Letters to the Editor
Regional Anesthesia and Pain Medicine • Volume 39, Number 6, November-December 2014
Continuous Versus Single-Injection Sciatic Nerve Block Added to Continuous Femoral Nerve Block for Analgesia After Total Knee Arthroplasty Accepted for publication: July 29, 2014.
To the Editor: e read with great interest the study by Sato et al1 about the value of adding a sciatic nerve block (SNB) to continuous femoral nerve block for analgesia after total knee arthroplasty (TKA). Sato and colleagues have shown that the overall morphine requirement was less in patients who had both SNB and femoral nerve block (FNB). In our experience, as many as 16% of patients suffer from severe pain that originates from sciatic nerve territory, and SNB confers benefits. The use of SNB in conjunction with FNB is marred with controversy, but we believe this requires further consideration. Here, we share a retrospective analysis of 2013 data relating to postoperative pain control in our patients who received FNB and SNB during TKA. Ultrasound-guided FNB catheter was inserted using a 50- or 100-mm Contiplex Ultra (18-gauge needle; B. Braun, Melsungen, Germany). The use of a peripheral nerve stimulator (MultiStim Sensor; Pajunk, Geisengen, Germany), out-of-plane or in-plane needle technique, depended on the preference of the clinician. Twenty milliliters of 0.5% ropivacaine was injected through the femoral catheter. If a single SNB was performed, 20 mL of 0.5% ropivacaine was injected. The primary method of anesthesia (spinal or general anesthesia [GA]) depended on the patient’s wish, comorbidities, and the anesthesiologist’s preference. Postoperatively, all patients received PROSPECT2 regimen (systemic analgesia consisting of conventional nonsteroidal anti-inflammatory drug/ cyclooxygenase 2–selective inhibitors with or without strong/weak opioids titrated to effects and paracetamol), continuous FNB (7 mL/h of 0.1% ropivacaine on day 1 and 5 mL/h on day 2), and the catheter was removed on day 3. If visual analog scale (VAS) score was more than 4, ropivacaine infusion was increased to 12 mL/h. If VAS score was more than 6, ultrasound-guided SNB by anterior approach was performed for rescue analgesia in patients who consented, and 20 mL of 0.5% ropivacaine was administered.
W FIGURE 1. The sciatic nerve (1) in the subgluteal area is not a single nerve, but a bundle of nerves that consist of the muscular branch to the hamstrings (a), the common peroneal nerve (b), and the tibial nerve (c). The sciatic nerve (1) posterior cutaneous nerve to the thigh (2) and quadratus femoris muscle (3), amongst others, share a common epimysium (4). Deep to this fascia layer is the sub-epimyseal space (5) that forms the well known “doughnut sign” on ultrasound if fluid is injected into it. The group of nerves that forms the sciatic nerve is surrounded by the circumneural sheath (6) (also referred to as the “paraneural sheath”), which is a thin but tough (perhaps fenestrated) layer (previously, especially in neurosurgical texts, referred to as the “gliding apparatus”), and deep to this sheath is the sub-circumneural space (7)—the “sweet-spot” of the nerve. Each nerve is in turn surrounded by an epineurium (8), which houses the nerve fascicles (9). Each nerve fascicle is surrounded by a tough and relatively non-compliant perineurium (10), which is thought to be embryological remnants of the dural sheath that surround nerve roots at the paravertebral level. The fluid and fibrous collagen inside the fascicles form the endoneurium (11) and the α-, γ-, c- and β-fibers are situated in the endoneurium. (Reprinted with permission from Mary K. Bryson.)
secondary block failure is unacceptably high. Thus, until we can place these catheters reliably with ultrasound guidance, and with a high chance of accuracy into this functional “sweet spot,” I will continue to follow our highly effective and successful catheter placement technique of placing the needle with ultrasound guidance and then electrically stimulating the catheter (the so-called “dual guidance”) to make sure that it not only enters this “sweet spot” but that it also stays in this “sweet spot” of the “circumneural space” during advancement of the catheter. André P. Boezaart, MD, PhD Division of Acute and Perioperative Pain Medicine University of Florida College of Medicine Gainesville, FL
The author receives royalty payments from TeleFlex. REFERENCES 1. Choquet O, Noble GB, Abbal B, Morau D, Bringuier S, Capdevila X. Subparaneural versus circumferential extraneural injection at the bifurcation level in ultrasound-guided popliteal
558
sciatic nerve blocks. Reg Anesth Pain Med. 2014; 39:306–311. 2. Key A, Retzius G. Stdien in der Anatomie des Nervensystems und des Bindegewebes (2. Häfte). Stockholm, Sweden: Samson & Wallin, 1876. 3. Karmakar MK, Shariat AN, Pangthipampai P, Chen J. High-definition ultrasound imaging defines the paraneural sheath and the fascial compartments surrounding the sciatic nerve at the popliteal fossa. Reg Anesth Pain Med. 2013; 38:447–451. 4. Anderson HL, Anderson SL, Tranum-Jensen J. Injection inside the paraneural sheath of the sciatic nerve: direct comparison among ultrasound imaging, macroscopic anatomy and histological analysis. Reg Anesth Pain Med. 2012;37:410–414. 5. Millesi H, Zoch G, Rath T. The gliding apparatus of peripheral nerve and its clinical significance. Ann Chir Main Memb Super. 1990;9:87–97. 6. Collins English Dictionary: Complete and Unabridged. 10th ed. Available at: http:// dictionary.references.com/browse/para-http:// dictionary.references.com/browse/circum. Accessed February 15, 2014. 7. Thompson GE, Rorie DK. Functional anatomy of the brachial plexus sheaths. Anesthesiology. 1983;59:117–122.
© 2014 American Society of Regional Anesthesia and Pain Medicine
Copyright © 2014 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Regional Anesthesia and Pain Medicine • Volume 39, Number 6, November-December 2014
TABLE 1. Primary Anesthesia, Visual Analog Scale Score, and Nerve Blocks VAS Score Primary Anesthesia ± Nerve Block GA GA + FNB GA + FNB + SNB Spinal Spinal + FNB Spinal + FNB + SNB Total
No. Mild Moderate Severe No. Patients Receiving Patients (VAS 0–3) (VAS 4–6) (VAS >6) Rescue Analgesia 1 85 5 2 81 2 176
0 52 4 2 68 1 127
One hundred seventy-six patients scheduled for TKA received the anesthesia and nerve blocks shown in Table 1 and as follows: GA alone (1), GA + FNB (85), GA + FNB + SNB (5), spinal alone (2), spinal + FNB (81), spinal + FNB + SNB (2). General anesthesia–alone patient had no nerve block and required patient-controlled analgesia with morphine. Sixteen percent (GA + FNB) had VAS score of more than 6, which received rescue analgesia. None of the patients (GA + FNB + SNB) required further analgesia. Surprisingly, 2 spinal (no nerve block) patients did not require further analgesia. Eleven percent of patients (spinal + FNB) required rescue analgesia. Two patients (spinal + FNB + SNB) did not require further analgesia. We are aware that sciatic nerve injury after TKA is a well-established complication with an overall incidence of 0.2% to 2.4%.3–5 Some risk factors, such as valgus deformity of more than 10 degrees, total tourniquet time of more than 120 minutes, preexisting neuropathy, and postoperative bleeding, have been described.4 The surgical procedure also places significant stress on the sciatic nerve, and the blood supply to the nerve can be decreased by additional perioperative factors such as tourniquet, vasoconstrictor use, and accidental intraneural injection.5 Preoperative SNB not only increases the risk of neural injury theoretically but also could delay diagnosis and treatment of that injury. An electromyographic study done before and after TKA shows that almost 30% of neural damage is undetectable clinically; furthermore, half of the sciatic nerve injuries show incomplete recovery after 5 years.5 Although improvement in analgesia by adding sciatic nerve does not justify the above risks, nevertheless, some patients suffer from severe pain in the distribution of the sciatic and obturator nerves. Based on our experience, we advocate SNB by the anterior approach as a rescue block rather than performing it preoperatively in all patients with FNB, thus sparing 87% patients from potential ill effects of SNB.
1 17 1 0 4 1 37
0 16 0 0 9 0 26
1 (100%) 14 (16%) 0 0 9 (11%) 0 24 (13%)
Joselo Macachor, MD, DPBA Uday Ambi, MD Mary J. Baula, MD, DPBA Bin Wern Hsien, MBBS, MMed Chandra M. Kumar, MBBS, MSc, FFARCS, FRCA, EDRA Department of Anesthesia Khoo Teck Puat Hospital 90 Yishun Central Singapore
The authors declare no conflict of interest. REFERENCES 1. Sato K, Adachi T, Shirai N, Naoi N. Continuous versus single-injection sciatic nerve block added to continuous femoral nerve block for analgesia after total knee arthroplasty: a prospective, randomized, double-blind study. Reg Anesth Pain Med. 2014;39:225–229. 2. PROSPECT. Overall recommendations for postoperative pain management for total knee arthroplasty. Web site. Available at: http://www.postoppain.org/image.aspx?imgid=654. Accessed June 24, 2014. 3. Mariano ER, Cheng GS, Choy LP, et al. Electrical stimulation versus ultrasound guidance for popliteal-sciatic perineural catheter insertion: a randomized controlled trial. Reg Anesth Pain Med. 2009;34:480–485. 4. Horlocker T, Cabanela ME, Wedel DJ. Does postoperative epidural analgesia increase the risk of peroneal nerve palsy after total knee arthroplasty? Anesth Analg. 1994;79:495–500. 5. Engerlhardt P, Roder R, Kohler M. Neurologic complications in implantation of knee endoprostheses: a clinical and GMG-documented study. Z Orthop Ihre Grenzgeb. 1987;125:190–193.
Reply to Dr Kumar Accepted for Publication: August 12, 2014. To the Editor: e thank Kumar and colleagues for their comments on our study, which have given us an opportunity to contribute
W
© 2014 American Society of Regional Anesthesia and Pain Medicine
Letters to the Editor
additional thoughts on sciatic nerve block (SNB) in patients undergoing total knee arthroplasty (TKA).1 Sciatic nerve injury, especially peroneal nerve injury, is a well-recognized and potentially devastating complication of TKA, although this complication is rare. Kumar et al pointed out 2 disadvantages of performing SNB preoperatively. First, SNB may increase the risk of peroneal nerve injury. Second, SNB may delay the diagnosis and treatment of that injury. We should consider carefully the major cause of sciatic nerve injury as a complication of TKA and the treatment strategies when it occurs. Although the definite cause of sciatic nerve injury after TKA remains uncertain, the theory most accepted is that the surgical correction of the malalignment, which stretches the sciatic nerve, contributes to the development of sciatic nerve injury.2 Patients with valgus deformity or flexion contracture were described to be predisposed to sciatic nerve injury because of this mechanism.3 Other additional factors are previous neuropathy, the pressure from soft tissue swelling, compressive dressings after surgery, hematoma, and prolonged tourniquet time. Does SNB really increase the risk of sciatic nerve injury by TKA? In our study, patients with valgus deformity, flexion contracture, and previous neuropathy were excluded, in order to avoid the potential sciatic nerve injury. We believe that preoperative SNB is beneficial in the selected patients. Once sciatic nerve injury occurs, immediate removal of any constrictive dressing and flexion of the knee are recommended.3 In our study, if we could not confirm the normal sciatic motor function postoperatively, we checked the pressure of dressings and kept the knee flexed not to stretch the sciatic nerve. It is recommended that patients with symptoms of peroneal nerve dysfunction who are having difficulty achieving an acceptable range of motion 4 weeks after TKA be considered for the surgical release of the peroneal nerve.4 We believe that SNB cannot delay the treatment of potential sciatic nerve injury. However, transient sciatic motor dysfunction by continuous SNB is common in our study, which inhibits early rehabilitation after TKA. We have to say that continuous SNB is problematic from the point of view of rehabilitation, and we agree that there are many institutions where SNB is not applied to patients undergoing TKA on this account. Unless SNB is performed, moderate to severe pain after TKA is common even if multimodal analgesia system is provided. The experiences of Kumar and colleagues showed 36% of patients felt moderate to severe pain after surgery, and
559
Copyright © 2014 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Regional Anesthesia and Pain Medicine • Volume 39, Number 6, November-December 2014
Continuous Versus Single-Injection Sciatic Nerve Block Added to Continuous Femoral Nerve Block for Analgesia After Total Knee Arthroplasty Accepted for publication: July 29, 2014.
To the Editor: e read with great interest the study by Sato et al1 about the value of adding a sciatic nerve block (SNB) to continuous femoral nerve block for analgesia after total knee arthroplasty (TKA). Sato and colleagues have shown that the overall morphine requirement was less in patients who had both SNB and femoral nerve block (FNB). In our experience, as many as 16% of patients suffer from severe pain that originates from sciatic nerve territory, and SNB confers benefits. The use of SNB in conjunction with FNB is marred with controversy, but we believe this requires further consideration. Here, we share a retrospective analysis of 2013 data relating to postoperative pain control in our patients who received FNB and SNB during TKA. Ultrasound-guided FNB catheter was inserted using a 50- or 100-mm Contiplex Ultra (18-gauge needle; B. Braun, Melsungen, Germany). The use of a peripheral nerve stimulator (MultiStim Sensor; Pajunk, Geisengen, Germany), out-of-plane or in-plane needle technique, depended on the preference of the clinician. Twenty milliliters of 0.5% ropivacaine was injected through the femoral catheter. If a single SNB was performed, 20 mL of 0.5% ropivacaine was injected. The primary method of anesthesia (spinal or general anesthesia [GA]) depended on the patient’s wish, comorbidities, and the anesthesiologist’s preference. Postoperatively, all patients received PROSPECT2 regimen (systemic analgesia consisting of conventional nonsteroidal anti-inflammatory drug/ cyclooxygenase 2–selective inhibitors with or without strong/weak opioids titrated to effects and paracetamol), continuous FNB (7 mL/h of 0.1% ropivacaine on day 1 and 5 mL/h on day 2), and the catheter was removed on day 3. If visual analog scale (VAS) score was more than 4, ropivacaine infusion was increased to 12 mL/h. If VAS score was more than 6, ultrasound-guided SNB by anterior approach was performed for rescue analgesia in patients who consented, and 20 mL of 0.5% ropivacaine was administered.
W FIGURE 1. The sciatic nerve (1) in the subgluteal area is not a single nerve, but a bundle of nerves that consist of the muscular branch to the hamstrings (a), the common peroneal nerve (b), and the tibial nerve (c). The sciatic nerve (1) posterior cutaneous nerve to the thigh (2) and quadratus femoris muscle (3), amongst others, share a common epimysium (4). Deep to this fascia layer is the sub-epimyseal space (5) that forms the well known “doughnut sign” on ultrasound if fluid is injected into it. The group of nerves that forms the sciatic nerve is surrounded by the circumneural sheath (6) (also referred to as the “paraneural sheath”), which is a thin but tough (perhaps fenestrated) layer (previously, especially in neurosurgical texts, referred to as the “gliding apparatus”), and deep to this sheath is the sub-circumneural space (7)—the “sweet-spot” of the nerve. Each nerve is in turn surrounded by an epineurium (8), which houses the nerve fascicles (9). Each nerve fascicle is surrounded by a tough and relatively non-compliant perineurium (10), which is thought to be embryological remnants of the dural sheath that surround nerve roots at the paravertebral level. The fluid and fibrous collagen inside the fascicles form the endoneurium (11) and the α-, γ-, c- and β-fibers are situated in the endoneurium. (Reprinted with permission from Mary K. Bryson.)
secondary block failure is unacceptably high. Thus, until we can place these catheters reliably with ultrasound guidance, and with a high chance of accuracy into this functional “sweet spot,” I will continue to follow our highly effective and successful catheter placement technique of placing the needle with ultrasound guidance and then electrically stimulating the catheter (the so-called “dual guidance”) to make sure that it not only enters this “sweet spot” but that it also stays in this “sweet spot” of the “circumneural space” during advancement of the catheter. André P. Boezaart, MD, PhD Division of Acute and Perioperative Pain Medicine University of Florida College of Medicine Gainesville, FL
The author receives royalty payments from TeleFlex. REFERENCES 1. Choquet O, Noble GB, Abbal B, Morau D, Bringuier S, Capdevila X. Subparaneural versus circumferential extraneural injection at the bifurcation level in ultrasound-guided popliteal
558
sciatic nerve blocks. Reg Anesth Pain Med. 2014; 39:306–311. 2. Key A, Retzius G. Stdien in der Anatomie des Nervensystems und des Bindegewebes (2. Häfte). Stockholm, Sweden: Samson & Wallin, 1876. 3. Karmakar MK, Shariat AN, Pangthipampai P, Chen J. High-definition ultrasound imaging defines the paraneural sheath and the fascial compartments surrounding the sciatic nerve at the popliteal fossa. Reg Anesth Pain Med. 2013; 38:447–451. 4. Anderson HL, Anderson SL, Tranum-Jensen J. Injection inside the paraneural sheath of the sciatic nerve: direct comparison among ultrasound imaging, macroscopic anatomy and histological analysis. Reg Anesth Pain Med. 2012;37:410–414. 5. Millesi H, Zoch G, Rath T. The gliding apparatus of peripheral nerve and its clinical significance. Ann Chir Main Memb Super. 1990;9:87–97. 6. Collins English Dictionary: Complete and Unabridged. 10th ed. Available at: http:// dictionary.references.com/browse/para-http:// dictionary.references.com/browse/circum. Accessed February 15, 2014. 7. Thompson GE, Rorie DK. Functional anatomy of the brachial plexus sheaths. Anesthesiology. 1983;59:117–122.
© 2014 American Society of Regional Anesthesia and Pain Medicine
Copyright © 2014 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Regional Anesthesia and Pain Medicine • Volume 39, Number 6, November-December 2014
TABLE 1. Primary Anesthesia, Visual Analog Scale Score, and Nerve Blocks VAS Score Primary Anesthesia ± Nerve Block GA GA + FNB GA + FNB + SNB Spinal Spinal + FNB Spinal + FNB + SNB Total
No. Mild Moderate Severe No. Patients Receiving Patients (VAS 0–3) (VAS 4–6) (VAS >6) Rescue Analgesia 1 85 5 2 81 2 176
0 52 4 2 68 1 127
One hundred seventy-six patients scheduled for TKA received the anesthesia and nerve blocks shown in Table 1 and as follows: GA alone (1), GA + FNB (85), GA + FNB + SNB (5), spinal alone (2), spinal + FNB (81), spinal + FNB + SNB (2). General anesthesia–alone patient had no nerve block and required patient-controlled analgesia with morphine. Sixteen percent (GA + FNB) had VAS score of more than 6, which received rescue analgesia. None of the patients (GA + FNB + SNB) required further analgesia. Surprisingly, 2 spinal (no nerve block) patients did not require further analgesia. Eleven percent of patients (spinal + FNB) required rescue analgesia. Two patients (spinal + FNB + SNB) did not require further analgesia. We are aware that sciatic nerve injury after TKA is a well-established complication with an overall incidence of 0.2% to 2.4%.3–5 Some risk factors, such as valgus deformity of more than 10 degrees, total tourniquet time of more than 120 minutes, preexisting neuropathy, and postoperative bleeding, have been described.4 The surgical procedure also places significant stress on the sciatic nerve, and the blood supply to the nerve can be decreased by additional perioperative factors such as tourniquet, vasoconstrictor use, and accidental intraneural injection.5 Preoperative SNB not only increases the risk of neural injury theoretically but also could delay diagnosis and treatment of that injury. An electromyographic study done before and after TKA shows that almost 30% of neural damage is undetectable clinically; furthermore, half of the sciatic nerve injuries show incomplete recovery after 5 years.5 Although improvement in analgesia by adding sciatic nerve does not justify the above risks, nevertheless, some patients suffer from severe pain in the distribution of the sciatic and obturator nerves. Based on our experience, we advocate SNB by the anterior approach as a rescue block rather than performing it preoperatively in all patients with FNB, thus sparing 87% patients from potential ill effects of SNB.
1 17 1 0 4 1 37
0 16 0 0 9 0 26
1 (100%) 14 (16%) 0 0 9 (11%) 0 24 (13%)
Joselo Macachor, MD, DPBA Uday Ambi, MD Mary J. Baula, MD, DPBA Bin Wern Hsien, MBBS, MMed Chandra M. Kumar, MBBS, MSc, FFARCS, FRCA, EDRA Department of Anesthesia Khoo Teck Puat Hospital 90 Yishun Central Singapore
The authors declare no conflict of interest. REFERENCES 1. Sato K, Adachi T, Shirai N, Naoi N. Continuous versus single-injection sciatic nerve block added to continuous femoral nerve block for analgesia after total knee arthroplasty: a prospective, randomized, double-blind study. Reg Anesth Pain Med. 2014;39:225–229. 2. PROSPECT. Overall recommendations for postoperative pain management for total knee arthroplasty. Web site. Available at: http://www.postoppain.org/image.aspx?imgid=654. Accessed June 24, 2014. 3. Mariano ER, Cheng GS, Choy LP, et al. Electrical stimulation versus ultrasound guidance for popliteal-sciatic perineural catheter insertion: a randomized controlled trial. Reg Anesth Pain Med. 2009;34:480–485. 4. Horlocker T, Cabanela ME, Wedel DJ. Does postoperative epidural analgesia increase the risk of peroneal nerve palsy after total knee arthroplasty? Anesth Analg. 1994;79:495–500. 5. Engerlhardt P, Roder R, Kohler M. Neurologic complications in implantation of knee endoprostheses: a clinical and GMG-documented study. Z Orthop Ihre Grenzgeb. 1987;125:190–193.
Reply to Dr Kumar Accepted for Publication: August 12, 2014. To the Editor: e thank Kumar and colleagues for their comments on our study, which have given us an opportunity to contribute
W
© 2014 American Society of Regional Anesthesia and Pain Medicine
Letters to the Editor
additional thoughts on sciatic nerve block (SNB) in patients undergoing total knee arthroplasty (TKA).1 Sciatic nerve injury, especially peroneal nerve injury, is a well-recognized and potentially devastating complication of TKA, although this complication is rare. Kumar et al pointed out 2 disadvantages of performing SNB preoperatively. First, SNB may increase the risk of peroneal nerve injury. Second, SNB may delay the diagnosis and treatment of that injury. We should consider carefully the major cause of sciatic nerve injury as a complication of TKA and the treatment strategies when it occurs. Although the definite cause of sciatic nerve injury after TKA remains uncertain, the theory most accepted is that the surgical correction of the malalignment, which stretches the sciatic nerve, contributes to the development of sciatic nerve injury.2 Patients with valgus deformity or flexion contracture were described to be predisposed to sciatic nerve injury because of this mechanism.3 Other additional factors are previous neuropathy, the pressure from soft tissue swelling, compressive dressings after surgery, hematoma, and prolonged tourniquet time. Does SNB really increase the risk of sciatic nerve injury by TKA? In our study, patients with valgus deformity, flexion contracture, and previous neuropathy were excluded, in order to avoid the potential sciatic nerve injury. We believe that preoperative SNB is beneficial in the selected patients. Once sciatic nerve injury occurs, immediate removal of any constrictive dressing and flexion of the knee are recommended.3 In our study, if we could not confirm the normal sciatic motor function postoperatively, we checked the pressure of dressings and kept the knee flexed not to stretch the sciatic nerve. It is recommended that patients with symptoms of peroneal nerve dysfunction who are having difficulty achieving an acceptable range of motion 4 weeks after TKA be considered for the surgical release of the peroneal nerve.4 We believe that SNB cannot delay the treatment of potential sciatic nerve injury. However, transient sciatic motor dysfunction by continuous SNB is common in our study, which inhibits early rehabilitation after TKA. We have to say that continuous SNB is problematic from the point of view of rehabilitation, and we agree that there are many institutions where SNB is not applied to patients undergoing TKA on this account. Unless SNB is performed, moderate to severe pain after TKA is common even if multimodal analgesia system is provided. The experiences of Kumar and colleagues showed 36% of patients felt moderate to severe pain after surgery, and
559
Copyright © 2014 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
