Intercostobrachial Nerve Block: Ultrasound Technique, Coverage, and Neuralgia Management

Intercostobrachial Nerve Block:

• What is Intercostobrachial Nerve Block?
• Ultrasound Technique
• Coverage
• Neuralgia Management

What is Intercostobrachial Nerve Block?

An Intercostobrachial Nerve Block (ICBN block) is a regional anesthesia technique used to numb the upper inner arm, axilla, and portions of the chest wall supplied by the intercostobrachial nerve. The intercostobrachial nerve originates from the T2 nerve root and travels through the axilla, providing sensory innervation to the upper medial arm. Because this nerve is not part of the brachial plexus, it is not anesthetized by routine brachial plexus blocks such as the supraclavicular or infraclavicular block.

The ICBN block is most often used for procedures involving the axilla, sentinel lymph node biopsies, breast surgeries, and upper medial arm interventions. It is also a valuable tool for treating certain types of neuropathic pain in this nerve distribution. The block is simple, quick, and can be performed using either landmark-based or ultrasound-guided methods, with ultrasound providing far greater accuracy.

Ultrasound Technique

The ultrasound-guided intercostobrachial nerve block is typically performed in the axillary region. A high-frequency linear transducer is placed transversely in the axilla to identify the fascial planes and the neurovascular structures. Since the intercostobrachial nerve is small and often difficult to visualize directly, clinicians usually target the fascial plane between the latissimus dorsi and the serratus anterior muscles at the level of the mid-axilla.

Once the correct plane is identified, a small volume of local anesthetic (usually 5–10 mL) is injected to spread between the muscles, anesthetizing the nerve as it traverses this region. The ultrasound technique offers improved accuracy, helps avoid vascular structures, and increases the likelihood of achieving complete sensory blockade. This method is considered more reliable than traditional landmark-based approaches.

Coverage

The coverage provided by an intercostobrachial nerve block includes:

• Upper medial arm
• Axilla (armpit region)
• Lateral chest wall near the second intercostal space
• Area around the axillary lymph nodes

Because the intercostobrachial nerve is purely sensory, blocking it does not affect motor function. This makes the block particularly helpful in surgeries where minimizing motor impairment is important, such as sentinel node biopsy or cosmetic breast surgery. The block is also frequently combined with a brachial plexus block for complete anesthesia during arm procedures.

Neuralgia Management

Intercostobrachial neuralgia refers to chronic pain arising from irritation or injury to the intercostobrachial nerve. Common causes include breast surgery, mastectomy, lymph node removal, thoracic surgery, or even trauma. Symptoms often include burning pain, tingling, hypersensitivity, or numbness in the upper medial arm and axilla.

An ICBN block can provide significant relief in these cases by interrupting abnormal pain signaling. It may be used diagnostically to confirm the source of pain or therapeutically to reduce neuralgia. Repeated blocks, peripheral nerve stimulation, radiofrequency ablation, and targeted physical therapy may also be incorporated into long-term management. For many patients, nerve blocks are an essential part of improving quality of life and reducing chronic postoperative pain.