Chapter 44 Interlaminar Epidural Steroid Injections for Lumbosacral Radicular Pain Flashcards
Most back pain seen in the primary care setting is largely due to
muscular and ligamentous strain and spasm.
Back pain may arise from the facet joint and the paraspinal muscles in the dorsal compartment, which is innervated by
the medial and lateral branches of the dorsal rami.
Back pain may also arise from the anterior and posterior longitudinal ligaments and the annulus of the disc in the ventral compartment, which
is innervated by
the sympathetic chain and the sinuvertebral nerves.
An annular tear may lead to
continued leakage of
nucleus pulposus material and associated chronic inflammation and altered central processing.
Radicular pain results from
chemical irritation and inflammation of the
nerve root, which may be swollen and edematous.
Disc herniation (HNP) results in
release of large amounts of phospholipase A2
(PLA2), which favors production of prostaglandins and leukotrienes from cell membrane phospholipids, and resultant inflammation, sensitization of nerve endings, and pain generation.
External pressure on
nerve roots by bone can result in
venous obstruction, neural
edema and eventual fibrosis of the nerve and surrounding tissues.
Degenerative disc
disease and tears of the annulus fibrosus may result in
leakage of this enzyme from the nucleus pulposus, producing chemical irritation of the nerve roots.
The primary indication for steroid injections (ESIs)
radicular pain due to nerve rootinflammation, irritation, and edema.
The most well-studied steroids used in ESIs are
methylprednisolone acetate and triamcinolone diacetate. The concentration of both is typically 40 to 80 mg/ml; the most common therapeutic dose range is 40 to 80 mg.
Steroid drugs are often diluted with
normal saline or local anesthetic with equivalent results. The volume of injectate varies greatly with the site of injection
How much volume is injected into the lumbosacral
epidural space?
The injection of 3 to 5 ml has been used in the lumbosacral epidural space. These volumes bathe both the injured
nerve root that is adjacent to the disc pathology and
additional nearby roots that are also inflamed
How much volume is injected into the cervical
epidural space?
In the less capacitant cervical space, 2 to
4 ml should be adequate to bathe the cervical roots at
several levels.
How much volume is injected into the caudal
epidural space?
When the caudal route is selected, a larger volume (approximately 10–15 ml) is used to ensure adequate spread of injectate to the midlumbar level.
MECHANISM OF ACTION of steroids
Steroids induce synthesis of a PLA2 inhibitor, preventing release of substrate for prostaglandin synthesis. Steroids may also decrease back pain due to inflammation and sensitization of nerve fibers in the posterior longitudinal ligament and annulus fibrosus. steroids
also block nociceptive input.
Response to ESI was predicted by
nerve root irritation, recent onset of symptoms, and the absence of psychopathology
Indications of ESI
ESI was therapeutic for patients with herniated disc and either nerve root irritation or compression. These latter two factors
were also associated with efficacy in patients with
spondylolisthesis or scoliosis. efficacy
for patients with radicular pain syndromes or herniated nucleus pulposus.
five most
important factors influencing the outcome of ESI
accuracy of the diagnosis of nerve root inflammation,
shorter duration of symptoms, no history of previous surgery, younger age of the patient, and location of the needle at the level of pathology
four selection criteria for ESI:
an intention to produce short-term pain relief during physical therapy/
rehabilitation; evidence of nerve root involvement; unfavorable response to 4 weeks of conservative therapy; and no contraindications to injection.
Patients with radicular
pain should fit into one of these categories:
sensory signs and symptoms of radiculopathy, disc herniation, tumor infiltration of nerve root, postural back pain with radicular symptoms, or acute back pain and radicular symptoms superimposed on more chronic back pain
EFFICACY OF ESI
effective in acute lumbosacral radiculopathy.
selection of patients
for cervical ESI by the
presence of radicular pain and either physical or radiologic findings corresponding to the painful nerve root
use of fluoroscopy would
decrease technical failures with ESI up to
50% to 60%
fluoroscopic guidance remains the gold standard for
caudal epidural injection in adults
fluoroscopy with epidurography can improve accuracy of blindly performed cervical ESIs by
ensuring correct needle placement and delivery of medication to the area of pathology
use of fluoroscopy
with contrast epidurography should increase
accuracy of needle placement in the epidural space and targeted delivery of injected medication to the site of pathology, which may often be unilateral spread into the anterior epidural space.
Complications of ESI can be separated into
those related to epidural technique and those related to injected
drugs.
Technical side effects include
back pain at the injection site and temporarily increased radicular pain
and paresthesias without persistent morbidity.
occur during procedures performed with the patient in the sitting position.
Acute anxiety, lightheadedness, diaphoresis, flushing, nausea, hypotension, and vasovagal syncope
the most common complication of epidural injection.
Headache may occur after accidental dural puncture
Side effect observed after
cervical ESI
Nonpostural headache
due to subarachnoid air injection, Pneumocephalus
associated with rapid,
large-volume caudal steroid injection performed under general anesthesia.
Retinal hemorrhage
epidural hematoma formation complication
acute paraplegia
Tuohy needle insertion for cervical ESI complication
- bilateral upper extremity
- radicular pain
- anterior spinal subdural hematoma
- intrinsic spinal cord damage and permanent neurologic symptoms
- paraplegia (occurred secondary to either a discal herniation or cord ischemia due to dominant radiculomedullary artery injury similar to the injuries described clasically with transforaminal techniques)
essential to reduce the risk of permanent neurologic deficit from epidural hematoma
Early diagnosis of epidural hematoma and immediate surgical decompression and evacuation
Minor complications
that came to full resolution within 24 hr, such as
flushing, vasovagal episodes, exacerbation of symptoms, and insomnia,
complications
could be reduced with
increased level of expertise, fluoroscopic
guidance, placement of needle at C6–C7 or lower
(where the epidural space is more capacitant), and with preinjection review of patient imaging
Infectious complications of ESI include
bacterial meningitis
and epidural abscess.
How did patients with epidural abscess present
3 days to 3 weeks after injection with fever, spinal pain, radicularpain, or progressive neurologic deficit;
treatment of epidural abscess
Rapid diagnosis and therapy, including surgical drainage, appears
necessary if one hopes to achieve patient recovery with intact neurologic function. Magnetic resonance imaging (MRI) appears to be the procedure of choice for the diagnosis of epidural abscess
predispose patient to epidural abscess formation
combination of diabetes
and steroid immunosuppression
major important components of
aseptic technique
removal of watches and jewelry, antiseptic
hand washing, protective barriers, hats and masks,
sterile gloves, proper choice and use of skin sterilizing solution, proper draping and maintenance of sterile field, and proper dressing technique.
Complications related to the drugs used for ESI include
pharmacologic effects of steroids and possible neurotoxity.Temporary development of Cushing’s syndrome, weight gain, fluid retention, hyperglycemia, hypertension, and congestive heart failure have all been reported after ESI.
Effects of ESI on adrenals
Adrenal suppression is a well-known result of ESI. Plasma cortisol levels are decreased for up to 3 weeks after epidural injection of 80 mg of methylprednisolone acetate
Neurotoxicity has been attributed to
spinal injections
of depot steroids or to their preservatives.
reported after repeated intrathecal steroid injections in patients with multiple sclerosis.
Adhesive arachnoiditis. There are no case reports of arachnoiditis after ESI
alone.
intraspinal methylprednisolone acetate recommended against its intrathecal use because of
potential polyethylene glycol toxicity.
several recommendations
to avoid further complications of ESI
meticulous aseptic technique, especially in diabetic patients, to prevent infectious sequelae.
Placing a needle transforaminally should theoretically result in a
a better delineation of the nerve root and possibly
better anterior epidural spread
concerns associated with transforaminal injection
With the concerns over
neurologic injury associated with transforaminal injection,
interlaminar injections still remain very common, especially at the cervical level.
Advantages of interlaminar injections
interlaminar injections are
simpler to perform for those with less expertise in fluoroscopy and less interventional pain experience
A great limitation
with the interlaminar approach
is the obliteration of the posterior epidural space from previous surgery, which would make needle entry into the posterior epidural space more difficult.
indications for ESI
with acute radicular pain, herniated disc, or new radiculopathy
superimposed on chronic back pain or cervical
spondylosis, lumbosacral radicular pain syndromes.
required to justify use of ESI
The presence of nerve root irritation
ESI should be avoided if there is
concern about localized or
systemic infection or clotting function. One should also consider the added risk of infection with diabetes and the reduced chance of success if there has been previous back
surgery, prolonged symptoms, substance abuse, disability, or litigation issues
employed as the steroid drug
Methylprednisolone acetate 80 mg, or triamcinolone diacetate. The diluent
usually is normal saline, with the total being 3 to 5 ml at
the lumbar level, 2 to 4 ml at the cervical level, and 10 to
15 ml when the caudal approach is selected
Lumbar ESI is performed
as close to the level of radicular pathology as
possible, often using a paramedian approach to target the lateral aspect of the interlaminar epidural space on the involved side.
Cervical ESI is most often performed at
the C7–T1 level; entry at higher levels is not advisable because of the noncontinuity of the ligament flavum at
these levels. A guided epidural catheter is inserted and advanced to the desired level under fluoroscopic control.
Rules of repeat injection
The injection is not repeated if there is complete relief. If partial relief occurs, a second injection is offered, but a third injection is only rarely used. Repeat injections are not offered when benefit is transient, but may be considered after prolonged responses of 6 to 12 months or longer.
Exclusion criteria of ESI
ESIs should play a role as part of a multidisciplinary plan to manage back, neck, and radicular pain syndromes. With exclusion of patients who may not tolerate steroid medications
(or dosing alterations) and with exclusion of patients
with significant infection control problems and
bleeding diathesis
Positive Factors
History
- Radicular pain
- Radicular numbness
- Short symptom duration
- Absence of significant psychological factors
Examination
- Dermatomal sensory loss
- Motor loss correlated to symptoms
- Positive straight-leg raise
Laboratory
- Abnormal EMG findings related to symptoms
- Lumbar herniated disc
- Cervical spondylosis
Evaluation Criteria: Selection of Patients for Epidural Steroid Injection
Negative Predictive Factors
History
- Axial pain primarily
- Work-related injury
- Unemployed due to pain
- High number of past treatments
- High number of drugs taken
- Compensation due to pain
- Litigation pending
- Previous back surgery
- Smoking history
- Very high pain ratings
Examination
- Myofascial pain prominent
Laboratory
- Normal cervical spine imaging results
- Cervical herniated disc
Evaluation Criteria: Selection of Patients for Epidural Steroid Injection
Increased Risk
Immunosuppression Diabetes Peptic ulcer disease Tuberculosis AIDS Bacterial infection
