Regional Anesthesia and Pain Medicine • Volume 40, Number 3, May-June 2015 3. Martin P, Bateson P. Measuring Behaviour: An Introductory Guide. 3rd ed. Cambridge, UK: Cambridge University Press; 2007. 4. Gallagher AG, O’Sullivan GC. Fundamentals of Surgical Simulation: Principles and Practice, London, UK: Springer-Verlag; 2012. 5. Wong DM, Watson MJ, Kluger R, et al. Evaluation of a task-specific checklist and global rating scale for ultrasound-guided regional anesthesia. Reg Anesth Pain Med. 2014;39:399–408.
Reply to Drs Srinivasan and Shorten Accepted for publication: February 6, 2015. To the Editor: e thank Drs Srinivasan and Shorten for their letter1 calling for further refinement of the assessment tool validated for evaluation of remote simulation-based ultrasound-guided regional anesthesia training.2 We address their concerns, in order, below: 1) Cheung et al3 developed the Global Rating Scale (GRS) and Checklist as a global assessment tool for ultrasound-guided peripheral nerve blocks. The process of development included the Delphi method where 18 ultrasound-guided nerve block specialists provided their expert opinion on what was to be included in the GRS and Checklist. Our study was designed simply to validate these assessment tools. Discussion and training among the raters were completed to determine the most appropriate interpretation of the definitions that are questioned. We believe that external validity is not compromised if raters agree on how to use these tools in evaluating a particular ultrasound-guided block. We would argue that these descriptions would be an objective assessment of the operator if end points for these values were decided on between raters. The Checklist and GRS were developed as a global assessment tool for all types of nerve blocks, and we believe that some wording choices were intentionally more subjective. “Carefully handles tissue but occasionally causes unintentional damage” in the GRS was decided as the inappropriate use of the needle as an instrument. Actions that cause damage include an undue number of needle insertions, inaccurate angle of insertion, and multiple attempts of trying to achieve the target. In the Checklist, “needling technique” was used to assess any mistakes commonly made by novice operators. Lastly, training does not take place in isolation from the instructor; detailed and specific feedback can always be
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provided to trainees—these tools are guideposts and do not substitute teaching. 2) A Likert scale system of grading may be less objective but allows the assessment to be more qualitative.4 The comment suggesting poor inter-rater reliability does indeed seem to be a generalization, without reference to the literature. A tool’s reliability is dependent on a number of factors, including the training of the assessors. A combination of a Checklist and GRS has been suggested as a complementary pair for comprehensive evaluation in education research.4 3) We agree that what is required in estimating reliability of an assessment tool is quantification of agreement. Intraclass correlation coefficients calculated using an absolute agreement definition can be used for this purpose, the principles of which are discussed in McGraw and Wong.5 4) Explicit dichotomous variables may be preferred for usability; however, this study aimed to validate the Checklist and GRS developed by Cheung et al.3 Rater training and discussion on the use of these tools were conducted to improve the reliability of ratings. The ability of evaluators to provide detailed specific feedback directly to participants was not limited by these tools.
To conclude, we will quote Reznick et al6 and remember that “validity cannot be proven in any one experiment. Rather, over time and experimentation, one accrues evidence for the validity of a test.”
Letters to the Editor
The authors declare no conflict of interest. REFERENCES 1. Srinivasan KK, Shorten G. New assessment tool for remote simulation-based ultrasound-guided regional anesthesia: a call for further refinement. Reg Anesth Pain Med. 2015;40:290–291. 2. Burckett-St Laurent DA, Niazi AU, Cunningham MS, et al. Avalid and reliable assessment tool for remote simulation-based ultrasound-guided regional anesthesia. Reg Anesth Pain Med. 2014;39:496–501. 3. Cheung JJ, Chen EW, Darani R, McCartney CJ, Dubrowski A, Awad IT. The creation of an objective assessment tool for ultrasound-guided regional anesthesia using the Delphi method. Reg Anesth Pain Med. 2012;37: 329–333. 4. Bould MD, Crabtree NA, Naik VN. Assessment of procedural skills in anaesthesia. Br J Anaesth. 2009;103:472–483. 5. McGraw KO, Wong SP. Forming inferences about some intraclass correlation coefficients. Psychol Methods. 1996;1:30–46. 6. Reznick R, Regehr G, MacRae H, Martin J, McCulloch W. Testing technical skill via an innovative “bench station” examination. Am J Surg. 1997;173:226–230.
Sonographic Localization of the Piriformis Muscle Using a Caudal-to-Cranial Approach Accepted for publication: January 20, 2015.
David A. Burkett-St. Laurent, MBBS, FRCA Ahtsham Uddin Niazi, MBBS, FCARCSI, FRCPC Department of Anesthesia and Pain Management Toronto Western Hospital University Health Network Toronto, Ontario, Canada
Melissa S. Cunningham, MSc Temerty/Chang International Center for Telesimulation Innovation in Medical Education Toronto Western Hospital University Health Network Toronto, Ontario, Canada
Melanie Jaeger, MD, FRCPC Department of Anesthesiology and Perioperative Mediine Queen’s University Kingston, Ontario, Canada
Sherif Abbas, MD Jason McVicar, MD, FRCPC Vincent W. Chan, MD, FRCPC Department of Anesthesia and Pain Management Toronto Western Hospital University Health Network Toronto, Ontario, Canada
© 2015 American Society of Regional Anesthesia and Pain Medicine
To the Editor: iriformis syndrome is a clinical condition associated with irritation to piriformis muscles or compression to sciatic nerves at the buttock level. In a recently published randomized controlled trial, ultrasound-guided corticosteroid injection with local anesthesia was proven to provide similar efficacy in pain relief and procedural time compared with fluoroscopically guided injections.1 However, because the piriformis muscle is deeply situated in the gluteal region, precise recognition of this muscle is never an easy task, especially in obese patients. There are 2 common methods to visualize piriformis muscles by ultrasound. The first is through placing the probe at the level of the posterior superior iliac spine and then moving it caudally until the sacrum and ilium are seen.1 The main concern of using the posterior superior iliac spine as the initial bony landmark is that the investigators may be puzzled by similar structures such as the posterior
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291
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Letters to the Editor
Regional Anesthesia and Pain Medicine • Volume 40, Number 3, May-June 2015 National Taiwan University Hospital Bei-Hu Branch Taipei, Taiwan
Levent Özçakar, MD Department of Physical Medicine and Rehabilitation Hacettepe University Medical School Ankara, Turkey
The authors declare no conflict of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.rapm.org).
REFERENCES 1. Fowler IM, Tucker AA, Weimerskirch BP, Moran TJ, Mendez RJ. A randomized comparison of the efficacy of 2 techniques for piriformis muscle injection: ultrasound-guided versus nerve stimulator with fluoroscopic guidance. Reg Anesth Pain Med. 2014;39:126–132. 2. Chen CP, Shen CY, Lew HL. Ultrasound-guided injection of the piriformis muscle. Am J Phys Med Rehabil. 2011;90:871–872.
FIGURE 1. A, Visualize the ischial tuberosity (IT) by placing the probe horizontally at the gluteal fold; (B) move the probe cranially until the posterior ischial spine (IS) is seen, and (C) turn the probe to let it point toward the greater trochanter to see the piriformis muscle (asterisks) below the gluteus maximus (GM).
inferior iliac spine. Another approach involves recognizing the sacral cornuae first and then redirecting the probe toward the greater trochanter until a hypoechoic band is seen deep to the gluteus maximus muscle (between the lateral border of the sacrum and the inner aspect of the greater trochanter).2 This method can theoretically target the piriformis muscle; however, less experienced sonographers may be confused while distinguishing the piriformis muscle from other hip external rotators such as the superior gemellus, obturator internus, inferior gemellus, and quadrates femoris muscles.3 Given these limitations, we present an alternative method to recognize the piriformis muscle. First, the patient lies prone with the lower extremity in a neutral position. Place the probe on the gluteal fold in the horizontal axis to localize the ischial tuberosity, where the ischiocrural tendons (semimembranosus, semitendinosus, and the long head of the biceps femoris) attach (Fig. 1A). Move the probe cranially until the posterior ischial spine is observed (Fig. 1B). Compared with the cortex of the ischial tuberosity, which is oblique and faces laterally, the bony plane of the posterior ischial spine is parallel
292
to the skin. Cranial to the posterior ischial spine will be the greater sciatic foramen through which the piriformis muscle passes. Turn the probe to let its lateral edge point toward the greater trochanter. The hypoechoic, band-like structure situated below the gluteus maximus will be the piriformis muscle (Fig. 1C). For confirmation, the sonographers should trace the piriformis muscle until it reaches the inner surface of the greater trochanter during hip rotations. The tracking process is also presented in the attached video (Supplemental Digital Content 1, http://links.lww.com/AAP/A136). Ultrasound should be considered as the first line to guide corticosteroid injection to the piriformis muscle because of its zero radiation exposure and direct visualization of muscles compared with fluoroscopic guidance. Chen-Yu Hung, MD Department of Physical Medicine and Rehabilitation National Taiwan University Hospital Chu-Tung Branch Hsinchu, Taiwan
Ke-Vin Chang, MD Department of Physical Medicine and Rehabilitation
3. Jankovic D, Peng P, van Zundert A. Brief review: piriformis syndrome: etiology, diagnosis, and management. Can J Anaesth. 2013;60: 1003–1012.
Adductor Canal Block A Great Block, But Not A Panacea Accepted for publication: January 26, 2015. To the Editor: e applaud the recent study by Grevstad et al1 comparing the differential effects of adductor canal and femoral nerve blocks on quadriceps muscle strength, patient mobilization, and pain after total knee arthroplasty (TKA). The data are compelling with both subjective (pain scale) and objective (maximum voluntary isometric contraction) end points. It is also particularly interesting that the adductor canal group demonstrated increased strength with improved analgesia. Although this study will help shape postoperative TKA pain management, certain points warrant further discussion. First, this study examined patients after primary TKA. These data may not be generalizable to revision TKA. The saphenous nerve, branches of the obturator nerve,
W
© 2015 American Society of Regional Anesthesia and Pain Medicine
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Reply to Drs Srinivasan and Shorten Accepted for publication: February 6, 2015. To the Editor: e thank Drs Srinivasan and Shorten for their letter1 calling for further refinement of the assessment tool validated for evaluation of remote simulation-based ultrasound-guided regional anesthesia training.2 We address their concerns, in order, below: 1) Cheung et al3 developed the Global Rating Scale (GRS) and Checklist as a global assessment tool for ultrasound-guided peripheral nerve blocks. The process of development included the Delphi method where 18 ultrasound-guided nerve block specialists provided their expert opinion on what was to be included in the GRS and Checklist. Our study was designed simply to validate these assessment tools. Discussion and training among the raters were completed to determine the most appropriate interpretation of the definitions that are questioned. We believe that external validity is not compromised if raters agree on how to use these tools in evaluating a particular ultrasound-guided block. We would argue that these descriptions would be an objective assessment of the operator if end points for these values were decided on between raters. The Checklist and GRS were developed as a global assessment tool for all types of nerve blocks, and we believe that some wording choices were intentionally more subjective. “Carefully handles tissue but occasionally causes unintentional damage” in the GRS was decided as the inappropriate use of the needle as an instrument. Actions that cause damage include an undue number of needle insertions, inaccurate angle of insertion, and multiple attempts of trying to achieve the target. In the Checklist, “needling technique” was used to assess any mistakes commonly made by novice operators. Lastly, training does not take place in isolation from the instructor; detailed and specific feedback can always be
W
provided to trainees—these tools are guideposts and do not substitute teaching. 2) A Likert scale system of grading may be less objective but allows the assessment to be more qualitative.4 The comment suggesting poor inter-rater reliability does indeed seem to be a generalization, without reference to the literature. A tool’s reliability is dependent on a number of factors, including the training of the assessors. A combination of a Checklist and GRS has been suggested as a complementary pair for comprehensive evaluation in education research.4 3) We agree that what is required in estimating reliability of an assessment tool is quantification of agreement. Intraclass correlation coefficients calculated using an absolute agreement definition can be used for this purpose, the principles of which are discussed in McGraw and Wong.5 4) Explicit dichotomous variables may be preferred for usability; however, this study aimed to validate the Checklist and GRS developed by Cheung et al.3 Rater training and discussion on the use of these tools were conducted to improve the reliability of ratings. The ability of evaluators to provide detailed specific feedback directly to participants was not limited by these tools.
To conclude, we will quote Reznick et al6 and remember that “validity cannot be proven in any one experiment. Rather, over time and experimentation, one accrues evidence for the validity of a test.”
Letters to the Editor
The authors declare no conflict of interest. REFERENCES 1. Srinivasan KK, Shorten G. New assessment tool for remote simulation-based ultrasound-guided regional anesthesia: a call for further refinement. Reg Anesth Pain Med. 2015;40:290–291. 2. Burckett-St Laurent DA, Niazi AU, Cunningham MS, et al. Avalid and reliable assessment tool for remote simulation-based ultrasound-guided regional anesthesia. Reg Anesth Pain Med. 2014;39:496–501. 3. Cheung JJ, Chen EW, Darani R, McCartney CJ, Dubrowski A, Awad IT. The creation of an objective assessment tool for ultrasound-guided regional anesthesia using the Delphi method. Reg Anesth Pain Med. 2012;37: 329–333. 4. Bould MD, Crabtree NA, Naik VN. Assessment of procedural skills in anaesthesia. Br J Anaesth. 2009;103:472–483. 5. McGraw KO, Wong SP. Forming inferences about some intraclass correlation coefficients. Psychol Methods. 1996;1:30–46. 6. Reznick R, Regehr G, MacRae H, Martin J, McCulloch W. Testing technical skill via an innovative “bench station” examination. Am J Surg. 1997;173:226–230.
Sonographic Localization of the Piriformis Muscle Using a Caudal-to-Cranial Approach Accepted for publication: January 20, 2015.
David A. Burkett-St. Laurent, MBBS, FRCA Ahtsham Uddin Niazi, MBBS, FCARCSI, FRCPC Department of Anesthesia and Pain Management Toronto Western Hospital University Health Network Toronto, Ontario, Canada
Melissa S. Cunningham, MSc Temerty/Chang International Center for Telesimulation Innovation in Medical Education Toronto Western Hospital University Health Network Toronto, Ontario, Canada
Melanie Jaeger, MD, FRCPC Department of Anesthesiology and Perioperative Mediine Queen’s University Kingston, Ontario, Canada
Sherif Abbas, MD Jason McVicar, MD, FRCPC Vincent W. Chan, MD, FRCPC Department of Anesthesia and Pain Management Toronto Western Hospital University Health Network Toronto, Ontario, Canada
© 2015 American Society of Regional Anesthesia and Pain Medicine
To the Editor: iriformis syndrome is a clinical condition associated with irritation to piriformis muscles or compression to sciatic nerves at the buttock level. In a recently published randomized controlled trial, ultrasound-guided corticosteroid injection with local anesthesia was proven to provide similar efficacy in pain relief and procedural time compared with fluoroscopically guided injections.1 However, because the piriformis muscle is deeply situated in the gluteal region, precise recognition of this muscle is never an easy task, especially in obese patients. There are 2 common methods to visualize piriformis muscles by ultrasound. The first is through placing the probe at the level of the posterior superior iliac spine and then moving it caudally until the sacrum and ilium are seen.1 The main concern of using the posterior superior iliac spine as the initial bony landmark is that the investigators may be puzzled by similar structures such as the posterior
P
291
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
Letters to the Editor
Regional Anesthesia and Pain Medicine • Volume 40, Number 3, May-June 2015 National Taiwan University Hospital Bei-Hu Branch Taipei, Taiwan
Levent Özçakar, MD Department of Physical Medicine and Rehabilitation Hacettepe University Medical School Ankara, Turkey
The authors declare no conflict of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.rapm.org).
REFERENCES 1. Fowler IM, Tucker AA, Weimerskirch BP, Moran TJ, Mendez RJ. A randomized comparison of the efficacy of 2 techniques for piriformis muscle injection: ultrasound-guided versus nerve stimulator with fluoroscopic guidance. Reg Anesth Pain Med. 2014;39:126–132. 2. Chen CP, Shen CY, Lew HL. Ultrasound-guided injection of the piriformis muscle. Am J Phys Med Rehabil. 2011;90:871–872.
FIGURE 1. A, Visualize the ischial tuberosity (IT) by placing the probe horizontally at the gluteal fold; (B) move the probe cranially until the posterior ischial spine (IS) is seen, and (C) turn the probe to let it point toward the greater trochanter to see the piriformis muscle (asterisks) below the gluteus maximus (GM).
inferior iliac spine. Another approach involves recognizing the sacral cornuae first and then redirecting the probe toward the greater trochanter until a hypoechoic band is seen deep to the gluteus maximus muscle (between the lateral border of the sacrum and the inner aspect of the greater trochanter).2 This method can theoretically target the piriformis muscle; however, less experienced sonographers may be confused while distinguishing the piriformis muscle from other hip external rotators such as the superior gemellus, obturator internus, inferior gemellus, and quadrates femoris muscles.3 Given these limitations, we present an alternative method to recognize the piriformis muscle. First, the patient lies prone with the lower extremity in a neutral position. Place the probe on the gluteal fold in the horizontal axis to localize the ischial tuberosity, where the ischiocrural tendons (semimembranosus, semitendinosus, and the long head of the biceps femoris) attach (Fig. 1A). Move the probe cranially until the posterior ischial spine is observed (Fig. 1B). Compared with the cortex of the ischial tuberosity, which is oblique and faces laterally, the bony plane of the posterior ischial spine is parallel
292
to the skin. Cranial to the posterior ischial spine will be the greater sciatic foramen through which the piriformis muscle passes. Turn the probe to let its lateral edge point toward the greater trochanter. The hypoechoic, band-like structure situated below the gluteus maximus will be the piriformis muscle (Fig. 1C). For confirmation, the sonographers should trace the piriformis muscle until it reaches the inner surface of the greater trochanter during hip rotations. The tracking process is also presented in the attached video (Supplemental Digital Content 1, http://links.lww.com/AAP/A136). Ultrasound should be considered as the first line to guide corticosteroid injection to the piriformis muscle because of its zero radiation exposure and direct visualization of muscles compared with fluoroscopic guidance. Chen-Yu Hung, MD Department of Physical Medicine and Rehabilitation National Taiwan University Hospital Chu-Tung Branch Hsinchu, Taiwan
Ke-Vin Chang, MD Department of Physical Medicine and Rehabilitation
3. Jankovic D, Peng P, van Zundert A. Brief review: piriformis syndrome: etiology, diagnosis, and management. Can J Anaesth. 2013;60: 1003–1012.
Adductor Canal Block A Great Block, But Not A Panacea Accepted for publication: January 26, 2015. To the Editor: e applaud the recent study by Grevstad et al1 comparing the differential effects of adductor canal and femoral nerve blocks on quadriceps muscle strength, patient mobilization, and pain after total knee arthroplasty (TKA). The data are compelling with both subjective (pain scale) and objective (maximum voluntary isometric contraction) end points. It is also particularly interesting that the adductor canal group demonstrated increased strength with improved analgesia. Although this study will help shape postoperative TKA pain management, certain points warrant further discussion. First, this study examined patients after primary TKA. These data may not be generalizable to revision TKA. The saphenous nerve, branches of the obturator nerve,
W
© 2015 American Society of Regional Anesthesia and Pain Medicine
Copyright © 2015 American Society of Regional Anesthesia and Pain Medicine. Unauthorized reproduction of this article is prohibited.
