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 Lokalanästesie.1 In the
1940s, clinicians noticed that intercostal nerve blocks (ICNBs) could
favorably effect a reduction in pulmonary complications and in narcotic
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
great variety of acute and chronic pain conditions affecting the thorax and
upper abdomen. Less commonly, it is also used for breast and minor chest
wall surgery and, in combination with celiac plexus blockade, abdominal
operations, usually with light sedation or general anesthesia. As with many
other regional techniques, the advantages of ICNBs include superior
analgesia, opioid-sparing effect, improved pulmonary mechanics, reduced central
nervous system depression, and avoidance of urinary retention. It should be
noted, however, that supplemental systemic analgesia is also almost always needed.
The disadvantages of the technique include the requirement for
technical expertise, risks of pneumothorax, and local anesthetic toxicity
with multiple levels of blockade.
ICNB provides excellent analgesia for chest trauma such as 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 improve with 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. It is
inadequate for renal surgery since a block from T5 to L3 is required. In
itself, ICNB alone does not provide adequate intraoperative anesthesia, and
supplemental analgesics or sedatives are usually required except for minor
body surface surgery. Neurolytic ICNB may be used to manage chronic pain
conditions such as postmastectomy pain (T2) and postthoracotomy pain.
1. When pneumothorax would be a disaster. ICNBs may help a patient
tethering on the brink of respiratory decompensation, but if an unintended
pneumothorax could have serious consequences, an alternative block should be
considered unless a chest tube is in place.
2. Coagulation abormalities. This contraindication is not as strong as in
central neuraxial blocks but may become absolute if
infection, lack of expertise and resuscitating equipment, and lack of any
short-term plan to wean from the ventilator should also discourage the use of
As thoracic nerves T1 to T12 emerge from their respective
intervertebral foramina, they divide into the following rami (Figure
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
3. The ventral ramus (ICN, the main focus of this chapter)
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