Overview of Cervical Plexus Block
Regional anesthetic blocks, a method of managing pain, are widely used in emergency departments and before surgery. They have many uses across various types of surgeries, as well as in emergency situations. For example, they can be used when placing a tube into a large vein in your neck, in fixing collarbone fractures, in repairing wounds, and when draining abscesses, or infected lumps, in areas like the earlobe or lower jaw.
A specific type of anesthetic block, the superficial cervical plexus block (CPB), numbs an area on the same side of the body. This region, often referred to as the “cape,” includes the area behind the earlobe, the side of the collarbone, the inner area of the lower jaw, and the underside of the collarbone.
What makes CPBs remarkable are their easy administration and effective numbing of the designated area. This area extends from C2 to C4, referring to the second to fourth vertebrae in the spinal column. CPBs are useful for procedures that includes clearing blocked arteries in the neck, removing lymph nodes, and certain plastic surgeries. Furthermore, the superficial version of CPBs can be combined with a deeper block to provide thoroughly numbing in the area, mainly used in oral and maxillofacial surgery, which encompasses surgery in the mouth, jaw and facial area.
Anatomy and Physiology of Cervical Plexus Block
The superficial cervical plexus is part of your nervous system that helps control feeling in your skin and shallow parts of your body—like the ear, shoulder, collarbone, and front half of your neck. It comes from the front part of the nerve roots named C2 to C4. The nerve branches emerge from a midpoint at the back edge of the sternocleidomastoid muscle (SCM), which is a muscle running along the side of the neck down to the collarbone. It is found at the level that matches the notch on the thyroid cartilage. From these roots, the plexus forms four terminal branches: the lesser occipital, greater auricular, transverse cervical, and supraclavicular nerves, all exiting from behind the posterior border of the SCM.
An injection of a local anesthetic may be given near the sensory branches emanating from nerve roots C2, C3, and C4, thus causing the region to become numb. This procedure is quite challenging because the SCM shields these nerve roots like a roof.
Three points are used to guide the accurate administration of this block:
- Mastoid process- a bony bump just behind and below the ear
- Chassaignac tubercle (the sharp edge of the sixth neck bone)
- The rear border of the SCM
These points help form a straight line that outlines the horizontal neck bones. Once this line is formed, marks are made to indicate where to inject.
For a superficial cervical plexus block, similar steps are taken but the injection spot is at the middle of the line instead where the branches of the superficial cervical plexus emerge from behind the posterior border of the SCM.
Why do People Need Cervical Plexus Block
The Cervical Plexus Block (CPB) is a critical method used to provide anesthesia (numbing) and pain relief to the head and neck area during certain surgical or medical procedures. Depending on the specific needs of the surgical procedure, different parts of the cervical plexus can be targeted to provide needed relief.
The cervical plexus, which is a network of nerves in the neck, can be divided into three distinct layers: deep, intermediate, and superficial. These layers allow numbing and pain relief to be given to different areas of the head, neck, and shoulder. For example, the superficial branches of the cervical plexus numb the skin and superficial structures, while the deep branches extend to muscles in the neck and even the diaphragm.
A superficial CPB, which targets the top layer, is often used when a strong numbing effect is required for the skin and underlying structures of the front and side of the neck. This kind of anesthesia can also provide relief for areas like the ear, shoulder, and collarbone. This approach is commonly used for specific surgical procedures like carotid endarterectomies (cleaning out a blockage in the main neck artery), lymph node dissection, and other superficial neck surgeries. In addition to surgery, this method can be used in an emergency room setting for treatment of injuries to the ear, neck, and collarbone region.
On the other hand, the deep CPB targets the deeper nerves along the cervical spine and is used for more significant head and neck surgeries such as vocal cord surgeries, dental abscess procedures, and certain plastic surgery repairs. The deep CPB can also be used for managing certain types of headaches and distinguishing them from migraines.
It’s also worth mentioning that CPBs can be used in combination with other anesthesia techniques for certain surgeries, such as those involving the shoulder. For instance, when performing a surgery on the shoulder, large doses can be used to provide adequate pain control. Alternatively, if there is a need to avoid affecting the phrenic nerve (which controls the diaphragm and breathing), the CPB can be combined with other methods to ensure comprehensive pain control.
CPBs can also be given on both sides of the neck for surgeries like thyroid and parathyroid procedures. In high-risk patients, these blocks can be the only anesthesia method used during their procedure. Despite its benefits, it’s worth noting that unilateral superficial cervical blocks are sometimes underutilized even though they provide adequate numbing to the neck as well as over the collarbone. This type of block has proven to be valuable for central venous cannulation, a procedure to place a tube in a large vein in the neck or collarbone.
When a Person Should Avoid Cervical Plexus Block
There are several situations where a superficial CPB (a type of nerve block) might not be the right choice for a patient:
Firstly, if a patient doesn’t wish to receive the procedure, it cannot be carried out. If there’s an active infection on the skin around the injection area, it would also make this procedure risky.
Interestingly, a neck procedure may limit your eligibility for a CPB. If you’ve had a neck surgery before, or if your neck has received radiation treatment, those could stop a CPB from being the best option.
Similarly, if a person has had paralysis in the phrenic nerve on the other side of their body, that may also prevent them from safely having a CPB. There’s also some concern for anyone who has a known allergy to certain types of local anesthetic agents (specifically, the amide and ester types).
Extra caution is necessary for patients with severe lung disease, specifically chronic obstructive pulmonary disease, or an untreated punctured lung on the other side (contralateral pneumothorax). This is because superficial CPB could unintentionally disrupt the functioning of the phrenic nerve – a key nerve related to breathing. However, a recent study has suggested that this risk may not be as substantial as previously thought.
Equipment used for Cervical Plexus Block
To carry out a nerve-blocking procedure called a CPB, the following tools and materials are needed:
- Sterile towels: Clean towels that are necessary to keep the procedure area clean and free from contamination.
- Sterile 4 × 4 inches gauze pads: Small, square pieces of material used to cover wounds or absorb body fluids.
- Sterile gloves: Clean gloves worn by your doctor to prevent infection.
- High-frequency (6-13 Hz) linear ultrasound probe, ultrasound gel, and sterile probe cover: An ultrasound device that helps your doctor to see beneath your skin, along with a special gel to improve the image quality, and a clean cover for the probe.
- Chlorhexidine or iodine-based solution for skin preparation: A type of antiseptic to cleanse your skin before the procedure.
- Local anesthetic: A medication that creates temporary loss of feeling in a small area of your body. Your doctor will choose anesthetic that lasts for a suitable duration, e.g., shorter-acting ones like lidocaine for quick procedures like stitch placement, or longer-acting ones like ropivacaine for something that takes longer, like setting a broken collarbone.
- 25 gauge 1.5-inch needle for the block: A small, thin needle used to inject the local anesthetic.
- 10 mL to 20 mL syringe: A medical tool that can hold and inject a designated amount of medication.
- Low-volume extension tubing: Extra tubing used to connect the syringe to the needle, usually used for procedures that require a large amount of liquid to be injected.
All these tools and materials are used to ensure that your procedure is conducted in a clean, safe manner and is as painless as possible.
Who is needed to perform Cervical Plexus Block?
A heart-lung bypass, known as CPB, is a complex medical procedure that needs a team of medical professionals. Here’s who’s involved:
First, we have the main doctor, the clinician, who will be doing the procedure. They have specialized training to safely conduct this operation.
While not always needed, an assistant might be present to help the main doctor. The assistant can help the main doctor by providing extra support, making the procedure run more smoothly.
Last but not least, there will be a nurse present. The nurse has an extremely important role to play. They will keep a close eye on your comfort levels and vital signs (such as heart rate and blood pressure), making sure you’re safe during the procedure. Plus, if the doctor needs any extra equipment or supplies during the operation, the nurse will get them. This way, the main doctor can focus on their work without interruptions.
Preparing for Cervical Plexus Block
When getting ready for a procedure called a CPB, certain steps are typically followed to keep the patient safe. First, the patient must be given full details about what the procedure involves. Depending on the rules of the hospital or clinic, the patient may need to agree to undergo the procedure either by signing a form or verbally expressing their consent.
The doctor, main nurse, and the person who handles the medicines need to know how to spot and treat any side effects of the local anesthesia, the medicine used to numb a specific area of the body during the procedure.
Another important safety measure is to make sure the area where the injection will happen doesn’t show any signs of infection. It must be thoroughly cleaned with a special germ-killing solution. The health professionals must always wear gloves that are totally germ-free, to prevent any possible infection. Any instrument that goes near or touches the patient’s body should also be sterile (germ-free), including the probe used during the procedure and even the gel that’s put on the patient’s skin for the probe to work effectively.
How is Cervical Plexus Block performed
Administering CPBs or cervical plexus blocks – a type of anesthesia often used for surgeries of the neck – requires careful consideration. The factors to be taken into account include the unique characteristics of the patient, possible complications, and choosing the right technique.
The positioning of the patient can be either lying back (supine) or half-lying (semi-sitting). The patient’s head is turned away from the side where the block will be administered. Another position is the lateral decubitus, where the patient is lying on his/her side. This position helps the medical practitioner see the ultrasound screen clearly. Comfort is the key, and the patient’s physical limitations must be considered. In patients who carry excess weight, a certain muscle along the neck (the posterior border of the SCM) might be hard to spot. To ease the process, the patient can raise their head a bit.
Ultrasound guidance is quite helpful as it allows seeing blood vessels, watching the distribution of anesthetic in real-time, and tracking the needle’s depth. While the use of ultrasound for superficial CPBs is fairly common, using it for deep CPBs is rather new and not frequently documented. Experienced medical practitioners can achieve similar success rates whether they use ultrasound or the traditional landmark-based method.
The landmark-based method focuses on points located along the posterior border of the SCM, with needle insertion at the midpoint of this line where branches of the superficial cervical plexus usually emerge. After the area is cleaned and prepared, anesthetic is injected along the aforementioned muscle line, with the needle not going deeper than 1 to 2 cm.
In the ultrasound-based method, a high-frequency linear probe is used to identify the structures inside the neck. The probe is positioned halfway between the mastoid process (a bone behind the ear) and the collarbone, just behind and slightly below the SCM. The thyroid cartilage (a part of your voice box or larynx) is another important landmark. As in the previous technique, the skin must be cleaned and properly prepared before starting.
Once the SCM is spotted, the probe moves backward until the edge of the SCM comes into view, exposing the levator scapulae muscle (a muscle that helps move and stabilize the shoulder blade) and the interscalene groove (a space between two neck muscles). Key points to consider are the major vessels and the group of nerves called the brachial plexus.
The fascial plane, or the connective tissue, between the levator scapulae and SCM is then identified. Once this area is seen on the ultrasound, one can notice a cluster that represents the superficial cervical plexus or a group of nerves.
The needle is then introduced with the help of ultrasound. It is inserted through the skin, moving from the back to the front side of the neck. Aspiration (sucking out) ensures the needle tip isn’t in a blood vessel. Once that is confirmed, small amounts of fluid are injected to verify the placement of the anesthetic. Approximately 10 mL of the anesthetic is delivered in 2 mL increments to spread across the back of the SCM.
Possible Complications of Cervical Plexus Block
When receiving a cervical plexus block(CPB), an injection to numb and block pain signals, some complications may occur. These are more common and severe with deep blocks, which target nerves located deeper below the skin, compared to superficial ones, which target nerves near the skin surface.
Common issues with all CPB procedures can include the accidental injection into a blood vessel, formation of a blood-filled swelling known as a hematoma, the risk of infections, and an adverse response to the local anesthetic used.
More serious complications may occur with deep CPB, such as mistakenly injecting anesthetic into the vertebral artery, a vital blood vessel found in the spinal canal. This artery is usually located about half a centimeter below a landmark used for injecting anesthetic during deep CPB. Since this artery carries blood directly to the brain, even a small amount of anesthetic can quickly reach the brain and affect the central nervous system. This can lead to symptoms such as numbness in and around the mouth, disorientation, or tinnitus(ringing in the ears). To avoid this, the doctor often maintains constant communication with the patient and injects the anesthetic slowly and cautiously.
Another serious risk with deep CPB is the subdural injection. This occurs when the needle goes too deep and penetrates the protective layer around the nerve root. This can lead to unconsciousness and low blood pressure and may require immediate medical intervention, including intubation and support for breathing and blood circulation.
There’s also a risk of accidentally puncturing large blood vessels near the cervical plexus (a network of nerves in the neck), leading to significant hematoma. Early identification can help manage this issue with simple local compression. However, if neglected, it can lead to problems with the airways. Accidental deep injection or using too much local anesthetic can block functioning of the laryngeal nerve (which controls the voice box), deep cervical plexus, and brachial plexus (nerves that send signals from your spine to your hand, arm and shoulder). Unintentional blocking of the accessory nerve can cause weakness in certain neck muscles, and some have suggested this could also affect the phrenic nerve, which controls the diaphragm (the primary muscle used in breathing), although recent studies dispute this.
What Else Should I Know About Cervical Plexus Block?
Cervical plexus block (CPB), a type of anesthesia, is highly beneficial in different types of surgeries. It’s a straightforward technique that doctors are increasingly using because it’s effective in numerous different situations. The most common use of CPB is in a procedure called carotid endarterectomy, which is a surgery that removes a build-up in the carotid artery to prevent strokes.
Besides this, CPB can be useful in a wide variety of neck surgeries, such as inserting a tube into the internal jugular vein, taking biopsies of lymph nodes, plastic surgery, treating lacerations, draining abscesses, and doing thyroid and parathyroid surgeries. CPB is also being used in emergency departments for minor procedures related to soft tissue and bone injuries in the ear, neck, and clavicular region, including fractures and dislocations. It’s even being used to manage cervicogenic headaches, a type of headache that starts in the neck or back of the head.
