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EPIDUROSCOPY
Interventional Pain Management for Backache
D K Baheti
Associate Professor, Anaesthesiology, Bombay Hospital Institute of Medical Sciences, 12, New Marine Lines,
Mumbai 400 020.
INTRODUCTION
Low back pain has been an ignoble part of human history since ancient times as mentioned by the authors like Hippocrates and Shakespeare. Post lumbar laminectomy syndrome with its resultant chronic low back pain is estimated to occur in 20% to 50% of the patients. Soft tissue pathology is not easily examined so it is often overlooked as a potential cause of some types of back pain syndrome.SPINE MEDICINE
Pope MH1 reported 10% population suffers from spinal pain. The total cost of health care on chronic pain is $70 Billion and out of which chronic low back pain takes away $16 billion annually as reported in a survey by Snook and Stover.[2] However natural course of recovery is favourable in most of patients but in 60-85% pain recurs two years after first episode of acute pain.[3] In 80% of herniated intervertebral disc surgical excision relieves symptoms in properly selected patients.[4]
When these results are compared with conservative treatment along with surgical intervention the results reported to be similar.[5]
FAILED BACK SYNDROME
The aetiology can be surgery or non-surgery related.[6]
Surgery related
Residual herniated disc
Radiculitis, epiduritis, discitis
Arachnoiditis, Epidural fibrosis
Spinal stenosis
Spinal stability
Non-Surgery related
Persistent related
Epiduritis
Facet syndrome - Neuritis, capsulitis, arthritis,
Myofascial syndrome - Myofascitis, ligamentitis, tendonitis
Scar tissue
Surgical scar tissue
Non-Surgical scar tissue - radicular, epidural
Inflammation
Radiculitis
Epiduritis
Smyth J, Wright V7 proved that compression on normal nerve root causes paraesthesia and numbness whereas compression on injured nerve root causes pain.
The inflammation and adhesions on and around the dura and spinal nerves are presumed to be the major causes of chronic back pain and radiculopathy. The lysis of epidural adhesions is considered as one of the effective therapeutic modalities of management of these patients. The adhesinolysis may be performed either non-endoscopically or endoscopically.
Unfortunately the standard technique that depends on loss of resistance does not guarantee this. In fact the injectate will often takes the path of least resistance that is, away from the target. When fluoroscopic imaging is used alone to direct the steroid injection, judging the distribution of nonionic contrast can be difficult because the fluoroscopic projection is two-dimensional. Spinal endoscopy delivers three dimensional colour views of investigated tissue in real time. As spinal endoscopy cannot distinguish one level from another and therefore fluoroscopy must be used simultaneously to insure delivery to a specific level.
Endoscopy can be useful as diagnostic cum therapeutic procedure in treatment of such pain. As it allows direct viewing of the content of the spinal canal in real colour and actual activity, as compared to results with static techniques like CT and MRI.
Preliminary reports on the use of fibreoptic epiduroscope in treatment of post laminectomy pain are encouraging. Endoscopy allows direct viewing of the contents of spinal canal in real color and actual activity. It is accomplished via a fibreoptic epiduroscope that offers visualization of spinal contents, separation of adhesions from surrounding structures and deposits of medication in the affected areas.
An epidural steroid injection must reach nerve root associated with pain.
Caudal spinal canal endoscopy has recently been introduced as a technique for directed injection of medication. The medication includes corticosteroids, normal saline and local anaesthetic.
Minimal invasive spinal endoscopy has been further advanced with the development of a 2.7 mm flexible steerable catheter with two ports. One port allows the introduction of fibreoptic lens epiduroscope. The other is used to inject fluids for greater clarity.
Pathophysiology
Pathologic features include a variety of immature and mature scar tissue. Early findings may include a wall of light filamentous cottony adhesions and tethering of normal structures to the adjacent normal anatomy.
It shows signs of epiduritis, such as polyradiculitis, ligamentitis, cellulitis, and epidural fibrosis, scar entrapment. Any degenerative disorder can lead to epiduritis, which results in unequal sharing of spinal loads, which alters kinematics of functional unit and end result is lumbosacral pain.
All the above causes of low back pain ultimately leads of Lumbo-Sacral epiduropathy or Failed Back Pain Syndrome.
Management options
Surgery
Spinal cord stimulation
Volumetric adhesinolysis
Epiduroscopy/Spinal endoscopy
Indications
Radiculopathy.
Failed response to epidural steroid injections.
Filling defects caused by adhesions.
Post-laminectomy failed back syndrome.
Failed conservative back therapy.
TECHNIQUE OF EPIDUROSCOPY/SPINAL ENDOSCOPY
Epiduroscopy or spinal endoscopy involves accessing of the epidural space at the caudal level. It should be performed in a treatment room or in operating theatre with access to fluoroscopy. An intravenous line is secured and monitoring of ECG, SaO2 and NIBP is mandatory. A stand by anaesthesiologist should provide mild sedation to allow for a feedback between patient and endoscopist. An appropriate recovery room facility is required.
The patient is placed in prone with a pillow under the abdomen and the sacral canal is identified. A midline position is confirmed. After preparation of the area local anaesthetic Inj. Lignocaine 1% 3-4 ml is injected into the floor of the canal.
A 17-gauge Tuoghy needle is inserted into the sacral canal and advanced cephalad. A lateral fluoroscopic projection confirms the placement of the needle inside the canal Inj. Omnipaque (Non ionic contrast) 5 ml to 15 ml is injected and followed by posteroanterior fluoroscopy. This outlines the epidural anatomy of nerve roots, fat and adhesions. This caudal epidurogram is preserved and documented by an X-ray.
The guide wire is placed through Tuoghy needle and needed and threaded cephalad under fluoroscopic guidance. The Tuoghy needle is then removed. The canal passage is widened with 11# scalpel, to allow easier passage of introducer sheath and dilator. Now dilator and sheath are passed over the wire. After the dilator and introducer sheath are inserted, the dilator and guide wire is removed, leaving the introducer sheath in situ. The sidearm of the introducer sheath is flushed with 10 ml of normal saline.
The steerable catheter containing fibreoptic cable is passed through the introducer. The epidural space is distended with 10 to 15 ml of normal saline. The fibreoptic cable along with steerable catheter is introduced in to the epidural space slowly and the contents of the epidural space should be identified.
The contents of epidural space such dura mater appears as either a blue-gray or gray-white exterior with small blood vessels on its surface. Epidural fat appears as globular and glistening, especially in areas with less scarring. It is usually yellowish in colour with small blood vessel on or in it. Nerve roots are white tinged with yellow. They are round, elongated and structured separately. When nerve roots are matted down, they may be less distinguishable until they are separated from adhesions. The nerve roots are characteristically traversed by longitudinally placed small arteries and veins. The ligametum flavum is seen as a white concave surface with no vascular element. The intermittent distension and irrigation of epidural space with normal saline may be required. The total volume of normal saline should not exceed more than 70 ml.
The hand control tip of fibreoptic catheter system should be gently steered in to the area of concern to break up visible adhesive bands that appear to be tethered to adjacent tissues. The intermittent steering of catheter helps in adhesinolysis. After the successful adhesinolysis the epidurogram is repeated with Inj. Omnipaque 5 to 15 ml and documented with an x-ray.
At the end of procedure, the Inj. Depomedrol 80 mg + Inj. Lignocaine 0.5% 20 to 30 ml and normal saline 10 to 20 ml is injected to have additional effect by volumetric adhesinolysis.
OUTCOMES
With epiduroscopy, the best outcome is found in cases of monoradicular pain without neurological deficit. A prospective outcome is comparison with use of a single endoscopic procedure to repeat epidural injections would be an important project. It is hypothesized that a single endoscopic procedure would bring quicker recovery than three epidural steroid injections given at intervals of 2 to 4 weeks apart. When rapid return to functional activities such as walking, bending, kneeling, sitting, climbing of stairs or experiencing sexual enjoyment, is a factor for the patient. It definitely adds to the advantages of spinal endoscopic diagnosis, followed by medication management are considerable.
Approximately 6000 or more cases have been performed during past five years. No permanent injury has been reported. Pre and post-procedural survey, data indicate a trend toward less opioid medication and improved functional capacity.
CONCLUSIONS
The science and art of knee arthroscopy and laparoscopy are the example that has advanced immeasurably since it became a part of the present usage. The same scenario is likely to occur with spinal endoscopy. Also the future of spinal endoscopy will depend on a greater understanding on neurobiomechanics and chemical change relationships to the affected areas of the body.
REFERENCES
- Pope MH, et al. Occupational low back pain assessment, treatment and prevention. Mosby Year Book St. Louis. 1991; 132-47.
- Snook and Stover. The cost of back pain in industry. In RA Deyo (Ed) Occupational back pain. Philadelphia, Hanley and Belfus.
- Deyo RA, Tsui-Wu YJ. Description epidemiology of low back pain and its related medical care in the United States. Spine 1987; 12 : 284-88.
- Spangfort EV. The lumbar disc herniation, a computer aided analysis of 2504 operations. Acta Orthop Scand 1972; 142 (suppl) : 1-95.
- Hakelius A. Prognosis in sciatica. A clinical follow-up of a surgical and non-surgical treatment. Acta Orthop Scand 1970; 129 (suppl) : 1-76.
- Fritsh EW, et al. The failed back surgery syndrome. Reasons, intraoperative findings, and long-term results. A report of 182 operative treatments. Spine 1996; 21 (5) : 626-33.
- Smith J, Wright V. Sciatica and the intervertebral disc. An experimental study. J Bone Joint (Am) 1959; 40A : 1401.
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