Radiculogram classification
- General
- Classifying the pattern of contrast solution flow around the nerve root after injection.
- The radiculogram is broadly classified into four types:
- "Arm" pattern:
- Defined as a thick band of dye around the entire thickness of the nerve root. This pattern typically demonstrated the spread of the dye along the nerve root and the thecal sac.
- Associated with good outcomes after SNRB
- "Arrow" pattern:
- Defined by the flow of the dye around the medial aspect of the nerve root, tracking down around the thecal sac. This pattern also typically demonstrated the spread of the dye along the nerve root and the thecal sac.
- Associated with good outcomes after SNRB
- "Linear" pattern:
- Denoted as a single streak of dye along the lateral aspect of the nerve root. Similar to the "arm" and "arrow" patterns, this indicated spread of the dye along the nerve root and the thecal sac.
- Associated with good outcomes after SNRB
- "Splash" pattern:
- Defined as an irregular distribution of the dye around the nerve root. This pattern indicated a non-spreading distribution of the dye.
- The "splash" pattern of radiculogram were predictive of a failed SNRB (P = .005).
- The non-spreading "splash" pattern could possibly be due to venous engorgement and perineural adhesions around the nerve root, which impede the spread of the drug around the inflamed nerve root's nociceptive regions. Despite this, MRI evidence of nerve root anomalies was not found in patients with the splash pattern, nor was intraoperative evidence of nerve anomaly in those who subsequently required surgery.
Selective Nerve Root Block (SNRB) technique
- Patient Positioning:
- The patient is placed in a prone position on a radiolucent table, without any sedation.
- Image Intensifier Setup:
- For L4 and L5 nerve, the image intensifier is tilted towards the side of radicular pain to achieve an oblique view of the spine and visualise the "Scotty Dog".
- For the S1 nerve root , the image intensifier is positioned to visualise the sacral foramen.
- Anaesthesia and Needle Introduction:
- The skin overlying the neck of the "Scotty Dog" (or the sacral foramen for L5-S1) is anaesthetised with 5 mL of 2% lignocaine.
- A 23-gauge spinal needle is introduced end-on towards the "safe triangle" (above the nerve root and below the pedicle).
- Needle Position Verification and Contrast Injection:
- The correct needle positioning is verified under anteroposterior and lateral fluoroscopic control.
- At the angle between the TP and Pars. This allows injection to be in the shoulder of the nerve however has the higher chance of damaging the radicular artery causing bleeding
- At the inferior (axillae of the nerve) border of the foramen.
- 1 mL of contrast solution (Ioxehol) is injected to confirm the needle is in the desired position close to the selected nerve root.
- The contrast dye also ensures that the drug is not administered intravascularly.
- Pain Reproduction and Medication Injection:
- Pain reproduction is elicited in all patients before the corticosteroid is infiltrated.
- Once the radiculogram is visualised, 2 mL of 0.5% bupivacaine mixed with 80 mg of triamcinalone is injected around the nerve root.
- Post-Procedure Care:
- The needle entry site is sealed with a sterile dressing.
- Patients are kept under observation for 45 minutes.
- Patients are discharged on the same day with a standard post-injection protocol, which includes:
- Rest for a day.
- Limited activities as per comfort limits.
- Tablet pregabalin 75 mg at bedtime for 3 weeks.
- Follow-up:
- Patients are serially followed up at 3 weeks, 6 weeks, 6 months, and 1 year.
- During clinical assessment, clinical data and outcome scores are independently documented by a physician assistant.
- Patients who fail to have adequate pain relief or experience recurrent pain are offered microsurgery.
- All patients received the nerve block only once.
Made with Bullet