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The thoracic spine is a common source of mid-back pain and is frequently overlooked despite it having the greatest number of levels and the greatest diversity between vertebral levels.
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For injections, it is important to confirm the correct level. Identify the appropriate level by starting at either the first or twelfth rib and counting from there.
Pertinent Anatomy
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The thoracic spine contains 12 levels, compared to 7 in the cervical and 5 in the lumbar spine.
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See Figs. 13.1–13.3 .
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The T2-T9 thoracic vertebrae have costovertebral and costotransverse articulations of the rib with the vertebral body and the rib with the transverse process. The wedge shape of these vertebrae results in the kyphotic curve of the thoracic spine.
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The other vertebrae of the thoracic spine are similar to either the cervical vertebrae (T1) or lumbar spine (T10-T12).
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Typical ligamentous anatomy includes anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), ligamentum flavum, interspinous ligament, supraspinous ligament (SSL), and intertransverse ligaments.
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Qualities unique to the thoracic spine include:
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Radial and intraarticular ligaments (costovertebral articulation—connection of the head of the rib with the vertebral body)
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Superior and lateral costotransverse ligaments (costotransverse articulation—connection of the neck/tubercle with the vertebral body)
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Thoracic facet joints have a different orientation than cervical or lumbar facets, approximately 60 degrees superiorly and 20 degrees anteriorly.
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The thoracic spine has a major impact on alignment of the entire spine. These changes in alignment can have both clinical and subclinical effects on a person’s biomechanical health.
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Three important measurements affecting biomechanics and pain are:
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Coronal balance
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Sagittal vertical axis
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Pelvic incidence.
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The artery of Adamkiewicz may originate from a segmental artery between T7 and L4, typically on the left side.
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Concerns with thoracic injections include adjacent vascular structures (bleeding from non-compressible arteries and/or veins), lung puncture (resulting in pneumothorax), cardiac (direct cardiac injury or secondary tamponade), sympathetic chain side effects (hypotension) spinal cord or intrathecal injection (see Fig. 13.3 ).
Ultrasound Guided
Supraspinous and Interspinous Ligaments
These ligaments can be targeted in isolation for specific injuries but are more commonly treated in combination with other components of the functional spinal unit, , including the spinal nerves in the epidural space, facet joints, paraspinal muscles, and occasionally the intervertebral discs.
Pertinent Anatomy
The interspinous ligament (ISL) is a thin membranous ligament that connects adjacent spinous processes. The ligament spans from the root to the apex of each spinous process, anteriorly to the ligamentum flavum and posteriorly to the nuchal ligament.
The supraspinous ligament (SSL) is a thin membranous ligament and lies superficial to the spinous processes of the thoracic spine overlying the interspinous ligament.
Common Pathology
Ligament strain, partial tear, relative laxity related to disc, and facet pathology.
Equipment
Ultrasound machine with high-frequency linear transducer.
Technique
Patient Position
Prone
Clinician Position
At the side of the patient, with the ultrasound monitor next to or on their opposite side.
Transducer Position
Long axis to the ISL and SSL with visualization of ligaments and spinous processes ( Fig. 13.4 ).
Needle Position
In plane (author preference) or out of plane
Target
Direct injection into the ligaments at the desired spinal level, injecting into areas of hypoechogenicity and throughout the ligament, including the bony attachments. Filling of interstitial injuries can be seen with injectate.
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In plane:
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With ligaments in long axis, introduce the needle in plane to the transducer with or without a gel stand-off to minimize anisotropy. Needle tip should be advanced to the spinous process to inject at the SSL, then walked and advanced into the interspinous space for the ISL.
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Injectate Volume
0.25 to 1 mL at each spinal level
Prolotherapy, orthobiologics
Needle: 25- to 27-gauge 1.5- to 2-inch needle
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These ligaments are difficult to visualize entirely, so adjacent and adjoining anatomy needs to be visualized.
Thoracic Facet Joints
Whereas the fluoroscopic approach to the lumbar facet joints is typically at 0 to 45 degree rotation, the thoracic facet joint is oriented at 90 to 110 degrees, which needs to be taken into consideration when assessing the joints with ultrasound.
Pertinent Anatomy
Facet joint
Common Pathology
Osteoarthritis, rotational scoliosis
Equipment
Ultrasound machine with low-frequency linear or a curvilinear transducer, which provides better visualization of deeper structures and a wider field of view.
Technique
Patient Position
Prone
Clinician Position
Clinician preference for optimal needle guidance and ultrasound transducer control, typically at the patient’s side with ultrasound monitor next to or on their opposite side.
Transducer Position
Midline along the long-axis, initially flat on the skin, but then angled 10 to 20 degrees medially to be perpendicular to the articular processes, which slope down from the midline to laterally.
Needle Position
Caudad-cephalad needle direction, in-plane visualization ( Fig. 13.5 ).
Target
Facet joint opening
Injectate Volume
0.25 to 1 mL
Dextrose prolotherapy, orthobiologics
Advanced ultrasound skills are required. Keep the needle and target in view at all times. Missing the target and going too deep laterally risks penetration into the lung, while going too medially risks penetrating the thecal sac. An echogenic or large-caliber can be helpful to optimize visualization, which can otherwise be difficult because of multiple overlying fascial planes.
Thoracic Costotransverse Joints
Important structure to consider in patients with chest and abdominal pain, difficulty breathing, or paresthesia in this area.
Pertinent Anatomy
Rib head, transverse process (TP) of thoracic vertebra
Common Pathology
Damaged or stretched ligaments from trauma , or hypermobility syndromes, osteoarthritis
Equipment
Ultrasound machine with high-frequency linear transducer
Technique
Patient Position
Prone
Clinician Position
At the side of the patient, with the ultrasound monitor next to or on the opposite side
Transducer Position
Transverse, with ultrasound transducer overlying the head of the rib and transverse process ( Fig. 13.6 ).
Needle Position
In-plane needle visualization, lateral to medial approach
Target
Posterior costal facet, costotransverse ligaments
Injectate Volume
0.25 to 0.75 mL
Dextrose prolotherapy, orthobiologics
Keep the needle and target in view at all times. Missing the target risks going into the pleura or thecal sac.
Costochondral Joints
Important structure to consider in patients with chest pain, abdominal pain, difficulty breathing, or paresthesia in this area. It is important to visualize the sternum, adjacent costal cartilage (typically hypoechoic), and rib (hyperechoic with typical bony acoustic shadowing).
Identify rib, costal cartilage, articulation at desired level, and lung pleura.
Pertinent Anatomy
Sternum, rib cartilage, lung pleura
Common Pathology
Damaged or stretched ligaments from trauma , or hypermobility syndromes, osteoarthritis
Equipment
Ultrasound machine with high-frequency linear transducer
Technique
Patient Position
Supine
Clinician Position
At the side of the patient, with the ultrasound monitor next to or on the opposite side
Transducer Position
In plane, with costochondral joint ( Fig. 13.7 ).
Needle Position
In plane: lateral to medial approach
Target
Costochondral joint
Injectate Volume
0.5 to 1.0 mL
Keep the needle and target in view at all times. If the needle deviates away from view, it can easily bypass the target, go into the pleura, and cause a pneumothorax.
Sternocostal Joints
Important structure to consider in patients with chest pain, abdominal pain, difficulty breathing, or paresthesia in this area. It is important to visualize the sternum, adjacent costal cartilage (typically hypoechoic), and rib (hyperechoic with typical bony acoustic shadowing).
Pertinent Anatomy
Sternum, costal cartilage, sternocostal joint, pleura of the lung.
Common Pathology
Damaged or stretched ligaments from trauma , or hypermobility syndromes, osteoarthritis
Equipment
Ultrasound machine with high-frequency linear transducer
Technique
Patient Position
Supine
Clinician Position
At the side of the patient, with the ultrasound monitor next to or on the opposite side
Transducer Position
Axial to the patient, in line with the sternocostal joint ( Fig. 13.8 ).
Needle Position
Medial to lateral or vice-a-versa depending on the side
Target
Sternocostal joint
Injectate Volume
0.5 to 1 mL
Dextrose prolotherapy, orthobiologics
Keep the tip of the needle in view at all times to avoid going too deep and causing pneumothorax. Avoid vascular structures and aspirate prior to injection to avoid intravascular injection.
Sternoclavicular Joints
Clarify anatomy of sternum and clavicle; use real-time ultrasound visualization to maintain safe depth.
Pertinent Anatomy
Clavicle, sternum, sternoclavicular (SC) joint
Common Pathology
Damaged or stretched ligaments from trauma, osteoarthritis, capsular strain
Equipment
Ultrasound machine with high-frequency linear transducer.
Technique
Patient Position
Supine
Clinician Position
For in-plane needle visualization, at the side of the patient with the ultrasound monitor next to or on the opposite side of the patient.
For out-of-plane visualization, at the patient’s side and ipsilateral to the joint being treated, with the ultrasound screen at or near the patient’s head.
Transducer Position
Overlying the clavicle and sternum, spanning the SC joint
Needle Position
Author’s preference: in-plane needle visualization. Slide the ultrasound transducer so that the SC joint lies close to its edge, reducing the distance from needle to target ( Fig. 13.9 ).
Alternative: out of plane. Ensure the transducer is centered and perpendicular to the joint; use the scale on the monitor to determine target depth, then insert needle, erring on the side of being shallow at first.
Target
Sternoclavicular joint
Injectate Volume
0.5 to 1 mL
Use three fingers to hold the transducer and the remaining two to stabilize the transducer on the joint. Keep the needle in view at all times for an in-plane approach, and err on the side of going shallow for an out-of-plane approach. Missing the joint risks penetration into the pleura or great vessels.
Fluoroscopy Guided
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To appropriately identify level, “square off” endplates to adjust for parallax error.
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Epidural approach is similar to intradiscal approach.
Pertinent Anatomy
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Kambin’s
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spinal nerve
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rib head
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vertebral body ( Fig. 13.2 ).
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intervertebral disc
Common Pathology
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Radiculitis
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Disc herniation
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Endplate modic changes
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Intervertebral narrowing
Equipment
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C-arm fluoroscopy
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25- to 22-gauge 3- to 3.5-inch spinal needle for transforaminals
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20- to 21-gauge 3.5-inch Tuoy needle for interlaminar
Common Injectates
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Local anesthetics
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Corticosteroids
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Orthobiologics (platelet lysate, dextrose neuroprolotherapy)
Injectate Volume
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1 to 5 mL
Technique for Transforaminal Infraneural Approach
Patient Position
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Prone
Clinician Position
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To the side of the patient contralateral to fluoroscopy unit base
C-Arm Position Fluoroscopy
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Angulate the C-arm to “square off” the level to be injected.
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Rotate 25 to 45 degrees to optimize foraminal view between superior articular process (SAP) of the lower vertebral bone and rib. Keep the lung field line lateral to the vertebral body.
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Use lateral view to check depth as needle nears target.
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Use anteroposterior (AP) view to check needle position and confirm epidural contrast flow.
Needle Position
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Aim for the posterior lateral disc space passing between the rib head laterally and the SAP medially ( Fig. 13.10A and B ).
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Visualize the lung field and keep the needle medial to the lung.
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Guide the needle with “tunnel” view orientation, periodically checking the AP view to ensure the needle does not go spinal medial to the pedicles.
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Once the needle is advanced deeper, the tip can be positioned over the vertebra to avoid entering the disc.
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If the needle touches the periosteal surface, it should be pulled back 1 to 2 mm.
Target
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Inferior aspect of intervertebral foramen at level of disc
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Once the needle is close to the foramen, check the lateral view. Needle should be in the central to anterior aspect of the foramen posterior to the inferior endplate.
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Check the AP view; the needle should not be beyond the 6 o’clock position of the inferior aspect of the pedicle.
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Inject and observe contrast flow using live fluoroscopy, ideally digital subtraction angiography. There should be anterior epidural flow in the lateral view and flow medial to the pedicle and around the nerve in the AP view (see Fig. 13.10C and D ).
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The rib and SAP position can vary, so observe the spaces between the bones before starting the injection but maintain trajectory in Kambin’s triangle.
Technique: interlaminar
Patient Position
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Prone
Clinician Position
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To the side of the patient, opposite the C-arm
C-Arm Position Fluoroscopy
Angulate the C-arm to “square off” the vertebrae at level to be injected; make sure the laminae are clearly visualized.
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Obtain a true AP view at the desired level.
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Use the contralateral oblique view to assess depth once the needle is near the target.
Needle Position
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The authors prefer paramedian approach, so start needle slightly off from midline on the more symptomatic side.
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The needle should be started in the interlaminar space ( Fig. 13.11A and B ).