Overview of Median Nerve Block Techniques

A median nerve block is a simple and safe procedure that numbs the palm side of the thumb, index finger, middle finger, ring finger, and the part of the palm nearest to the thumb. This has been done for years by using familiar body landmarks to guide the placement of the medication.

However, with the development and common use of ultrasound technology, doctors can now more precisely place the medication, needing less of it and reducing the chance of complications. Primarily, anesthesiologists and hand surgeons have used this kind of hand numbing procedure for patients around the time of surgery.

That said, emergency doctors and those treating injuries have become more comfortable using these blocks for immediate pain relief and during care for injuries.

Anatomy and Physiology of Median Nerve Block Techniques

The median nerve is a major nerve that stems from a network of nerves in your shoulder area known as the brachial plexus. The nerve stretches from the shoulder, down to your arm, runs close to the main arm artery, and continues down to your hand. The median nerve is vital because it controls the majority of your hand muscles, which allow you to perform different movements. In other words, it’s much like an electrical cable that carries signals from your brain to your hand.

As the median nerve travels down the arm, it passes between the two primary muscles of your upper arm. It continues across the inner part of the elbow, and down into your forearm. Here, it provides power to the deep muscles of your forearm responsible for bending your fingers and wrist.

The median nerve then passes through a narrow, rigid pathway in your wrist called the carpal tunnel, along with several hand tendons. The tunnel is surrounded by bones and a tough ligament. In the tunnel, the median nerve is positioned towards the inner edge of the wrist. It’s worth mentioning that the nerve can be numbed at any point along the arm or forearm. However, it’s relatively easier and safer in the forearm due to its superficial location and its distance from the main arm artery.

Blocking the median nerve at the carpal tunnel levels is a common procedure, but it doesn’t have a consistent success rate due to different wrist and nerve structures among individuals. A 2015 study devised a technique using wrist width to enhance injection accuracy in the wrist. The tactic suggests injecting the numbing medicine at specific points of the wrist, which vary from person to person, to avoid injuring nearby tendons and structures. The study found that injecting on the thumb-side (radial side) of the wrist is generally safer.

Why do People Need Median Nerve Block Techniques

When the median nerve is blocked, the person can’t feel anything on the palm side of the thumb, index, middle and part of the ring finger, as well as the same side of the palm. This includes the skin and the bones in the hand (metacarpals) and fingers (phalanges). This method can be used as the only anaesthetic or it can support other treatments such as resetting or fixing broken bones and dislocations, repairing complex cuts, or draining cysts (fluid-filled sacs) and abscesses (infections filled with pus).

Using these nerve blocks after surgery has shown to speed up recovery times and reduce the use of strong painkillers known as opioids. It’s also particularly helpful as a painkiller for burns that affect the areas of the hand and arm controlled by the median nerve. This technique is also useful to complete nerve blocks in the arm (brachial plexus blocks) that didn’t fully work.

While there may be concerns about compartment syndrome (a painful condition that occurs when pressure within the muscles builds to dangerous levels) with high energy injuries, nerve blocks in the forearm have been used in cases of blast injuries and other high energy injuries without serious problems. It’s always important to assess the patient and the type of injury with the doctor before starting any nerve block treatment.

When a Person Should Avoid Median Nerve Block Techniques

There are several reasons why a nerve block (a type of anesthesia that numbs a specific area) may not be possible:

– The patient does not want to have it.
– There is skin infection or pus-filled pocket, known as cellulitis or an abscess, where the injection would be given.
– The person may have had a severe allergic reaction, called an anaphylactic reaction, to the local anesthetics used in the nerve block.
– If a patient has high-energy injuries and there is a risk for compartment syndrome (a painful condition that occurs when pressure within the muscles builds to dangerous levels), doctors might have to consider other options and discuss first with specialists.

Equipment used for Median Nerve Block Techniques

The equipment used for the medical procedure includes:

* Local anesthetic – This is the substance that makes you numb so you don’t feel pain or other sensations in a specific area. The type and how much used might vary based on how long the numbness needs to last. For example, 5mL of lidocaine 2% could be used when the numbness needs to last for a short to medium duration (1-2 hours), and 5mL of bupivacaine 0.5% or ropivacaine 0.5% for longer numbness (2-4 hours).

* Block needle – This needle with a short bevel type edge (6cm or longer) is used to inject the local anesthetic.

* Chlorhexidine 2% or povidone-iodine – These are disinfectants used to clean your skin and prevent infection.

* High frequency (8MHz or greater) linear ultrasound probe – This device uses sound waves to create an image of the body’s internal structures so the doctor can see where to place the needle.

* Sterile ultrasound gel – This gel is applied on your skin and it helps the ultrasound probe to slide smoothly on your skin and capture clear images.

* Sterile probe cover – This cover is used to keep the ultrasound probe sterile, or germ-free.

* Access to intralipid 20% (1.5mL/kg bolus, 0.25mg/kg/hr drip) – This is a type of medicine on standby ready to be used in the case of a sudden occurrence of heart attack due to local anesthetic systemic toxicity (LAST). It’s a rare but serious side effect from the local anesthetic that can affect the heart.

Who is needed to perform Median Nerve Block Techniques?

A medical professional skilled in a procedure called a peripheral nerve block is responsible for this. A peripheral nerve block is a type of anesthesia where an anesthetic is given near a specific nerve or group of nerves in order to numb them, decreasing the pain in certain areas of your body. Also, there is a nurse present who is proficient in giving resuscitation medications if necessary. Resuscitation medications are drugs used to restore the body or to bring it back to a normal state when something goes wrong during the treatment.

Preparing for Median Nerve Block Techniques

Before beginning a nerve block procedure, there are a few critical steps. A nerve block is a procedure where medicine is injected into a particular nerve or group of nerves to prevent feeling pain in that particular area.

First, doctors must explain the process, including the potential risks and benefits of the nerve block, along with options for treatments. After explaining these details, doctors will ask for your approval to continue with the procedure to ensure you are informed and comfortable.

Ensuring the patient’s identity and the correct location for the nerve block is the next step. It is crucial to conduct a detailed inspection of the nerves and blood vessels in the affected limb. This examination allows the doctor to understand the condition of your nerves and make sure nothing unexpected happens during the procedure.

Next, your arm will be positioned on a stand, with your elbow straight out and your palm facing up. The doctor will clean the area from the bend of your elbow to the middle part of your forearm with a special antiseptic solution like 2% chlorhexidine or povidone-iodine, which helps to kill bacteria and other germs. You’ll have to wait for this solution to dry before moving forward.

The doctor will arrange the ultrasound machine within their direct view to aid in targeting the precise nerve to be blocked. The ultrasound uses sound waves to create images of the inside of your body. A sterile protective cover and sterile gel will be applied to the ultrasound probe, a device that sends and receives the ultrasound signals.

Finally, they will fill a sterile syringe with a local anesthesia solution. This medicine numbs the area they’re working on so you won’t feel any pain during the procedure. Following these preparatory steps helps ensure the nerve block procedure is safe and effective.

How is Median Nerve Block Techniques performed

A nerve block is a procedure done to stop certain signals from nerves, which can help with pain relief. Here’s how a doctor performs a nerve block:

1. A probe, a device used to get images from inside the body, is placed in the bend of your elbow over a bone called the proximal radius.
2. The doctor identifies the radius bone. Near to this, there’s a muscle called the pronator teres.
3. Other muscles, named the flexor digitorum superficialis and flexor digitorum profundus, are found near the pronator teres.
4. The median nerve, which controls feeling and movement in parts of your hand, is seen between these two muscles. It has a special look on the imaging, like a honeycomb, and is brighter than the surrounding area.
5. A needle for the block is carefully inserted. It’s placed in the same direction as the probe. It’s really important that the doctor sees the needle tip at all times.
6. The needle is aimed at the fascial plane. This is the connective tissue that separates different layers of the body, in this case, between the flexor digitorum superficialis and flexor digitorum profundus muscles.
7. The doctor will gently suck in some body fluid into the needle (aspirate) to make sure no blood vessels have been hit.
8. They then inject a tiny bit of a local anesthetic, which is a medicine that numbs the area.

The needle’s position may need to be adjusted until it’s in the perfect spot. Once it’s in the right place, the doctor will continue to aspirate and then inject small amounts (1-2 mL) of the local anesthetic. They will continue this step by step injection until the medicine has spread adequately around the nerve. That’s how a nerve block is done!

Possible Complications of Median Nerve Block Techniques

Complications from medical procedures can sometimes happen, including:

– Bleeding at the place where the doctor inserted a needle.

– Intramuscular hematoma, which is a fancy word for a blood clot that forms inside a muscle.

– Infection at the spot where the doctor inserted the needle.

– An allergic reaction to the local anesthetic, which is a medication used to numb a specific part of your body during the procedure.

– Vascular puncture, or accidentally puncturing a blood vessel.

– Intravascular injection, which means the medication was accidentally injected directly into a blood vessel.

– Local anesthetic systemic toxicity (LAST), which can happen if your body absorbs too much of the local anesthetic.

– Nerve damage, including neuropraxia (a mild type of nerve injury that can cause temporary loss of motor and sensatory functions) or neurolysis (which is a more severe and possibly permanent damage to a nerve).

– Unsuccessful block, meaning that the procedure did not have the desired effect.

Remember, your doctors will always work hard to prevent these complications. They are trained professionals and will do their best to make sure your procedure goes as smoothly as possible.

What Else Should I Know About Median Nerve Block Techniques?

Blocking this nerve will cause numbness in the palm side of the thumb, index finger, middle finger, half of the ring finger, and the part of the palm closest to these fingers. It will also impact feeling in the long bones of the fingers (metacarpals) and small bones of the fingers (phalanges) that match these digits. A complete block could cause temporary paralysis of some muscles in these fingers.

If the nerve is blocked closer to the forearm, it might also paralyze the muscles that bend the wrist and fingers, except for the muscle that bends and moves the wrist side to side, which is controlled by a different nerve. This process is particularly useful if a person has injured the palm, thumb, index finger, middle finger, or the side of the ring finger closest to the thumb. If there needs to be additional numbing for injuries to the ring finger, a different nerve block, called an ulnar nerve block, should be used.

This numbness can also be achieved by injecting between two tendons — the flexor carpi radialis and palmaris longus — at the wrist fold. However, using ultrasound may make the nerve block more successful and intense, resulting in complete numbness.

Frequently asked questions

1. How does a median nerve block work and what areas of my hand will be affected? 2. What are the potential risks and complications associated with a median nerve block? 3. How will the ultrasound technology be used during the procedure and how does it improve the accuracy and effectiveness of the nerve block? 4. What type and amount of local anesthetic will be used for my nerve block, and how long can I expect the numbness to last? 5. Are there any alternative treatments or pain management options that I should consider before proceeding with a median nerve block?

Median Nerve Block Techniques can affect individuals differently due to variations in wrist and nerve structures. The technique involves injecting numbing medicine at specific points in the wrist to block the median nerve. This procedure is commonly done at the carpal tunnel level, but its success rate is not consistent.

There are several reasons why someone may need Median Nerve Block Techniques: 1. Pain relief: Median Nerve Block Techniques can be used to provide pain relief in the hand, wrist, and forearm. This can be particularly helpful for conditions such as carpal tunnel syndrome, where the median nerve is compressed and causes pain, numbness, and tingling. 2. Diagnostic purposes: Median Nerve Block Techniques can also be used as a diagnostic tool. By temporarily numbing the median nerve, doctors can determine if the nerve is the source of the patient's symptoms. If the pain is relieved after the nerve block, it suggests that the median nerve is indeed the cause of the problem. 3. Therapeutic purposes: In some cases, Median Nerve Block Techniques can be used as a therapeutic treatment. For example, if a patient has chronic pain in the hand or wrist due to a condition like arthritis or tendinitis, a nerve block can provide temporary relief and allow for physical therapy or other treatments to be more effective. It is important to note that the decision to undergo a Median Nerve Block Technique should be made in consultation with a healthcare professional, who can assess the individual's specific condition and determine if this procedure is appropriate and beneficial.

You should not get Median Nerve Block Techniques if you do not want to have it, if you have a skin infection or abscess in the injection area, if you have had a severe allergic reaction to local anesthetics used in the nerve block, or if you have high-energy injuries with a risk for compartment syndrome.

To prepare for Median Nerve Block Techniques, the patient should first be informed about the procedure, including its risks and benefits, and give their consent to proceed. The doctor will then conduct a detailed examination of the nerves and blood vessels in the affected limb to ensure the procedure goes smoothly. The patient's arm will be positioned and cleaned with a special antiseptic solution, and the ultrasound machine will be set up to aid in targeting the precise nerve.

The complications of Median Nerve Block Techniques include bleeding, intramuscular hematoma, infection, allergic reaction to the local anesthetic, vascular puncture, intravascular injection, local anesthetic systemic toxicity, nerve damage (neuropraxia or neurolysis), and unsuccessful block.

Symptoms that require Median Nerve Block Techniques include the inability to feel anything on the palm side of the thumb, index, middle, and part of the ring finger, as well as the same side of the palm. This can include the skin, bones in the hand and fingers, and can be used for various treatments such as resetting broken bones, repairing cuts, draining cysts and abscesses, and as a painkiller for burns.

Join our newsletter

Stay up to date with the latest news and promotions!

"*" indicates required fields

This field is for validation purposes and should be left unchanged.

We care about your data in our privacy policy.