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Interscalene block to the brachial plexus
Vol. 12A, No.6 November 1987
9. Howell JD, Mehregan AH. Pursuit ofthe pits in the nevoid basal cell carcinoma syndrome. Arch Dermatol 1970; 102: 586-96.
Interscalene block to the brachial plexus To the Editor: We have read with much interest the article "Interscalene Brachial Plexus Block Anesthesia for Upper Extremity Surgery" in the March 1986 issue of J HAND SURG.' We must congratulate the authors on their success rate and totally agree with their comments that the interscalene approach to blocking the brachial plexus provides an excellent alternative technique in patients with limited shoulder mobility. However, we must take issue on several points and would like to add a few suggestions from our own experience. First, as for the description of the technique for the interscalene approach, we believe that by angling the needle on a medial, inferior and slightly anterior fashion then the incidence of hitting the epidural and subarachnoid spaces, or the vertebral artery, can be reduced. We also believe that to state that "Interscalene block is easy to administer, even in obese patients" is somewhat inaccurate-interscalene blocks are easy, if an interscalene groove can be palpated. In the obese patient this is rarely the case. Again, we were interested to observe that the local anesthetic is then injected on a milligram per kilogram body weight basis. This could explain the sparing of the ulnar nerve that is reported in the article.' A person weighing 60 kg would only receive 30 mL of Bupivacaine 0.5% (based on a toxic dose of 2.5 mg/kg). It is commonly accepted that when using the interscalene approach large volumes have to be instilled to achieve a complete block of the lower roots to the brachial plexus. The minimum volume of injection usually advised for this size patient is 40 mL. We have also been concerned with the incidence of failed interscalene blocks due to sparing of the ulnar nerve and also its delayed onset. Our solution to this is to combine the interscalene approach with an axillary approach and placing one half of the total volume of local anesthetic at each site. In patients with limited shoulder mobility it is often possible to do an axillary block, as full abduction of the shoulder is not absolutely essential. We have had experience in almost 100 cases using the combined interscalene axillary technique and have an overall success rate of 92%. In our technique 20 mL are placed at each site. The only side effect of sig-
Letters to editor
1127
nificance was the development of Horner's syndrome in 25% of cases (an incidence much lower than previously reported for techniques involving the interscalene approach).2 Also by using a 45° needle the classic parasthesia needed is not a necessity for good results, a "pop" can be felt when entering the brachial plexus sheath. We use a 22 g Accu-Block Plexufix needle (Burron Medical Inc.). It is also interesting that the authors reported that tourniquet pain was not a problem-this theoretically should not be the case as the intercostobrachial nerve will not have been blocked, and the medial brachial cutaneous nerve may be missed. 2 In conclusion, we strongly agree that the interscalene approach to blocking the brachial plexus is a very valuable tool in the armamentarium of any anesthesiologist or surgeon involved in upper limb surgery. We would like to remind all those involved in upper extremity plexus block, that adequate volumes of injection are required, and sufficient time is necessary to allow the block to set up. Anthony P. Jarvis, M.B.B.Ch., F.F.A.R.C.S. Jacqueline Smith, M.D. Department of Anesthesiology College of Medicine University of Oklahoma Health Science Center Oklahoma City, OK 73104
REFERENCES 1. Kuflik P, Ankolekar A, Stuchin S, Steinbach S, Bern-
stein R. Interscalene brachial plexus block anesthesia for upper extremity surgery. J HAND SURG 1986;llA:246-8. 2. Winnie AP. Plexus anesthesia-perivascular techniques of brachial plexus block. New York: Churchill Livingstone, 1982.
Reply We are most gratified to learn that Drs. Jarvis and Smith's experience with the interscalene block technique has been so successful, and that in the main, it parallels our own. In response to their questions we would like to present the following information: When identifying the interscalene groove the needle should be directed medial, inferior, and posterior to the plane of the neck. In this way one avoids entering the subarachnoid and epidural spaces, as well as the vertebral artery.' An anterior direction for the needle may cause the anesthetic material to be placed on the body of the vertebra. This of course would increase the
9. Howell JD, Mehregan AH. Pursuit ofthe pits in the nevoid basal cell carcinoma syndrome. Arch Dermatol 1970; 102: 586-96.
Interscalene block to the brachial plexus To the Editor: We have read with much interest the article "Interscalene Brachial Plexus Block Anesthesia for Upper Extremity Surgery" in the March 1986 issue of J HAND SURG.' We must congratulate the authors on their success rate and totally agree with their comments that the interscalene approach to blocking the brachial plexus provides an excellent alternative technique in patients with limited shoulder mobility. However, we must take issue on several points and would like to add a few suggestions from our own experience. First, as for the description of the technique for the interscalene approach, we believe that by angling the needle on a medial, inferior and slightly anterior fashion then the incidence of hitting the epidural and subarachnoid spaces, or the vertebral artery, can be reduced. We also believe that to state that "Interscalene block is easy to administer, even in obese patients" is somewhat inaccurate-interscalene blocks are easy, if an interscalene groove can be palpated. In the obese patient this is rarely the case. Again, we were interested to observe that the local anesthetic is then injected on a milligram per kilogram body weight basis. This could explain the sparing of the ulnar nerve that is reported in the article.' A person weighing 60 kg would only receive 30 mL of Bupivacaine 0.5% (based on a toxic dose of 2.5 mg/kg). It is commonly accepted that when using the interscalene approach large volumes have to be instilled to achieve a complete block of the lower roots to the brachial plexus. The minimum volume of injection usually advised for this size patient is 40 mL. We have also been concerned with the incidence of failed interscalene blocks due to sparing of the ulnar nerve and also its delayed onset. Our solution to this is to combine the interscalene approach with an axillary approach and placing one half of the total volume of local anesthetic at each site. In patients with limited shoulder mobility it is often possible to do an axillary block, as full abduction of the shoulder is not absolutely essential. We have had experience in almost 100 cases using the combined interscalene axillary technique and have an overall success rate of 92%. In our technique 20 mL are placed at each site. The only side effect of sig-
Letters to editor
1127
nificance was the development of Horner's syndrome in 25% of cases (an incidence much lower than previously reported for techniques involving the interscalene approach).2 Also by using a 45° needle the classic parasthesia needed is not a necessity for good results, a "pop" can be felt when entering the brachial plexus sheath. We use a 22 g Accu-Block Plexufix needle (Burron Medical Inc.). It is also interesting that the authors reported that tourniquet pain was not a problem-this theoretically should not be the case as the intercostobrachial nerve will not have been blocked, and the medial brachial cutaneous nerve may be missed. 2 In conclusion, we strongly agree that the interscalene approach to blocking the brachial plexus is a very valuable tool in the armamentarium of any anesthesiologist or surgeon involved in upper limb surgery. We would like to remind all those involved in upper extremity plexus block, that adequate volumes of injection are required, and sufficient time is necessary to allow the block to set up. Anthony P. Jarvis, M.B.B.Ch., F.F.A.R.C.S. Jacqueline Smith, M.D. Department of Anesthesiology College of Medicine University of Oklahoma Health Science Center Oklahoma City, OK 73104
REFERENCES 1. Kuflik P, Ankolekar A, Stuchin S, Steinbach S, Bern-
stein R. Interscalene brachial plexus block anesthesia for upper extremity surgery. J HAND SURG 1986;llA:246-8. 2. Winnie AP. Plexus anesthesia-perivascular techniques of brachial plexus block. New York: Churchill Livingstone, 1982.
Reply We are most gratified to learn that Drs. Jarvis and Smith's experience with the interscalene block technique has been so successful, and that in the main, it parallels our own. In response to their questions we would like to present the following information: When identifying the interscalene groove the needle should be directed medial, inferior, and posterior to the plane of the neck. In this way one avoids entering the subarachnoid and epidural spaces, as well as the vertebral artery.' An anterior direction for the needle may cause the anesthetic material to be placed on the body of the vertebra. This of course would increase the