IVB1 - Myelogram Setup

Question 1

What is myelography?

Answer 1

Radiology after injection of contrast medium into the spinal subarachnoid space which is useful for evaluating the spinal cord and cauda equina

Question 2

What are the indications for performing a myelogram?

Answer 2

1) Confirming a spinal lesion seen or suspected on radiographs
2) Defining the extent of a lesion seen on survey radiographs
3) Identifying lesions that were not seeing radiographs
4) Identifying patients that would likely benefit from surgery
5) Studying for board – really the only valid answer in this day in age

Question 3

What are the main disadvantages to a myelogram?

Answer 3

May cause worsening of prior neurologic signs
Not as sensitive or specific as CT or MRI

Question 4

What doses of contrast should be used for a myelogram that is intended to be:

1) Full spine
2) Regional

Answer 4

Full spine = 0.45ml/kg

Regional = 0.3ml/kg

Question 5

What two contrast agents are typically used for myelography?

Answer 5

Iohexol and iopamidol

Both safe and effective non-ionic contrast media

Question 6

Where is contrast media injected if performing a cervical myelography?

Answer 6

Into the cerebromedullar cistern
Ensure there is CSF flow before injecting contrast media

Question 7

Why is it preferential to use a more caudal space when performing a lumbar myelograthy (e.g. L5-6 over L4-5)?

Answer 7

There is a greater chance of injury to the spinal cord if the myelography injection is performed more cranially

Question 8

How is the movement of contrast agent different in the lumbar myelography than the cervical myelography?

Answer 8

The lumbar region is enclosed so contrast in this area can only move cranially and will therefore be pushed past any area of restricted flow

The cervical region is open to the ventricular system more cranially and therefore when resistance is met in the spinal canal, the contrast will move in the path of least resistance rather than past the restricted flow

Question 9

What is the benefit and the risk associated with advancing the needle to the floor of the vertebral canal when injecting contrast for a lumbar myelography?

Answer 9

Benefit - you are less likely to inject contrast intramedullary

Risk - More likely to traumatize the spinal cord

Question 10

How do you confirm the correct position of contrast agent when performing a myelography?

Answer 10

Fluoroscopy or a radiograph should be taken after injecting 0.5 - 1 ml of contrast agent