Low Back Pain & Caudal epidural block

 

Caudal epidural block is a commonly used technique for surgical anesthesia in children and chronic pain management in adult. It is also used in postoperative pain management in children.

Anatomy

The laminae of the fifth sacral vertebra fail to unite posteriorly to form a sacral hiatus, which is U – or V -shaped. The tubercles that represent the inferior articular processes make up the sacral corona and are connected inferiorly to the coccygeal cornua. Sacral hiatus is covered by sacrococcygeal membrane from which epidural space lies anterior to it.

The vertebral canal otherwise called as sacral canal runs throughout the greater pari of the bone; above, it is triangular in form; below, its posterior wall is incomplete due to non development of the laminae and spinous processes. It lodges the  sacral nerves, and its walls are perforated by the anterior and posterior sacral foramina through which these nerves pass out.

The dural sac ends at SI and S2 vertebra. The_S5 roots and coccygeal nerves leave the sacral canal through the sacral hiatus. Epidural space which lies between two sacral plates contains sacral nerves, artery, vein, lymphatics and fat.

Pain

International association  for the study of pain defines pain as an “ An unpleasant sensory an emotional experience  associated with actual or potential tissue damage, or described in terms of  such damage.

Low back pain

Low back pain is one of the most common complaints  to seek medical care as on adult in a primary cave setting earlier mechanical back pain or non  specific back pain was described as the major cause of law back pain in 70 – 80 % of the individuals.

Major causes of back pain are facet joint arthropathy 15 – 45 % intervartebral disc disruption 25 -40 % sacroiliac  joint arthropatty 15 – 30 5 disc prolapse/herniated disc/slipped disc 2-5 % CRPS/RSD 2-8%. Osteoporotic compression fracture 3-5 % orther facture <1% . Fibromyalgia and myofascial pain 2-5% . Spinal canal stenosis 2-3 % . Spondylolisthesis 2-3 % tumor < 1% . Intection < 1% and Fbss < 1%

Patho physiology:

neuropathic pain results from anatomical and / or physiogical changes which may be due to damage to nerves or neural tissue rather than the stimulation of nociceptors by tissue injury or information. pain results from spontaneous electrical activity of the damaged nerves or to increased sensitivity to exogenous srimuli,the neural path ways are the same as for nociception. damage to sensory afferent fibres results in a significant  reduction in the number of opoid receptors in the presynaptic terminals of the affected fibres in the dorsal horn , possible explaining the reduced opoid sensitivity of neuropathic pain. Damage to sympathetic nerve fibres may lead to sympathetic type pain in which neuropathtic pain is accompanied by signs of autonomic dysfunction including vasomotor instability and sudomotor (sweating) changes.

Red Flags

  1. Trauma: H/o of fall from a height, trauma from a motor vehicle crash, osteoporosis, chronic steroid use.
  2. Infection: H/o unexplained fever, immuno­suppression, intravenous drug abuse.
  3. Tumor: H/o of cancer, unexplained weight loss
  4. Cauda equina syndrome: Bowel incontinence, urinary retention, saddle anesthesia, lower limb weakness and gait disturbance,
  5. Progressive motor deficit with a power of ,4/5.
  6. Progressive sensory deficit which includes increase in the area of sensory loss and increase in the quality of sensation as compared to normal area.
  7. Moderate to severe debilitating pain not getting relieved with conservative treatment modalities both pharmacotherapy and non-pharmacological management.

Pain History

  1. Predominant back pain with non-dermatomal leg pain mostly limited up to knee: IDD, SI (sacroiliac joint) arthropathy, vertebral compression fracture, facet arthropathy, MPS, etc.
  2. Predominant leg pain with back pain: CRPS, PIVD, PHN, diabetic Neuropathy etc.
  3. Qnset: It is acute in case of trauma, large central disc, muscle sprain. However, in inflammatory pathologies it is more of a gradual onset.
  4. Site: Disc, vertebral body and interspinous ligaments, bilateral facetjoint, coccygodynia mostly produces midline or axial pain however unilateral facet joints, sacroiliac joint dysfunctions and myofascial pain syndromes commonly presents with paramedian pain.
  5. Localized/diffuse: Facet joint and sacroiliac joint pain is well localized with a definite pain map however discogenic pain is diffuse and poorly localized.
  6. Radiation: Radicular pain mostly point towards pain of neural origin. It is derma-tological distributed. Irritation, com­pression and impingement of nerve roots causes radicular pain. For example, pain from L1-L3 nerve roots will radiate up to the hip/thigh whereas radiation below knee is attributed to L5-S1 nerve root. Piriformis myofascial pain can also mimic SI radiculopathy which needs to be thought of when we are thinking of L5-S1 PIVD
  7. Referred pain: It has nondermatological distribution and it is deep aching in quality. Pain from spine musculature, ligaments, facet joint and sacroiliac joint can be referred to thigh rarely below the knee and in the rarest of case beyond ankle. It can also be seen in pathologies of abdominal origin like aortic pancreatitis, pelvic conditions like endometriosis, inflammatory bowl diseases retroperitojteal conditions like renal colic and pyelonephritis.
  8. Night pain: It is more in favor of in­flammatory conditions and malignancy.
  9. Aggravating factors
  10. Sitting: Midline back pain aggravated on sitting, internal disc disruption (IDD), vertebral compression fracture, coccy­godynia, interspinal ligament sprain.
  11. Paramedian back pain aggravated on sitting: Sacroiliac (SJQ joint dysfunction, piriformis syndrome, myofa^ciaTpain^of quadrates lumborum.

Walking increases pain in spinal canal stenosis both central and JateraLiadi-culopathies.

  1. Walking does not increase the pain of facet and sacroiliac joint arthropathy.
  2. Standing increases pain in case of .spinal
  3. canal stenosis, spondyloarthropathies. ci. Sitting to standing Facet joint pain,
  4. vertebral compression fracture. e. Supine to sitting aggravates pain of vertebral
  5. compression fracture. /. Forward flexion IDD, ligaments sprain. g. Extension and lateral rotation Facet joint pain
  • Relieving factors
  1. Sitting: Spinal canal stenosis, bilateral or unilateral facet joint, MPS (iliopsoas)
  2. Curling up position: PIVD
  3. Standing and walking tor a short while: IDD.

Indication:

Indication for caudal epidural block includes :

  • Herniated disc with or without radiculopathy below L4
  • Discogenic pain below L4.
  • Radiculopathy below L4.
  • Spondylolisthesis below L4.
  • Spinal canal stenosis
  • Failed back surgery syndrome
  • Epidurolysis

Contraindications

Absolute contraindication includes:

  • Local or systemic infection.
  • Coagulopathy and patient on anticoagulants without

adequate recommended drug free period

  • Lack of consent.

Relative contraindication includes:

  • Pregnancy
  • Patient not able to lie prone
  • Non cooperative patient
  • Patient with severe cognitive dysfunction
  • Allergy to any drugs used for procedure
  • Unstable vital parameters
  • Previous surgery
  • Anatomical variation

 

Preparation:

Once clinical diagnosis is made and planned for the procedure, then patient is prepared for procedure

  • Rule out red flags including infection, tumor, fracture and significant neurological deficit
  • Informed and written consent is foremost important step.
  • Patient should he explained about the procedure
  • Assess patient general and cardiorespiratory status with appropriate consultation and investigation before procedure
  • Whenever planning for procedure, do certain basic investigation which includes bleeding-coagulation profile and blood sugar
  • Get conventional lumbosacral X ray to rule out anatomical difficulty in procedure
  • Get Financial clearance from insurance bodies or other governing bodies before admission if possible
  • Advise for standard pre procedural lasting
  • Advise to come with accompanying person on day of procedure

Pre Procedural Protocol

  • Confirm the identity, diagnosis, consent and clearance for procedure
  • Check for availability of lab reports and radiological studies which may be required during procedure
  • Star intravenous 20 gauge cannula in non dominant hand
  • Administer prophylactic antibiotic as per institutional protocol
  • Patient can be sedated with titrating dose of midazolam or propofol or sometimes with opioids so that patient will be comfortable during procedure

Requirements:

Check for the availability of following materials before taking the patient inside the procedure room

  • Metal locator
  • Carm Radiation safety devices
  • X ray compatible surgical table
  • Sterile gaue pieces
  • Gloves according to performer
  • Betadine / chlorhexidine solution,
  • Sterile drapes
  • 154 inch, 26 gauge needle for skin infiltration.
  • 2 ml syringe for local anesthetic injection
  • 5ml syringe for contrast injection.
  • 10 ml syringe for caudal injection
  • 1% lidoeaine for skin infiltration.
  • Contrast solution like iohexol or iopomidol.
  • 1 % lignocaine for diagnostic injection.
  • Depot steroid like methylprednisolone or triamcilone 40mg/ml vial.
  • 20G, 80 mm, louhy needle or RX coude needle
  • Low volume extension tubing
  • Adhesive tapes

Position and monitoring:

Once everything is ready, patient can be taken inside the procedure room and

  • Place the patient in prone position
  • Keep pillow of appropriate size under iliac crest to correct lordosis
  • Keep the patient comfortable with adequate head and leg rest and keep both arms by the side of head. The legs and heels are abducted to prevent tightening of the gluteal muscles, which could make identification of the sacral hiatus more difficult
  • Attach standard basic monitoring as recommended by American society of anesthesiologist
  • Prepare the skin with betadine / ehlorhexidine and drap the site with sterile materials.

Procedure steps

  • Take AP image with X ray tube below the table and use automatic brightness mode and collimator if available.
  • Mark the midline of sacral hiatus
  • Now C arm is turned to lateral view and sacral hiatus is identified
  • Needle entry is few cms below sacral hiatus so as the needle hits the inferior part of sacral hiatus at an angle of 30-45″
  • Infiltrate the needle entry with 1% lignocaine and wait for I minute
  • 20G, epidural needle is inserted and hit the posterior surface of S5 vertebral body just below sacral hiatus and then insertion angle is decreased so as to slip into sacrococcygeal membrane
  • It is inserted futher for 2 cm in sacral canal
  • Now C arm is moved to AP and needle is advanced till S3 vertebra
  • 5 ml of contrast is injected after negative aspiration which will form inverted Christmas tree appearance
  • After ruling out intravascular, subdural and subarachnoid needle posjtion, 10 ml of 1% lignocaine is injected for diagnostic purpose
  • 40 mg of depot steroid is added for therapeutic purpose
  • In case of epidural fibrolysis, 1500 IU hyaluronidasc and 10% hypertonic saline is injected with maximum volume of 30 ml.
  • Remove needle and apply sterile dressing
  • Observe lot 10 minutes for hypotension inside procedure room and once hemodynamicaly stable patient can be shifted to post procedure room

Post procedure protocol

Patient is observed lot 2 hours in post procedure room

  • Monitor vitals every 10 minutes for first 30 minutes and every 30 minutes for next 1.5 hours
  • Monitor for new onset muscle weakness
  • Check for any fresh bleeding
  • Check for bladder and bowel control
  • Once patient is out of sedation and physician feel that patient can take care of their need, then patient can be discharged

Complications expected are

  • Bleeding
  • Hypotension
  • Nerve injury
  • Accidental subdural, subarachnoid, subdural, intraosseous or intravascular injection
  • Infection
  • Allergic reaction
  • Soft tissue damage

Discharge advice:

  • Advice patient to maintain pain diary
  • Antibiotic and analgesics as per institution protocol
  • In case where steroid is used, inform them that there is a chance that pain can increase in next 24-48 hours and will usually come down after 48 hours
  • Instruct the patient that if injection site is painful, then advice for local ice fomentation for 2 days then hot fomentation until feeling better
  • Advice the patient not to drive and do ski lied work for next 24 hours
  • Advice not to do exaggerated physical straining for 2 weeks
  • Give casualty contact number in case of emergency.