Elbow block

Following nerves can be blocked at the level of elbow:  

Median nerve
Radial nerve
Ulnar nerve
 
Median Nerve:

Anatomy

The Median nerve lies on the medial side of the brachial artery at the level of elbow crease.     
This image is from Gray's anatomy and shows median nerve lying medial to the artery at the level of elbow. 

 

Locating the nerve:
Use a linear high frequency transducer. 
Position it just above the elbow crease so as to obtain a cross sectional view of the brachial artery. 
Do not look for the nerve initially.  Find the artery, then look medial to the artery. 
The Nerve lies medial to the artery.
You will have to adjust the probe (tilting and clockwise and counterclockwise movement) to get the best view of the nerve.
Most of the time it is quite closely associated with the artery but sometimes it can be further away. 
The best way to confirm it is the nerve is to scan back towards the axilla. The median nerve always stays with the artery and if it is further away at the elbow then it will join the artery by midarm level.

Mobile users please click here for video



Anisotropy demonstrated by median nerve at midforearm level


 Indication:
1.To supplement an incomplete brachial plexus block done proximally
2.To provide postoperative analgesia  

Contraindications:
1.Patient refusal
2.Infection at the site of block
3.Coagulopathy

Equipment:
1. Ultrasound machine with high frequency linear transducer.
2. Probe cover with ultrasound jelly
3. 50 mm insulated stimulating needle with a nerve stimulator
4. 5 ml of 0.5% or 0.25% levobupivacaine.

Performing the nerve block:
After intravenous access is established and appropriate monitoring used. 
Patient, anaesthetist and the ultrasound machine are positioned as shown in the picture.



The needle is inserted in-plane so that the entire needle is visualised as it approaches the nerve. 
You may do this block without a nerve stimulator but it is our practise to combine both techniques. 
The nerve stimulator is set to deliver a current of 0.5mA. 
The needle at first is directed above the nerve and local anaesthetic is injected above it. 
Then the needle is directed below the nerve and local anaesthetic injected below the nerve. 
In case the needle produces motor stimulation (finger flexion/wrist flexion/supination) then the current is reduced so that no motor stimulation is produced at current less than 0.2mA. 
Also the twitch should disappear as soon as local anaesthetic is injected.  
The local anaesthetic (shown in blue) is injected around the nerve as shown:




The following is video of a median nerve block. Video courtesy Nerve Imaging group and can also be found on RA-UK website :



Ulnar nerve block:  

Anatomy:
The ulnar nerve emerges from behind the medial epicondyle and descends on the medial side of the forearm. 
At a variable point in the forearm it is joined by ulnar artery.  The ulnar artery is formed by the division of brachial artery in front of elbow into radial and ulnar artery. 

The ulnar nerve lies on the medial side of the ulnar artery. 
The point at which they lie close to each other is highly variable.  This point can be high in the forearm or as low as just above the wrist. 

The following video demonstrates this point.  Both forearms of the same individual are scanned. 
On scanning the right hand you can see the nerve joining the artery at the level of midforearm. 
On the left hand side the artery does not join the nerve till the level of wrist.   

Scanning the right side first and then the left side



 
Locating the nerve:

Use a high frequency linear transducer. 
Place the probe over the midforearm level on medial side so that a cross sectional view of the ulnar artery is visible.  Look at medial side of the artery. The nerve may be visible close to the artery at this level. 
If not scan towards the wrist maintaining the cross section view of the artery in the middle of picture. 
You will see the nerve joining the artery from the medial side.   
Once the nerve is identified then trace the nerve all the way back to the elbow.  See that the nerve seperates from the artery and then descends towards the medial epicondyle.   

Indication:
1.To supplement an incomplete brachial plexus block done proximally
2.To provide postoperative analgesia  

Contraindications:
1. Patient refusal
2. Infection at the site of block
3. Coagulopathy  

Equipment:
1.Ultrasound machine with high frequency linear transducer.
2.Probe cover with ultrasound jelly
3.50 mm insulated stimulating needle with a nerve stimulator
4.5 ml of 0.5% or 0.25% levobupivacaine.  

Performing the nerve block:
After intravenous access is established and appropriate monitoring used. 
Patient, anaesthetist and the ultrasound machine are positioned as shown in the picture.    



The needle is inserted in-plane so that the entire needle is visualised as it approaches the nerve.
You may do this block without a nerve stimulator but it is our practise to combine both techniques. 
The nerve stimulator is set to deliver a current of 0.5mA.  The needle at first is directed above the nerve and local anaesthetic is injected above it. 
Then the needle is directed below the nerve and local anaesthetic injected below the nerve. 
In case the needle produces motor stimulation (finger flexion on ulnar side/ulnar deviation of wrist) then the current is reduced so that no motor stimulation is produced at current less than 0.2mA. 
Also the twitch should disappear as soon as local anaesthetic is injected.

Following is the video of ulnar nerve block. Video courtesy Nerve Imaging group and can also be found on RA-UK website :



Radial block:

Anatomy
The radial nerve arises from the posterior cord of the brachial plexus. 
In the axilla the radial nerve is with the axillary artery but goes posteriorly along the medial border of the arm. 
The radial nerve winds around the arm in the spiral groove between medial and lateral heads of triceps. 
The radial nerve then emerges on the lateral aspect of the arm.  Iit pierces the lateral intermuscular septum at this point and then lies in the anterior compartment of the arm.
It then travels between the brachialis and brachioradialis muscles to the front of elbow. 
Here it divides into superficial and deep branch


Locating the nerve:

Use a high frequency linear transducer.
Start scanning four finger breadths above the lateral epicondyle. 
You will see bony the shadow produced by the humerus. 
The radial nerve will be seen just in front of humerus. 
As you follow the nerve towards the elbow you will see it flattening out and then divide in front of the elbow into the superficial and deep branch.   





Indication:

1.To supplement an incomplete brachial plexus block done proximally
2.To provide postoperative analgesia  

Contraindications:
1.Patient refusal
2.Infection at the site of block
3.Coagulopathy  

Equipment:
1. Ultrasound machine with high frequency linear transducer.
2. Probe cover with ultrasound jelly
3. 50 mm insulated stimulating needle with a nerve stimulator
4. 5 ml of 0.5% or 0.25% levobupivacaine.  

Performing the block:
After intravenous access is established and appropriate monitoring used.
Patient, anaesthetist and the ultrasound machine are positioned as shown in the picture.



The needle is inserted in-plane so that the entire needle is visualised as it approaches the nerve. 
You may do this block without a nerve stimulator but it is our practise to combine both techniques. 
The nerve stimulator is set to deliver a current of 0.5mA.
The nerve is surrounded by local anaesthetic. 
In case the needle produces motor stimulation (finger extension) then the current is reduced so that no motor stimulation is produced at current less than 0.2mA. 
Also the twitch should disappear as soon as local anaesthetic is injected.
The following video is from RA-UK website of ultrasound guided radial nerve block. It is courtesy of 'Nerve Imaging Group'.