Use of Lidocaine Patch 5% for Chronic Low Back Pain: A Report of Four Cases

Transcription

1 PAIN MEDICINE Volume 3 Number CASE REPORTS Use of Lidocaine Patch 5% for Chronic Low Back Pain: A Report of Four Cases Robert Hines, MD, Diane Keaney, RN, BSN, Michael H. Moskowitz, MD, and Steven Prakken, MD Bay Area Pain Medical Associates, Mill Valley, California ABSTRACT Objective. To describe the use of the lidocaine patch 5% (Lidoderm ), a targeted peripheral analgesic, in treatment of patients with chronic low back pain. Design. This retrospective case series examines four patients with pain secondary to spinal degeneration and complications from failed back surgery syndrome, who were prescribed the lidocaine patch as an add-on to their analgesic regimen. Setting. Bay Area Pain Medical Associates, Mill Valley, California. Patients. Patients (age range: years) were all complicated cases in which multiple analgesics had been prescribed with varying degrees of success. Intervention. Lidocaine patch 5%. Results. The addition of the lidocaine patch helped relieve varying characteristics of pain, including general pain, shooting pain, burning pain, and allodynia, and had a significant impact on the quality of life of all patients. Some patients were able to reduce or altogether stop some medications. No adverse events were reported from the lidocaine patch. Conclusions. Based on our experience with the four cases presented here and with other patients in our clinic, we believe that addition of the lidocaine patch 5% to the analgesic regimen in chronic low back pain may be beneficial. Prospective, controlled clinical trials are planned to further evaluate the efficacy and safety of the lidocaine patch for treatment of chronic low back pain with or without a neuropathic component. Key Words. Lidocaine Patch; Neuropathic Pain; Chronic Pain; Low Back Pain; Targeted Peripheral Analgesic Introduction Chronic low back pain (LBP) is a common condition. It has been estimated that 31 million people in the United States experience chronic LBP [1], and the burden of this disability has risen steadily over the last few decades in western countries [2]. Back Reprint requests to: Robert Hines, MD, Bay Area Pain Medical Associates, 311 Miller Avenue, Suite B, Mill Valley, CA Tel: (415) ; Fax: (415) ; dmkeaney@bayareapainmedical.com. injury may lead to complicated pain syndromes that are difficult to treat and may not respond to even a wide range of currently used therapies, including nonsteroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, opioid analgesics, tricyclic antidepressants, injection therapies (nerve blocks, epidural injections), electrical stimulation, and implanted intrathecal infusion pumps [3 7]. Although effective in some cases, surgery may fail to relieve or may even worsen pain in as many as 50% of patients [8]. The primary pain mechanism in many American Academy of Pain Medicine /02/$15.00/

2 362 Hines et al. patients with chronic LBP is mechanical/myofascial without any neuropathic component [9], but neuropathic pain may also be a significant factor. Its presence may complicate therapy and increase the risk of treatment failure. The lidocaine patch 5% (Lidoderm, Endo Pharmaceuticals Inc., Chadds Ford, PA), a targeted peripheral analgesic, has been shown to be effective for the treatment of neuropathic pain and is currently indicated for the management of patients with postherpetic neuralgia (PHN) [10 12]. The efficacy of the lidocaine patch established in PHN, combined with its low side-effect profile, has led clinicians to prescribe this treatment modality for other pain states. Recent case reports have documented successful pain reduction in neuropathic, as well as in myofascial, pain states [13]. This case series reviews results from four patients with refractory chronic LBP, with and without a neuropathic component, whose pain was successfully treated by the addition of the lidocaine patch to their analgesic therapy. Case Reports Patient 1 A 53-year-old woman with LBP pain presented in December She had been in pain since an automobile accident that occurred in July In addition to LBP, the patient developed urinary urgency, which limited her ability to work. Her back symptoms included sharp pain from mid back to hip, rated as 8 9/10 (using a 0- to 10-point analog numeric pain scale), which kept her awake at night. She also experienced pain in the right leg and some numbness in the right foot. Besides the presence of neuropathic pain, clinical evaluation established nociceptive pain in the back as her primary condition. Magnetic resonance imaging showed lumbar spine degeneration and a bulging disc, but no frank herniation. Physical examination indicated no neurologic deficits. The patient s medical history included prior back injury in 1993, rotator cuff injury, and hypertension. She was intolerant of both hydrocodone/ acetaminophen (due to increased anxiety) and NSAIDs (edema), so treatment was initiated with tramadol (50 mg up to four times a day). The patient was also taking antihypertensive medication (sustained-release diltiazem 120 mg bid), hormone replacement therapy (conjugate estrogen mg qd), and medication for overactive bladder (triamterene 100 mg bid). Evaluation at 6 weeks after the initiation of tramadol indicated only a slight improvement in her symptoms. She could sit or stand for no more than 3 hours and continued to have pain in her lower back and right hip. At that time, tramadol dosing was doubled to 50 mg up to eight times/day and the lidocaine patch (one on the right lower back and one on the right leg) was also added to the treatment regimen. The patient also began wearing a brace. She indicated that treatment with the lidocaine patch helped about 80% and has reported no adverse effects associated with its use. Subsequently, the tramadol dosage was reduced by half. The patient did have one episode of allodynia, in a band from the lower costal margin to the hips with duration of 1 week, but this has not recurred. She has continued this successful daily treatment regimen, with the addition of amitriptyline (10 mg qhs) to assist with sleep, up to the present time. Patient 2 A 30-year-old woman suffered a lifting and twisting injury in February In April 1999, the patient presented with chronic neck, back, and leg pain, and a medical history including lumbar spinal fusion. She was being treated for pain and complications (depression and sleep disturbance) with sertraline (300 mg qd, for anxiety), diazepam (5 mg prn, for sleep), rofecoxib (25 mg prn), and oxycodone controlled-release tablets (80 mg tid) and was also receiving progesterone therapy. While on this treatment regimen in January 2001, the patient complained of pain with neuropathic characteristics (including burning, stabbing pain in the lower back and right leg, with associated dysethesias and allodynia). The lidocaine patch (two patches, 12 hours on/12 hours off, applied to the affected areas) was then added to her treatment regimen. After 1 month on the lidocaine patch, the patient was significantly more active and was able to return to work. Her pain was reduced by three points on the analog numeric pain scale from 8 to 5/10. She had occasional shooting pain in her buttocks, and this pain was effectively treated with the lidocaine patch. The patient is continuing treatment with one lidocaine patch daily in addition to the aforementioned treatment regimen, with good efficacy and no adverse events. Patient 3 A 64-year-old man presented in September 2000 with a cold and discolored left foot, together with numbness and allodynia. The patient also had pain in both the left lower leg and foot. The pain was rated as 4/10 in the morning and increased to 8/10 with activity. The patient had a long history of LBP, beginning in 1987 with a lifting injury. His medical history included spinal anterior interbody

3 Lidocaine Patch 5% for Chronic Low Back Pain 363 arthrodesis at L4 L5 in 1998, which resolved his LBP at that time. The pain recurred and was treated with sympathetic blockade in May The initial injections improved the lower extremity symptoms by 30%, but another block 2 months later produced only 10% improvement. The patient had no other relevant medical history. His diagnosis was lumbar degenerative disc disease, L4 L5 arthrodesis, and complex regional pain syndrome type 2 in the left lower extremity. The patient was initially treated with gabapentin (300 mg qd), atenolol (25 mg qd, for management of mild ectopy), and ibuprofen (600 mg qd). This combination of drugs did not control his symptoms. He was intolerant of opioid analgesics due to severe constipation, whereas previous treatment with clonidine (0.1 mg bid) had been ineffective. In November 2000, the patient began treatment with the lidocaine patch (two to three patches, 12 hours on/ 12 hours off, placed on foot and leg), tizanidine (4 mg every 8 hours), and verapamil (120 mg qd, for the management of supraventricular tachycardia). This regimen resulted in a 75% improvement in pain symptoms, and the patient was described as satisfied with his pain control; the regimen also helped to reduce swelling. The patient s status continued to improve through February 2001, when verapamil was discontinued due to itchy skin; the number of lidocaine patches was reduced to one per day, but was increased again to two per day in April In July 2001, he was able to discontinue treatment with tizanidine. Treatment with the lidocaine patch and no other pharmacologic intervention continues to provide good results in this patient and has not been associated with any adverse events. The patient s LBP has remained resolved and direct application of the lidocaine patch has provided effective pain relief of his foot. Patient 4 A 50-year-old woman with a 22-year history of back pain presented in October 2000 with low right back pain (aching and burning) that extended to her buttocks and right leg. The patient also reported muscle spasms in her back, but denied hyperalgia or allodynia. Magnetic resonance imaging in 1999 had indicated a herniated disc (L4 L5) and idiopathic and degenerative scoliosis. At the time of presentation, the patient was being treated with citalopram (60 mg qd), olanzapine (5 mg qd), lorazepam (1 mg qd or bid), and cyclobenzaprine (10 mg prn). She was also receiving hormone replacement therapy. The patient had failed prior treatment with hydrocodone (due to constipation), fluoxetine (lack of efficacy), amitriptyline (sedation), venlafaxine (lack of efficacy), and buspirone (lack of efficacy). In December 2000, therapy was changed with the substitution of clonidine (3 mg qd) for lorazepam, the addition of baclofen (20 mg tid), and another trial of venlafaxine (150 mg qd). At the end of 2000, the patient complained of an area of burning pain and allodynia in her lower back, and the lidocaine patch (one patch, 12 hours on/12 hours off, placed over the area of the allodynia) was added to her therapeutic regimen. Gabapentin (300 mg tid) was also added. Initially, the patient noted some short-term pain relief with the patch. Further evaluation in March 2001 indicated that her burning pain responded well to the combination of the lidocaine patch and gabapentin. At present, she continues this therapeutic regimen with good efficacy and no adverse events. Discussion Chronic LBP is a complex and difficult-to-treat condition that may often involve multiple pain mechanisms, including neuropathic, myofascial, and chronic inflammatory elements [4,5,9,14]. The most commonly prescribed medications for the alleviation of LBP are NSAIDs, including cyclo-oxygenase-2 inhibitors, muscle relaxants, and opioids. It is currently believed that NSAIDs, cyclo-oxygenase-2 inhibitors, and opioids may be beneficial if nociceptive pain is present in patients with this condition. Muscle relaxants are actually sedative hypnotic drugs that do not have direct activity on the muscle and are thought by many pain authorities not to possess analgesic properties [15,16]. If a neuropathic component is believed to be present in a patient with LBP, then those drugs often prescribed for the treatment of neuropathic pain, e.g., tricyclic antidepressants, anticonvulsants, and opioids, may be administered. Tricyclic antidepressants may have mechanisms related to the endogenous central nervous pain-modulating system or may have sodium-channel-blocking activity. Some anticonvulsants also possess a sodium-channel-antagonistic mechanism, whereas others, such as gabapentin, have unknown analgesic mechanisms [17]. It is frequently found that patients with chronic LBP have little response to, or great difficulty in tolerating, treatment with these analgesics [18,19]. A novel pharmacologic approach to treating chronic pain use of the lidocaine patch 5% has recently gained favor among pain specialists due to its efficacy, once-daily dosing without necessary titration, and lack of systemic side effects [10,20].

4 364 Hines et al. Results from controlled clinical trials have demonstrated that the lidocaine patch is effective for the treatment of neuropathic pain associated with PHN [10 12]. Recent clinical experience indicates that the lidocaine patch may also be effective for the treatment of other neuropathic and non-neuropathic pain states [10,13,20]. Most recently, Dalpiaz et al. [13] showed that five of six patients with chronic myofascial pain syndrome treated for 28 days with the lidocaine patch had a partial or complete response to therapy. In the treatment of neuropathic pain, e.g., PHN or neuropathic LBP, the mechanism of action of the lidocaine patch is believed to be related to the action of lidocaine on the sodium channels of dysfunctional nociceptors in the dermal layers directly underlying the area of patch application [10]. In myofascial pain, however, the mechanism of action is less clear. It can be hypothesized that a similar mechanism of action is occurring, i.e., lidocaine binds to the sodium channels of dysfunctional nociceptors that also may be abnormally active in the muscles and soft tissues in chronic myofascial pain syndromes. In patient 3, a multimodal treatment regimen, including the lidocaine patch, was shown to help reduce swelling. A recent study demonstrated the immunoregulatory effects of lidocaine on T cells in patients with allergic asthma [21]. The lidocaine patch may, therefore, also possess anti-inflammatory actions. In patient 4, the combination of the lidocaine patch and gabapentin was successful in managing burning pain and allodynia of the lower back. In regard to allodynia, there are four theoretical mechanisms to explain the possible beneficial effects of the lidocaine patch in this patient. First, blockade of abnormally functioning sodium channels on damaged peripheral nerves may decrease ectopic nociceptive pain signals transmitted to the dorsal horn of the spinal cord. Second, the lidocaine patch may act as a mechanical barrier to the area of allodynia, thus preventing stimulation [10]. A third possible mechanism in both chronic nociceptive and neuropathic allodynia involves disruption of the cycle of recruitment outside the zone of injury by chronically stimulated nociceptors of non-nociceptor A mechanoreceptors and touch receptors [22,23]. The fourth possibility is interruption of the proposed mechanism of antidromic neurogenic inflammation. Efferent stimulation of injured nerves via antidromic signals traveling back down afferent nociceptors is speculated to cause inflammation that does not respond to NSAIDs or cyclo-oxygenase-2 inhibitors. Release of histamines, substance P, and calcitonin-gene-related peptide causes recruitment of non-nociceptors. It is possible that the lidocaine patch interrupts this cycle [22 24]. In comparison with other drugs currently being prescribed to treat LBP, the lidocaine patch has several important clinical advantages in the management of pain syndromes. Since the target of the drug s mechanism of action is restricted to the peripheral nerve and soft tissues, no significant plasma levels of lidocaine are produced, even with 24-hour daily dosing (systemic absorption from the patch is minimal 3% 2%) [10]. Thus, there are no significant pharmacokinetic or pharmacologic interactions with other drugs [25]. Using the principle of first prescribing the least invasive and safest treatment, the lidocaine patch represents an effective first step in the management of pain conditions where a peripheral pain mechanism (neuropathic, myofascial, and/or chronic inflammatory) is thought to be operative, as in the case of LBP. The four patients described in this case series demonstrate that the use of the lidocaine patch 5% as part of a multimodal therapeutic approach can produce positive results in the management of patients with chronic LBP. Although three of the patients had the lidocaine patch added as part of a multimodal intervention, patient 2 had the patch added as the sole intervention. The use of a combination of interventions is reflective of general clinical practice and, therefore, we recognize that the successful pain relief observed in patients 1, 3, and 4 cannot be solely attributed to the lidocaine patch. Further controlled trials are needed to fully examine the effect of the lidocaine patch in LBP. One such trial, in which the authors are participating investigators, is ongoing [26]. Conclusions The positive results obtained in the present case series suggest that the lidocaine patch 5%, a targeted peripheral analgesic, is a novel, effective, well-tolerated, and safe medical treatment for LBP. Prospective, controlled trials should be conducted to further evaluate the utility of the lidocaine patch for the treatment of this condition. Acknowledgments Bay Area Pain Medical Associates received financial support from Endo Pharmaceuticals Inc. for this case series. We would also like to express thanks to Adelphi Inc. for assistance with manuscript preparation.

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