|Year : 2016 | Volume
| Issue : 3 | Page : 209-210
Epidural block and the pain cycle
Nivedita Page, Vivek Nirabhawane, Ravindra Ghooi
Cipla Palliative Care and Training Centre, Pune, Maharashtra, India
|Date of Web Publication||10-Jan-2017|
Cipla Palliative Care and Training Centre, Survey No. 118/1, Off Mumbai Bengaluru Highway, Warje, Pune - 411 058, Maharashtra
Source of Support: None, Conflict of Interest: None
A 68 year old female with carcinoma vulva, presented with severe unrelenting, burning pain in the vulval region. The pain was not controlled by dispersible Morphine 20 mg q4h, and a dose of 25 mg q4h produced intolerable side effects like nausea, vomiting and drowsiness, without additional pain relief. A ganglion impar could not be done due to altered anatomy. A lumbar epidural block with a catheter to deliver a continuous infusion of 0.125% bupivacaine at 2.0 ml/hour was initiated. She had excellent analgesia and she could be taken off morphine. Her epidural catheter dislodged in 3 days and could not be reinserted immediately. When we started her on morphine, her pain was well controlled with Morphine 5 mg q4h. We propose this increase in sensitivity to morphine to be due to breaking of the pain cycle with the epidural block.
Keywords: Cancer pain, epidural block, morphine, pain cycle
|How to cite this article:|
Page N, Nirabhawane V, Ghooi R. Epidural block and the pain cycle. Indian J Pain 2016;30:209-10
| Introduction|| |
This case emphasized the importance of breaking the pain cycle in providing analgesia in unrelenting cases. Complete analgesia, even for a short period, alters the neurophysiology, chemical mediators, and very importantly the psychology of the patient leading to prolonged pain relief.
We wish to highlight the challenges we faced. Firstly, intractable pain which is very common in cancer is frustrating for the patient, the family, and the treating physician. What is proven to work, just does not! Conventional analgesics and morphine which is the "gold standard," seem to lose their charm. Nerve/ganglion block that is known to be effective was not possible in this case, as the disease had progressed too far. The efficacy of epidural analgesia in cancer pain is well known, and as expected, provided excellent analgesia. However, our major concern was how the epidural would be managed at home after discharge. We use Portex catheters, which our patients can afford. Silicon catheters are quite beyond the reach of most patients. We also avoid sending patients home with an indwelling catheter, due to risk of dislodgement, which can be prevented by subcutaneous tunneling to some extent. We were about to devise some plan of action when the epidural came off in 72 h, and we were caught unprepared.
| Case Report|| |
The patient was registered with us since 2 years, during which she was under our home-based care. She had a small ulcerative lesion over the vulva, which progressively increased in size. She initially had pain on and off, for which she was started on dispersible morphine. She gradually progressed to her present condition, with a large ulcer extending over the entire left side of the vulva and severe burning pain, not relieved with dispersible morphine 20 mg 4 hourly and several breakthrough doses. Gabapentin in a dose of 300 mg tds was initiated but failed to relieve the pain. Her Eastern Cooperative Oncology Group (ECOG) performance status was 2. We increased the dose of morphine to 25 mg q4 h, but, she developed drowsiness, nausea, and vomiting. Considering her ECOG status of 2, these adverse effects were unacceptable. In a joint clinical meeting between the palliative physicians and the pain physician, it was unanimously decided to perform a ganglion impar block, which is known to be extremely effective for vulval and vaginal pain. She was posted for the procedure, which unfortunately could not be completed due to altered radiologic anatomy, as was evident during procedural imaging. We decided to insert a lumbar epidural catheter for continuous epidural analgesia. Epidural space was accessed using "loss of resistance to air" technique and confirmed using fluoroscopic imaging. She was provided continuous epidural analgesia using 0.125% bupivacaine infusion through an elastomeric pump, at a rate of 2 ml/h. She was absolutely pain-free, and her morphine could be discontinued. She was extremely happy that she could perform her daily activities with no pain.
As she was pain-free, she planned a visit to her village after discharge. Our clinical team was concerned about dislodgement or relocation of the epidural catheter and possible infection. Sending her home after removing the epidural catheter and restarting morphine would mean incomplete analgesia. During this period, her epidural catheter came off spontaneously after 72 h and could not be reposited. Since she was pain-free, we decided to start with a low dose of 5 mg q4 h, with breakthrough doses to be given as required. To our surprise, she was well controlled with that minimum dose, which was one-fifth of the dose she was initially receiving. We discharged her after 48 h and shifted her under the care of our home-based team. She has been under observation for the last 42 days, and we have noted no increased requirement of morphine for her pain.
| Discussion|| |
Pain in advanced cancer is a therapeutic challenge. The type of pain these patients suffer from is often mixed including somatic and neuropathic types.  Patients who are well controlled often have breakthrough pain for which additional analgesics have to be considered. For long, the WHO pain ladder has been considered as the last word in pain control, of late intervention has been considered the fourth step.  Our patient had completed the three steps of the ladder, but with inadequate pain control. Ganglion impar block could not be done, but epidural block produced deep and long lasting pain relief.
The increased sensitivity to morphine was an unexpected but welcome change following epidural block. Morphine is known to cause tolerance after continuous use, but the mechanism of tolerance remains obscure.  Drug holiday is a common method of reducing tolerance, but this is not a likely explanation in our case. In fully tolerant animals, a drug holiday of nearly 6 days is required to regenerate 50% of the original response,  and the reduction in the dose of morphine here, was nearly by 75% in, in just 3 days.
We postulate that this change is due to a break in the vicious pain cycle which had trapped the patient since nearly a year. Chronic pain leads to a vicious cycle of anxiety, depression, altered sleep, muscle atrophy, neurophysiological changes, which, if left untreated, can worsen the pain.  Breaking the pain cycle for just 72 h, probably reversed the psychological state and altered neurophysiology, which in turn resulted in a reduction in opioid requirement.
| Conclusion|| |
Use of epidural block leading to intense and prolonged analgesia in a case of carcinoma vulva resulted in a reduction in the opioid requirement. One of the possible explanations for this could be a break in the pain cycle. This however needs further study on a larger number of patients which may help us confirm this observation and suggest the mechanism.
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Conflicts of interest
There are no conflicts of interest.
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