Interventional Pain Management
Pain is a multidimensional experience. Chronic pain differs from acute pain in that it lasts for more than 3-6 months, and there may not be obvious tissue injury leading to the pain. The pathway leading from stimulus to perception may be sensitised . There is often associated depression. Management of chronic pain therefore requires a holistic multi-disciplinary approach . In addition to pharmacological treatment, psychosocial support, physiotherapy and operative treatment, interventional techniques may benefit some patients by defining the pain generator and offers prolonged relief.
Interventional Pain Procedures
Commonly performed interventional procedures for pain of spinal origin include trigger point injections, facet blocks, sacroiliac joint blocks, epidural steroids and epidural lysis. Blocks with local anaesthetics identify the source of pain when pain level is reduced significantly after the block. Local administration of steroids decreases inflammation. Denervation by a radiofrequency current can bring prolonged relief by interrupting the sensory pathway. A very small group of selected patients benefits from spinal cord stimulation or insertion of an intra-thecal drug delivery system. Diagnostic blocks with a local anaesthetic help to ascertain the source of pain.
Back & Neck Pain
Facet joints are small synovial joint connecting the posterior aspects of the vertebrae. Inflammation of these joints or abnormal stress on them can lead to facet joint pain. There are back or neck pain with radiation, but no radicular symptoms. Pain typically worsens on extension. Facet pain syndrome often co-exists with disc pathologies . These joints are supplied by medial branches of adjacent spinal segments. Diagnostic blocks are performed by injection of the joints or the medial branches under fluoroscopy. Joint injections can be supplemented by local steroids. Longer term effect is achieved by radiofrequency lesioning of the medial branches [4,5] (Fig.1).
Sacro-Iliac Joint Pain
Sacroiliac joint pain presents with back pain, usually to the side of lesion, with radiation to the groin or the knee. Bilateral joint involvement may present as central back pain. Interventional treatment approach is similar to facet joint pain [6,7]. More recently developed Cooled Radiofrequency technique produces more consistent lesions for the multiple sacral nerves .
Radiculopathy presents with back or neck pain with radiation. Lesions in the lumbar levels produce the familiar ‘sciatica’ symptoms, whereas cervical lesions cause pain radiating to the shoulder or upper limb. Radicular pain may be caused by pressure or irritation of the nerve roots by degenerated intervertebral discs. Nerve impingement may also be caused by spinal stenosis, spondylolisthesis or failed back surgery syndrome. Injection of steroids into the epidural space may help these patients. The approaches may be translaminar, transforaminal or caudal [9,10] (Fig. 2). If multiple levels involvement is suspected or for resistant cases, a specially designed Racz catheter can be introduced from the sacral hiatus to define the levels of nerve impingement on epidurogram . Hydrodissection is performed and steroid is deposited  (Fig. 3).
Spinal Cord Stimulation
Melzack and Wall proposed the gate-control theory in 1965 . The concept of stimulation of large afferent fibres to close the ‘gate’ for pain perception lead to the development of spinal cord stimulation. Shealy published the application of ‘dorsal column stimulation’ in 1967 . Over the years spinal cord stimulation has developed into a percutaneous technique where a lead with multiple contact points is inserted into the epidural space and is connected to an implanted pulse generator. Programmable electric current stimulates the spinal cord, leading to pain relief. This is particularly useful for very carefully selected patients who suffer from failed back surgery syndrome  or arachnoiditi.
Intrathecal Drug Delivery Systems
Implantable intrathecal drug delivery systems are available for delivery of medications into the subarachnoid space directly. This may be of use for some very selected patients.
1. Latremoliere A, Woolf CJ. Central sensitization: a generator of pain hypersensitivity by central neural plasticity. J Pain 2009;10:895-926.
2. Siddal PJ, Cousins MJ. Persistent pain as a disease entity: implications for clinical management. Anesth Analg 2004;99:510-20.
3. Schwarzer AC et al. The relative contributions of the disc and zygapophyseal joint in chronic low back pain. Spine 1994;19:801–6.
4. Boswell MV et al. A systematic review of therapeutic facet joint interventions in chronic spinal pain. Pain Physician 2007;10:229-53.
5. Falco FJE et al. Systematic review of diagnostic utility and therapeutic effectiveness of cervical facet joint interventions. Pain Physician 2009;12:323-44.
6. Cohen SP. Sacroiliac joint pain: a comprehensive review of anatomy, diagnosis, and treatment. Anesth Analg. 2005 Nov;101(5):1440-53.
7. Rupert MP et al. Evaluation of sacroiliac joint interventions: a systematic appraisal of the literature. Pain Physician. 2009 Mar-Apr;12(2):399-418.
8. Patel N et al. A randomized, placebo-controlled study to assess the efficacy of lateral branch neurotomy for chronic sacroiliac joint pain. Pain Medicine 2012; 13: 383–398.
9. Parr AT et al. Lumbar interlaminar epidural injections in managing chronic low back and lower extremity pain: a systematic review. Pain Physician 2009; 12:163-188
10. Gharibo CG et al. Interlaminar versus transforaminal epidural steroids for the treatment of subacute lumbar radicular pain: a randomized, blinded, prospective outcome sstudy. Pain Physician 2011; 14:499-511.
11. Racz GB et al. Percutaneous lysis of epidural adhesions-evidence for safety and efficacy. Pain Pract. 2008 May 23.
12. Epter R et al. Systematic review of percutaneous adhesiolysis and management of chronic low back pain in post lumbar surgery syndrome. Pain Physician. 2009; 12:361-378.
13. Melzack R, Wall PD. Pain mechanisms: a new theory. Science 1965;150:971-9.
14. Shealy CN, Mortimer JT. Electrical inhibition of pain by stimulation of dorsal columns: Preliminary clinical report. Anesth Analg 1967; 46: 489-91.
15. North RB et al. Spinal cord stimulation vs reoperation for failed back surgery syndrome: A cost effectiveness and cost utility analysis based on a randomized controlled trial. Neurosurgery 2007; 61(2):361-8.
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