Cervical Paravertebral Block for Chronic Pain

Question:
“I did the first cervical paravertebral block as described by Boezaart in a patient with complex regional pain syndrome of the right upper limb. Everything went smoothly and exactly as described in the excellent movie. The patient reported sensation just before muscular twitches. When the current was decreased to 0.04 milliamps with very minimal muscle twitches, the patient was still reporting “paraesthesia”. I needed to dilate the space with 10 ml of .4 and 10 ml of .2% ropivacaine before I could thread in an ordinary epidural catheter. The result was good but the patient reported difficulty in breathing and also hoarseness. Three dimensional x-ray reconstruction confirmed spread of local anesthetic agent anterior to the nerve root spanning from C-4 to T-1. The right vocal chord paralysis could also be seen. After six hours, the hoarseness disappeared, the patient was complaining of discomfort in the neck and insisted on catheter removal”.

Why the neck discomfort?

Answer:
Thank you for your interesting questions. I think chronic pain scenarios as you describe is a bare landscape that begs to be visited by continuous nerve blocks.

This block that you described, respectfully, is not consistent with the block described by me in the movie nor the literature. I suggest that you revisit the movie since I do not advocate, “dilating the space”, and I certainly do not advocate the use of an “ordinary epidural catheter”. I use stimulating catheters and “dilating the space” makes this impossible.

The finding of sensory pulsations down the arm (which you call “paraesthesia”) is very common especially in young people, since the roots of the brachial plexus are approached from posterior, where the roots have already split into sensory posterior fibers and anterior motor fibers.

The pain that this patient complained of in the neck is very common with catheter procedures from posterior, as opposed to single-injection approaches from posterior as reported in the recent literature (see Anesth Analg 2005; 100: 1496 – 8 and Reg Anesth Pain Med 2005; 30: 238 – 242).  I think it is because we sometimes penetrate the extensor muscles of the neck.

When we first started doing this block some 12 years ago, our first 48 patients all complained of posterior pain and this was most likely due to the catheter penetrating the extensor muscles of the neck. As our experience grew, we learned that there is a “window” between the trapezius muscle and levator scapulae muscle at the level of C6. Entering between these muscles and pushing these muscles apart with the fingers of the non-operative hand, solved this problem for us.  I am convinced it will ensure that your future patients do not have this neck pain. The ones that do have pain, I think, are the ones in who you were not successful in separating these muscles and you actually penetrated them. In our institution, we typically get  neck pain in patients in the July to October period of our academic calendar, since that is the time that the new residents and fellows are still inexperienced with this block. After November, they usually start to comprehend this and this is normally the end of the problem until the end of June the next year.

Again, I would urge you to study the movies on this website and RAEducation, and perhaps download this particular movie and Tutorial. This is certainly an advanced block and should not be viewed as a basic block and should not be done by people who do not frequently perform continuous nerve blocks. In our pilot study, the first 48 patients all had major shoulder surgery and all of them reported that the shoulder felt great but they all complained of posterior neck pain – some requested that we remove the catheter because of the severe pain in the neck (see Reg Anesth Pain Med 2003: 28: 406 – 13). Once we addressed this problem by avoiding these muscles, this is not a problem anymore.

The vocal chord paralysis is obviously due to recurrent laryngeal nerve paralysis and as you know, the recurrent laryngeal nerve  is frequently blocked with most approaches to the roots of the brachial plexus.

Yours Sincerely

Andre P. Boezaart, MD, Ph.D

Question: Why is the posterior approach a better choice for arthroscopic surgery of the shoulder? Is that because its relative motor sparing effect?

Answer:
There is no definite data available to answer this question so the best I can do is to provide you with my personal opinion based on my experience on this matter.

Motor sparing is one of the big advantages of the posterior approach or the cervical paravertebral block but it is not the only advantage. Other advantages include the fact that, certainly in our experience, we do not threaten the area of maximum irritation of the brachial plexus namely where it crosses the first rib, with this approach. Many cases of arthroscopy of the shoulder and subacromial decompression are in actual fact because of existing brachial plexitis, which causes shoulder pain and not impingement. The patient ends up at the office of a shoulder surgeon who does what a shoulder surgeon does, namely operate the shoulder. It is wise if the patient complains of pain distal to the elbow not to do a brachial plexus block for this patient until the pathology becomes clear, since pain and paresthesia distal to the elbow is almost never a symptom of bona fide shoulder pathology.  This block is very easy to do postoperative if we need to.

Other reasons why we prefer the cervical paravertebral block, which by the way is not a basic block and should not be performed by people who only occasionally do regional anesthesia, includes the fact that you can use one block (well) for any major surgery of the entire upper limb and you therefore, do not have to learn or teach any of the other procedures like continuous interscalene block, continuous supraclavicular block, continuous infraclavicular block or continuous axillary block. All four blocks have good indications but with experience, you will find that their performance is disappointing to say the least – especially when compared to CCPVB. If the cervical paravertebral block replaces all four continuous blocks, you will have peace and quiet in your practice. This is an easy block to do and an easier block to teach since there is a bony backstop which removes complexity but it has rules and these rules have to be obeyed diligently.

When Kappis described the cervical paravertebral block for the first time in 1912, he noticed that all the dangerous structures in the posterior triangle of the neck are situated anterior to the brachial plexus. This includes the vertebral arteries, artery and veins, all the big arteries of the neck and all the other nerves that one does not want to block. It therefore makes perfect sense to approach the brachial plexus from posterior. When Kappis first described this block, he did not have access to a nerve stimulator and he did not know when he went through the brachial plexus other than by eliciting paresthesia. If however, you did not get paresthesia, it was possible to penetrate the brachial plexus and structures anterior to the brachial plexus.

Nowadays, with the use of modern nerve stimulators and ultrasound, you will have a definite motor response when you get near the brachial plexus with the needle. As previously said no studies that compare the interscalene block with a paravertebral block has been done and I am anxiously awaiting these studies.

Yours sincerely,

Question: What are your thoughts on pectoral versus deltoid twitch when performing an interscalene block?

Answer:
Both of these responses are adequate, since both of these responses are derived from the superior trunk of the brachial plexus. For interscalene block for shoulder surgery, we are most comfortable with a biceps twitch. However, it is essential that the response seen is indeed a plexus response. When performing an interscalene block, there are several motor responses that can be seen that may confuse the practitioner. A true deltoid twitch occurs when the 5th and 6th cervical roots are stimulated. However, stimulating the dorsal scapular nerve will result in twitching of the rhomboid muscles. The rhomboid stimulation via the dorsal scapular nerve draws the vertebral border of the scapula medially and upwards. This movement can easily be confused with a deltoid twitch, but its blockade will certainly not be confused with analgesia. Likewise, the nerve to levator scapula and the 11th cranial nerve to trapezius can falsely resemble a deltoid twitch.

As a general rule of thumb, any anterior chest and upper arm motor response will result in a successful interscalene block, while posterior chest motor responses (rhomboid for example) will result in a failed block. Motor responses in-between (deltoid) can cause confusion.

Question: Do you find that you get ulnar sparing when using the posterior approach to the interscalene space?

Answer:
We do not typically find ulnar sparing with the cervical paravertebral block. In fact, we have had very good success with the CCPVB for wrist, elbow and hand surgery. What is getting more and more apparent is that for wrist and elbow surgery you should seek a triceps motor response (C7/8), while for shoulder surgery you should seek a biceps response C5/6). This block is done on the level of the roots of the brachial plexus, which are situated in the paravertebral space – a triangular continuous space in the same compartment.

Question: What is the loss of resistance in a cervical paravertebral actually caused by?

Answer:
The loss of resistance in the CCPVB is more correctly a change in resistance that is found when the needle tip passes through the attachments of the medial and posterior scalene muscle to the transverse processes of the vertebrae into the space between the anterior and middle scalene muscles.

Question: Why do you use loss of resistance with a cervical vertebral block?

Answer:
The loss of resistance in the CCPVB is more correctly a change in resistance. It is much more subtle than the loss of resistance appreciated when passing through ligamentum flavum, for example. As a result, we perform the loss of resistance with nerve stimulation as a means to appreciate the subtlety of the change of resistance present when doing this block. This allows us to perform this block post-operatively through only the loss of resistance technique, when motor responses due to nerve stimulation are painful and undesirable, and ultrasound is not available. It is also better to have two positive confirmatory tests of correct needle placement than one.

Question: How can I learn more about the cervical paravertebral block?

Answer:
Please visit the RA Education website and download these movies. The movie and description is also on this website and even on YouTube.  Go to YouTube and search cervical paravetebral block. Please also see Reg Anesth Pain Med 2003: 28: 241 – 244 and Reg Anesth Pain Med 2003; 28: 406 – 413 for the original description and our experience with the first 256 CCPVB/s.

Question: What is your experience with CCPVB in kids?

Answer:
My personal use of cervical paravertebral block in kids is fairly extensive but is only limited to oncology patients and trauma. As you know, children don’t get shoulder operations for the usual adult indications (and I actually believe that is why nerve injuries are so seldom seen in children – they  just don’t get interscalene blocks). And interscalene blocks with the Winnie approach (as modified through th eyears – mostly in a bad way) in my humble opinion is responsible for most of the nerve damage that we see and read about. The other etiology, almost always blamed on our blocks, is the shoulder surgery itself, which is now well-recognised to have an independant incidence of 4.5% during shoulder arthroplasty and as much as (in one report) 38% during arthroscopic shoulder surgery.  This is independant of the nerve blocks.  It has nothing to do with awake vs. asleep. My shoulder blocks in children are for children with shoulder and humerus surgery due to bone tumors or fractures. Here I use the paravertebral approach and do it under GA after explaining our (prevailing wisdom) approach and possible higher incidence of complications of blocks under GA to the parents (although I seriously do not believe this to be true!). If not under GA, I use remifentanyl 0.3 – 0.5 microgram per kg as bolus for the placement of the block.  The technique and equipment used is exactly the same as for adults.

Question: What corrections do you make with the needle and catheter when performing an infraclavicular block?

Answer:

Nowadays we do most of our infraclavicular blocks with ultrasound only.  We identify each cord and place the local anesthetic agent on that cord.

If, cowever, you don’t have access to ultrasound, corrections, or redirections, are  essential components of successful peripheral nerve block placement. In fact, it is in cases when redirections are needed that a strictly landmark-based approach would result in block failure. The important point about redirecting a needle or catheter is to understand the relationship between the elicited and desired motor response, and to understand the changes necessary to achieve the desired response. In the case of an infraclavicular block, knowledge of the relationship of the brachial plexus cords is essential. Since the cords are named after their relationship to the 2nd portion of the axillary artery, we know that the posterior cord will be further posterior to the lateral cord, and will redirect in that manner if a lateral cord response is found while a posterior cord response is desired (see Reg Anesth Pain Med 2004; 29: 125 – 9).

Basically you have to look at the pinkie:  “At the cords, the pinkie towards”.  If the posterior cord is stimulated, the pinkie moves posterior.  If the medial cord is stimulated, th epinkie moves medial.  And if the lateral cord is stimulated, the pinkie moves lateral (pronation of the hand).

Also, if you get a musculocutaneous nerve (biceps) or axillary nerve (deltoid) ISOLATED twitch, do not accept it and move the needle a little deeper.  A pectoralis major twitch means the needle is too anterior and it needs to be redirected more posterior.  If, lastly, the arm rotates it means the nerve to subscapularis muscle is stimulated and the needle is too deep.

Question: Which infraclavicular landmark do you find most reliable?

Answer:

Most, if not all of our infraclavicular blicks, ultrasound or nerve stimultor, are done in the sagittal plane from a point just caudad of the clavicle in the deltopectoral trough. The classical landmarks as described through the years (VIP, pericoracoid, line from interscalene groove to deltopectoral groove (not to be confused with deltopectoral trough), however, will all typically result in a confluence of lines that outline the expected path of the brachial plexus, and the best approach to the cords of the plexus would be through this trough.  The deltopectoral trough is bordered by the clavicle cephalad, the pectoralis minor on its implant area on the coracoid process lateral, and the pectoralis major muscle medial.  An ultrasound probe placed in the trough in the sagittal plane make the artery easily visible.   Doppler identification of the artery is also useful for orientation. We have started to use this “superior approach to the cords” some years ago, in which we pass our needle directly under the clavicle at a point where the indentation just medial to the coracoid process is (see “Anesthesia and Orthopaedic Surgery”, Ed A P Boezaart, McGraw-Hill, Chapter 24, or Atlas of Regional Anesthesia and Anatomy for Orthopaedic Surgery, A P Boezaart. Elsevier, New York 2008). This approach may offer the advantage of less patient discomfort due to the avoidance of penetrating the pectoral minor or major muscles, a more direct route to the posterior cord with less risk of axillary artery puncture, and a less acute angle to the plexus that might make catheter placement easier to accomplish and ultrasound visualization of the needle better.

Question: What cord do you preferentially block when doing an infraclavicular block?

Answer:

The location and type of surgery dictates what cord we preferentially block. If the proposed surgery falls in the distribution of a particular cord, we block that cord first, or place a catheter on it. For single injection blocks, it is our practice to locate all three cords, or at least two of the three cords, inject on the cord that is most appropriate for the surgery, then seek out the remaining cords and block them. We also have very good success when we block a combination of the posterior cord and one of the other cords (medial or lateral). (see Reg Anesth Pain Med 2004; 29: 125 – 9).  We have to obay Hilton’s Law of Anatomy though.  This Law states that a nerve that innervates a muscle that moves a joint or the skin overlying a joint, will also innervate that joint.  If one now thinks about that, all the joints of the upper limb are moved by muscles that are innervated by the entire brachial plexus.  This means that for any joint of the upper limb, the entire brachial plexus needs to be blocked.  The same is true for the lower limd and the lumbosacral plexus.

Question: What do you think of a transarterial approach to the infraclavicular block?

Answer:

This is justifiably an outmoded technique.  In modern times most patients are on some sort of anticoagulat – even if it is only aspirin or NSAID, and if the artery bleeds, you cannot get to it to compress it like you can in the axilla.  Furthermore, we have much better ways of doing this block than that, but if you are alone in the middle of nowhere with only a needle and syringe, then okay, go for it (just kidding), but even then axillary block may be a better and more reliable choice.  If you are lucky the block may work, but I can almost guarantee you a failure if you don’t have the appropriate muscle twitches. We don’t want to rely on luck. These cords each lie in it’s own fascial sheath. We don’t try to get blood; if we do we regard it as a complication,  and even sometimes go for another approach,  i.e. supraclavicular or axillary. My advice to you is to forget that you ever heard about any trans-arterial techniques – axilla or infraclavicular, or anywhere else.

Question: Can an infraclavicular block be used for gleno-humeral joint surgery? If yes, what are the concerns with the phrenic nerve? Please tell me a bit about the nerve supply of the shoulder joint.

Answer:

Of course infraclavicular block would be fine if combined with superficial cervical plexus block for the GH joint, since the axillary nerve supplies it. But if it involves the rotator cuff and subacromial and AC joints, you need to get the suprascapular nerve as well, which supplies the posterior parts of the rotator cuff, the subacromial joint and the AC joint. The articular branch of the lateral pectoral nerve, which comes off the lateral cord supplies the anterior parts of these joints, but remember that the medial pectoral nerve, which comes off the medial cord, has a connection to the lateral pectoral nerve. So ALL THREE the cords have to be blocked if the infraclavicular block is used for GH joint surgery (posterior goes to axillary, lateral to LPN and medial to MPN). Then the suprascapular nerve has to be blocked where it comes through the suprascapular notch or higher up in th einterscalene groove – and the superficial cervical plexus for good measure. Then if you are totally confused – do a GA, but if the lungs are so bad that you don’t want to do an interscalene, you probably don’t want to do a GA as well.

Remember severe COPD is not really a problem with phrenic nerve paresis. The diaphragms are flat in any case due to the hyperinflation in COPD of the lungs so they don’t really contribute to breathing. Granted it does not make the patient any better off to block their phrenics, but it likewise does not really harm them. Restrictive disease and mild to moderate COPD are, of course totally different stories.