ORIGINAL ARTICLE. S. S. Liu, 1 J. T. YaDeau, 2 P. M. Shaw, 3 S. Wilfred, 4 T. Shetty 5 and M. Gordon 6

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1 doi: /j x ORIGINAL ARTICLE Incidence of unintentional intraneural injection and postoperative neurological complications with ultrasoundguided interscalene and supraclavicular nerve blocks* S. S. Liu, 1 J. T. YaDeau, 2 P. M. Shaw, 3 S. Wilfred, 4 T. Shetty 5 and M. Gordon 6 1 Attending Anesthesiologist, Hospital for Special Surgery, Clinical Professor of Anesthesiology, Weill Cornell Medical College, New York, USA 2 Assistant Attending Anesthesiologist, Hospital for Special Surgery, Clinical Assistant Professor of Anesthesiology, Weill Cornell Medical College, New York, USA 3 Assistant Research Coordinator, 4 Research Assistant, Department of Anesthesiology, Hospital for Special Surgery, New York, USA 5 Assistant Attending Neurologist, Hospital for Special Surgery, Assistant Professor of Neurology, Weill Cornell Medical College, New York, USA 6 Attending Anesthesiologist, Hospital for Special Surgery, Assistant Clinical Professor in Anesthesiology, Weill Cornell Medical College, New York, USA Summary It is proposed that ultrasound guidance decreases the risk of intraneural injection and associated postoperative neurological complications. However, the incidence of unintentional intraneural injection with ultrasound is unknown. Two hundred and fifty-seven patients were enrolled in a prospective, single-blind observational study. All patients underwent a pre-operative neurological examination before ambulatory shoulder arthroscopy with sedation and ultrasound-guided interscalene or supraclavicular block. Patients were followed up at 1 week and at 4 6 weeks postoperatively. Two blinded anaesthesiologists viewed the same video of the ultrasound image during the block offline to determine intraneural trespass. Intraneural injection occurred in 42 patients (17%; 95% CI 12 22%). No patient suffered from postoperative neurological complications (0%; 95% CI 0 1.6%) at follow-up.... Correspondence to: Dr Spencer S. Liu liusp@hss.edu *Presented in part at the Annual Meeting of the American Society of Anesthesiologists, New Orleans, October Accepted: 2 December 2010 A primary and potentially modifiable risk factor for neurological complications after nerve blockade is direct intraneural needle trauma or injection [1]. Direct nerve trauma may be particularly important during proximal brachial plexus block as these blocks have the highest incidence (1 6%) of neurological complications [2]. Anatomical studies have noted that the amount of non-neural tissue around the brachial plexus is least at proximal sites (such as the interscalene area) and increases distally (axillary) [3, 4]. Thus, there may be a smaller margin for error for extraneural placement of needles and local anaesthetic solution at proximal sites and precise targeting of block needles may be advantageous. It has been proposed that ultrasound guidance provides precise targeting and decreased risk of intraneural injection, potentially decreasing the risk of postoperative nerve injury. However, results from studies comparing ultrasound with other guidance techniques for postoperative neurological complications have been inconclusive [5, 6]. A major limitation in the interpretation of previous studies is that unintentional intraneural injection during nerve stimulator or surface landmark guided techniques may be frequent (up to 88%), yet the incidence during ultrasound 168 Anaesthesia Ó 2011 The Association of Anaesthetists of Great Britain and Ireland

2 S. S. Liu et al. Æ Incidence of unintentional intraneural injection guidance is unknown. Intuitively, the risk of unintentional intraneural injection (swelling or halo of neural structure) with ultrasound may seem remote yet maintaining consistent views of the needle tip and neural target may be challenging even for experts [7, 8]. We performed a prospective observational series to determine the incidence of unintentional intraneural injection during ultrasound-guided proximal brachial plexus block (interscalene or supraclavicular) and to observe the association with subsequent postoperative neurological complications. Methods With Institutional Review Board approval, written informed consent was obtained from 268 patients scheduled to undergo ambulatory arthroscopic surgery from November 2008 to May This series was a subset of a larger clinical registry [9]. Patients were not studied if general anaesthesia was planned, if there was a pre-existing contra-indication to regional anaesthesia (for example, infection at the block site, or pre-existing neurological injury), if an open shoulder procedure was planned, or if a research assistant was not available. Each subject underwent a standardised sensory and motor neurological evaluation and physical examination to determine baseline neurological function (Appendix 1) [6]. This tool was prospectively designed by a neurologist (TS) who subsequently trained two co-investigators to use it (PS, SW). After placement of standard monitoring, patients received sedation at the discretion of the anaesthesia team. The type of block (interscalene or supraclavicular) was selected at the discretion of the anaesthesia team. Ultrasound was performed with a linear MHz probe, using an in-plane technique and a blunt tip block needle (22-G Stimuplex A, BBraun, Mulsungen, Germany or 22-G Chiba, Hakko Co Ltd, Cincinnati, OH, USA). Interscalene block was performed at the level of C6 (approximately) with the needle placed through the middle scalene muscle. Supraclavicular block was performed in the supraclavicular fossa with a lateral to medial approach. The needle was to be placed immediately adjacent to the neural target with intended avoidance of intraneural placement. Final needle path, endpoints for needle target, type of block needle, use of hydrodissection, and type and volume of local anaesthetic solution were at the discretion of the anaesthesia team. The needle was repositioned if there was blood during aspiration after every 5 ml of injection, or for difficult or painful injection. The block was performed either by an attending anaesthesiologist or by a supervised trainee, and ultrasound images were recorded continuously from skin puncture until completion of injection during routine performance in the operating room. Complications such as vascular puncture (blood on aspiration) or systemic toxicity were recorded. Following completion of the block, the patient was placed in sitting beach chair position for the surgical procedure. Intra-operative sedation was at the discretion of the anaesthesia team. The patients were discharged home from the postanaesthesia care unit after achieving routine discharge criteria and with a functional block. To determine if intraneural injection occurred during the block, all recorded block videos were reviewed by two out of three investigators (SSL, JTY, or MG) offline after performance of the block and were with the investigators blinded to all patient and block data. As there are no agreed criteria by which ultrasound can be used to determine whether an intraneural injection is in neuronal connective tissue or neural fascicles [10], we considered needle placement in the sub epineurium followed by previously described criteria such as neuronal swelling or halo during injection to identify intraneural injection [11]. A third investigator was appointed to resolve disagreement between the initial two reviewers. Approximately 1 week after surgery (excluding holidays and weekends), all patients were followed up by the same co-investigators (PS or SW) and the same standardised neurological questionnaire was administered. Potential neurological complications occurring at any time in the postoperative period were reviewed by a neurologist (TS) who was blinded to block technique and patients characteristics. A postoperative neurological complication was prospectively defined as neurological symptoms within the territory of the brachial plexus of the operative limb that were related to brachial plexus irritation, but were unrelated to the surgical procedure as determined by the neurologist. If present, patients were asked to rate overall severity of postoperative neurological complications (mild = barely noticeable, moderate = definitely noticeable, severe = very preoccupied). Any patient with a postoperative neurological complication was to be seen by the neurologist for a complete neurological evaluation and standard diagnostic testing to define the cause and determine the prognosis of postoperative neurological symptoms. At the same 1-week follow-up, patients Anaesthesia Ó 2011 The Association of Anaesthetists of Great Britain and Ireland 169

3 S. S. Liu et al. Æ Incidence of unintentional intraneural injection Anaesthesia, 2011, 66, pages were asked to rate their satisfaction with anaesthesia on a 0 10 scale (0 = not satisfied, 10 = completely satisfied). Patients were again evaluated for postoperative neurological complications at follow-up by their surgeons 4 6 weeks postoperatively. Finally, at completion of the study, our hospital quality assurance database was queried for late complications. There were no previous estimates for the incidence of unintentional intraneural needle placement or injection under ultrasound guidance and we arbitrarily decided to enrol at least 250 patients. Statistical analysis was planned with the use of descriptive statistics and 95% confidence intervals to report the incidences of intraneural needle placement, injection and postoperative neurological complications. Univariate and contingency table analysis of peri-operative risk factors followed by logistic regression would then be used to identify whether intraneural needle placement or injection was an independent risk factor for postoperative neurological complications. An adjusted p < 0.05 was considered significant. Results We enrolled 268 patients and 11 were lost to followup. One hundred and thirty-five (53%) patients received a supraclavicular block and 122 (47%) received an interscalene block (Table 1). The first two reviewers concurred in 224 (87%) of the patients. The third, blinded reviewer resolved the disputes in the remaining 33 (13%) patients. Intraneural injection (Fig. 1) was detected in 43 patients (17%, 95% CI 12 22%). The injection was immediately terminated in 21 patients, but the remainder received between 25 and 65 ml of intraneural injection. Peri-operative characteristics were similar between patients who did or did not have intraneural injection including patient characteristics, type of block, type of block needle and whether the block was performed by an attending anaesthesiologist or a supervised trainee (Table 1). No patient had a failed block requiring general anaesthesia. No patient noted postoperative neurological complications (0%; 95% CI 0 1.6%) at follow-up (1 week, 4 6 weeks and end of study). As there were no patients with postoperative neurological complication, no risk factors could be identified. Discussion Our prospective survey was intended to provide an estimate for the incidence of unintentional intraneural Table 1 Patients characteristics, details of block and complications after brachial plexus block. Values are number (proportion), mean (SD) or median (IQR [range]). No intraneural injection (n = 214) Intraneural injection (n = 43) Age; years 47 (17) 44 (15) Sex; M F 154 (72%) 60 (28%) 30 (70%) 13 (30%) Weight; kg 82 (18) 82 (12) BMI; kg.m )2 27 (4) 27 (4) Diabetes 6 (3%) 1 (2%) Intra-operative sedation Midazolam 207 (97%) 42 (98%) Midazolam dose; mg 5 (1) 5 (1) Fentanyl 113 (53%) 22 (51%) Fentanyl dose; lg 86 (25) 85 (25) Location of block Interscalene 99 (46%) 19 (44%) Supraclavicular 115 (54%) 24 (56%) Nerve stimulator used 4 (2%) 0 (0%) Type of needle 22-G Stimuplex 128 (60%) 28 (65%) 22-G Chiba 86 (40%) 15 (35%) Local anaesthetic solution Total volume injected; ml 50 (9) 47 (8) Mepivicaine + adrenaline 70 (33%) 16 (37%) Mepivicaine + bupivacaine 144 (67%) 27 (63%) + adrenaline Block performed by Attending anaesthesiologist 122 (57%) 26 (61%) Supervised trainee 92 (43%) 17 (39%) Type of intraneural injection Halo N A 1 (2%) Swelling N A 35 (81%) Other N A 7 (17%) Postoperative 0 0 neurological complications Satisfaction (0 = not satisfied, 10 = completely satisfied) 8 (8 8 [5 9]) 8 (7 8 [6 9]) injection with ultrasound guidance during routine clinical practice. Our department has extensive experience with ultrasound-guided regional blocks; we performed 5584 ultrasound-guided nerve blocks in 2009, out of which 2435 were either interscalene or supraclavicular ultrasound-guided blocks ( The 17% incidence of unintentional intraneural injection with ultrasound compares favourably with other guidance techniques. Although only small surveys for other guidance techniques are available (between 20 and 42 patients), these noted an 85% incidence of unintentional intraneural injection with anatomical landmark guidance for axillary block and an 88% incidence with nerve stimulator for popliteal block as noted on subsequent ultrasound imaging [11 13]. While it may 170 Anaesthesia Ó 2011 The Association of Anaesthetists of Great Britain and Ireland

4 S. S. Liu et al. Æ Incidence of unintentional intraneural injection (a) (b) (c) Figure 1 Still images from a representative video of an intraneural injection during supraclavicular block. (a) Ultrasound image of brachial plexus for supraclavicular block; (b) block needle in intraneural (sub epineurium) position at beginning of intraneural injection; and (c) brachial plexus swelling after completion of intraneural injection. seem intuitive that ultrasound guidance should prevent needle misadventure, previous reviews have noted difficulties in correct identification of regional block targets such as image artefacts and suboptimal use of ultrasound machine settings [14]. Even after correct target identification, available studies have observed that even experienced practitioners (with > 100 ultrasound-guided nerve blocks) persistently failed to maintain the needle tip in view [15]. A recent cadaveric study reported a 50% incidence of unintentional intraneural (sub epineurium) injection during simulated ultrasound-guided interscalene block [8]. Reviews have suggested that difficulty in maintaining an optimal alignment between the needle and ultrasound beam and the relatively poor echogenecity of most needle tips hampers consistent needle tip views [7]. Thus, our findings provide clinical correlation of the current difficulty in perfecting consistency of ultrasound guidance for regional blocks. Typical clinical recommendations and formal guidelines from the American Society of Regional Anesthesia consider direct intraneural needle trauma or injection as a risk factor for postoperative neurological complications [1] although the magnitude of such risk is controversial. For example, previous case reports noted postoperative neuropathy after ultrasound-guided unintentional intraneural injection of local anaesthetic during femoral nerve block [16], interscalene block [17] and supraclavicular block [18]. Animal studies have also reported permanent neuropathy after intentional intraneural injection under direct vision [19, 20] thus substantiating the potential risk of needle and injection trauma. However, we observed a 17% incidence of unintentional intraneural injection under ultrasound guidance with no neurological complications at early and late follow-ups. These findings are in agreement with previous limited human experience where intraneural injection of 2 5 ml of local anaesthetic solution in the brachial plexus [11, 21] and 4 40 ml in the sciatic nerve [12, 13, 22] results in ultrasound images of nerve swelling, but without subsequent neurological complications. One explanation for absence of injury is that intraneural injection is likely to be placed harmlessly in intraneural connective tissue without disrupting nerve fascicles and causing nerve injury. Cadaver studies indicate that the amount of connective tissue within the epineurium of the brachial plexus is least at proximal sites (55% for interscalene and 52% for supraclavicular) compared with distal sites (66% for subcoracoid) [3]. However, even at proximal brachial plexus block sites, the majority of the intraneural space typically consists of connective tissue. A correlative ultrasound imaging study has been performed reporting the ultrasound appearance of the brachial plexus at common regional block sites with cross-sectional gross anatomy and Anaesthesia Ó 2011 The Association of Anaesthetists of Great Britain and Ireland 171

5 S. S. Liu et al. Æ Incidence of unintentional intraneural injection Anaesthesia, 2011, 66, pages histology [4]. This study also documented increasing amounts of connective tissue in the distal brachial plexus and suggested that the typical increased hyperechoic appearance of the distal brachial plexus on ultrasound correlated with the increase in connective tissue. Even with intraneural injection, functional cadaveric studies suggest that intrafascicular injection is rare and difficult to accomplish with blunt-tipped block needles. For example, in cryopreserved human sciatic nerves, blunt- and sharp-tipped needles were each inserted five times. Microscopic examination of 520 stained fascicles demonstrated that no fascicles were damaged by the blunt needles and only 3.2% were damaged by the sharp needles [23]. Other investigators using an animal model, have, however, reported that should a fascicle become impaled, the use of a blunt needle resulted in more frequent and severe nerve injury than a sharp tipped needle [24]. Other safety steps in our protocol may have also minimised the risk of intrafascicular injection [1]. Our patients were asked to report painful injections suggestive of intrafascicular injection and injury that would prompt repositioning of the needle. Our protocol required needle adjustment for difficult injection suggestive of high pressure and previous animal studies suggest avoidance of high intraneural injection pressures may be important for prevention of nerve injury. In dogs, direct intraneural injection of 4 ml of local anaesthetic solution resulted in neurological deficits only if high pressures (> 25 psi; 172 kpa) suggestive of intrafascicular injection occurred [19, 20]. In pigs, direct intraneural injection of up to 20 ml local anaesthetic solution with low injection pressures (< 10 psi; 69 kpa) resulted in ultrasound and histological markers for nerve expansion and inflammation, but did not result in functional neurological deficits at 1, 2 and 7 days post-injection [25]. Although avoidance of high intraneural injection pressure may be important, the ability of clinicians to determine pressure by the syringe s feel is variable and may not be reliable as a sole safety step [26]. There are limitations to this study. The incidence of permanent peripheral nerve injury after regional anaesthesia is inherently low (estimates range from 1:1000 to 1:30 000) [27, 28] and we cannot exclude needle injury as a risk factor despite the complete absence of postoperative neural complications in our patients. It is possible that our incidence of intraneural placement is incorrect due to misinterpretation of the ultrasound images. This possibility is unlikely as nerve swelling and halo with intraneural injection are easily noted on ultrasound [29, 30] and both reviewers concurred on video interpretation in 87% of patients. There are no agreed criteria for precise indentification by ultrasound of whether an intraneural needle is placed into connective tissue or into neural fascicles, and we were unable to ascertain if nerve fascicles were actually impaled during intraneural injection [10]. Our patient population was generally young and healthy, as is typical for ambulatory sports medicine procedures, and other populations with greater inherent risk for nerve injury (for example, diabetes) may differ. In conclusion, our observational study provides an estimate for the incidence of unintentional intraneural injection with ultrasound guidance during routine clinical practice. Our findings may partially explain the current inability to detect a substantial decrease in the risk of neurological complications with ultrasound guidance versus other techniques, and may aid in the design of future studies. Competing interests This study was funded by the Hospital for Special Surgery Anaesthesiology Department Research and Education Fund. No external funding or competing interests declared. References 1 Neal JM, Bernards CM, Hadzic A, et al. ASRA practice advisory on neurologic complications in regional anesthesia and pain medicine. Regional Anesthesia and Pain Medicine 2008; 33: Brull R, McCartney CJ, Chan VW, El-Beheiry H. Neurological complications after regional anesthesia: contemporary estimates of risk. Anesthesia and Analgesia 2007; 104: Moayeri N, Bigeleisen PE, Groen GJ. Quantitative architecture of the brachial plexus and surrounding compartments, and their possible significance for plexus blocks. Anesthesiology 2008; 108: van Geffen GJ, Moayeri N, Bruhn J, Scheffer GJ, Chan VW, Groen GJ. Correlation between ultrasound imaging, cross-sectional anatomy, and histology of the brachial plexus: a review. Regional Anesthesia and Pain Medicine 2009; 34: Neal JM, Brull R, Chan VW, et al. The ASRA evidence-based medicine assessment of ultrasound-guided regional anesthesia and pain medicine: executive 172 Anaesthesia Ó 2011 The Association of Anaesthetists of Great Britain and Ireland

6 S. S. Liu et al. Æ Incidence of unintentional intraneural injection summary. Regional Anesthesia and Pain Medicine 2010; 35: S Liu SS, Zayas VM, Gordon MA, et al. A prospective, randomized, controlled trial comparing ultrasound versus nerve stimulator guidance for interscalene block for ambulatory shoulder surgery for postoperative neurological symptoms. Anesthesia and Analgesia 2009; 109: Chin KJ, Perlas A, Chan VW, Brull R. Needle visualization in ultrasound-guided regional anesthesia: challenges and solutions. Regional Anesthesia and Pain Medicine 2008; 33: Orebaugh SL, McFadden K, Skorupan H, Bigeleisen PE. Subepineurial injection in ultrasound-guided interscalene needle tip placement. Regional Anesthesia and Pain Medicin 2010; 35: Liu SS, Gordon MA, Shaw PM, Wilfred S, Shetty T, Yadeau JT. A prospective clinical registry of ultrasoundguided regional anesthesia for ambulatory shoulder surgery. Anesthesia and Analgesia 2010; 111: Morfey D, Brull R. Ultrasound-guided supraclavicular block: what is intraneural? Anesthesiology 2010; 112: Bigeleisen PE. Nerve puncture and apparent intraneural injection during ultrasound-guided axillary block does not invariably result in neurologic injury. Anesthesiology 2006; 105: Robards C, Hadzic A, Somasundaram L, et al. Intraneural injection with low-current stimulation during popliteal sciatic nerve block. Anesthesia and Analgesia 2009; 109: Sala Blanch X, Lopez AM, Carazo J, et al. Intraneural injection during nerve stimulator-guided sciatic nerve block at the popliteal fossa. British Journal of Anaesthesia 2009; 102: Sites BD, Brull R, Chan VW, et al. Artifacts and pitfall errors associated with ultrasound-guided regional anesthesia. Part I: understanding the basic principles of ultrasound physics and machine operations. Regional Anesthesia and Pain Medicine 2007; 32: Sites BD, Spence BC, Gallagher JD, Wiley CW, Bertrand ML, Blike GT. Characterizing novice behavior associated with learning ultrasound-guided peripheral regional anesthesia. Regional Anesthesia and Pain Medicine 2007; 32: Schafhalter-Zoppoth I, Zeitz ID, Gray AT. Inadvertent femoral nerve impalement and intraneural injection visualized by ultrasound. Anesthesia and Analgesia 2004; 99: Cohen JM, Gray AT. Functional deficits after intraneural injection during interscalene block. Regional Anesthesia and Pain Medicine 2010; 35: Reiss W, Kurapati S, Shariat A, Hadzic A. Nerve injury complicating ultrasound electrostimulation-guided supraclavicular brachial plexus block. Regional Anesthesia and Pain Medicine 2010; 35: Hadzic A, Dilberovic F, Shah S, et al. Combination of intraneural injection and high injection pressure leads to fascicular injury and neurologic deficits in dogs. Regional Anesthesia and Pain Medicine 2004; 29: Kapur E, Vuckovic I, Dilberovic F, et al. Neurologic and histologic outcome after intraneural injections of lidocaine in canine sciatic nerves. Acta Anaesthesiologica Scandinavica 2007; 51: Bigeleisen PE, Moayeri N, Groen GJ. Extraneural versus intraneural stimulation thresholds during ultrasoundguided supraclavicular block. Anesthesiology 2009; 110: Rodriguez J, Taboada M, Blanco M, Oliveira J, Barcena M, Alvarez J. Intraneural catheterization of the sciatic nerve in humans: a pilot study. Regional Anesthesia and Pain Medicine 2008; 33: Sala-Blanch X, Ribalta T, Rivas E, et al. Structural injury to the human sciatic nerve after intraneural needle insertion. Regional Anesthesia and Pain Medicine 2009; 34: Rice AS, McMahon SB. Peripheral nerve injury caused by injection needles used in regional anaesthesia: influence of bevel configuration, studied in a rat model. British Journal of Anaesthesia 1992; 69: Lupu CM, Kiehl TR, Chan VW, El-Beheiry H, Madden M, Brull R. Nerve expansion seen on ultrasound predicts histologic but not functional nerve injury after intraneural injection in pigs. Regional Anesthesia and Pain Medicine 2010; 35: Claudio R, Hadzic A, Shih H, et al. Injection pressures by anesthesiologists during simulated peripheral nerve block. Regional Anesthesia and Pain Medicine 2004; 29: Auroy Y, Benhamou D, Bargues L, et al. Major complications of regional anesthesia in France: the SOS Regional Anesthesia Hotline Service. Anesthesiology 2002; 97: Borgeat A, Ekatodramis G, Kalberer F, Benz C. Acute and nonacute complications associated with interscalene block and shoulder surgery: a prospective study. Anesthesiology 2001; 95: Altermatt FR, Cummings TJ, Auten KM, Baldwin MF, Belknap SW, Reynolds JD. Ultrasonographic appearance of intraneural injections in the porcine model. Regional Anesthesia and Pain Medicine 2010; 35: Chan VW, Brull R, McCartney CJ, Xu D, Abbas S, Shannon P. An ultrasonographic and histological study of intraneural injection and electrical stimulation in pigs. Anesthesia and Analgesia 2007; 104: Anaesthesia Ó 2011 The Association of Anaesthetists of Great Britain and Ireland 173

7 S. S. Liu et al. Æ Incidence of unintentional intraneural injection Anaesthesia, 2011, 66, pages Appendix Neurologic screening tool 1 Subjective assessment of motor function A. Have you noticed any weakness in your hands or arms? B. If so, is it mild, moderate, or severe? C. Is there any part of your arm, hand, elbow, or shoulder that is difficult to move? When did you first notice it? If it wore off, when did it wear off? D. Do you have difficulty opening jars? (Please write N A if you have not tried) E. Do you have difficulty lifting your arms above your head? (Please write N A if you have not tried) F. Do you often drop things from your fingers, e.g. a drinking cup? (Please write N A if you have not tried) 2 Subjective assessment of sensory function A. Do you feel any sensations such as numbness, tingling, or pins and needles in the hand after the anaesthesia wore off? B. Which specific fingers has it affected? (List involved digits here) C. Is there any numbness in your arm? (Ask the patient to point to whether it is medial or lateral in the arm and to point to whether it is in the hand, elbow, forearm, or shoulder) D. Is it mild, moderate, or severe? (Mild = barely noticeable, moderate = definitely noticeable, severe = very preoccupied by the sensation) E. When did you first notice it? If it wore off, when did it wear off? F. Is the numbness or tingling you have noticed present only in the area covered or held in your sling or cast? G. Have you noticed numbness or tingling which is alleviated by changing the position of your sling? 3 Subjective assessment of postoperative pain A. Do you have pain in your hand, arm, or shoulder other than the pain at the surgical site? B. Where is or was the pain? C. If yes, on a scale of 0 10, where 0 is no pain and 10 is the worst imaginable pain, how would you rate that pain? D. When did you first notice it? Did it wear off? When? E. At the site that the anesthesiologist put in the block (neck), do you have any pain, tenderness, swelling, discoloration, or skin breaks? F. Are you satisfied with the anaesthesia you received? G. Would you have it again? 4 Objective assessment of motor and sensory function A. Motor examination of biceps, deltoid, triceps, wrist extensors, wrist flexors, finger flexors and extensors, and intrinsic hand muscles using the MRC Scale from 0 to 5 for assessment of motor function. Biceps: 0, 1, 2, 3, 4, 5 (Circle one) Deltoid: 0, 1, 2, 3, 4, 5 Triceps: 0, 1, 2, 3, 4, 5 Wrist extensors: 0, 1, 2, 3, 4, 5 Wrist flexors: 0, 1, 2, 3, 4, 5 Finger flexors: 0,1, 2, 3, 4, 5 Finger extensors: 0,1, 2, 3, 4, 5 Intrinsic hand muscles: 0, 1, 2, 3, 4, 5 B. Sensory examination of different dermatomes and median, ulnar, and radial distributions with light touch and pinprick. Check one of the below dermatomes or nerves if it corresponds to the area of sensory deficit and indicate whether it is present with light touch or pinprick: Light touch C5-6: C7-C8: C8-T1: Median: Ulnar (note median and ulnar split third digit usually): Radial (dorsal surface of hand): Pinprick 174 Anaesthesia Ó 2011 The Association of Anaesthetists of Great Britain and Ireland