Deep Cervical Plexus Block "article"

Deep Cervical Plexus Block


Overview

* Indications: Carotid endarterectomy, neck surgery
* Landmarks:
o Mastoid process
o Sternocleidomastoid muscle; posterior border of the clavicular head
o Transverse process of C6
* Equipment: 1½" 22-gauge short bevel needle
* Local Anesthetic: 15-20 mL
* Complexity level: Intermediate

General considerations


A deep cervical plexus block is essentially a paravertebral block of the
C2, C3, and C4 spinal nerves as they emerge from the foramina of
the respective vertebrae. Blockade of the deep cervical plexus
also results in the blockade of the superficial cervical plexus.
A deep cervical block is often accidentally accomplished when
a larger volume of local anesthetic is used in the interscalene brachial plexus block.
The most common clinical use for this block in our practice includes a carotid

0 endarterectomy and removal of cervical lymph nodes.


Regional anesthesia anatomy


The cervical plexus is formed by the anterior divisions of the four upper cervical nerves
. The plexus is situated on the anterior surface of the four upper cervical vertebrae,
resting on the levator anguli scapulae and scalenus medius muscle, and is covered by
the sternocleidomastoid muscle. Their dorsal and ventral roots combine to form spinal
nerves as they exit through the intervertebral foramen. The anterior rami of C2 through C4 form the cervical plexus (the C1 root is a primarily motor nerve and it is not blocked by this technique). The cervical plexus lies in the plane just behind the sternocleidomastoid muscle, giving off both superficial (superficial cervical plexus) and deep branches (deep cervical plexus). The branches of the superficial cervical plexus supply innervation to the skin and superficial structures of the head, neck, and shoulder. The deep branches of the cervical plexus innervate the deeper structures of the neck, including the muscles of the anterior neck and the diaphragm (phrenic nerve). The third and fourth cervical nerves typically send a branch to the spinal accessory nerve, or directly into the deep surface of the trapezius to supply sensory fibers to this muscle.

The fourth cervical nerve may send a branch downward to join the fifth cervical nerve and
participate in the formation of the brachial plexus.


Distribution of anesthesia




The cutaneous innervation of both the deep and superficial cervical plexus blocks includes
skin of the anterolateral neck and the ante- and retro-auricular areas.

Patient positioning

The patient is in the supine or semi-sitting position with the head facing away from the
side to be blocked.



Equipment

A standard regional anesthesia tray is prepared with the following equipment:

* Sterile towels and 4"x4" gauze packs
* 20-mL syringe(s) with local anesthetic
* Sterile gloves and marking pen
* 1½" 25-gauge needle for skin infiltration
* 1½ cm-long, 22-gauge, short bevel needle


Landmarks
Surface Landmarks


The following surface anatomy landmarks are helpful for estimating the location of
the transverse processes: mastoid process, transverse process of the sixth cervical
vertebra (C6), and the posterior border of the sternocleidomastoid muscle.

TIP: The proportions of the shoulder girdle, size of the neck, prominence of the muscles, and other areas vary among patients. For that reason, always perform a "reality check" when in doubt and estimate the three bony landmarks: sternal notch, clavicle, and mastoid process.
Anatomic Landmarks


The following three landmarks for a deep cervical plexus block are identified and marked:

1. Mastoid process
2. Chassaignac's tubercle of C6
3. Posterior border of the sternocleidomastoid muscle




The anatomic landmarks for this block can be accentuated by asking the patient to:

* Turn the head slightly away from the side to be blocked
* Lift the head up (tenses the sternocleidomastoid muscles)
* Reach the knee with the hand on the ipsilateral side

To estimate the line of needle insertion that overlies the transverse processes,
the mastoid process (MP) and Chassaignac's tubercle of C6 transverse process
are identified and marked. The transverse process of C6 is usually easily palpated
behind the clavicular head of the sternocleidomastoid muscle at the level just below
the cricoid cartilage.

Next, a line is drawn connecting the mastoid process (MP) to Chassaignac's tubercle of C6 transverse process. The palpating hand is best positioned just behind the posterior border of the sternoclediomastoid muscle.

Once this line is drawn, the insertion sites over the C2, C3, and C4 are labeled as follows: the C2, C3, and C4 are located on the MP-C6 line some 2-cm, 4-cm, and 6-cm caudal from the mastoid process, respectively.
Technique

Local anesthetic skin infiltration


After cleaning the skin with an antiseptic solution, local anesthetic is infiltrated
subcutaneously alongside the line estimating the position of the transverse processes.
The local anesthetic is best infiltrated over the entire length of the line, rather than at the projected insertion sites. This allows reinsertion of the needle slightly caudally or cranially when the transverse process is not contacted without the need to infiltrate the skin at a new insertion site.
Needle insertion



A needle connected via flexible tubing to the syringe with local anesthetic is inserted between the palpating fingers and advanced at an angle perpendicular to the skin plane. The needle should never be oriented cephalad. A slight caudal orientation of the needle is the single best method to prevent the inadvertent insertion of the needle toward the cervical spinal cord. The needle is advanced slowly until the transverse process is contacted. At this point, the needle is withdrawn 1-2 mm, firmly stabilized, and 4 mL of local anesthetic is injected, after a negative aspiration test for blood. The needle is then removed and the entire procedure is repeated at the consecutive levels.

TIPS:

* The transverse process is typically contacted at a depth of 1-2 cm in most patients. This distance can be further shortened by exerting pressure on the skin during needle advancement.
* The needle should never be advanced beyond 2.5 cm to avoid the risk of cervical cord injury or carotid or vertebral artery puncture.
* Paresthesia is often elicited in proximity to the transverse process but it should not be relied on because of its non-specific radiating pattern.

Goal

* Contact with the posterior tubercle of the transverse process.
* The spinal nerves at the individual levels are located just in front of the transverse process.

TIP: While some books recommend eliciting paresthesia, the nature of the paresthesia is non-specific and often difficult to discern from the local pain during needle advancement.
Image
Failure to contact the transverse process on the first needle pass

When insertion of the needle does not result in contact with the transverse process
within 2 cm, the following maneuvers are followed:

1. Keep the palpating hand in the same position and the skin between the fingers
stretched while avoiding skin movement.
2. Withdraw the needle to the skin, redirect it 15o inferiorly, and repeat
the procedure.
3. Withdraw the needle to the skin, reinsert the needle 1cm caudal, and repeat
the above procedure.

TIPS:

* When these maneuvers fail to result in contact with the transverse process,
the needle should be withdrawn and the landmarks should be reassessed.
* Redirecting the needle cephalad in an attempt to contact the transverse process
should be avoided because it carries a risk of cervical cord injury when the needle
is advanced too deep.

Choice of local anesthetic

A deep cervical plexus block requires 3-5 mL of local anesthetic per level to ensure
reliable blockade. Except perhaps with patients with significant respiratory disease
(blockade of the phrenic nerve), most patients benefit from the use of a long-acting
local anesthetic.
Onset
(min) Anesthesia (hrs) Analgesia (hrs)
1.5% Mepivacaine (+HCO3; + epinephrene) 10-15 2-2.5 3-6
2% Lidocaine (+HCO3; + epinephrene) 10-15 2-3 3-6
0.5% Ropivacaine 10-20 3-4 4-10
0.25% Bupivacaine (+ epinephrene) 10-20 3-4 4-10

Although the placement of deep cervical block may be associated with moderate patient discomfort, excessive sedation should be avoided. During neck surgery the airway management may be difficult due to the shared access to the head and neck with the surgeon. Surgeries like carotid endarterectomy require that the patient be fully conscious, oriented and cooperative during the entire surgical procedure. In addition, excessive sedation and the consequent lack of patient cooperation can result in restlessness and create a difficulty for the surgeon. The onset time for this block is 10-15 minutes. The first sign of the blockade is the decreased sensation in the area of the distribution of the respective components of the cervical plexus. It should be noted that due to the complex arrangement of the neuronal coverage of the various layers in the neck area as well as the cross-coverage from the contralateral side, the anesthesia achieved with cervical plexus block is rarely complete. While this should not be discouraging from the use of cervical plexus block, its use does require an understanding surgeon who is willing to supplement the block with the local anesthetic as necessary.

TIP: Carotid surgery also requires blockade of the glossopharyngeal nerve branches.
This is easily accomplished intraoperatively by injecting the local anesthetic inside the carotid artery sheath.
Complications and How to Avoid Them

Infection
- Low risk
- A strict aseptic technique is used
Hematoma - Avoid multiple needle insertions, particularly in anticoagulated patients
- Keep a 5 minute steady pressure on the site when the carotid artery is inadvertenly
punctured
Phrenic Nerve Blockade - Phrenic nerve blockade (diaphragmatic paresis) invariably
occurs with a deep cervical plexus block
- A deep cervical plexus block should be carefully considered in patients with significant respiratory disease
- Bilateral deep cervical block in such patients may be considered contraindicated
- Blockade of the phrenic nerve does not occur after superficial cervical plexus block
Local anesthetic toxicity - Central nervous system toxicity is the most serious
consequence of the cervical plexus block. This complication occurs because of the rich
vascularity of the neck, including vertebral and carotid artery vessels;
it is usually caused by an inadvertent intravscular injection of local anesthetic rather
then absorbtion
- Careful and frequent aspiration should be performed during the injection
Nerve injury - Local anesthetic should never be injected against resistance or
when the patient complains of severe pain on injection
Spinal anesthesia - This complication may occur with injection of a larger volume of
local anesthetic inside the dural sleeve that accompanies the nerves of the cervical
plexus
- It should be noted that a negative aspiration test for CSF does not rule out the
possibility of intrathecal spread of local anesthetic
- Avoidance of high volume and pressure during injection are the best measures to
avoid this complication