Clinical Refresher for Myelography

Module Overview

• Instructor: Vicki Sanders, MSRS, RRA, RTR, CV, CT
• Objectives:
  • Identify indications, contraindications, and complications of myelography
  • Explain pre-procedure preparation and assessment
  • Apply radiation protection and technical factors
  • List equipment and contrast materials used
  • Describe patient positioning and step-by-step procedures for cervical, thoracic, and lumbar myelography
  • Discuss post-procedure care and instructions

Pre-Procedure Preparation and Assessment

• Patient Evaluation:

  • Procedure must be cleared by a physician
  • Ensure patient is well hydrated
  • Nothing by mouth for 4 to 6 hours prior to procedure
  • Evaluate medications affecting seizure threshold; may need to withhold 48 hours before and 24 hours after

• Patient History:

  • Record current medications, allergies, pregnancy status, symptoms, previous spinal surgeries, history of seizures
  • Review previous studies and orders for laboratory testing of CSF samples
  • Document opening/closing pressure and fluid to be removed

• Informed Consent:

  • Must include:
    • Purpose and nature of the procedure
    • Risks, complications, and expected benefits
    • Risks of refusal and reasonable alternatives
    • Opportunity for questions

• Risks of Myelography:

  • Post-procedure spinal headache
  • Infection, bleeding, seizures, cerebral herniation
  • Local pain, nerve root trauma, possible extraarachnoid injection
  • Numbness, cyst formation, abducens nerve palsy

Equipment and Contrast Materials

• Equipment Required:
  • Lidocaine 1% without epinephrine
  • Two 18-gauge needles, one 25-gauge needle
  • Manometer, three-way stopcock, plastic tubes
  • Syringes for lidocaine and contrast
  • Sterile fenestrated drape, sponges, antiseptic solution (avoid chlorhexadine near meninges)
  • Sterile gloves, hemostat, marker, spinal needle (22 or 25 gauge)
  • Non-ionic water-soluble contrast media (Iohexol, Iopamidol)
    • Dose: 3,060 mg iodine max; 300 mg iodine/mL for adults
    • Contraindication: Ionic contrast due to seizure risk

Patient Positioning and Procedure Steps

Cervical Myelography

1. Hyperextend patient's head on chin rest
2. Tilt table into Trendelenburg position to direct contrast
3. Obtain PA images, oblique views, and cross-table lateral images

Thoracic Myelography

1. Roll patient into lateral/supine position with head elevated
2. Tilt table into Trendelenburg position
3. Obtain AP and lateral views, oblique views if necessary

Lumbar Myelography

1. Confirm spread of contrast in lumbar region
2. Obtain PA images, oblique views, cross-table lateral images
3. Move to stretcher carefully, transport to CT

Radiation Protection and Technical Factors

• Table and Imaging Techniques:

  • Use tilting fluoroscopy table and support devices
  • Pulsed fluoroscopy (7.5 pulses/sec) and LIH (last image hold) to reduce exposure
  • Manual collimation of images and field of view
  • Use of lead aprons and protective gear for personnel

• Technique Adjustments:

  • Adjust KVP and MA automatically for lowest exposure
  • Limit beam time using intermittent fluoroscopy

Post-Procedure Care and Instructions

• Image Quality Evaluation:

  • Verify proper level of spinal column with visible contrast
  • Review images to ensure adequate opacification by a radiologist
  • Ensure no anatomical information is lost in image processing

• Patient Discharge:

  • Address any questionable findings before discharge to avoid repeat procedures
  • Provide appropriate post-procedure instructions

Conclusion

• Importance of thorough preparation, risk assessment, and patient communication in myelography procedures.