Circulatory Shock, types and stages, compensatory mechanisms
Myelography
1.
2. 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.
4.
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.
5.
6.
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.
7.
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 (T1T12), 5 lumbar pairs
(L1-L5), 5 sacral
pairs (S1-S5), and 1
coccygeal pair.
8.
The brain and
spinal cord are
enclosed in three
continuous,
protective
membranes called
meninges.
9. 3. Pia mater
2. Arachnoid
1. Dura mater
3 Layers of the Meninges
10.
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.
11.
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
12.
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
13. CSF serves four primary purposes:
1.Buoyancy
2.Protection
3.Chemical stability
4.Prevention of brain ischemia
14.
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.
15.
It houses and
protects the
spinal cord in its
spinal canal, and
hence is
commonly called
the spine, or
simply
backbone.
16. 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.
17. 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.
18. 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.
19.
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.
20.
Omnipaque (Iohexol)
– a nonionic, water
soluble contrast that
is less toxic than
contrast media
previously used in
myelography.
21.
Isovist (Iotrolan) – another nonionic, watersoluble 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.
22.
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.
23.
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.
24.
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.
25.
26.
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)
27.
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.
28.
1.
2.
1.
2.
Body position for lumbar puncture:
Prone position.
Left lateral position, with the spine flexed to widen
the interspinous space.
Body position for cervical puncture:
Erect position.
Prone position, with the head flexed to open the
interspinous space.
29.
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 L3L4.
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.
30.
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.
31.
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.
