Atlas Section



10.1055/b-0039-167998

8 Thoracic Injection Therapy


Acute and chronic pain in the thoracic spine plays only a minor role compared to that of the cervical and lumbar spine. This applies both to the incidence and to the severity of symptoms: only 2% of all painful spinal syndromes affect the thoracic spine. In very rare cases, therapy-resistant nerve root irritation (intercostal neuralgia) occurs that requires surgical treatment.



8.1 Specialized Thoracic Neuroanatomy


The spinal canal is relatively narrow in the thoracic area and there is only a slender epidural space between the spinal cord, the bony surroundings, and the intervertebral disk. The canal is at its narrowest between T4 and T9.


The thoracic spine consists of the zygapophyseal joints, as well as the joints between the vertebrae and ribs (costovertebral joints, costotransverse joints), which jut out from the inferior part of the intervertebral foramen and push the spinal nerve out into the open section above (Fig. 8‑1).

Fig. 8.1 Segments of the midthoracic spine on a skeleton, posterior view. In addition to the thoracic facet joints, the thoracic spine also contains costotransverse joints that jut out from the lower part of the intervertebral foramen and push the spinal nerve (arrows) into the freely open section above.


Because of the relatively large diameter of the intervertebral foramen, the osteogenic constrictions that are commonly found in the cervical spine, for example, are rarely seen in the thoracic spine. The intervertebral foramen is not adjacent to the intervertebral disk, as is the case in the cervical and lumbar spine. Rather, it is located at the same level as the vertebral body (Fig. 8‑2a, b).

Fig. 8.2 Lateral sagittal section of the midthoracic spine shown on an anatomical specimen (a) and the radiological image of the same specimen (b) with a lateral view. The intervertebral foramina are not located next to the intervertebral disk, but rather at the level of the vertebral body.


The displacement of the spinal cord segments in relation to the corresponding vertebral motor segments, as previously described for the cervical spine, continues in the thoracic spine. Between the 1st and 6th thoracic spinous process, the displacement amounts to the height of two segments; between the 7th and 10th spinous processes, the displacement amounts to the height of three segments. Ventral branches of the thoracic spinal nerve, the intercostal nerve, supply the wall of the rib cage, i.e., the intercostal muscles, the costotransverse joints, the parietal pleura, and the skin. A so-called intercostal neuralgia evolves when the thoracic spinal nerves are irritated.



8.2 Clinical Picture


The symptoms arising from a compromised thoracic spinal nerve root are characterized by a girdle-shaped pattern of pain with possible discrete algesic disorders. Its topology is based on the dermatomal pattern. The boundaries between the individual dermatomes are not as well defined in the thoracic area as they are in the peripheral sections of the limbs. Another important diagnostic criterion for intercostal neuralgia due to degenerative changes is the dependency on position of the thoracic spine. Pain is relieved when the thoracic spine is unloaded or extended. Pain increases on loading and with certain rotary movements of the body. This provides information about how the condition should be treated.


Unloading the thoracic vertebral motor segments using the horizontal position is important in therapy. The application of all types of heat treatment is perceived as pleasant because the heat relieves the reflex hypertonicity of the trunk muscles, in particularly the paravertebral back extensors, and stimulates blood flow. These techniques are complemented by the use of manipulation, mainly in the form of traction, physical therapy exercises to strengthen the trunk muscles, and local injections.


The irritation of thoracic spine nociceptive afferents is considerably more common than the irritation of spinal nerves. This form of irritation arises from incorrect posture or loading, or in some cases, segmental dysfunction or degenerative changes. It can cause extremely painful and treatment-refractory reflexive pain syndromes in the thoracic spine.


So-called viscerovertebral pain syndromes and pain syndromes associated with psychosocial problems can also manifest themselves in the thoracic spine.



8.3 Thoracic Injection Therapy



8.3.1 Thoracic Spinal Nerve Analgesia



Principle

Posterolateral injection of a local anesthetic (mixed with steroids when necessary) into the foraminoarticular region of the vertebral motor segment.



Indication

Any therapy-resistant intercostal neuralgia or intercostal neuralgia-like pain with girdle-shaped ipsilateral or bilateral radiation is an indication for thoracic spinal nerve analgesia (TSPA) treatment.



Technique

In order to carry out TSPA, bony contact has to be made with the transverse processes of the thoracic vertebral bodies. As the spinous process angle changes along the thoracic spine, the topographical relationship between spinous and transverse processes also varies. The spinous processes are found just under the transverse process belonging to the underlying segment between the fourth and ninth thoracic segments. Both of these corresponding points are found nearer to each other superior to T4 and inferior to T9 (Wolber 1999). The distance between the spinous process and the transverse process varies from 2.5 to 3.5 cm (Fig. 8‑3).

Fig. 8.3 Posterior view of the entire thoracic spine, shown on a skeleton. Topographic relationship between the spinous processes and the transverse processes: the spinous processes are found just under the transverse process belonging to the underlying segment between the fourth and ninth thoracic segments. Both of these corresponding points are found nearer to each other superior to T4 and inferior to T9.


A recent radiograph should be available for orientation purposes. The patient is positioned in a relaxed kyphotic posture with the arms hanging down by the sides. The infiltration can also be administered in a sitting position when a kyphosis table is not available.



■ T1–T4 Nerve Roots

Locate the lower edge of the spinous process to form a horizontal guideline. The transverse process line is found 3 cm lateral to this. A radiograph of the thoracic spine should be used for further orientation. The corresponding transverse process is found 2 cm superior to the horizontal guideline running from the lower edge of the spinous process. Insert a 6- to 8-cm needle vertically toward the corresponding transverse process. Retract the needle until the muscle fascia releases the needle tip. The injection is directed at a 20-degree caudal and 30- to 40-degree medial angle. When bony contact is lost, insert the needle a further 1 to 2 cm (approximately), then aspirate and inject about 1 to 2.5 mL per segment.



■ T5–T9 Nerve Roots

Locate the inferior edge of the T5, T6, T7, T8, or T9 spinous process. The transverse process line is found by running a line 3 cm horizontal and paraspinal to the lower edge of the spinous process. The corresponding transverse process can be palpated 3 cm superior to this line (the so-called rule of threes). The needle is inserted vertically to the skin, toward the transverse process. Following sufficient retraction of the needle out of the muscle fascia, the needle is then inserted at a 20-degree caudal and 30- to 40-degree medial angle. When bony contact is lost, insert the needle a further 1 to 2 cm (approximately), then aspirate and inject about 1–2.5 mL per segment.


It can be a problem for inexperienced practitioners to make targeted bony contact with the transverse process. In thoracic vertebral segments, the prominence of the transverse process is found significantly more posterior than the facet (Fig. 8‑4). The administration of a thoracic facet infiltration (see “Thoracic Facet Infiltration” below) can therefore be used for orientation, to aid practitioners in ascertaining the insertion depth. In other words, the bony contact with the transverse process must be no deeper than the bony contact with the facet (Fig. 8‑5a, b). A TSPA must not be administered without previous bony contact being made with the transverse process.

Fig. 8.4 The right posterolateral view of the upper thoracic spine shown on a skeleton. The prominence of the transverse processes is found significantly more posterior to the facet in the thoracic vertebral segments, i.e., during infiltration, the bony contact with the transverse process must not be deeper than the bony contact with the facet.
Fig. 8.5 Transverse images in the MRI of the thoracic spine: the transverse process (a) is located 3 cm paravertebral at a depth of approximately 2.5 cm. The thoracic facet joints (b) are located much deeper (approximately 4 cm) 1 cm paravertebral.



■ Effects of Thoracic Spinal Nerve Analgesia

The patient may report segmental paresthesias. To reach a sufficient analgesic effect, 1 to 2 mL should be infiltrated per segment. An optimal block effect can be obtained even if the tip of the needle only comes within a few millimeters of the targeted site, because the anesthetic agent diffuses.



8.3.2 Injection Procedure for TSPA


See Fig. 8‑6, Fig. 8‑7, Fig. 8‑8, Fig. 8‑9, Fig. 8‑10, Fig. 8‑11, Fig. 8‑12, Fig. 8‑13, Fig. 8‑14, Fig. 8‑15, Fig. 8‑16, Fig. 8‑17, Fig. 8‑18, Fig. 8‑19, Fig. 8‑20, Fig. 8‑21, Fig. 8‑22, Fig. 8‑23, Fig. 8‑24, Fig. 8‑25, Fig. 8‑26.

Fig. 8.6 TSPA is conducted with the patient sitting down and the cervical and thoracic spine in flexion. The patient’s arms hang down by their sides. The flexed cervical spine makes it easier to palpate the vertebra prominens (C7 spinous process). The physician’s assistant stands in front of the patient. Oxygen saturation and pulse frequency are monitored using a pulse oximeter. The treating physician or the assistant verbally monitors the patient throughout the procedure.
Fig. 8.7 The hand position used when locating the C7 spinous process (see also Fig. 7‑9).
Fig. 8.8 Marking the tips of the C6 and C7 spinous processes.
Fig. 8.9 For better orientation, reliable location, and palpation of the tip of the T7 spinous process, in this phase both thumbs glide from the midline across the medial border of the scapula (margo medialis) in a lateral direction into the inferior border of the scapula (angulus inferior). The T7 spinous process is located at this level. A radiographic orientation should guide the procedure. In this way, it is possible to reliably identify the T7 spinous process.
Fig. 8.10 Marking the lower border of the left scapula. The T7 spinous process is located at this level.
Fig. 8.11 After palpation, the remaining tips of the spinous processes are marked down to the level of T7.
Fig. 8.12 Irritation point at the level of T5 on the right-hand side. The lower edge of the T5 spinous process and the transverse process line to the right are located by placing a ruler horizontal to the inferior edge of T5. The transverse process line is located 3 cm horizontal and paraspinal to the inferior edge of the T5 spinous process. Marking the distance 3 cm to the right.
Fig. 8.13 Locating the transverse process line on a skeleton first of all 3 cm horizontal and paraspinal to the inferior edge of the T5 spinous process.
Fig. 8.14 Locating the transverse process line on an anatomical specimen of the thorax (posterior view) first of all 3 cm horizontal and paraspinal to the inferior edge of the T5 spinous process (blue marking pin).
Fig. 8.15 The corresponding T5 transverse process is found parallel to the spinous process line 3 cm superior to the end of the 3 cm horizontal line (so-called rule of threes). Marking the 3 cm long vertical line. The injection site for the TSPA at T5 on the right-hand side is found at the end of this line. The injection site is marked by rotating a pen tip over the injection site (with retracted ink cartridge). The mark is still visible after disinfection.
Fig. 8.16 The position of the needle over the right T5 transverse process, shown on a skeleton.
Fig. 8.17 Marking pins on an anatomical specimen of the thorax. The corresponding T5 transverse process (red marking pin) is found parallel to the spinous process line 3 cm superior to the end of the 3 cm horizontal line (so-called rule of threes). The injection site for the TSPA at T5 on the right-hand side is found at the end of this line.
Fig. 8.18 Compresses are placed caudal to the injection site. The skin is then disinfected with a colorless disinfectant spray. The skin has to be intact and free from infection, especially in the injection area. The physician’s assistant positions the head and upper body.
Fig. 8.19 To begin with, the needle is inserted vertical, directed toward the transverse process. The handling of the syringe with the slow insertion of the cannula. The left hand maintains contact with the syringe while the back of the hand remains in contact with the patient. This ensures that the syringe will follow the patient’s movement if the patient moves backward suddenly.
Fig. 8.20 Protecting the T4/T5 and T5/T6 intercostal spaces using the two-finger technique. To reach the spinal nerve, the cannula has first to be retracted sufficiently. It is first inserted 30 to 40 degrees in a medial direction toward the transverse process.
Fig. 8.21 Position of the needle shown on a skeleton: the cannula is first inserted 40 degrees in a medial direction toward the transverse process.
Fig. 8.22 Position of the needle shown on an anatomical specimen of the thorax: 40-degree medial injection direction toward the transverse process in the posterior view (a) and cranial view (b). The injection site is located at the level of the transverse process (red marking pin) in accordance with the “rule of threes.”
Fig. 8.23 To reach the spinal nerve, the cannula has first to be retracted slightly. It is advanced a further ~1–2 cm at an angle of 20 degrees in a caudal direction, bypassing the transverse process. The two-finger technique is continued to be used to protect the intercostal spaces. After aspiration, ~1–2.5 mL is injected.
Fig. 8.24 Final position of the needle during TSPA as demonstrated on a skeleton. The thoracic spinal nerve is reached after the two-finger technique is used to protect the intercostal spaces.
Fig. 8.25 Final position of the needle during a right TSPA at T5 as demonstrated on an anatomical specimen using the two-finger technique to protect the intercostal spaces.
Fig. 8.26 Cranioposterior view as demonstrated on an anatomical specimen. The final position of the needle at the right T5 level and depiction of the injection steps (1–4) of the TSPA technique. If the measurements and angle are observed, the risk of injuring the lung is low.

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May 14, 2020 | Posted by in NEUROSURGERY | Comments Off on Atlas Section

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