45 year old male presents for foreign body evaluation
A 45 year old male without significant past medical history presents for evaluation of a nailgun injury. The patient was working on his house when he accidentally impailed himself with a nail similar to below.
thumb+nail=thumbnail
An x ray is ordered and while a digit block would be a fine option for analgesia, they are quite painful for the patient. We elected to use regional anesthesia because it involves anesthetic injection into the much less sensitive forearm.
The median, radial and ulnar nerve sensory distributions are shown below as well as the general course of the nerves. The median nerve is the easiest to identify-just slap the probe in the middle of the forearm and youll see a nice honeycomb looking structure. The radial and ulnar nerves can be a little more subtle but they are reliably in the same location up until about 3/4 of the way up the forearm. Just know that the radial nerve lies radial to the radial artery and the ulnar nerve lies ulnar to the ulnar artery
Courtesy of highland ultrasound
For our patient we elected to perform a median and radial nerve block since our patient had some of the nail more on the palmar aspect.
Below is a picture of the radial artery and circled in red is the radial nerve. While i can understand how it can be hard to see on the exact outline of the nerve on the native image, the good news is that you dont need to identify the EXACT borders of the nerve. Knowing that the nerve is radial to the radial artery, you can target the fascial plane lateral to the artery and inject anesthetic into that. This fascial plane is highlighted in blue. Once anesthetic begins flowing into that fascial plane the nerve boundaries become much more clear. This is seen in the gif below.
note how only 180 degrees of anesthetic is really required for adequate anasthesia
Blocking the median nerve is much easier-it is the honeycomb like structure that lies in the middle of the forearm. Similar to the radial nerve you can just target the nearby fascia to get adequate spread rather than getting right up against the nerve.
After performing the block, the patient went to xray. There was no fracture so you plan to take the nail out at beside. By the time he got back he was completely numb and the nail came out painlessly. The patient is astonished and thinks you are a wizard.
I know what youre thinking “blah blah blah a digit block would have worked fine”. And that is totally true but I will counter with this-itll add 10 minutes(max) to your time providing patient care and if done successfully your patient will have a significantly better experience. More importantly, if you dont practice these you may not be prepared to provide adequate pain control for your patient who comes in after a degloving injury when youre working in the middle of the desert and its going to take 4 hours to get them to a hand surgeon.