MYELOGRAPHY

Also known as Myelogram

is a type of radiographic examination that uses a contrast medium to detect pathology of the spinal cord, including the location of a spinal cord injury, cysts, and tumors.

MYELOGRAPHY

Anatomy &Physiology

is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain.

It begins at the occipital bone and extends down to the space between the first and second lumbar vertebrae; it does not extend the entire length of the vertebral column.

Spinal Cord

It is around 45 cm (18 in) in men and around 43 cm (17 in) long in women. Also, the spinal cord has a varying width, ranging from 1/2 inch thick in the cervical and lumbar regions to 1/4 inch thick in the thoracic area.

The spinal cord is connected to 31 pairs of spinal nerves, each roughly corresponding to a segment of the vertebral column: 8 cervical spinal nerve pairs (C1-C8), 12 thoracic pairs (T1-T12), 5 lumbar pairs (L1-L5), 5 sacral pairs (S1-S5), and 1 coccygeal pair.

The brain and spinal cord are enclosed in three continuous, protective membranes called meninges.

Meninges

3 Layers of the Meninges

3. Pia mater

2. Arachnoid

1. Dura mater

Dura mater – ( Latin, "hard mother"), is the outermost layer, and it forms a tough protective coating. It is separated from the Arachnoid by the subdural space and from the vertebral periosteum by the epidural space.

Arachnoid mater – is the middle protective layer. It is a thin, weblike membrane without blood vessels that lies between the dura and pia maters.

Pia mater – ( Latin, "tender mother"), is the innermost protective layer. It is very thin and contains many nerves and blood vessels that nourish the underlying cells of the brain and spinal cord.

Subarachnoid space The space between the arachnoid and the

underlying pia mater Filled with CSF Bathes brain and spinal cord with nutrients Cushions against shock and blows Where contrast media is injected for

myelograms

Cerebrospinal fluid (CSF) is the tissue fluid of the brain and spinal cord. It surrounds and cushions the structures of the central nervous system.

Total adult CSF volume is 150 ml

Cerebrospinal Fluid

CSF serves four primary purposes:

1.Buoyancy2.Protection3.Chemical stability4.Prevention of brain

ischemia

usually consists of 24 articulating vertebrae, and nine fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs.

Vertebral column

It houses and protects the spinal cord in its spinal canal, and hence is commonly called the spine, or simply backbone.

The cause of arm or leg numbness, weakness, or pain.

Narrowing of the spinal canal (spinal stenosis).

A tumor or infection causing problems with the spinal cord or nerve roots.

A spinal disc that has ruptured (herniated disc).

Inflammation of the membrane that covers the brain and spinal cord.

Problems with the blood vessels to the spine.

INDICATIONS

Blood in the CSF - the presence of blood in the CSF indicates probable

irritation within the spinal canal, which can be aggravated by the contrast medium.

Arachnoiditis (inflammation of the arachnoid membrane)

- the contrast medium may increase the severity of the inflammation.

CONTRAINDICATIONS

Increased intracranial pressure - tapping of the subarachnoid space with needle insertion may

cause severe complications to patient as the pressure equalizes between the areas of brain and the spinal cord.

Recent lumbar puncture (within 2 weeks of the current procedure)

- Performing Myelography on a patient who has had a recent lumbar puncture may result in extravasations of the contrast medium outside the subarachnoid space through the hole left by the previous puncture.

Previous reaction to the same contrast medium.

Non-ionic, water-soluble, iodine-based contrast media.

Water soluble contrast media provides excellent radiographic visualization of the nerve roots, is easily absorbed into the vascular system, and is excreted by the kidneys.

Contrast Media

Omnipaque (Iohexol) – a nonionic, water soluble contrast that is less toxic than contrast media previously used in myelography.

Isovist (Iotrolan) – another nonionic, water-soluble contrast agent that tests have shown to be even less toxic than Omnipaque.

DOSAGE: The dosage is recommended by the manufacturer and

varies with the concentration of the medium used and the area of the spine under examination.

In general, a range of approximately 9-15 ml is used.

Injectable sedative/muscle relaxant usually is administered 1 hour before the examination to reduce anxiety and relax the patient.

The type and amount of premedication used are determined by the radiologist who performs the procedure.

Premedication of the patient for Myelography

is rarely necessary.

Premedication

Solid foods should be avoided for several hours before the exam, but fluids may be continued.

The patient should be well hydrated before the procedure.

Informed consent should be secured. The patient should remove all clothing and don a

patient gown. The procedure should be fully explained to the

patient, and an adequate history should be taken. Vital signs are taken before commencement of

the procedure to serve as a baseline.

Patient Preparation

Some drugs should be stopped one or two days before Myelography. These include certain antipsychotic medications, antidepressants, blood thinners, and some other drugs. The most important type of medication that must be stopped is blood thinners (anticoagulants).

Do NOT take dipyridamole (Persantine) or warfarin (Coumadin) within 72 hours prior to the test. These medications are often referred to as blood thinning pills.

Needle Placement & Injection Process

Introduction of contrast medium for myelography is accomplished via puncture of subarachnoid space. Generally two locations are used as puncture sites:

Lumbar (L3-L4) Cervical (C1-C2)

Of these two locations, the lumbar area is safer and easier on the patient and is used most often for the procedure.

After the puncture site has been selected the radiologist may use fluoroscopy to facilitate needle placement.

Body position for lumbar puncture:1. Prone position.2. Left lateral position, with the spine flexed to widen

the interspinous space. Body position for cervical puncture:1. Erect position.2. Prone position, with the head flexed to open the

interspinous space.

Puncture Positions

The procedure begins with a lumbar puncture. The lumbar site is cleaned and a local anesthetic is applied. The lumbar puncture needle is inserted generally at the level of

L3-L4. The needle is slowly advanced until spinal fluid flows from the

lumen of the needle (after withdrawal of stilette). The stylet is returned and the needle advanced an additional 2

mm to ensure that the entire bevel of the needle is within the subarachnoid space.

A small amount of spinal fluid is withdrawn to maintain stasis and to provide a sample.

Contrast medium is injected under fluoroscopic guidance. Under fluoroscopic guidance, an AP or PA, or both, obliques, and a

lateral of the spine are generally taken. Before overhead imaging, the patient is tilted slightly toward the

feet to allow pooling of the contrast material in the subarachnoid space between low L1.

Procedure

PA and lateral spine Prone decubitus spine Lateral flexion and extension images to

demonstrate dynamic stenosis, spinal stability, and degree of movement of disk protrusion.

Imaging:

The patient should be on bed rest for 8-24 hours, with the head slightly elevated.

The patient should drink plenty of fluids. The patient should be instructed to notify

the physician or medical staff if he or she experiences severe headache or nausea and vomiting.

Post Procedure Care:

Lumbar myelogram (AP, Lateral & both oblique views)

1

7

NO DYE

DYE

CERVICAL MYELOGRAM - LATERAL VIEW LUMBAR MYELOGRAM - AP

VIEW

THE END.Reported by: JOAN C. VARGAS