Epidural Steroids Flashcards
What is the chemical mechanism proposed for
radicular pain?
When the intervertebral disc is damaged, it releases the
enzyme phospholipase A2, which promotes the release of
arachidonic acid into the epidural space. The arachidonic acid
instigates an inflammatory response that is mediated by
leukotrienes and prostaglandins. Neuropeptides such as
substance P and calcitonin gene-related peptide also become
involved in elevating the degree of inflammation.
Wong, CA. Spinal and Epidural Anesthesia. New York:
McGraw-Hill; 2007: 349.
What are the mechanisms of action by which
steroids injected into the epidural space reduce
inflammation?
Corticosteroids injected into the epidural space inhibit
prostaglandin synthesis, stabilize cell membranes, inhibit the
synthesis and action of neuropeptides such as substance P,
inhibit phospholipase A2 activity, inhibit the vasoneurium
vascular response, and exert an anesthetic-like action on C
fibers (but specifically, not A-beta fibers).
Wong, CA. Spinal and Epidural Anesthesia. New York:
McGraw-Hill; 2007: 349.
Clinical practitioners dilute epidural steroids with
either local anesthetic or saline. Which is more
effective?
Neither diluent has been shown to be more effective than the
other in relieving symptoms, although there are some authors
who recommend using local anesthetic as the diluent when
muscle spasms are present.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1576.
What is the primary inflammatory mediator
implicated in disc herniation?
Phospholipase A2, which is the rate-limiting enzyme in the
conversion of arachidonic acid into prostaglandins and
leukotrienes
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1575
When during the course of illness is epidural steroid
injection most beneficial?
It is most advantageous early in the course of the disease or
during a severe exacerbation of a chronic course of pain due to
disc herniation.
Wong, CA. Spinal and Epidural Anesthesia. New York:
McGraw-Hill; 2007: 349.
What is the minimum time to wait between epidural
steroid injections before attempting an additional
injection and why?
No additional injections should be given for at least a week to
allow time for the corticosteroid to exert its effects. Also,
repeated doses of steroids can result in suppression of the
hypothalamus-pituitary-adrenal axis.
Wong, CA. Spinal and Epidural Anesthesia. New York:
McGraw-Hill; 2007: 349.
What is the efficacy rate of epidural steroid injection?
Epidural steroid injection has been demonstrated to be effective
at reducing leg pain, the degree of sensory deficit, and the need
for opioids during the acute phase of the injury. The incidence
of surgery, however, has been shown to be identical between
patients who receive epidural injections and those who do not.
Studies have also demonstrated that the improvements seen
with epidural injections are transient, lasting only about 3
months. Because of these findings, the American Academy of
Neurology recommends against the routine use of epidural
steroid injections.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 1651-1652.
What steroid is recommended for cervical
transforaminal injections?
Dexamethasone
Wong, CA. Spinal and Epidural Anesthesia. New York:
McGraw-Hill; 2007: 1511.
What is the most common injection site for cervical
epidural steroids and why?
The most common approach is the C6-C7 or C7-T1 interspace
because of the large interlaminar distance and the prominence
of the C7 vertebra. This is done regardless of the level of
pathology. Practitioners rely on the flow of the injected
medication to the site of injury.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1576.
Which steroid for epidural use is considered the least
irritating?
Methylprednisolone
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1576.
Which steroid for epidural use results in the least
amount of sodium retention?
Triamcinolone
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1575.
Why is vascular injury a significant risk with cervical
transforaminal epidural steroid injections?
Several blood vessels, such as the vertebral, ascending
cervical, and deep cervical arteries pass within 2 mm of the
path of the needle for this procedure. These small vessels can
be transected by a needle or compressed by the volume of
steroid injected.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 1652.
What are the potential complications of epidural
steroid injections?
Complications include needle trauma, vasospasm, and
infection. The glucocorticoids used in the injection can interfere
with glucose metabolism, resulting in elevated glucose levels for
about a week following treatment. Serum cortisol levels can
also be suppressed for an average of one month.
Cerebrovascular events can occur with cervical ESI’s due to
vasospasm, trauma to the vertebral artery, or embolism from
steroid particles. Inadvertant injection into the radicular artery
adjacent to the nerve root can result in spinal cord injury.
Injection into a low-lying artery of Adamkiewicz can even occur
as a result of some lumbar injections.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 1652.
What are the advantages of using a transforaminal
approach to an epidural steroid injection over an
interlaminar?
The transforaminal approach allows the steroid to be injected in
the anterolateral epidural space closer to the point of disc
herniation. Studies have demonstrated that transforaminal and
interlaminar injections are equally efficacious in reducing
symptoms, but patients who undergo transforaminal injections
have a reduced incidence of surgery after treatment.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 1651.
Between the interlaminar and transforaminal
approaches to epidural steroid injection, which one
can be performed using a paramedian approach?
Both can be performed from a midline approach, but the
interlaminar can be performed using the paramedian approach.
Longnecker DE, Newman MF, Brown DL, Zapol WM.
Anesthesiology. 2nd ed. New York: McGraw-Hill; 2012: 1576.
