activities and concentration are markedly affected by pain), or 4 (extreme pain; continuous and overwhelming pain). Performance status was graded with reference to the ECOG (East-ern Cooperative Oncology Group) Performance Sta-tus. The total opioid dose was defi ned as the total amount of oral morphine equivalents administered according to a standard ratio.

Statistical analyses to determine differences were performed using a paired Student’s t-test. A p-value of <0.05 was considered statistically signifi -cant. To explore the predictors of treatment success, we compared the changes in percentage of serious cases (performance status ≧3) with severe pain (pain intensity ≧3) between before and after intervention.

The study protocol was approved by the St. Marianna University School of Medicine Institution Committee (No. 2719).

Results

Table 1 shows the demographic characteristics of the patients. The primary cancers included colorectal, lung, and breast cancers. Table 2 sum-

marizes the procedures and characteristics. Common procedures included an epidural block with local anesthetics, an intrathecal nerve block with phenol, and peripheral nerve blocks. The epidural block was temporary in all patients, and the medial duration of placement was 10 days. During the study, 16 patients (42.1%) received radiotherapy or chemotherapy with a nerve block at the same time.

Overall, pain intensity as measured by the STAS-J decreased, and performance status improved signifi cantly after the nerve blocks. There were no signifi cant differences in the changes in opioid con-sumption after intervention (Table 3). Subgroup analyses (epidural block, intrathecal nerve block, and peripheral nerve blocks) revealed that pain intensity

Table 1. Patient Characteristics (n=38)

Patients’ characteristics included age, gender, and prima-

ry tumor site. Data is expressed as mean±SD.

Peripheral nerve blocks included intercostal (n=6) ,

superfi cial cervical (n=1), supraorbital (n=1),

and suprascapular nerve blocks (n=1).

Table 2. Procedure and Pain Characteristics (n=43 Inter-

ventions)

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signifi cantly decreased after intervention in all sub-groups (Table 4). Performance status signifi cantly improved in patients who received epidural blocks, but not in those who received intrathecal and periph-eral nerve blocks. Opioid consumption signifi cantly increased in patients who received epidural blocks. Adverse effects occurred in 3 of 14 patients who re-ceived the intrathecal nerve block (21.4%). Detrusor sphincter dyssynergia also occurred after the intrathe-cal nerve block, although this was a predictable and informed complication in all cases.

Discussion

The results of this study showed the nerve block signifi cantly decreased pain intensity, and, improved the performance status of cancer pain. Many prior studies have revealed the effi cacy of nerve blocks in cancer pain management to be refractory to standard pharmacological treatments. Nerve blocks were ad-ministered to 12.9% of the cancer patients who were introduced to the PCT of St. Mariannna University Hospital. According to a multicenter study in Japan, the frequency of nerve block administration in the palliative care unit ranged from 0.6% to 15% (me-dian, 4.5%)3). We generally used actively blocking therapy. Our PCT members included an anesthesiolo-gist, who produced nerve blocks as well as written recommendations for nerve blocks.

In our study, the epidural block was an effective method for pain control; this was consistent with the

Table 3. Overall Treatment Effi cacy (n=43 interventions)

Pain: Evaluated using the STAS-J over the range of 0-4.

A higher score indicates a greater level of pain intensity.

Performance status: Graded with reference to the ECOG Performance Status.

Severe pain: (pain intensity ≧ 3)

Serious case: performance status: 3 or 4

Opioid consumption: Calculated as the total amount of oral morphine equivalent to a daily

dose.

Data expressed as mean±SD.

fi nding of a previous study4) in which the epidural block was reportedly effective in 80.4% of the pa-tients. The indications for the epidural block include neuropathic pain associated with nerve cancer inva-sion, somatic pain associated with cancer metastasis in the abdomen, and skin, skeletal, and visceral pain. Epidural analgesia is frequently used for a temporary block, not as a principal treatment, and it is fre-quently combined with other therapies such as sys-temic analgesia, radiotherapy, and chemotherapy. In our study, the epidural block was effective immedi-ately after injection in the majority of patients; how-ever, most patients showed signs of decreasing effi -cacy over time. Therefore, opioid consumption was signifi cantly higher in patients who received an epi-dural block. Mercadante5) suggested that tumor pro-gression, psychological factors, development of pseudotorance caused by dural thickening, imped-ance of transdural diffusion, epidural metastasis with the invasion of nerve roots, and reactive fi brosis were some of the potential causes of reduced effectiveness over time.

The intrathecal nerve block with phenol has been advocated for the treatment of pain caused by rectal and pelvic malignancies. Candido and Ste-vens6) analyzed 12 patients with cancer pain and re-ported that the intrathecal nerve block resulted in effective pain relief in 58% of the patients. Blockage of the anterior roots of 2–4 sacral nerves interrupts the parasympathetic nerve system innervation to the

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bladder and rectum, which can result in detrusor sphincter dyssynergia, which typically occurs after intrathecal nerve block. Therefore, patients receiving a block must be informed of this complication. Most patients who receive the intrathecal nerve block tend to experience lower extremity paralysis, which de-creases their quality of life. Thus, although pain in-tensity signifi cantly decreases after the intrathecal nerve block, performance status does not, as ob-served in the present study.

Peripheral nerve blocks can be used when pain occurs in the region of one or more peripheral nerves. Peripheral nerve blocks include intercostal7), superfi -cial cervical8), supraorbital9), and suprascapular nerve blocks10). The intercostal nerve block is effective for pain caused by intercostal metastasis, chest wall me-tastasis, and thoracic spine metastasis; the superfi cial

Pain: Evaluated using the STAS-J over the range of 0-4.

A higher score indicates a greater level of pain intensity.

Performance status: Graded with reference to the ECOG

Performance Status.

Severe pain: pain intensity ≧ 3

Serious case: performance status: 3 or 4

Opioid consumption: Calculated as the total amount of

oral morphine equivalent to a daily dose.

Data expressed as mean±SD.

Table 4. Treatment Effi cacy of Each Procedure cervical block is effective for pain caused by cervical lymph node metastasis; the supraorbital nerve block is effective for pain caused by frontal bone metasta-sis, and the suprascapular nerve block is effective for pain caused by shoulder cancer.

Sympathetic plexus blocks can signifi cantly im-prove the quality of life of patients with abdominal or pelvic cancer pain11). Two patients in this study received such blocks; however, opioids are generally used for the management of abdominal or pelvic cancer pain in our university hospital.

During the study, 16 patients (42.1%) received radiotherapy or chemotherapy with a nerve block at the same time. We also noted that the nerve block infl uenced the effects of anticancer therapies, anti-cancer therapies infl uenced the effects of nerve block.

In conclusion, nerve blocks were administered to 12.9% of the cancer patients who received palliative care at St. Mariannna University Hospital, resulting in a decrease in pain intensity and an increase in performance status without unpredictable, serious side effects. The nerve blocks also infl uenced the ef-fects of other therapies, including systemic analgesia, radiotherapy, and chemotherapy. A prospective study is expected to identify the treatment effi cacy of each type of nerve block in palliative care.

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