3.10 Intercostal Nerve

Question 1

Describe the course of the Intercostal Nerve

Answer 1

Ventral and Dorsal Thoracic Spinal N. Roots
Unite and Exit the Vertebral Canal

Via intervertebral foramen

Divide into 
Ventral
\+
Dorsal 
Rami

Question 2

Dorsal Ramus supplies

Answer 2

Dorsal ramus supplies extensor muscles

of back and overlying skin

Question 3

Ventral Ramus supplies

Answer 3

Ventral Ramus
Runs in NVB
Below Vein and Artery

In groove on underside of corresponding rib

Supply motor innervation
To Intercostal and TV and thoracic muscles

Question 4

Path Ventral

Answer 4

Initially Lies between pleural and posterior intercostal muscle

Moves to lie between internal + innermost intercostal

Gives off a lateral branch around mid axillary line
supply corresponding dermatome to mid clav line

Question 5

Termination of ventral

Answer 5

Terminates as anterior cutaneous branch
Sensory supply from mid axillary line
to anterior midline of chest wall

Communicating branches cross intercostal spaces
Uniting with ventral ramus
origin of lateral cutaneous branch

Grey and White Rami communicantes
connect intercostal nerve to symp chain

Question 6

Indications for ICN block

Answer 6

1. Rib #
2. Intercostal procedures
   - drain
3. Post op analgesia
   - Thoracic / Upper abdo

Adjunct tecnhique
Superseded by PVB / Epidural / TAP

VATS

2 dermatomes above 2 below

4. Acute herpes zoster
   Neurolysis for chronic pain

Question 7

Technique ICN

Answer 7

Procedure consent + pre assess

SLIMRAG

1. Injection
   @ or before angle of Rib
2. Block Nerve before divides
3. Tether Skin + Palpate rib to block
4. Insert Needle 20’ cephalad
   until lower border of rib encountered
5. Release skin
   allow needle realign
6. Walk needle tip off lower border rib
   advance 2-3mm
   puncture innermost intercostal
7. Aspirate + inject 2-5ml LA
8. Average depth of pleura
   <- posterior aspect rib 8mm

Advancing beyond 5mm greatly increase risk PTX

Question 8

Complications

Needle

Answer 8

Vessel Injury

PTX
Visceral injury (<1%)

SAH Injection
Dural cuff can extend 8cm along root

Question 9

Complications- LA

Answer 9

Resp distress
concurrent resp disease
block of intercostal
Diaphragm in lower roots

2. LAST
3. Blood supply
   rapid absorption
   -caution w/ continual infusion
4. Spread to adjacent levels
   incl. Sympathetic chain block