Fig. 12.1
AP fluoroscopic view of right cervical medial branch block
Fig. 12.2
Lateral illustration of cervical medial branch block. From Fung DA et al. Injections of the Cervical, Thoracic, and Lumbar Spine. In: Surgical Approaches to the Spine, Watkins RG III and Watkins RG, IV, eds. Springer New York;2015:389–409. Reprinted with permission from Springer
In the thoracic spine, the medial branches course over the superior aspect of the transverse process. Patients are placed in the prone position and the fluoroscopic beam is oriented in an AP or slightly oblique view. The needles are directed towards the superior aspect of the transverse process [10].
In the lumbar spine, the medial branch is at the junction between the superior articular process and the transverse process [11]. Patients are placed in the prone position and the fluoroscopic beam is oriented to square off the vertebral end plates in an AP or slightly oblique view. The spinal needles are directed towards the superolateral aspect of the pedicle at the junction of the superior articular process and transverse processes (Figs. 12.3 and 12.4).
Fig. 12.3
AP fluoroscopic view of left lumbar medial branch block
Fig. 12.4
AP and lateral medical illustration of bilateral lumbar medial branch block. From Fung DA et al. Injections of the Cervical, Thoracic, and Lumbar Spine. In: Surgical Approaches to the Spine, Watkins RG III and Watkins RG, IV, eds. Springer New York;2015:389–409. Reprinted with permission from Springer
Radiofrequency ablation of the medial branches is performed at a similar location to the medial branch blocks. An insulated needle with an active tip is used to carry out the ablation. Sensory and/or motor stimulation are used to confirm placement of the needle near the medial branch nerves and away from the dorsal roots. Local anesthetic is administered prior to the ablation and the ablation is typically carried out at around 80 °C for a duration of 60–90 s [12] (Fig. 12.5).
Fig. 12.5
AP fluoroscopic view of bilateral lumbar medial branch radiofrequency ablation
Facet Joint Intra-Articular Injection
Cervical facet joint injections are performed with the patient lying prone and a 25–35 ° caudal tilt of the fluoroscopic beam to line up the facet joint space. The needle is advanced towards and into the joint space, and slight resistance is felt when the joint capsule is engaged. A lateral fluoroscopic view can be used to assess the depth of the needle. Contract is used to confirm location of the needle tip in the facet joint and 0.5–1 cc of medication is then typically injected to avoid distending the joint capsule.
Thoracic facet joint injections are performed with the patient lying prone and the fluoroscopic beam in a far (50–60 °) caudal tilt. Using fluoroscopic guidance the needle is directed towards the inferior articular process; once bone is contacted the needle type is walked superiorly into the facet joint. Once needle is in place, contrast is used to confirm the locations and approximately 1 cc of medication is typically injected.
Lumbar facet joint injections can be performed in two ways. Both require the patient to be in a prone position. The traditional way is with the fluoroscopic beam orientated obliquely approximately 20–30 ° to visualize the facet joint. The needle is directed towards the facet joint and once entered contrast is injected to confirm location and approximately 1–1.5 cc of medications is typically injected. The author’s preferred method is to keep the fluoroscopic beam in a direct AP position. The target is the posterior inferior aspect of the joint capsule. The needle is inserted in a medial to lateral, inferior to superior trajectory. The needle tip contacts the pars interarticularis of the inferior vertebrae, and then is marched up to the inferior aspect of the joint space. A step off can be appreciated when the joint is entered. This method is felt to be superior to the traditional intra-articular facet approach for safety and reproducibility. The tip is on bone throughout the procedure; therefore, the depth of the needle tip is known during the procedure, which makes it safe and easy to avoid spinal canal entry. The technique is reproducible from an anatomic perspective. The oblique fluoroscopic perspective of the lumbar facet joint can be deceiving. The joint line can often appear to be a flat line under fluoroscopy, but in reality, the joint is not a flat line, and can have scalloping traction osteophytes on the posterior lateral margin of the superior articular process blocking the access to the facet joint from the oblique approach.
Facet joint injections are relatively safe procedures in the right hands. Pain can temporarily worsen after injection due to muscle spasms, contact with the articular surface, or joint capsule expansion. Cervical injections can be risker due to the denser arrangement of nerves and arteries; nonparticulate steroids should be used to minimize the risk of arterial embolism. Another complication is injury to the spinal cord if the needle is placed too deeply and medially [8, 9].
Epidural Injections
The epidural space surrounds the dural sac and exiting spinal nerve roots within the spinal canal. The exiting spinal roots are typically the targets for epidural injections to treat radicular symptoms.
Indications and Rationale
A radicular referral pattern of pain caused by injury or irritation to a spinal nerve root is the primary indication for epidural injections. Radiculitis is often associated with dull aching centrally at the level of the exiting nerve root with sharp radiating pain along a dermatomal pattern that can be associated with numbness, paresthesia, and myotomal weakness. Proper history and physical exam should be correlated with imaging studies to visualize the pathology at the exiting nerve root. Electromyography (EMG) can also be used to confirm a diagnosis of radiculitis. Subjects with radiculitis and positive findings on EMG are reported to have improved functional outcomes from epidural steroid injections as compared to EMG-negative subjects [13]. Epidural steroid injections are accepted as a standard treatment for radiculitis and neurogenic claudication [14].
The American Society of Interventional Pain Physicians (ASIPP) guidelines advise that epidurals should be limited to a maximum of six per year and only repeated as medical necessary. Numerous studies have validated the efficacy and outcomes of caudal, interlaminar, and transforaminal steroid injections [15–18]. There is strong-to-moderate evidence supporting caudal and transforaminal epidural steroid injections [8]. Evidence for interlaminar injections is considered moderate to limited. However, multiple observational studies have shown positive results with all forms of epidural injections [8].
In order to meet CMS documentation requirements, providers must document moderate-to-severe pain, greater than 3/10, and functional impairment in activities of daily living. At least 4 weeks of failed conservative management must be adequately documented.
Accurate documentation of medication dosing, symptom location, as well as pre- and post-procedure response to the injection, including pain level and ability to perform previously painful movements, is also required [1].
Technique
Caudal, transforaminal, and interlaminar approaches to the epidural space are described.
Caudal Epidural Injection
The patient is placed in the prone position. The sacrum and sacral hiatus are identified using a lateral fluoroscopic view. A spinal or Tuohy epidural needle is advanced at a shallow angle in a cephalad direction into the sacral hiatus. A loss of resistance technique with a glass syringe and saline can be used to identify entrance of the needle through the sacral hiatus and into the epidural space. An epidural catheter can be advanced up to the desired level of injection or injectate can be administered into the lower caudal space with enough volume such that it spreads in a cephalad direction. Contrast solution is injected to confirm ideal placement in the epidural space without intravascular uptake and then the medications are injected. The needle should not be advanced past the S2 level to avoid the risk of dural puncture [19]. The risk of cauda equina syndrome is low, at around 2.7 per 100,000 epidural blocks [7].
Interlaminar Epidural Injection
The patient is placed in the prone position with slight flexion of the spine to help open up the intralaminar space (Fig. 12.6). AP fluoroscopy is used to visualize the intralaminar space and the lamina above and below. The spinal needle is advanced to just contact the superior aspect of the inferior lamina adjacent to the spinous process to confirm appropriate depth of the needle. The needle is then slowly walked off the lamina and advanced with a loss of resistance technique into the epidural space (Fig. 12.7). Contrast is injection to confirm ideal placement of the needle and then medications are injected. The thoracic and cervical epidural space can be extremely narrow; thus entering at a more caudal interlaminar level and advancing an epidural catheter up to the desired level are often advised.
Fig. 12.6
Positioning for cervical interlaminal epidural injection. From Fung DA et al. Injections of the Cervical, Thoracic, and Lumbar Spine. In: Surgical Approaches to the Spine, Watkins RG III and Watkins RG, IV, eds. Springer New York;2015:389–409. Reprinted with permission from Springer
Fig. 12.7
Paramedian approach for cervical interlaminar epidural injection. From Fung DA et al. Injections of the Cervical, Thoracic, and Lumbar Spine. In: Surgical Approaches to the Spine, Watkins RG III and Watkins RG, IV, eds. Springer New York;2015:389–409. Reprinted with permission from Springer
Aspiration is performed prior to injection of contrast to check for blood or CSF. The potential size of the dorsal epidural space is directly related to the volume of the spinal canal at the targeted level [20, 21] (Fig. 12.8).
Fig. 12.8
AP fluoroscopic view of cervical interlaminar epidural steroid injection with entry point at the T1–T2 interlaminar space
Transforaminal Epidural Injection
The authors will present and prefer the retroneural method for transforaminal epidural steroid injections. The patient is placed in the prone position and an AP or oblique fluoroscopic view is used to direct the spinal needle from a lateral starting position medially towards the neural foramen. The needle is advanced obliquely toward the inferior lateral aspect of the pedicle at the junction of the transverse process and the pars. Lateral fluoroscopic imaging is then used to place the needle tip at the 10 o’clock position of the foramen, also known as the “safe triangle” (Figs. 12.9, 12.10, 12.11, and 12.12). Cervical transforaminal epidural injections are not advised for unexperienced physicians; serious adverse events have been reported including paralysis, stroke, and death [22, 23].
Fig. 12.9
AP fluoroscopic view of lumbar transforaminal epidural steroid injection with needles in place
Fig. 12.10
Lateral fluoroscopic view of lumbar transforaminal epidural steroid injection with needles in place
Fig. 12.11
AP fluoroscopic view of lumbar transforaminal epidural steroid injection after administering contrast and medications
Fig. 12.12
AP and lateral medical illustration of lumbar transforaminal epidural steroid injection. From Fung DA et al. Injections of the Cervical, Thoracic, and Lumbar Spine. In: Surgical Approaches to the Spine, Watkins RG III and Watkins RG, IV, eds. Springer New York;2015:389–409. Reprinted with permission from Springer
Complications
Epidural injections are relatively safe procedures and complications are low. Previous studies have reported complications rates around 2.4 % with the most common complication being pain at the injection site [24]. Other studies have reported the incidence of a minor infection at 1–2 %, major infections 0.1–0.01 %, and the risk of epidural hematoma at less than 1 in 150,000 [25]. The risk of intravascular injection can be prevented by injecting contrast first to rule out intravascular placement but this is a possible complication and the use of nonparticulate steroid is recommended. A dural puncture can occur if the needle is advanced passing the epidural space; most patients will heal without intervention but if a dural leak persists it can be treated with staying supine, hydration, analgesics, and an autologous blood patch [26]. If the needle is advanced further into the dural space, contact with the spinal cord or nerve roots can occur. Epidural infections and epidural hematomas are rare occurrences that can lead to cauda equina syndrome. Extra care needs to be taken during left-sided injections between T8 and L1 because the artery of Adamkiewicz, the largest spinal segmental artery, lies at these levels in 60–80 % of patients [27, 28]. Certain steroid solutions now come with warning labels “not for epidural use.” These are the same steroids that have been used in the epidural space for many years. The use of these products with this specific wording on the label in the epidural space is discouraged and very difficult to defend from a medical legal perspective.
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