How is the paramedian approach to thoracic epidural nerve blocks for pain management administered?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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Answer

Answer

Procedural risks relate to the proximity of the needle tip to the posterior border of the lung; If the needle penetrates the intervertebral foramen, puncture of the dura and spinal cord are possible. To circumvent the risks of this procedure, Bonica developed a paralaminar technique with the patient positioned horizontally and laterally. A 5-cm to 8-cm, 22-gauge, short-bevel needle is inserted through a skin wheal of short-acting LA and advanced to the lateral edge of the lamina.

After contact with the lateral edge of the lamina, the needle is withdrawn until its point is subcutaneous and the skin is moved laterally, approximately 0.5 cm. The needle is then readvanced until it reaches a point just lateral to the upper edge of the lamina engaging the uppermost part of the superior costotransverse ligament just below the adjacent transverse process. A 2-mL glass syringe filled with saline solution is then attached to the needle. As long as the tip of the needle is within the ligament, the operator can perceive some resistance to injection. [19, 20, 21]

The paramedian approach to the epidural space is primarily used for blockade of the middle thoracic vertebral interspaces in which the acute downward angulation of the spinous processes make the midline approach to the thoracic epidural space unsatisfactory. Mid-thoracic epidural block has a limited number of applications for thoracic surgical anesthesia. Mid-thoracic epidural nerve block with local anesthetic can be used as a diagnostic tool when performing differential neural blockade on an anatomic basis in the evaluation of chest wall and thoracic pain. If destruction of the mid-thoracic nerve roots is being considered, this technique is useful as a prognostic indicator of the degree of motor and sensory impairment that the patient may experience.


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