Department of Anesthesiology, Pain Relief Unit, Academic Medical Center, University of Amsterdam, The Netherlands
July 30, 2002.
Address correspondence and reprint requests to Jan H. Vranken, MD, Department of Anesthesiology, Pain Relief Unit, Academic Medical Center, University of Amsterdam, PO Box 22700, 1100 DE Amsterdam, The Netherlands. Address e-mail to email@example.com.
The effective treatment of patients suffering from neuropathic pain caused by tumor infiltration in the sacral plexus remains a clinical challenge (1). In patients with poor pain control despite pharmacotherapy, including opioids, corticosteroids, antidepressants, and anticonvulsants, combined with antineoplastic therapies (2), reversible peripheral nerve catheterization techniques may be considered. In this paper, we present a patient with an ovarian carcinoma infiltrating the sacral plexus causing a sacral radiculopathy not reacting sufficiently to pharmacological treatment. To obtain adequate pain relief, a catheter for the continuous administration of local anesthetics was inserted along the first sacral root.
A 37-yr-old woman presented with severe neuropathic pain and sensory impairment in the left leg. Computerized axial tomography revealed an ovarian carcinoma with malignant infiltration of the psoas muscle and invasion of the left foramen of S1 with possible nerve root compression. At the time of admission, the patient experienced a constant severe burning pain located in the posterior thigh and calf radiating to the great toe (i.e., dermatome S1). The pain was resistant to a combination of nonsteroidal antiinflammatory drugs, dexamethasone 12 mg, carbamazepine 900 mg, amitriptyline 50 mg, and slow-release morphine 400 mg per day. Increasing the opioid dose was impossible because of dose-limiting side effects.
An infiltration with 1.5 mL of bupivacaine 0.25% along the S1 root resulted in an almost complete resolution of the neuropathic pain in the left leg. To obtain long-lasting pain relief, a catheter was inserted along the S1 nerve root. The patient was placed in a prone position, and the left S1 foraminal opening on the posterior plate of the sacrum was identified using a C-arm fluoroscopic device. Subsequently, an 18-gauge, 110-mm, 15-degree short bevel cannula (Contiplex D®, Braun, Melsungen, Germany) was introduced at the inferior lip of the S1 foraminal opening and advanced parallel to the beam of the fluoroscopic tube. Needle placement was confirmed using electrical stimulation at <1.0 V at 50 Hz, which resulted in paraesthesias in the S1 dermatome. Contrast fluid was injected to outline the S1 root sleeve (Fig. 1). The needle was removed, and a catheter (20-gauge, Perifix®, Braun) was advanced 1–2 cm beyond the tip of the cannula. Finally, the catheter was tunneled subcutaneously to the hip and was fixed with transparent dressing. The administration of bupivacaine 0.125% at an initial rate of 2 mL/h resulted in a significant improvement in pain relief. The daily opioid dose could be reduced, and side effects disappeared. After 5 days, the patient was discharged from the hospital with a continuous infusion of bupivacaine 0.125% at a rate of 4 mL/h.
However, after 5 wk, while the neuropathic pain in the left leg was still absent, the patient was readmitted with severe pelvic pain resistant to slow-release morphine. Increasing the opioid dose led again to unacceptable side effects. Spinal treatment with opioids and local anesthetics was now proposed, but the patient refused further treatment and died 2 days later.
Opioid analgesics are the mainstay in the management of cancer pain. However, neuropathic pain caused by tumor infiltration in the brachial or lumbosacral plexus is inherently less responsive to morphine and other potent opioids (3). For treating neuropathic pain, adjuvant drugs such as corticosteroids, antidepressants, anticonvulsants, and N-methyl-d-aspartate antagonists are frequently used with variable results (4).
In these patients with severe pain despite pharmacological treatment, invasive pain therapies should be contemplated. Percutaneous cervical cordotomy may be a useful blockade in terminally ill patients suffering from sacral plexopathy. Complications and side effects, such as respiratory failure, ipsilateral hemiparesis, urinary dysfunction, and in bilateral cordotomies and sleep apnea, have been reported using this technique (5).
Before performing neuroablative procedures, reversible peripheral nerve catheterization techniques may be evaluated for the management of neuropathic cancer pain. A catheter placed within the psoas muscle sheath or in the psoas compartment (virtual space between the psoas and the quadratus muscles) can be used to block the lumbar plexus. However, a successful blockade of the sacral nerves is only possible when large volumes of injectant are administered, which makes the psoas compartment technique unfeasible for continuous blockade (6).
In our patient suffering from a radiculopathy in the S1 dermatome, a catheter for the continuous administration of local anesthetics was inserted along the S1 root. To reduce the risk of nerve damage, a blunt needle was used to perform the neural blockade (7). The main advantage of this technique is the possibility of relieving neuropathic pain localized in the somatosensoric distribution of sacral nerve roots. The application of this technique resulted in a significant improvement in pain relief and a significant reduction in opioid consumption with the disappearance of the opioid-induced side effects.
Local anatomic distortions because of tumor growth may interfere with proper placement of a sacral catheter. Additionally, long-term pain relief may be compromised because of catheter-related complications such as dislocation and leakage.
Moreover, progressive tumor invasion with involvement of the whole sacral plexus can result in neuropathic pain in more than one dermatome. In these patients, intrathecally administered morphine, alone or in combination with local anesthetics, can be more appropriate in controlling cancer pain (8). Complications such as meningitis discourage the indiscriminate use of neuraxial analgesic techniques, and such risks should always be considered before these techniques are applied (9).
In conclusion, our patient with severe neuropathic cancer pain caused by infiltration of a sacral nerve (single dermatome) was effectively treated using a continuous sacral root nerve block. Although this new technique is promising, more experience is required to determine the safety and efficacy of this approach in cancer pain management.
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