Myelography Myelography

MyelogramMyelogramMyelogram: Myel/o means spinal

cord or bone marrow – gram: …………

Note DO NOT confuse for my/o, which means muscle)

The spinal cord is part of the Nervous System. Therefore, this a study focused on the spinal cord anatomy which could be affected by the bony anatomy of the spine.

Basic Spinal Cord Basic Spinal Cord AnatomyAnatomyFor description, the central

nervous system (CNS) is divided into◦Brain◦Spinal cord

CNS tissue composed of two main portions◦Gray matter = outer portion or cortex◦White matter = inner portion

Spinal CordSpinal CordSlender, elongated

structure Consists of an inner gray

cellular substance and an outer white fibrous substance◦Gray substance forms H-

shape seen on transverse section

Extends from the brain to the L1-L2 space

Conus medullaris = pointed end of spinal cord

SPINAL CORDSPINAL CORDGray substance forms H-shape seen on transverse section

SPINAL CORDSPINAL CORDFilum terminale = delicate fibrous portion that connects the terminal tip to the first coccygeal segment

Spinal CordSpinal CordConnected to 31 pairs of spinal nerves

◦Arise from roots on each side of cord◦Transmitted through intervertebral and

sacral foraminaCauda equina refer to spinal

nerves

MeningesMeningesThree continuous, protective

membranes that enclose the brain and spinal cord

Pia mater = inner sheath; highly vascular and closely adhered

Arachnoid = delicate central sheath

Subarachnoid space = wide space between arachnoid and pia mater◦Continuous with ventricular system

MeningesMeningesSubarachnoid cisterns = areas of

subarachnoid space that are increased in width

Cisterna magna = widest of subarachnoid cisterns◦Located in lower posterior fossa

between base of cerebellum and dorsal surface of medulla oblongata

MeningesMeningesDura mater = outermost

meningeal layer; strong, fibrous◦Separated from arachnoid by

subdural space◦Separated from vertebral periosteum

by epidural space◦These spaces do not communicate

with ventricular system

MeningesMeninges◦Dural sac (Thecal sac) = encloses cauda equina

Myelography (procedure)Myelography (procedure)General term applied to the radiologic

examination of the CNS structures situated in the vertebral canal

Requires contrast introduction into the subarachnoid space by spinal puncture (sterile procedure)

Puncture made at L2-L3 or L3-L4 space◦ May also be introduced into cisterna magna

at C1 and occipital bone (this is no longer standard procedure in USA)

Standard ProcedureStandard ProcedureStandard procedure is the most

common way to proceed in a determined area or region.

In USA, myelograms are commonly done injecting in the thecal sac using a Sprotte Needle. (this is a blunt needle that has been replacing the spinal needle)

Water soluble contrast

Thecal SacThecal SacCommonly located

between L3 and L5Made by the

outermost meninge

Which is the ?Dura mater =

outermost meningeal layer; strong, fibrous

MyelographyMyelographyUsually performed as outpatient

basis◦Patients held for recovery after

procedure for 4 to 8 hours, then released to go home

MRI often used insteadMyelography still used for patients

with contraindications for MRI◦Pacemakers and metal fusion rods

MyelographyMyelographyContrast is generally water-soluble,

nonionic, and preservative free iodinated medium

Invasive ProcedureRoom should be prepared by RT before

patient arrival ◦ Table and equipment (FL IR) cleaned◦ Footboard and shoulder supports attached◦ Radiographic equipment checked◦ Image intensifier locked to prevent accidental

contact with sterile field or spinal (Sprote) needle

MyelographyMyelographyPremedication rarely needed

(allergies)Patient should be well hydratedProcedural details, including table

movement and sensations, should be explained

Scout images made: AP & LatProne position usually used for

spinal puncture◦Lateral with spine flexed may also be

used

MyelographyMyelographyLocal anesthesia given at puncture

siteSpinal needle insertedCSF usually withdrawn and sent to

laboratoryContrast injected and needle removedTable angle and gravity used to move

contrast under fluoroscopySpot images taken as needed

(protocol)

MyelographyMyelographyIf contrast is moved into cervical

area, head is positioned in acute extension to prevent contrast from entering ventricular system (varies depending on T, L and/or C spine◦Acute extension compresses cisterna

magna and is the only position that will prevent contrast from entering ventricles

MyelographyMyelographyPostprocedure monitoring

required◦Head and shoulders elevated 30 to 45 degrees

◦Bed rest for several hours (Dr instructions)

◦Fluid encouraged (caffeine not recommended)

◦Puncture site checked before release

MyelographyMyelographyInstructions for a possible contrast

reactionInstructions for a possible spinal

headache

Spinal Cord Spinal Cord AnatomyAnatomy

Transverse section of spinal cord