The most common complication associated with a supraclavicular brachial plexus block is:

The most common complication associated with a supraclavicular brachial plexus block is:

• A. Blockade of the phrenic nerve
• B. Pneumothorax
• C. Spinal blockade
• D. Blockade of the recurrent laryngeal nerve

Answer: (A)

The key idea here is that injections for a supraclavicular brachial plexus block can spread to nearby nerves, with the phrenic nerve being particularly susceptible due to its close proximity to the brachial plexus region. When local anesthetic diffuses cephalad and around the neck, it can block the phrenic nerve on the same side, causing diaphragmatic paralysis or reduced diaphragmatic movement. This tends to be the most common complication because the phrenic nerve lies just near the area where the block is performed, so even small amounts of spread can affect it. Clinically, this may be seen as ipsilateral diaphragmatic paresis, which can worsen breathing in patients with limited pulmonary reserve but is often tolerated in healthy individuals. Pneumothorax is a known risk due to the pleura’s proximity, but with careful technique and, increasingly, ultrasound guidance, its incidence is lower than phrenic nerve involvement. Blockade of the recurrent laryngeal nerve and a spinal block are far less likely; they would require unusual patterns of spread or injection into spaces not typically reached by this approach.

The key idea here is that injections for a supraclavicular brachial plexus block can spread to nearby nerves, with the phrenic nerve being particularly susceptible due to its close proximity to the brachial plexus region. When local anesthetic diffuses cephalad and around the neck, it can block the phrenic nerve on the same side, causing diaphragmatic paralysis or reduced diaphragmatic movement. This tends to be the most common complication because the phrenic nerve lies just near the area where the block is performed, so even small amounts of spread can affect it. Clinically, this may be seen as ipsilateral diaphragmatic paresis, which can worsen breathing in patients with limited pulmonary reserve but is often tolerated in healthy individuals.

Pneumothorax is a known risk due to the pleura’s proximity, but with careful technique and, increasingly, ultrasound guidance, its incidence is lower than phrenic nerve involvement. Blockade of the recurrent laryngeal nerve and a spinal block are far less likely; they would require unusual patterns of spread or injection into spaces not typically reached by this approach.