Bob Dalley, M.D.

6/11/99

A lumbar myelogram is a short and simple procedure (15-20 minutes) that too often is made into a long ordeal for the resident and patient because of poor technique and poor understanding of the simple geometry involved.

Assess the patient’s level of physical comfort or degree of pain. Evaluate the patient’s stress level. The patient has an I.V. access (usually a hep-lock). Make the patient comfortable. After asking about allergies, give Versed for anxiety and/or Fentanyl for pain.

Consent the patient for potential complications of local pain, headache, infection, and bleeding. Allergies and medication history.

Look for areas of spinal stenosis and avoid puncturing at those levels. This alone may save you a lot of time.

Look for prior laminectomies and AVOID puncturing at these levels which often have arachnoiditis. Assess the interspinous gaps at L2-3 or other level you are considering puncturing. Mentally record the angle needed to negotiate between the spinous processes if going midline.

Before you start, make sure the patient is wearing a gown WITHOUT SNAPS or has PJ bottoms. Too often I see the patient standing nearly naked during filming, which is unnecessary.

Lower lumbar levels are generally more prone to focal degenerative canal stenosis than L2-3, so avoid making it hard on yourself and the patient.

Use L1-2 cautiously (ONLY if you have an MRI showing the conus lies ABOVE this level), since the conus medullaris may lie this low in some patients.

Obtain any PRIOR STUDIES before you start!: MR, CT and/or myelogram

Put a pillow or bolster under the patients abdomen directly under the puncture site to reduce the lumbar lordosis and open up the interspinous distance. This is very important!

In very obese people, consider saving time by beginning with a LONGER NEEDLE.

NEEDLE CHOICE: Beveled tip spinal needle 22 ga. is generally more useful, since it may be steered by rotating the bevel direction. Sprott side-hole needle has a statistically lower incidence of spinal headache complications, but cannot be steered other than by withdrawal and redirecting it.

MIDLINE APPROACH: Make sure the patient is flat on the table. If scoliotic, roll the patient until the spinous process at the intended puncture level is midway between the pedicles.

Fluoro to identify the desired disk level. Now remember your geometry with the spinous processes projecting LOWER than the disk level.

Clean and prep the puncture site. Cover with fenestrated drape.

PALPATE!, PALPATE!, PALPATE! You learned this skill as a medical student and intern for doing decubitus LP’s for CSF. Use this skill now. When possible, palpate for the interspinous depression between the spinous processes and MARK THIS SPOT AS YOUR SKIN PUNCTURE SITE. (An easy trick to temporarily mark the skin site is to press a needle HUB into the skin firmly for a few seconds, leaving a little ring depression.) Remember, this skin puncture site will ALWAYS be several centimeters LOWER than the projection of the desired disk level. Remember the geometry from the AP & lateral scouts. (More time is lost by ignoring this step and placing the puncture side on top of the spinous process so that you keep hitting bone or go to a level higher than intended.)

Anesthetize the skin generously, and also the top of the spinous process and interspinous ligament. Use the needle as an initial probe to confirm the location of the interspinous space and then NOTE the degree of cranial angulation. Your spinal needle will use the same angle.

Place the spinal needle though the skin 2-3 cm and check position with fluoro to confirm both the appropriate spinal level and that the needle is midline. Rule: The needle will almost always have 10-30 degrees of cranial angulation. Advance the needle initially about a centimeter at a time and fluoro frequently to readjust the needle angle to stay midline.

You can steer the needle a few millimeters in any direction depending on which way you turn the bevel (same side as the notch in the hub). Rule: The needle will curve AWAY from the face of the bevel.

As you get deeper, use both hands to move the needle. One had at the hub and the other fingers pinching the needle a centimeter or less above the skin surface. This creates more control of depth. You may or may not feel the actual "pop" as you puncture the dura. For this reason, you need to empirically and frequently pull the stylet out of the needle and check for CSF, EACH TIME you move the needle (When you are close to the canal).

PARASPINOUS APPROACH: As with the midline approach, POSITIONING IS KEY to a speedy puncture. Roll the patient 10-15 degrees to the left or right so that under fluoro, you can see the "white" space between the lamina, over or just below the desired disk space.

Mark this spot either before or after prepping and draping the patient.

The needle position is different than the midline approach. Place the skin puncture site directly over the "white" space. This will usually be 2-5 cm lateral to the midline of the skin. Anesthetize the skin. Then place the spinal needle vertically.

Just as with the midline approach, the closer you are to the middle of the spinal canal when the needle punctures the dura, the fewer painful complications. Steer the needle to the midline, midway between the pedicles. Check frequently, both the needle position under fluoro and for CSF return after each needle advance.

If you feel the "pop" or if CSF return is minimal, gently push the needle 1-2 mm deeper with the stylet in. This will often reduce the chance of a mixed subdural/subarachnoid injection.

Rule: If you want to confirm CSF return or if you need to collect CSF and want to aspirate on the syringe to speed the process, make sure the bevel of the needle is either CRANIAL or CAUDAL. If it is sideways the cauda equina roots can suck up against the needle tip preventing fluid return and giving the patient a rude shock down the leg. Tipping the table head-up will increase hydrostatic pressure if needed.

If you keep hitting bone after numerous attempts or go all the way to the needle hub without getting CSF, get a cross-table lateral film to determine why your needle is out of position. Use this information to then adjust needle angulation and/or depth.

Inject the contrast under periodic fluoro. Avoid the heavy foot.

CALL THE ATTENDING TO NOTIFY YOU ARE BEGINNING THIS STEP!!! This is important, because by waiting for the Attending to arrive and supervise the actual injection, the Attending can quickly intervene if a mixed injection is suspected.

Draw up more contrast than you need. Remove any bubbles from the syringe and connecting tubing. Attach the connecting tubing to the spinal needle hub CAREFULLY USING BOTH HANDS FOR NEEDLE SUPPORT. Inject slowly. Inject a total of 15 ml of 180-200 concentration contrast for lumbar myelograms. (Use 10 ml of 300 concentration contrast for thoracic or cervical myelograms performed via lumbar puncture.)

Fluoro frequently when first injecting. You want to detect a mixed injection as early as possible. If after 3-5 ml’s you are concerned, then STOP! Get a cross table lateral and call the attending Neuroradiologist or fellow for consultation.

If the contrast is in the subarachnoid space it will disperse then collect in a somewhat central pool. A mixed injection will often collect off to one or both sides in a more irregular pattern.

After all the contrast is in, pull the needle out. It won’t hurt, and may help, if you take the time to put the stylet back in the needle before you pull it out.

Pull the drapes off the patient and image intensifier. Put a bandaide on the patient’s back.

Preserve the patient’s dignity by closing up their gown and/or trowsers.

Check to make sure the LEFT or RIGHT marker is visible on the fluoro screen.

The are many "right" ways to film the myelogram. Here is my method:

1. AP prone table flat. This gets the upper lumbar canal and sometimes the conus medullaris.

2. AP prone table head up 60-80 degrees. This drains the contrast down to the lower lumbar canal and lumbosacral junction, where 90% of the degenerative disk disease will occur.

If there is a block to contrast movement, you can try several things.

Wait 1-5 minutes with the patient upright.

3. Two right (RPO) AND two left (LPO) prone upright obliques.

4. Upright lateral weight bearing spot film. Remember to ask the tech to boost the kV to 90 for this to improve penetration of the beam. Turn the patient with the back towards you, it’s easier to judge laterality from behind. (If the projected image is angled obliquely to the rectangular field of view, push the patient’s hips forward away from you and pull his shoulders toward you.)

5. Optional: One right and one left table flat prone obliques. This is often necessary if the patient has a large patulous dural sac where the contrast tends to puddle very locally and you aren’t seeing the mid-to-upper lumbar root sleeves.

6. Cross table lateral prone and 7x17 overhead views by tech. YOU must position the table with enough head upward tilt (usually 10-20 degrees) to ensure that the contrast does not run out of the lumbosacral area, yet fills as cranial as possible.

Ask yourself this question: "Have I seen all the lumbar roots?" If you haven’t, then go back and get some more films until the answer is "YES".

7. Conus view. This is the LAST FILM YOU DO!! It dilutes the contrast making any subsequent views suboptimal. (Often not as critical if the patient has a lumbar MR.)

Prone tipping method: Hook in the feet if you plan to tip over 20 degrees. Give the patient hand holds. Tip the prone patient head down until the contrast runs up out of the lumbar area into the low thoracic area around T12. Shoot an AP spot film. A lateral decubitus spot film is optional.

Supine log-roll method: The goal is to get the contrast out of the sacral area into the thoracic area. Tip the table top head down 10 degrees while the patient is still prone. Log roll the patient into a lateral decubitus position for 20 seconds to allow the contrast to run out of the sacral area. Then log roll the patient supine on to the back and put a pillow under the head to prevent contrast from flowing into the cervical area. Now, UNDER fluoro, tilt the table horizontal and the just enough feet downward until the contrast runs from the mid thoracic area to the T12 region. STOP. Have the tech then take a 7x17 AP film centered at T12. (This method is a little more involved, but gives a "free" view of the lower thoracic cord as well as the conus.

You may now move the patient to the stretcher to go to CT. Have the patient sit up with the HEAD OF BED UP 30-40 degrees to minimize the intracranial concentration of contrast.

Ask the CT technologist to log roll the patient 360 degrees on the CT table to "MIX" the contrast up again prior to scanning. This reduces the notorious CSF / Contrast fluid levels in the sacral area.

This allows you to easily assess the specific roots and write a quick note.

Please bring a LATERAL L-SPINE FILM WITH THE DESIRED LEVELS DRAWN ON THE FILM!

Minimum 3 levels: L3-4, L4-5, and L5-S1.

Additional levels if abnormalities seen on the lateral or AP/oblique films.

3 mm contiguous sections.

Multiple angles: Pedicle to pedicle contiguous sections parallel to each respective disk.

Write the protocol desired on the CT requisition and discuss with the CT tech.

OR

Progress Note: Briefly state the preliminary findings.

Orders:

1. Bed rest X 4-6 hrs (Discretion of Attending) with head of bed up 30-45 degrees.

2. Bathroom priveledges with attendant.

3. Encourage p.o. fluids and regular diet.

4. Pain reliever of choice PRN headache.

5. Discharge after 4 hrs (If outpatient)

6. No Phenothiazines