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Suprascapular Nerve Block for Shoulder Arthroscopy
Technical Note
Suprascapular Nerve Block for Shoulder Arthroscopy F. Alan Barber, M.D.
Abstract: The suprascapular nerve (SSN) originates from the C5 and C6 nerve roots and provides sensation for the posterior shoulder capsule, acromioclavicular joint, subacromial bursa, and coracoclavicular ligament. Blocking it provides pre-emptive anesthesia, decreased intraoperative pain, and postoperative pain relief in shoulder arthroscopy. Under general anesthesia, 25 mL of 0.5% bupivacaine is injected by a spinal needle placed 1 cm medial to the convergence of the spine and clavicle, angling toward the coracoid. At a depth of 3 to 4 cm, the needle strikes the scapula body. The surgeon probes with the needle anteriorly until the scapula is no longer felt, then moves the needle back posteriorly until the bone is felt again. This places the needle at the coracoid base in the supraspinatus fossa where the SSN curves around the coracoid and heads to the glenohumeral joint. At this point, the anesthetic is injected, “flooding” the SSN location. In addition to the SSN block, other pain-control procedures should be performed, including bupivacaine injection of all portals and an intra-articular injection of morphine sulfate at the end of the procedure. The SSN block is an effective technique and can reduce postoperative medication needs and allow earlier patient discharge from the surgery center. Key Words: Suprascapular nerve block—Anesthesia—Bupivacaine— Shoulder arthroscopy—Pain management.
A
variety of approaches have been advocated to reduce postoperative pain after outpatient shoulder surgery. Methods of providing pain relief include interscalene nerve blocks,1-4 bupivacaine injections,5 intraarticular morphine,6,7 the application of crushed ice, continuous flow cold therapy machines,8,9 and constant flow anesthetic pumps.10,11 The suprascapular nerve block (SSNB) is an established anesthetic technique that is safe and effective,12,13 and was recently described as effective for outpatient shoulder arthroscopy.13 The SSN originates from the C5 and C6 nerve roots of the superior trunk of the brachial plexus, with a
From the Plano Orthopedic and Sports Medicine Center, Plano, Texas, U.S.A. Address correspondence and reprint requests to F. Alan Barber, MD, Plano Orthopedic and Sports Medicine Center, 5228 West Plano Pkwy, Plano, TX 75093, U.S.A. © 2005 by the Arthroscopy Association of North America Cite this article as: Barber FA. Suprascapular nerve block for shoulder arthroscopy. Arthroscopy 2005;21:1015.e1-1015.e4, [doi:10.1016/j.arthro.2005.05.033]. 0749-8063/05/2108-4356$30.00/0 doi:10.1016/j.arthro.2005.05.033
contribution from C4 usually present as well. The SSN descends posteriorly, passing through the scapular notch and innervating the supraspinatus muscle and, more distally, the infraspinatus muscle. The SSN provides sensation for a significant amount of the posterior shoulder capsule. It joins with the lateral pectoral nerve to supply sensory innervation to the acromioclavicular joint, subacromial bursa, and the coracoclavicular ligament. An anesthetic block of the SSN with an injection administered preoperatively should provide both pre-emptive pain control during a procedure and a reduction in postoperative pain. The use of a SSNB has been reported before for a variety of situations including open shoulder procedures,14,15 chronic shoulder pain16,17 including cancer,18,19 frozen shoulder treatment,20,21 and recently with arthroscopic shoulder surgery.13 Although continuous SSN blocks are possible,22 the technique that is the subject of this report is a simple 1-time injection that can be readily administered by the surgeon before the start of the procedure. The purpose of this report is to describe the technique for administering a SSN block.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 21, No 8 (August), 2005: pp 1015.e1-1015.e4
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FIGURE 3. The needle is located near the suprascapular nerve and flooding this area with local anesthetic blocks the nerve.
FIGURE 1. Superficial anatomy showing the clavicle, acromion, coracoid process, and Neviaser portal location.
TECHNIQUE Once general anesthesia has been administered, the patient can be positioned in either the lateral decubitus or beach-chair position. The superficial anatomy of the shoulder is identified and the skin marked to outline the clavicle, scapula including the acromion and spine, and the coracoid process before skin preparation and draping (Fig 1).
FIGURE 2. Place the needle medial to the convergence of the spine and clavicle (Neviaser portal) and advance the needle toward the coracoid process.
A large syringe attached to a spinal needle is used for the SSNB. The syringe is filled with 20 to 25 mL of the appropriate solution (our preference is 0.5% bupivacaine) and the area between the clavicle and the scapular spinous process is sterilized using alcohol before the needle is inserted. The surgeon palpates the spine of the scapula with the arm in traction. There are several landmarks used to locate the appropriate insertion site. One way is to find a point 1 inch anterior to the junction of the middle and distal thirds of the spine. Another is to find and palpate the “soft spot” medial to the junction of the scapular spine and clavicle. The location is 1 cm medial to the convergence of the spine and clavicle, sometimes called the Neviaser portal.23,24 Place the needle at this location and advance it while angling it toward the coracoid process (Fig 2). At a depth of about 3 to 4 cm, the needle will strike the body of the scapula. Probe with the needle anteriorly until the scapula is no longer felt. Then move the needle back posteriorly until the bone is felt again. This will place the needle at the base of the coracoid in the supraspinatus fossa where the SSN curves around the coracoid and heads to the glenohumeral joint (Fig 3). At that point, 25 mL of solution is injected, flooding the area where the SSN lies. In addition to the SSNB, other routine pain-control procedures should be carried out. These include the instillation of bupivacaine into all portal sites before these portals are established and an intra-articular injection of morphine sulfate at the end of the procedure.
SUPRASCAPULAR NERVE BLOCK
1015.e3
DISCUSSION
REFERENCES
Postoperative pain control is an important aspect of outpatient surgery. This is especially true of arthroscopic shoulder procedures, which tend to have significant postoperative pain. Ways to control outpatient postoperative pain include oral medications, cold therapy, constant-infusion medication pumps, and nerve blocks. Oral medications include narcotics such as hydrocodone and oxycodone. Intra-articular injections include bupivacaine and morphine. A bupivacaine injection lasts up to 12 hours whereas morphine binds the pain receptor sites and has a longer effect.6,7 Other effective options present both challenges and concerns. Interscalene nerve blocks are more difficult to deliver, result in an increased cost, a greater time commitment, and the potential of diaphragmatic dysfunction and associated respiratory depression,25 nerve injury, incomplete effectiveness, and rebound pain.1-4 Continuous-flow cold therapy does decrease postoperative pain,8,9 but its effectiveness is less than that of the blocks, must be applied externally, requires maintenance to keep the reservoir filled with ice, and has reimbursement problems. Constant medication infusion pumps have been effective in randomized prospective trials of shoulder arthroscopy10,11 and have a moderate cost, but are not available to some patients because of inconsistent reimbursement by some insurance programs. Problems associated with these pumps include the potential for infection caused by the indwelling catheter, occasional equipment malfunction, leakage, blocked tubes, and drainage after the multiport catheter is removed. In addition, pumps that allow patient control may have different degrees of effectiveness.10,11 The SSNB effectively blocks sensory innervation to the shoulder joint and some surrounding tissues, resulting in decreased pain in the immediate postoperative period. The time interval before the onset of significant pain has been reported to approach 10 hours.14 This time frame is significant because it delays the onset of postoperative pain and hopefully reduces the subsequent severity of that pain. Although the SSNB will not remove all postoperative pain, it should decrease the intraoperative pain and delay the onset of pain by several hours. This simple technique has been used clinically for over 1 year with consistently good results in our hands. It is a safe and simple technique that the surgeon can employ to make his patients more comfortable in the postoperative period. There is a procedure code associated with its use: 64418-59.
1. Wurm WH, Concepcion M, Sternlicht A, et al. Preoperative interscalene block for elective shoulder surgery: Loss of benefit over early postoperative block after patient discharge to home. Anesth Analg 2003;97:1620-1626. 2. Al-Kaisy A, McGuire G, Chan VW, et al. Analgesic effect of interscalene block using low-dose bupivacaine for outpatient arthroscopic shoulder surgery. Reg Anesth Pain Med 1998;23: 469-473. 3. Arciero RA, Taylor DC, Harrison SA, Snyder RJ, Leahy KE, Uhorchak JM. Interscalene anesthesia for shoulder arthroscopy in a community-sized military hospital. Arthroscopy 1996;12: 715-719. 4. Brown AR, Weiss R, Greenberg C, Flatow EL, Bigliani LU. Interscalene block for shoulder arthroscopy: Comparison with general anesthesia. Arthroscopy 1993;9:295-300. 5. Uysalel A, Kecik Y, Kirdemir P, Sayin M, Binnet M. Comparison of intra-articular bupivacaine with the addition of morphine or fentanyl for analgesia after arthroscopic surgery. Arthroscopy 1995;11:660-663. 6. Boden BP, Fassler S, Cooper S, Marchetto PA, Moyer RA. Analgesic effect of intra-articular morphine, bupivacaine, and morphine/bupivacaine after arthroscopic knee surgery. Arthroscopy 1994;10:104-107. 7. Richardson MD, Bjorksten AR, Hart JA, McCullough K. The efficacy of intra-articular morphine for postoperative knee arthroscopy analgesia. Arthroscopy 1997;13:584-589. 8. Speer KP, Warren RF, Horowitz L. The efficacy of cryotherapy in the postoperative shoulder. J Shoulder Elbow Surg 1996;5:62-68. 9. Barber FA, McGuire DA, Click S. Continuous flow cold therapy for outpatient ACL reconstruction. Arthroscopy 1998; 14:130-135. 10. Savoie FH, Field LD, Jenkins RN, Mallon WJ, Phelps RA 2nd. The pain control infusion pump for postoperative pain control in shoulder surgery. Arthroscopy 2000;16:339-342. 11. Barber FA, Herbert MA. The effectiveness of an anesthetic continuous-infusion device on postoperative pain control. Arthroscopy 2002;18:76-81. 12. Alam S. Suprascapular nerve block. Reg Anesth 1996;21:371373. 13. Ritchie ED, Tong D, Chung F, Norris AM, Miniaci A, Vairavanathan SD. Suprascapular nerve block for postoperative pain relief in arthroscopic shoulder surgery: A new modality? Anesth Analg 1997;86:217-218. 14. Neal JM, McDonald SB, Larkin KL, Polissar NL. Suprascapular nerve block prolongs analgesia after nonarthroscopic shoulder surgery but does not improve outcome. Anesth Analg 2003;96:982-986. 15. Fournier R, Haller G, Hoffmeyer P, Gamulin Z. Suprascapular nerve block by a new anterior approach for perioperative analgesia during major scapular surgery in two patients. Reg Anesth Pain Med 2001;26:288-289. 16. Shanahan EM, Ahern M, Smith M, Wetherall M, Bresnihan B, FitzGerald O. Suprascapular nerve block (using bupivacaine and methylprednisolone acetate) in chronic shoulder pain. Ann Rheum Dis 2003;62:400-406. 17. Lewis RN. The use of combined suprascapular and circumflex (articular branches) nerve blocks in the management of chronic arthritis of the shoulder joint. Eur J Anaesthesiol 1999;16:37-41. 18. Mercadante S, Sapio M, Villari P. Suprascapular nerve block by catheter for breakthrough shoulder cancer pain. Reg Anesth 1995;20:343-346. 19. Meyer-Witting M, Foster JM. Suprascapular nerve block in the management of cancer pain. Anaesthesia 1992;47:626. 20. Karatas GK, Meray J. Suprascapular nerve block for pain
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relief in adhesive capsulitis: Comparison of 2 different techniques. Arch Phys Med Rehabil 2002;83:593-597. 21. Dahan TH, Fortin L, Pelletier M, Petit M, Vadeboncoeur R, Suissa S. Double blind randomized clinical trial examining the efficacy of bupivacaine suprascapular nerve blocks in frozen shoulder. J Rheumatol 2000;27:1464-1469. 22. Coetzee GJ, de Beer JF, Pritchard MG, van Rooyen K. Suprascapular nerve block: An alternative method of placing a catheter for continuous nerve block. Reg Anesth Pain Med 2004;29:75-76.
23. Neviaser TJ. Arthroscopy of the shoulder. Orthop Clin North Am 1987;18:361-372. 24. Nord KD, Mauck BM. The new subclavian portal and modified Neviaser portal for arthroscopic rotator cuff repair. Arthroscopy 2003;19:1030-1034. 25. Urmey WF, McDonald M. Hemidiaphragmatic paresis during interscalene brachial plexus block: Effects on pulmonary function and chest wall mechanics. Anesth Analg 1992; 74:352-357.
Suprascapular Nerve Block for Shoulder Arthroscopy F. Alan Barber, M.D.
Abstract: The suprascapular nerve (SSN) originates from the C5 and C6 nerve roots and provides sensation for the posterior shoulder capsule, acromioclavicular joint, subacromial bursa, and coracoclavicular ligament. Blocking it provides pre-emptive anesthesia, decreased intraoperative pain, and postoperative pain relief in shoulder arthroscopy. Under general anesthesia, 25 mL of 0.5% bupivacaine is injected by a spinal needle placed 1 cm medial to the convergence of the spine and clavicle, angling toward the coracoid. At a depth of 3 to 4 cm, the needle strikes the scapula body. The surgeon probes with the needle anteriorly until the scapula is no longer felt, then moves the needle back posteriorly until the bone is felt again. This places the needle at the coracoid base in the supraspinatus fossa where the SSN curves around the coracoid and heads to the glenohumeral joint. At this point, the anesthetic is injected, “flooding” the SSN location. In addition to the SSN block, other pain-control procedures should be performed, including bupivacaine injection of all portals and an intra-articular injection of morphine sulfate at the end of the procedure. The SSN block is an effective technique and can reduce postoperative medication needs and allow earlier patient discharge from the surgery center. Key Words: Suprascapular nerve block—Anesthesia—Bupivacaine— Shoulder arthroscopy—Pain management.
A
variety of approaches have been advocated to reduce postoperative pain after outpatient shoulder surgery. Methods of providing pain relief include interscalene nerve blocks,1-4 bupivacaine injections,5 intraarticular morphine,6,7 the application of crushed ice, continuous flow cold therapy machines,8,9 and constant flow anesthetic pumps.10,11 The suprascapular nerve block (SSNB) is an established anesthetic technique that is safe and effective,12,13 and was recently described as effective for outpatient shoulder arthroscopy.13 The SSN originates from the C5 and C6 nerve roots of the superior trunk of the brachial plexus, with a
From the Plano Orthopedic and Sports Medicine Center, Plano, Texas, U.S.A. Address correspondence and reprint requests to F. Alan Barber, MD, Plano Orthopedic and Sports Medicine Center, 5228 West Plano Pkwy, Plano, TX 75093, U.S.A. © 2005 by the Arthroscopy Association of North America Cite this article as: Barber FA. Suprascapular nerve block for shoulder arthroscopy. Arthroscopy 2005;21:1015.e1-1015.e4, [doi:10.1016/j.arthro.2005.05.033]. 0749-8063/05/2108-4356$30.00/0 doi:10.1016/j.arthro.2005.05.033
contribution from C4 usually present as well. The SSN descends posteriorly, passing through the scapular notch and innervating the supraspinatus muscle and, more distally, the infraspinatus muscle. The SSN provides sensation for a significant amount of the posterior shoulder capsule. It joins with the lateral pectoral nerve to supply sensory innervation to the acromioclavicular joint, subacromial bursa, and the coracoclavicular ligament. An anesthetic block of the SSN with an injection administered preoperatively should provide both pre-emptive pain control during a procedure and a reduction in postoperative pain. The use of a SSNB has been reported before for a variety of situations including open shoulder procedures,14,15 chronic shoulder pain16,17 including cancer,18,19 frozen shoulder treatment,20,21 and recently with arthroscopic shoulder surgery.13 Although continuous SSN blocks are possible,22 the technique that is the subject of this report is a simple 1-time injection that can be readily administered by the surgeon before the start of the procedure. The purpose of this report is to describe the technique for administering a SSN block.
Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 21, No 8 (August), 2005: pp 1015.e1-1015.e4
1015.e1
1015.e2
F. A. BARBER
FIGURE 3. The needle is located near the suprascapular nerve and flooding this area with local anesthetic blocks the nerve.
FIGURE 1. Superficial anatomy showing the clavicle, acromion, coracoid process, and Neviaser portal location.
TECHNIQUE Once general anesthesia has been administered, the patient can be positioned in either the lateral decubitus or beach-chair position. The superficial anatomy of the shoulder is identified and the skin marked to outline the clavicle, scapula including the acromion and spine, and the coracoid process before skin preparation and draping (Fig 1).
FIGURE 2. Place the needle medial to the convergence of the spine and clavicle (Neviaser portal) and advance the needle toward the coracoid process.
A large syringe attached to a spinal needle is used for the SSNB. The syringe is filled with 20 to 25 mL of the appropriate solution (our preference is 0.5% bupivacaine) and the area between the clavicle and the scapular spinous process is sterilized using alcohol before the needle is inserted. The surgeon palpates the spine of the scapula with the arm in traction. There are several landmarks used to locate the appropriate insertion site. One way is to find a point 1 inch anterior to the junction of the middle and distal thirds of the spine. Another is to find and palpate the “soft spot” medial to the junction of the scapular spine and clavicle. The location is 1 cm medial to the convergence of the spine and clavicle, sometimes called the Neviaser portal.23,24 Place the needle at this location and advance it while angling it toward the coracoid process (Fig 2). At a depth of about 3 to 4 cm, the needle will strike the body of the scapula. Probe with the needle anteriorly until the scapula is no longer felt. Then move the needle back posteriorly until the bone is felt again. This will place the needle at the base of the coracoid in the supraspinatus fossa where the SSN curves around the coracoid and heads to the glenohumeral joint (Fig 3). At that point, 25 mL of solution is injected, flooding the area where the SSN lies. In addition to the SSNB, other routine pain-control procedures should be carried out. These include the instillation of bupivacaine into all portal sites before these portals are established and an intra-articular injection of morphine sulfate at the end of the procedure.
SUPRASCAPULAR NERVE BLOCK
1015.e3
DISCUSSION
REFERENCES
Postoperative pain control is an important aspect of outpatient surgery. This is especially true of arthroscopic shoulder procedures, which tend to have significant postoperative pain. Ways to control outpatient postoperative pain include oral medications, cold therapy, constant-infusion medication pumps, and nerve blocks. Oral medications include narcotics such as hydrocodone and oxycodone. Intra-articular injections include bupivacaine and morphine. A bupivacaine injection lasts up to 12 hours whereas morphine binds the pain receptor sites and has a longer effect.6,7 Other effective options present both challenges and concerns. Interscalene nerve blocks are more difficult to deliver, result in an increased cost, a greater time commitment, and the potential of diaphragmatic dysfunction and associated respiratory depression,25 nerve injury, incomplete effectiveness, and rebound pain.1-4 Continuous-flow cold therapy does decrease postoperative pain,8,9 but its effectiveness is less than that of the blocks, must be applied externally, requires maintenance to keep the reservoir filled with ice, and has reimbursement problems. Constant medication infusion pumps have been effective in randomized prospective trials of shoulder arthroscopy10,11 and have a moderate cost, but are not available to some patients because of inconsistent reimbursement by some insurance programs. Problems associated with these pumps include the potential for infection caused by the indwelling catheter, occasional equipment malfunction, leakage, blocked tubes, and drainage after the multiport catheter is removed. In addition, pumps that allow patient control may have different degrees of effectiveness.10,11 The SSNB effectively blocks sensory innervation to the shoulder joint and some surrounding tissues, resulting in decreased pain in the immediate postoperative period. The time interval before the onset of significant pain has been reported to approach 10 hours.14 This time frame is significant because it delays the onset of postoperative pain and hopefully reduces the subsequent severity of that pain. Although the SSNB will not remove all postoperative pain, it should decrease the intraoperative pain and delay the onset of pain by several hours. This simple technique has been used clinically for over 1 year with consistently good results in our hands. It is a safe and simple technique that the surgeon can employ to make his patients more comfortable in the postoperative period. There is a procedure code associated with its use: 64418-59.
1. Wurm WH, Concepcion M, Sternlicht A, et al. Preoperative interscalene block for elective shoulder surgery: Loss of benefit over early postoperative block after patient discharge to home. Anesth Analg 2003;97:1620-1626. 2. Al-Kaisy A, McGuire G, Chan VW, et al. Analgesic effect of interscalene block using low-dose bupivacaine for outpatient arthroscopic shoulder surgery. Reg Anesth Pain Med 1998;23: 469-473. 3. Arciero RA, Taylor DC, Harrison SA, Snyder RJ, Leahy KE, Uhorchak JM. Interscalene anesthesia for shoulder arthroscopy in a community-sized military hospital. Arthroscopy 1996;12: 715-719. 4. Brown AR, Weiss R, Greenberg C, Flatow EL, Bigliani LU. Interscalene block for shoulder arthroscopy: Comparison with general anesthesia. Arthroscopy 1993;9:295-300. 5. Uysalel A, Kecik Y, Kirdemir P, Sayin M, Binnet M. Comparison of intra-articular bupivacaine with the addition of morphine or fentanyl for analgesia after arthroscopic surgery. Arthroscopy 1995;11:660-663. 6. Boden BP, Fassler S, Cooper S, Marchetto PA, Moyer RA. Analgesic effect of intra-articular morphine, bupivacaine, and morphine/bupivacaine after arthroscopic knee surgery. Arthroscopy 1994;10:104-107. 7. Richardson MD, Bjorksten AR, Hart JA, McCullough K. The efficacy of intra-articular morphine for postoperative knee arthroscopy analgesia. Arthroscopy 1997;13:584-589. 8. Speer KP, Warren RF, Horowitz L. The efficacy of cryotherapy in the postoperative shoulder. J Shoulder Elbow Surg 1996;5:62-68. 9. Barber FA, McGuire DA, Click S. Continuous flow cold therapy for outpatient ACL reconstruction. Arthroscopy 1998; 14:130-135. 10. Savoie FH, Field LD, Jenkins RN, Mallon WJ, Phelps RA 2nd. The pain control infusion pump for postoperative pain control in shoulder surgery. Arthroscopy 2000;16:339-342. 11. Barber FA, Herbert MA. The effectiveness of an anesthetic continuous-infusion device on postoperative pain control. Arthroscopy 2002;18:76-81. 12. Alam S. Suprascapular nerve block. Reg Anesth 1996;21:371373. 13. Ritchie ED, Tong D, Chung F, Norris AM, Miniaci A, Vairavanathan SD. Suprascapular nerve block for postoperative pain relief in arthroscopic shoulder surgery: A new modality? Anesth Analg 1997;86:217-218. 14. Neal JM, McDonald SB, Larkin KL, Polissar NL. Suprascapular nerve block prolongs analgesia after nonarthroscopic shoulder surgery but does not improve outcome. Anesth Analg 2003;96:982-986. 15. Fournier R, Haller G, Hoffmeyer P, Gamulin Z. Suprascapular nerve block by a new anterior approach for perioperative analgesia during major scapular surgery in two patients. Reg Anesth Pain Med 2001;26:288-289. 16. Shanahan EM, Ahern M, Smith M, Wetherall M, Bresnihan B, FitzGerald O. Suprascapular nerve block (using bupivacaine and methylprednisolone acetate) in chronic shoulder pain. Ann Rheum Dis 2003;62:400-406. 17. Lewis RN. The use of combined suprascapular and circumflex (articular branches) nerve blocks in the management of chronic arthritis of the shoulder joint. Eur J Anaesthesiol 1999;16:37-41. 18. Mercadante S, Sapio M, Villari P. Suprascapular nerve block by catheter for breakthrough shoulder cancer pain. Reg Anesth 1995;20:343-346. 19. Meyer-Witting M, Foster JM. Suprascapular nerve block in the management of cancer pain. Anaesthesia 1992;47:626. 20. Karatas GK, Meray J. Suprascapular nerve block for pain
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relief in adhesive capsulitis: Comparison of 2 different techniques. Arch Phys Med Rehabil 2002;83:593-597. 21. Dahan TH, Fortin L, Pelletier M, Petit M, Vadeboncoeur R, Suissa S. Double blind randomized clinical trial examining the efficacy of bupivacaine suprascapular nerve blocks in frozen shoulder. J Rheumatol 2000;27:1464-1469. 22. Coetzee GJ, de Beer JF, Pritchard MG, van Rooyen K. Suprascapular nerve block: An alternative method of placing a catheter for continuous nerve block. Reg Anesth Pain Med 2004;29:75-76.
23. Neviaser TJ. Arthroscopy of the shoulder. Orthop Clin North Am 1987;18:361-372. 24. Nord KD, Mauck BM. The new subclavian portal and modified Neviaser portal for arthroscopic rotator cuff repair. Arthroscopy 2003;19:1030-1034. 25. Urmey WF, McDonald M. Hemidiaphragmatic paresis during interscalene brachial plexus block: Effects on pulmonary function and chest wall mechanics. Anesth Analg 1992; 74:352-357.