Ulnar Nerve Block

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Background

Nerves of the left upper extremity.

Transverse section across distal ends of radius and ulna.

Ulnar nerve block is a quick, safe, and effective means of pain reduction for hand injuries, including reduction of Boxer's Fracture^[1]

Boxer's Fracture
Hand Burns
Complex Hand Injury
Need for pain control or to perform painful procedure in distribution of ulnar nerve

Ulnar Nerve Block at the Wrist

Ulnar Nerve at the Distal Wrist

Following the Ulnar Nerve Distally

Obtain informed consent
- Patient should be made aware that they will lose both sensory and motor function of the ulnar distribution until the anaesthetic wears off
Place the patient's extremity in the supinated position
Cleanse the skin with chosen antiseptic
Create a sterile field using sterile drape
In a sterile fashion, apply a small wheel of local anaesthetic to the area immediately medial to tendon of the Flexor Carpi Ulnaris and approximately 2 cm proximal to the wrist crease.
The ulnar nerve should be immediately deep to the Flexor Carpi Ulnaris Tendon

Direct the Needle radially, deep to the Flexor Carpi Ulnaris
The ulnar nerve is ulnar in relation to the ulnar artery; even still, it is important to aspirate prior to injecting anaesthetic to rule out intra-arterial placement
Discontinue and reposition should the patient report shooting "electrical" pains or numbness prior to injection
Inject approximately 5 mL of local anesthetic

Have a partner help place the Linear Ultrasound Probe into the Sterile Probe Cover
Starting mid forearm of the volar aspect in a transverse plane, locate the Ulnar Nerve
Sliding Distally, the Ulnar Nerve and Artery should separate from each other
Injection site is generally approximately 2 cm proximal to the wrist crease.
In plane, visualize the needle on the Ultrasound monitor as you advance towards the Ulnar Nerve.
Make sure to aspirate prior to injecting to rule out vascular penetration (low risk given ultrasound guidance)
Discontinue and reposition should the patient report shooting "electrical" pains or numbness prior to injection
Inject approximately 5 mL of local anaesthetic in the area immediately surrounding the Ulnar Nerve

Ulnar Nerve Path at Elbow

Obtain informed consent
- Patient should be made aware that they will lose both sensory and motor function of the ulnar distribution until the anesthetic wears off
Place the patient's extremity in the supinated position with elbow flexed between 45 & 90 degrees
Cleanse the skin with chosen antiseptic
Create a sterile field using sterile drape
In a sterile fashion, apply a superficial small wheel of local anaesthetic to the area proximal to the medial humeral epicondyle

Injection site should be chosen approximately 2-3 cm proximal to the sulcus ulnaris groove
- This is done as the ulnar nerve is relatively fixed in the tight groove and it is important to minimize risk of direct nerve trauma and neurapraxia due to pressure build up
Direct the needle cephalad at 45 degrees^[2]
Aspirate prior to injection to rule out intravascular placement
Discontinue and reposition should the patient report shooting "electrical" pains or numbness prior to injection
Inject approximately 3-5 mL of local anaesthetic

↑ Ünlüer, EE. Ultrasound-guided Ulnar Nerve Block For Boxers Fractures. Am.J.Emerg.Med. 2016;34(8):1726.
↑ McCahon, RA et al. Peripheral nerve block at the elbow and wrist. Contin Educ Anaesth Crit Care Pain (2007) 7 (2): 42-44.