The epidural space was first shown to be important in radicular
pain states by Lindahl and Rexed in 1950.1 Subsequently,
Goebert performed the first reported epidural steroid injection.2 Since
that time physicians have used the epidural space to gain direct
access to traversing nerve roots and indirect access to the intrathecal
space for medication delivery.
Anatomically, the epidural space is tubular and exists as a potential
space. This tubular three-dimensional structure surrounds the dura
and spinal cord. It extends from the foramen magnum to the upper
sacrum. When examined in transverse plane, its external boundaries
are the ligamentum flavum posteriorly, lamina and pedicles laterally,
and the vertebral body and intervertebral disc anteriorly. The internal
boundary is the dura.
Medication administration into the epidural space has been used
to treat both acute and chronic pain. Examples include regional
anesthesia for surgery, trauma, and labor. Dilute local anesthetic infusions
have been used to treat postherpetic neuralgia, complex regional
pain states, and cancer-related pain. Opioids and sympathomimetics
have been added for synergy. Epidural steroids have been used to
treat inflammatory nerve root irritation. Volumemetric injections
and flouroscopically guided catheters have been used to direct medication
delivery, wash away inflammatory mediators, lyse epidural adhesions,
and deliver anti-inflammatory medication.
Efficacy of epidural treatment for radiculopathy is determined
by multiple factors. Medical factors influencing outcome include
accuracy of diagnosis, presence of nerve root inflammation, symptom
duration, previous surgical intervention, patient age, and clinician
ability to place the epidural steroid at the level of pathology.3 Treatment
outcome also depends on psychological and social issues. Abram delineated
factors correlating with treatment failure at twice the rate expected.
These factors include poor education, unemployment, pain constant
in nature, sleep disturbance, nonradicular diagnosis, duration >6
months, change in recreational activities, and tobacco use.4
Epidural space endoscopy or spinal canal endoscopy may improve
outcome by addressing some of the medical factors discussed above.
The region of erythema that is likely related to inflammation is
visually confirmed with the endoscope. Fluoroscopy is used to confirm
the spinal level. The flexible steerable handle allows placement
of medication in the lateral gutter adjacent to the nerve root.
Reproduction of pain during the procedure while exploring pathology
helps to confirm diagnosis.5
Psychological and social factors are more difficult to treat
and unfortunately they are not amenable to procedural intervention.
These factors cannot be ignored, however, because they are of equal
or greater importance than the medical pathology.6 Therefore
attempts to address these issues by modification of behavior, structured
water or land exercise programs, tobacco cessation, and improved
sleep hygiene need to be made. Interventions such as targeted pharmacologic
therapy to enhance restful sleep and programs to structure daily activity
to enhance self-esteem are no less important. Lastly, functional
goals should be set. To focus on complete pain cessation in the
patient suffering from chronic pain distracts from attainable goals
and ultimately ...