X-rays, CT Scans and MRI's provide excellent images of various spinal
disorders. However, they cannot show pain. Spinal injections, typically
used to control pain are also used diagnostically to locate the
pain source. Diagnostic spinal injections include discography (discogram),
selective nerve root block (SNRB), sacroiliac joint injection and facet
In the spine, nerve roots and intervertebral discs are the usual sources
of pain. For example, a lumbar herniated disc may entrap a nearby nerve
causing buttock and leg pain. A pinched cervical nerve root may cause
shoulder and arm pain. The type of diagnostic spinal injection chosen
is determined by the patient's medical history, physical and neurological
examination, and findings from other studies such as CT Scan.
A discography helps to determine if a particular intervertebral disc
is the pain generator. This is not a routine test. It may be used when
surgery is considered.
A contrast dye is injected into the suspect disc (or discs) under fluoroscopy
(a technique that allows for real-time imaging of the patient's internal
anatomy). The dye enhances the anatomical characteristics of the disc.
The disc may appear normal or the disc lining may show tears (fissures).
Discography can be an uncomfortable test. As the dye is injected, the
patient's typical symptoms may be reproduced. This is called a positive
discogram. The patient's pain response is important to help diagnose
the exact source of the pain. If the injection does not replicate the
patient's pain, then the test is a negative discogram.
The procedures take 30 to 45 minutes depending on the number of discs
(spinal levels) injected. Infection is a possible risk although rare.
Antibiotics are injected before the procedure or with the dye to avoid
Selective Nerve Root Block (SNRB)
SNRB is performed to determine if a specific spinal nerve is the source
of pain. It can help to diagnose cervical or lumbar radiculopathy (irritation
and inflammation of a nerve root serving a particular body part).
Under fluoroscopic guidance, the specialist injects steroid medication
at a specific nerve root. The steroid is a strong anti-inflammatory. If
the injection reduces or alleviates the patient's symptoms, then the source
of pain is located. The test takes 15-30 minutes per spinal level.
Facet and Medial Blocks
Joint inflammation between the spinal bones can cause back pain. Facet
and medial blocks involve the injection of steroid medication into joint
areas to determine if that joint is a pain generator. Steroids reduce
inflammation and alleviate pain.
A facet joint block is an injection of local anesthetic and steroid
medication into the joint. A medial block uses similar medication
injected outside the joint space near the nerve that feeds that
joint. These injections are performed under fluoroscopy.
If pain is relieved, it could mean that the suspect joint or medial
nerve is the pain generator.
Sacroiliac Joint Injection
The sacroiliac joint is the largest joint. It is located in the
lower spine above the tailbone. Inflammation of the sacroiliac joint can
cause low back and buttock pain.
||1 Sacroiliac Joint
2 Coccyx (tailbone)
Using fluoroscopy, local anesthetic and steroid medication is injected
into the sacroiliac joint. If pain is relieved, it could mean that the
suspect joint is the pain generator.
For their safety, some patients are not allowed to undergo diagnostic
spinal nerve injections for the following reasons:
- Allergy to the contract medium and/or drugs to be injected
- Bleeding Problems
- Kidney Disease
- Pregnancy/breast feeding
- Severe Spinal Abnormality
Patient Preparation: At Home
It is important that the patient follow all pre-test instructions.
Some of these instructions include:
- Stop blood-thinning medication
2 days prior to the test
- Do not take any aspirin product
5 days prior to the test
- Stop anti-inflammatory medication
5 days prior to the test (Vioxx or Celebrex is an exception)
- Stop pain medication 8 hours prior
to the test
- Do not eat or drink 6 hours prior
to the test
- Arrange for someone to provide
Patient Preparation: At the Medical Facility
- The medical staff will review
the patient's history, condition, medications taken on a daily basis,
food and/or drug allergies, and other information.
- The patient changes into a gown
and lies down in a hospital bed.
- An EKG monitor (heart function),
automatic blood pressure cuff (blood pressure), and oximeter (measures
blood-oxygen levels) are attached to the patient. This equipment enables
the medical staff to consistently monitor the patient's vital signs before,
during and after the procedure.
- Medication to relax the patient
is administered by injection. In some cases, light intravenous sedation
may be given. Diagnostic spinal injections require the patient to be awake
to respond to the injection specialist's questions.
What to Expect During the Procedure
- The procedure is performed
in a sterile setting similar to an operating room.
- The injection site is cleaned and
draped. Skin numbing medication is injected into and around the procedure
- Before proceeding, the fluoroscopy
C-arm is positioned over the patient. Fluoroscopic guidance is used during
the procedure to guide the needle into the proper position.
- After the needle is placed, a contrast
dye is injected to enhance visualization of the site. An anesthetic in
a steroid solution is injected after the contrast dye. The steroid solution
may include an antibiotic.
- The goal of the procedure is to
replicate the patient's typical discomfort (symptoms). The patient may
reproduce symptoms by bending, twisting, walking or sitting. The patient's
feedback helps to identify the cause of pain.
After the Procedure
- The patient is wheeled to the recovery
area where the medical staff continues to monitor vital signs.
- Patients are usually discharged
home within 30-60 minutes with written instructions.
- The area around the injection site
will feel numb. Relief from typical symptoms may last for six hours following
- Steroids may cause side effects
that include blurred vision, frequent urination, increased thirst and
change in blood sugar levels. If these side effects become bothersome
or worsen, seek medical attention.
- If fever, chills, increased pain,
weakness or loss of bowel/bladder function occurs, seek immediate medical
- Follow-up with the treating physician.
Diagnostic spinal injections, like other medical procedures, have risks.
Complications include risk of infection, low blood pressure, headache,
and injury to nerve tissue.
Diagnostic injections play a useful role in identifying the source
of a patient's pain. However, the procedures are often uncomfortable and
painful for the patient. At CCSI we recognize both the value of these
tests, and the discomfort they can cause patients. Our experts are committed
to making these procedures as comfortable as possible. We also focus on
carefully explaining the procedures to patients, as we find that patients
handle the procedures better if they understand what is being done.