Brachial Plexus Blocks
Last updated 22nd November 2019 - Tom Heaton
Important blocks of the brachial plexus include:
The specific indications are slightly different for each block but are to provide analgesia or anaesthesia of the upper limb.
In skilled hands these blocks can provide an alternative to general anaesthesia for upper limb surgery.
Introduction of catheters instead of a single-shot injection can allow for a more prolonged infusion and analgesia in significant surgery.
Blocks can be done through a variety of techniques, with ultrasound guided blocks becoming the most common approach due to benefits in terms of speed of onset and better quality block (level 1b evidence).
There are also theoretical advantages in safety from being able to visualise key structures, but there isn’t yet strong evidence of this.
Landmark techniques with nerve stimulation have also been used.
The addition of nerve stimulation to the ultrasound guided technique is not thought to add any additional benefit.
The general principles of regional anaesthesia all apply, with certain additional components for some blocks.
- Interscalene
- Supraclavicular
- Axillary
The specific indications are slightly different for each block but are to provide analgesia or anaesthesia of the upper limb.
In skilled hands these blocks can provide an alternative to general anaesthesia for upper limb surgery.
Introduction of catheters instead of a single-shot injection can allow for a more prolonged infusion and analgesia in significant surgery.
Blocks can be done through a variety of techniques, with ultrasound guided blocks becoming the most common approach due to benefits in terms of speed of onset and better quality block (level 1b evidence).
There are also theoretical advantages in safety from being able to visualise key structures, but there isn’t yet strong evidence of this.
Landmark techniques with nerve stimulation have also been used.
The addition of nerve stimulation to the ultrasound guided technique is not thought to add any additional benefit.
The general principles of regional anaesthesia all apply, with certain additional components for some blocks.
Anatomy
An understanding of the anatomy of the brachial plexus and its relationship with surrounding tissues is essential for safe and effective regional anaesthesia.
These are some good videos on the basic anatomy of the brachial plexus:
AnatomyZone - Brachial plexus - Structure and location: https://www.youtube.com/watch?v=hrKesc_XSzo
AnatomyZone - Brachial plexus - Branches: https://www.youtube.com/watch?v=VdiFNYdIo1o&t=15s
This is quite a good video for learning to draw the brachial plexus from Handwritten Tutorials:
https://www.youtube.com/watch?v=9gPsHCflFfA
TeachMeAnatomy have a good review of the anatomy here:
http://teachmeanatomy.info/upper-limb/nerves/brachial-plexus/
This is a good video for drawing the brachial plexus: https://www.youtube.com/watch?v=Z_Y_kVdH9zE
These are some good videos on the basic anatomy of the brachial plexus:
AnatomyZone - Brachial plexus - Structure and location: https://www.youtube.com/watch?v=hrKesc_XSzo
AnatomyZone - Brachial plexus - Branches: https://www.youtube.com/watch?v=VdiFNYdIo1o&t=15s
This is quite a good video for learning to draw the brachial plexus from Handwritten Tutorials:
https://www.youtube.com/watch?v=9gPsHCflFfA
TeachMeAnatomy have a good review of the anatomy here:
http://teachmeanatomy.info/upper-limb/nerves/brachial-plexus/
This is a good video for drawing the brachial plexus: https://www.youtube.com/watch?v=Z_Y_kVdH9zE
Interscalene Block
Indications:
Procedures involving:
The ISB blocks the superior roots/trunks of the brachial plexus close to their origin.
As such, it is the block of choice to capture the nerves that leave the brachial plexus early in its course e.g. suprascapular nerve.
This makes it the block of choice for shoulder surgery as it is more likely to catch all the required nerves.
However, the inferior trunk is less well blocked by this block, and so it is less effective for surgery more distally on the limb - ulnar sparing is common (C8,T1)
Contraindications (in addition to general):
The ISB has a very high rate of blockade of the ipsilateral phrenic nerve - nearly 100% if large volumes (>20ml) are used.
As such, the impact of this on the patient must be taken into account, and it means that bilateral ISBs are contraindicated.
However, careful, low volume ISB to allow avoidance of GA may be better in patients with severe lung disease, and so is a balance.
Procedures involving:
- Shoulder
- Distal clavicle
- Proximal humerus
The ISB blocks the superior roots/trunks of the brachial plexus close to their origin.
As such, it is the block of choice to capture the nerves that leave the brachial plexus early in its course e.g. suprascapular nerve.
This makes it the block of choice for shoulder surgery as it is more likely to catch all the required nerves.
However, the inferior trunk is less well blocked by this block, and so it is less effective for surgery more distally on the limb - ulnar sparing is common (C8,T1)
Contraindications (in addition to general):
- Contralateral phrenic nerve impairment e.g. contralateral ISB
- Severe respiratory disease
The ISB has a very high rate of blockade of the ipsilateral phrenic nerve - nearly 100% if large volumes (>20ml) are used.
As such, the impact of this on the patient must be taken into account, and it means that bilateral ISBs are contraindicated.
However, careful, low volume ISB to allow avoidance of GA may be better in patients with severe lung disease, and so is a balance.
Technique
The equipment is similar to most regional anesthetic blocks:
The volume of local anaesthetic will vary depending on the goal of the block (anaesthesia vs analgesia) and the technical ease.
Very low volumes (if carefully placed) can be used to excellent effect and have a reduced chance of resulting in phrenic nerve blockade.
These are some videos on the technique:
NYSORA: https://www.youtube.com/watch?v=Zke6938Y1k4
The Pain Source: https://www.youtube.com/watch?v=Dg9BJ-32yLc
- Linear probe of US machine
- 50mm 22g block needle
- 20ml local anaesthetic
- Aseptic kit
The volume of local anaesthetic will vary depending on the goal of the block (anaesthesia vs analgesia) and the technical ease.
Very low volumes (if carefully placed) can be used to excellent effect and have a reduced chance of resulting in phrenic nerve blockade.
These are some videos on the technique:
NYSORA: https://www.youtube.com/watch?v=Zke6938Y1k4
The Pain Source: https://www.youtube.com/watch?v=Dg9BJ-32yLc
Positioning
The patient is commonly positioned semi recumbent with the head turned away from the side of the block.
The use of a head ring rather than a pillow may make the block easier, as the approach angle can be quite posterior and may be impeded by a pillow.
As with all blocks the positioning of US screen should be optimal.
Performance
The block starts with ultrasound imaging of the neck and the important structures identified.
This can be identification of the trachea centrally, followed by lateral movement of the probe with identification of the carotid artery and internal jugular vein.
Continuing to move the probe laterally should allow identification of the brachial plexus between the anterior and middle scalene muscles.
The nerves will often appear as a ‘traffic light’ appearance.
The usual level is about 2-3cm above the clavicle, or around the level of the cricoid cartilage.
An in-plane approach, usually from lateral to medial is then used , keeping the needle tip in view at all times.
The plexus is surrounded by a fascial sheath and this is often punctured (with a tactile ‘pop’ sensation).
Injection of local anaesthetic can then be commenced, ensuring negative aspiration and low resistance to injection, as well as visualising the spread of local anaesthetic.
If the fascial sheath is punctured then it is important to ensure that the needle tip is not intraneural, and so visualising the LA spread is a key step.
In cases of difficulty identifying the correct space, a recommended approach is to identify the brachial plexus at the supraclavicular location.
It can then be tracked up the neck to the interscalene position.
The patient is commonly positioned semi recumbent with the head turned away from the side of the block.
The use of a head ring rather than a pillow may make the block easier, as the approach angle can be quite posterior and may be impeded by a pillow.
As with all blocks the positioning of US screen should be optimal.
Performance
The block starts with ultrasound imaging of the neck and the important structures identified.
This can be identification of the trachea centrally, followed by lateral movement of the probe with identification of the carotid artery and internal jugular vein.
Continuing to move the probe laterally should allow identification of the brachial plexus between the anterior and middle scalene muscles.
The nerves will often appear as a ‘traffic light’ appearance.
The usual level is about 2-3cm above the clavicle, or around the level of the cricoid cartilage.
An in-plane approach, usually from lateral to medial is then used , keeping the needle tip in view at all times.
The plexus is surrounded by a fascial sheath and this is often punctured (with a tactile ‘pop’ sensation).
Injection of local anaesthetic can then be commenced, ensuring negative aspiration and low resistance to injection, as well as visualising the spread of local anaesthetic.
If the fascial sheath is punctured then it is important to ensure that the needle tip is not intraneural, and so visualising the LA spread is a key step.
In cases of difficulty identifying the correct space, a recommended approach is to identify the brachial plexus at the supraclavicular location.
It can then be tracked up the neck to the interscalene position.
Complications
Specific to this block include:
- Phrenic nerve paralysis
- Horner’s syndrome (stellate ganglion blockade)
- Hoarseness (recurrent laryngeal nerve blockade)
- Total spinal (accidental dural puncture of nerve root)
- Vascular injury
Links & References
- Baju, P. Coventry, D. Ultrasound guided brachial plexus blocks. CEACCP. 2014. 14(4): 185-191 https://academic.oup.com/bjaed/article/14/4/185/294013
- AnatomyZone. Brachial plexus - structure and location. 2012. https://www.youtube.com/watch?v=hrKesc_XSzo
- Jones, O. The brachial plexus. TeachMeAnatomy. 2018. http://teachmeanatomy.info/upper-limb/nerves/brachial-plexus/
- NYSORA. Ultrasound guided interscalene brachial plexus block. https://www.nysora.com/ultrasound-guided-interscalene-brachial-plexus-block
- NYSORA. Interscalene brachial plexus block. https://www.nysora.com/interscalene-brachial-plexus-block
- NYSORA. Ultrasound-guided axillary brachial plexus block. https://www.nysora.com/techniques/upper-extremity/axillary/ultrasound-guided-axillary-brachial-plexus-block/
