|Year : 2013 | Volume
| Issue : 3 | Page : 182-184
Role of Duloxetine in management of cervical or lumbosacral neuralgia of unknown etiology: A preliminary study
Digambar P Nawani1, Sanjay Agrawal2, Veena Asthana2
1 Pain Specialist, Doon Nursing Home, Dehradun, Uttarakhand, India
2 Department of Anesthesia, Himalayan Institute of Medical Sciences, Dehradun, Uttarakhand, India
|Date of Web Publication||7-Jan-2014|
Department of Anesthesia, Himalayan Institute of Medical Sciences, Swami Ram Nagar, Dehradun - 248 140, Uttarakhand
Source of Support: None, Conflict of Interest: None
Background: Duloxetine is a selective serotonin reuptake inhibitor (SSRI) used for treatment of neuropathic pain associated with diabetic neuropathy and fibromyalgia. Use of duloxetine for idiopathic neuropathic pain is not known. We present our experience for treatment of such painful conditions. Materials and Methods: Twenty patients, either sex, aged 30-65 years presenting for cervical and lumbosacral pain were administered duloxetine 40 mg/day in two divided doses. They were followed for a total period of 20 weeks and pain was assessed periodically using Numerical scale and Facies scale. Results: Fifteen patients showed complete resolution of pain. No major side effects were seen. No patient showed less than 50% resolution of pain. Conclusion: Duloxetine 40 mg/day is effective for control of painful neuropathic condition in our Indian setup.
Keywords: Duloxetine, neuropathic, pain
|How to cite this article:|
Nawani DP, Agrawal S, Asthana V. Role of Duloxetine in management of cervical or lumbosacral neuralgia of unknown etiology: A preliminary study. Indian J Pain 2013;27:182-4
|How to cite this URL:|
Nawani DP, Agrawal S, Asthana V. Role of Duloxetine in management of cervical or lumbosacral neuralgia of unknown etiology: A preliminary study. Indian J Pain [serial online] 2013 [cited 2019 Dec 10];27:182-4. Available from: http://www.indianjpain.org/text.asp?2013/27/3/182/124605
| Introduction|| |
Spinal neck and low back pain has a prevalence of 60-80%. ,, Common causes of radiculopathy are degenerative spinal changes such as disc herniation and spondylosis leading to compression or irritation of the nerve.  However at times, exact cause of such painful syndrome is not elicited by usual modes of investigation and such patients present with a history of chronic painful condition associated with depression, anxiety, or sleep deprivation.
Various modalities of treatment are tried in such cases with varied results. Duloxetine a new antidepressant drug approved by US Food and Drug Administration (FDA) for management of chronic pain syndromes. We present here our experience of 20 patients who presented with idiopathic neuropathic pain in upper and lower limbs who responded well to the administration of duloxetine. We discuss the management and review of literature about the use of duloxetine for pain relief.
| Materials and Methods|| |
Twenty patients of either sex, aged between 35 and 65 years presented to the pain clinic over the period of 1 year (January 2011-December 2011) with the symptoms of lower limb or cervical radiating pain, tingling, or numbness for a period ranging from 6 months to 2 years. All the patients were investigated by X-ray of cervical/lumbosacral spine and MRI. However, in all such cases there was no evidence of organic disease in term of narrowing of intervertebral space or disc herniation on magnetic resonance imaging (MRI). They were all managed conservatively with passive physiotherapy, bed rest, and oral nonsteroidal anti-inflammatory drugs (NSAIDS). Since these patients did not show any improvement over a period of 2 weeks, they were administered tablet (tab.) duloxetine 40 mg/day in two divided doses for an initial period of 1 week. Of the 20 patients so presented, 15 showed some improvement in their symptoms as assessed by numerical score and facies score. All were advised to continue the treatment with tab. duloxetine 40 mg/day for further 4 weeks. The patients were assessed periodically every fortnightly. As the patients were showing improvements in their pain, the same medications were continued for another 8-10 weeks. Every fortnightly the patients were assessed for their pain and side effects of the medications; at the end of 16 weeks the medication was gradually tapered over 15 days and finally stopped. After another 4 weeks the patients were assessed for their pain.
| Results|| |
A total of 20 patients (15 males and 5 females) were studied. Mean age of the patients were 46 years with a range of 30-65 years. C5,6 and L4,5/L5S1 were the most commonly affected vertebral level with radicular pain along the distribution of the nerves [Table 1]. Mean pain score as assessed by numerical and facies score was 8 and 9, respectively. Change in the score after a period of 8 weeks of medication was 4 and 5, respectively, which decreased to 2 each after 20 weeks of therapy [Table 2]. Side effects seen in our cases were nausea and vomiting in two patients and dizziness and somnolence in one patient.
Clinical response was graded as good, satisfactory, and poor. Good response was defined as complete resolution of pain, while satisfactory response was defined as 50-75% pain relief and poor response had no improvement/less than 50% pain relief. Fifteen patients (75%) graded their pain relief as good, while five patients (25%) graded as satisfactory. No patient had less than 50% pain relief.
| Discussions|| |
Management of neuropathic pain is multidisciplinary. Various modalities are used for their treatment. In conditions where the exact cause for pain is not found, treatment is symptomatic. Such painful conditions are usually associated with sleep disturbances, anxiety, and mood disorders.  Use of conservative modalities of pain relief such as physiotherapy, exercise, sleep hygiene, and transcutaneous nerve stimulation provides variable results. Other supportive modalities such as patient's education, support, reassurance, and cognitive behavioral therapy assists patients in dealing with such conditions. ,,,
Chronic pain is usually thought to arise due to central sensitization of pain receptor system. Role of serotonin and norepinephrine in the spinal cord was found responsible for such pain. Duloxetine is a selective serotonin and norepinephrine uptake receptor inhibitor that acts on the descending inhibitory pathway and modulates pain relief as well as depression associated with chronic pain symptoms.  Advantage of duloxetine lies in the fact that it does not cause blockade of other neurorecptors responsible for typical tricyclic antidepressant side effects.  It is found efficacious in doses of 60-120 mg/day for treatment of painful conditions associated with fibromyalgia, diabetic neuropathy, and low backache. Use of duloxetine 40 mg/day for treatment of trigeminal neuralgia showed a significant pain relief in 60% patients in one study. 
Our study was unique in two ways. Firstly, the exact cause of neuralgia was not known and they were termed idiopathic. It involved pain distribution along the course of the nerve. Secondly, the doses used by us and found efficacious, was less than the Western literature; which reported a dose of 60-120 mg/day as efficacious, while 20 mg/day as not beneficial. We postulate that probably the pharmacodynamics and pharmacodynamics of drug may be different in our study population and so lower doses were found efficacious in both our study as well as of Anand et al. In other study use of 60 mg/day has been found efficacious for treating of low backache. Side effects noted in our study were also low and drug was well-tolerated by patients. No discontinuation of treatment was seen in our cases. The side effects are more linked to the dosage of the drug being high with increasing dose to 60-120 mg.
Limitation of the study maybe that it is a single institutional study and our results may not be generalized. Another limitation was the small number of patients assessed. A large multicenter trial in our Indian setup will give a better idea, however initial results are encouraging.
| Conclusion|| |
In conclusion duloxetine in the dose of 40 mg/day is efficacious for pain relief in patients suffering from neuropathic pain of unknown origin.
| Acknowledgement|| |
The authors acknowledge the Institutional support necessary to conduct this study.
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[Table 1], [Table 2]