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The intercostal nerves (ICNs) innervate the major parts of the skin and musculature of the chest and abdominal wall. The block of these nerves was first described by Braun in 1907 in the textbook Die Lokalanastesie.1 In the 1940s, clinicians noticed that intercostal nerve blocks (ICNBs) can reduce pulmonary complications and in opioid requirements after upper abdominal surgery.1 In 1981, continuous ICNB was introduced to overcome the problems associated with repeated multiple injections.1 Today, ICNB is used in a variety of acute and chronic pain conditions affecting the thorax and upper abdomen, including breast and chest wall surgery. Introduction of ultrasound guidance to the practice of regional anesthesia further facilitates its practice. The disadvantages of intercostal block, however, include the requirement for technical expertise, risks of pneumothorax, and local anesthetic toxicity with multiple levels of blockade.


ICNB provides excellent analgesia in patients with rib fractures2,3 and for postsurgical pain after chest and upper abdominal surgery such as thoracotomy, thoracostomy, mastectomy, gastrostomy, and cholecystectomy.4 Respiratory parameters typically show impressive improvements on relief of pain.2,3 Blockade of the two dermatomes above and the two below the level of surgical incision is required. ICNB does not block visceral abdominal pain, for which a celiac plexus block is required. Neurolytic ICNB is used to manage chronic pain conditions such as postmastectomy pain (T2) and postthoracotomy pain.

Figure 81B–1.

Anatomy of the spinal nerve.


  1. Disorders of coagulation, although this is not an absolute contraindication

  2. Local infection, lack of expertise and resuscitating equipment


As thoracic nerves T1 to T12 emerge from their respective intervertebral foramina, they divide into the following rami (Figure 81B–1):

  1. The paired gray and white anterior rami communicantes, which pass anteriorly to the sympathetic ganglion and chain.

  2. The posterior cutaneous ramus, supplying skin and muscle in the paravertebral region.

  3. The ventral ramus (ICN, the main focus of this chapter).

T1 and T2 send nerve fibers to the upper limbs and the upper thorax, T3 through T6 supply the thorax, T7 through T11 supply the lower thorax and abdomen, and T12 innervates the abdominal wall and the skin of the front part of the gluteal region (Figure 81B–2). Carrying both sensory and motor fibers, the ICN pierces the posterior intercostal membrane about 3 cm (in adults) distal to the intervertebral foramen to enter the subcostal grove where it, for the most part, continues to run parallel to the rib, although branches may often be found anywhere between adjacent ribs. Its course within the thorax is sandwiched between the parietal pleura and innermost intercostal (intercostalis intimus) muscles and the external and internal intercostal muscles ...

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