 Injection of intra-thecal contrast material to visualize disease or injury within the spinal column using CT and fluoroscopy  Invasive test with associated risks  Has been largely replaced by MR, which is non-invasive and therefore safer

 10-20% of patients are unable to tolerated MR secondary to claustrophobia or the inability to remain still Post-op metallic hardware (e.g. pedicle screws) and pacemakers cause distortion of MR images

 Still considered the “gold standard” for degenerative disease  Confirmation of equivocal MR findings particularly in the cervical spine (such as small tumor nodules on nerve roots)  Used to visualize nerve roots in direct coronal plane to better assess degree of compression seen on MR  Often surgeons request myelography because they are more familiar with this technique

 Osteophytic disease is accurately identified owing to exquisite bone detail The left side of the spinal cord is compressed by an osteophyte

 Subarachnoid spread of tumor and small tumor implants on nerve roots  Arachnoiditis  Nerve root compression, extradural impressions, and disc protrusion  Visualization of dilated veins in patients with spinal A-V malformations Note: MR is the test of choice for visualizing the spinal cord and soft tissues if there is no contraindication

 Patient with known severe hypersensitivity to contrast  Significant local or systemic infection where bacteremia is likely  Very recent prior myelogram (concern for contrast overdosage)

 Explain procedure to patient  Typically a lumbar approach is used to access the thecal sac since this is easier and has a lower complication rate  If patient has a complete block or lumbar access cannot be obtained it may be necessary to perform a cervical tap to analyze the cervical spine  Inform patient of risks (bleeding, HA, infection, pain, and seizure) and obtain consent  Stop all meds that lower seizure threshold (e.g. phenothiazines, antipschotics, tricyclic antidepressants, MAOIs, lithium, INH) 24 to 48 hrs prior to the procedure

 Follow lumbar puncture protocol (see appropriate section)  Once in the thecal sac CSF should be collected if it is needed for examination  Administer contrast (typically Omnipaque 300,240, 210, or 180)  Generally, 3.06g of iodinated contrast instilled intrathecally is the limit in adults (2.94g in children)  This corresponds to 10ml of contrast with a concentration of 300mg/ml or 12ml at 240mg/ml  Concentration in children should be less than 210mg/ml

 Contrast should be instilled with intermittent fluoroscopy to determine the correct amount to be administered (amount will vary depending on size of thecal sac)  AP, lateral and oblique films are obtained with patient in the prone position within 30 minutes after contrast injection (standing views may accentuate disk herniation)  Postmyelogram CT (several hours after administration of contrast)  Sections angled through the disks  Contiguous straight transaxial sections allow high- quality sagittal and coronal reconstruction

Caudal termination of the subarachnoid space Nerve roots of the cauda equina Spinous process of L3 L4 vertebral body Sacral promontory

 sd Caudal termination of subarachnoid space Lateral extensions of subarachnoid space L4 spinal nerve L5 spinal nerve S1 spinal nerve L4 pedicle Cauda Equina

Axial Sagittal reconstruction

 Lumbar Approach  Easier, less patient anxiety, and lower complication rate when compared to cervical approach  Contrast is inserted as a bolus in the lumbar region of the spine and maintained as a bolus as the patient is tilted downward  Patient’s head is maintained in a hyperflexed fashion to prevent contrast from entering the intracranial sac  Once contrast is in the cervical region, the patient is flattened and the contrast pools in the natural lordosis of the cervical spine

 Cervical Approach  Reserved for patients with complete block or severe degenerative changes, scoliosis, or infection that prevent lumbar tap  Risk is increased (still low at.17 percent) owing to the presence of the spinal cord and vertebral arteries  Needle is inserted just anterior to the spinal lamina line at C1-C2 using cross-table lateral and AP fluoro  Needle is inched forward using lateral fluoro to ensure that the needle does not puncture the spinal cord  Permanent damage from puncturing the spinal cord is very rare unless contrast is injected into the cord itself.  Low dose contrast should be instilled into the thecal sac for cervical examination

 Obtain AP, lateral, and oblique films  Postmyelogram CT scans are obtained through suspicious levels seen on plain films  Sections angled through the disks  Contiguous straight transaxial sections allow high-quality sagittal and coronal reconstruction

Lateral AP

Sagittal Reconstruction Axial section showing right-sided disk herniation

 Bed rest for 4 hrs  No heavy lifting or bending for 24 hrs  Keep head elevated to limit contrast flowing intracranially  Ibuprofen or Acetaminophen prn pain and HA  Resume restricted meds after 24 hrs