Disk Herniation-Related Sciatica Radicular Pain: An Expression of a CRPS ?
Authors: Ochoa G. , Abella P. 
Published: June 2012

Introduction

Traditionally, Radicular pain has been described as a pain coming from the cervical or lumbar area irradiating down to an arm or a leg in an specific dermatomal distribution and it is associated to a disk herniation. The pain was long ascribed to pressure put on the nerve root by a herniated disk. However, a role for chemical factors acting in conjunction with this mechanical insult is suggested by a number of clinical observations. There is a group of patients presenting with clinical symptoms very similar to those described in the complex regional pain syndrome type II: sensory disturbances, burning deep spontaneous pain and mechanical allodynia, disturbances in the skin blood circulation, sweating, and edema. All symptoms are distributed in the distal extremity and not limited to the region of the peripheral nerves. The usual treatment of a radicular pain includes NSAID's, epidural or foraminal blocks, and physical therapy. However, the group of patients with the symptoms described before do not respond well to this therapy but to a sympathetic blocks and low doses of ketamine. The first has been postulated as an adjuvant to treat CRPS II and the latest has gained a role in the treatment of CRPS II in recent years.

Materials and Methods

It is a retrospective review on five patients presented with acute neuropathic pain associated to a disk herniation (three lumbar and two cervical ) documented by an MRI. Their physical examination revealed edema of the affected leg or arm along with the vascular changes, allodynia, and hyperalgesia similar to that seen in patients with CRPS. All patients were treated with the traditional protocol of NSAID's, opioids, and foramina-epidural blocks with no pain control. Subsequently, they were treated with a sympathetic block and an initial bolus of 0.1 to 0.2 mg/kg, followed by a continuous infusion of 0.5 mg/hour during 2 to 4 days. After control of allodynia and hyperalgesia, bolus of Tramadol was used until the total control of the pain was achieved.

Results

The control of the pain was achieved between 24 hours to 5 days; edema disappeared at the end of the first week and a protocol of physical therapy was started. All the patients were discharged from the hospital at the end of the first week of treatment without surgical intervention.

Conclusion

These clinical observations have driven to set out the hypotheses that radicular pain can also has within it pathophysiology, a component similar to that of the CRPS II. Discussion of these hypotheses and clinical observations can lead to the introduction of new tools to treat radicular pain associated to a disk herniation in a selected group of patients presenting with a clinical expression of a CRPS type II. I confirm having declared any potential conflict of interest for all authors listed on this abstract No Disclosure of Interest None declared Correll GE, Maleki J, Gracely EJ, Muir JJ, Harbut RE. Subanesthetic ketamine infusion therapy: a retrospective analysis of a novel therapeutic approach to complex regional pain syndrome. Pain Medicine 2004;5(3):263–275 de Mos M, Sturkenboom MC, Huygen FJ. Current understandings on complex regional pain syndrome. Pain Practice 2009;9(2):86–99 Köck FX, Borisch N, Koester B, Grifka J. Complex regional pain syndrome type I (CRPS I). Pathophysiology, diagnostics, and therapy Orthopade 2003;32(5):418–431 Mulleman D, Mammou S, Griffoul I, Watier H, Goupille P. Pathophysiology of disk-related sciatica. Evidence supporting a chemical component. Joint Bone Spine 2006;73(2):151–158 Mulleman D, Mammou S, Griffoul I, Watier H, Goupille P. Pathophysiology of disk-related low back pain and sciatica. II. Evidence supporting treatment with TNF-alpha antagonists. Joint Bone Spine 2006;73(3):270–277 Ochoa G., Abella P. Low doses of I.V. Ketamine in the treatment of acute neuropathic pain. Poster presented at the Third International Congress on Neuropathic Pain. IASP, NeuPSIG. May 27–30, 2010, Athens, Greece Sigtermans MJ, van Hilten JJ, Bauer MC. Ketamine produces effective and long-term pain relief in patients with Complex Regional Pain Syndrome Type 1. Pain 2009;145(3):304–311