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Nerve Injury After Peripheral Nerve Block: Allbest Rights Practices Reserved PRINTER-FRIENDLY VERSION AVAILABLE AT ANESTHESIOLOGYNEWS.COM Nerve Injury After Peripheral Nerve Block: AllBest rights Practices reserved. Reproduction and Medical-Legal in whole or in part without Protection permission isStrategies prohibited. Copyright © 2015 McMahon Publishing Group unless otherwise noted. DAVID HARDMAN, MD, MBA Professor of Anesthesiology Vice Chair for Professional Affairs Department of Anesthesiology University of North Carolina at Chapel Hill Chapel Hill, North Carolina Dr. Hardman reports no relevant financial conflicts of interest. he risk for permanent or severe nerve injury after peripheral nerve blocks (PNBs) is Textremely low, irrespective of its etiology (ie, related to anesthesia, surgery or the patient). The risk inherent in a procedure should always be explicitly discussed with the patient (sidebar, page 4). In fact, it may be better to define this phenomenon ultrasound-guided axillary blocks were used, demon- as postoperative neurologic symptoms (PONS) or peri- strated a very low nerve injury rate of 0.0037% at hos- operative nerve injuries (PNI) in order to help stan- pital discharge.1-7 dardize terminology. Permanent injury rates, as defined A 2009 prospective case series involving more than by a neurologic abnormality present at or beyond 12 7,000 PNBs, conducted in Australia and New Zealand, months after the procedure, have consistently ranged demonstrated that when a postoperative neurologic from 0.029% to 0.2%, although the results of a recent symptom was diagnosed, it was 9 times more likely to multicenter Web-based survey in France, in which be due to a non–anesthesia-related cause than a nerve ANESTHESIOLOGY NEWS • JULY 2015 1 block–related cause.6 On the other hand, it is well doc- PNI rate of 1.7% in patients who received a single-injec- umented in the orthopedic and anesthesia literature tion interscalene block (ISB). Patients who received an that there is an alarmingly high incidence of temporary ISB had significantly reduced odds for PNI (odds ratio, postoperative neurologic symptoms after arthroscopic 0.47).11 Factors not associated with an increased risk for shoulder surgery, both with and without regional blocks. PNI in this study included patient sex and longer oper- Most of these involve minor sensory paresthesias and ative time. dysesthesias, but they can range as high as 16% to 30% Over 97% of patients who developed PNI eventu- in the first week postoperatively.1,8,9 ally recovered completely or partially at 2.5 years after The PNI rate associated with total shoulder arthro- the procedure, and 71% experienced full recovery. Nota- plasty has been previously reported to be 4% under bly, there was no difference in overall recovery from generalAll anesthesia rights reserved. alone, and Reproduction represents the underlyingin whole or PNIin part between without patients permission who received is prohibited. ISB and those who independent surgical risk.10 Despite advances in surgi- received general anesthesia alone.11 cal techniques, this Copyrightnumber has © not 2015 changed McMahon apprecia- PublishingNot allGroup surgical unless procedures otherwise have the noted. same incidence bly over time. of PNI, and this variation may be due to procedure-spe- The most recent data from a clinical registry at Mayo cific risk for nerve injury, apart from the use of periph- Clinic, for 1993 to 2007, demonstrated a PNI rate of eral nerve blockade and regional anesthesia. Data from 3.7% during general anesthesia.11 This contrasts with a three clinical registries at a single institution demon- strated a PNI incidence of 2.2% after total shoulder arthroplasty, 0.79% after total knee arthroplasty and 11-13 Arthroscopic shoulder surgery ± 0.72% after total hip arthroplasty (Figure). regional block, 7 days postoperatively: The use of regional anesthesia was not an indepen- dent risk factor for PNI in any of these procedures; in fact, it reduced the risk for PNI in total shoulder 16%-30% arthroplasties. Total shoulder arthroplasty: Strategies To Reduce Medical-Legal Risk Before initiating a block, and particularly in a patient with previous injuries, I recommend that you take a 2.2% focused history for the presence of current or previ- ous paresthesias, dysesthesias, or pain in the limb that will receive the block. It would also be helpful to do Single-injection interscalene block: a quick, focused sensory and motor neurologic exam. Many of these patients have preexisting lesions; unfor- tunately, they are not noticed until the postoperative 1.7% period, when we become much more observant of abnormalities. Be careful with the administration of sedatives dur- Total knee arthroplasty: ing the block procedure in order to not obscure any symptoms of paresthesia, dysesthesia, or pain during 0.79% injection.14 Refer to the American Society of Regional Anesthesia and Pain Medicine (ASRA) Practice Advi- sory on Complications in Regional Anesthesia.15 Be advised that a favorite tactic of medical malpractice Total hip arthroplasty: attorneys is to argue that patients given any amount of sedation would be unlikely to be able to report pain or 0.72% paresthesia on injection. I would recommend that you document in the chart that meaningful verbal communication with the patient was maintained throughout the block procedure. Ultrasound-guided axillary blocks, Documentation of blocks is essential for clinical care, at discharge: regulatory, billing, and medical-legal reasons. ASRA has published a recommended PNB note template.16 My 0.0037% experience reviewing cases for potential medical-legal problems has shown me that many of the block notes are poorly documented. Figure. Rates of perioperative nerve This is an area that can be rectified with the introduc- injuries following each type of tion of an electronic anesthesia medical record, which procedure. can allow you to create custom templates for every type of block you perform, and document detailed 2 ANESTHESIOLOGYNEWS.COM information pertaining to the block. Table 1 shows an is challenging to keep the tip of the needle visualized in example of a block form. the plane of the ultrasound beam at all times, it is diffi- Patients discharged home after a PNB procedure cult to distinguish between a subfascial, subepineural, should receive written instructions with precautions or intrafascicular injection.28 about how to take care of an insensate extremity, and Even exceptionally well-trained experts in regional how to prevent injury. Patients with a single-injection anesthesia have subsequently realized that they may block should be called the next day and questioned have contributed to a PNI after reviewing video clips of about complete block resolution or persistent symp- an interscalene block demonstrating intraneural injec- toms, and this contact should be documented until the tion, despite an uneventful block procedure without symptoms resolve. Any patient with persistent motor pain or paresthesia.29 Allweakness rights beyondreserved. the Reproductionnormal expected in recovery whole timeor in partCurrent without thinking permission is geared is toprohibited. depositing local anes- should be seen in clinic immediately, for examination thesia farther away from the nerves, rather than around and potential Copyrightneurologic consultation. © 2015 McMahon Publishingthe Group nerves unless in the interscaleneotherwise brachialnoted. plexus region.30 You should be particularly vigilant when dealing with We should consider thinking about the maximum effec- a patient returning for a second surgical procedure and tive distance from the plexus that will still result in an block within an intervening short interval, for example, effective block,31 with a paraplexus approach rather 3 months or less. Nerve injury can exist with subclinical than an intraplexus approach. A conservative tech- symptoms, and a second insult, either distal or prox- nique would involve using a hydrodissection approach imal, without necessarily having anything to do with with needle advancement, along with a nerve stimula- your nerve block, can elicit clinical findings postopera- tor (no data support this) and a lower anesthetic mass tively. This phenomenon is known as the double-crush and volume.32 theory of nerve injury.17 Is There Anything We Can Do To Prevent Table 1. A Form Template for Nerve Injury? Describing a Block Ultrasound-guided techniques have been shown to have many advantages, including shorter procedure An example of a block form might include the time, faster block onset, lower drug volume, fewer vas- following items: cular punctures and, most recently, a reduction in the Focused neurologic exam prior to block incidence of local anesthetic systemic toxicity (rela- tive risk reduction, 65%).4,18-20 Although many benefits Time-out (patient and block site identified and are associated with ultrasound-guided blocks, there is marked, informed consent verified) insufficient evidence to demonstrate a lower neurologic Patient level of awareness during block complication rate with this technique.21,22 For that mat- ter, there is no evidence to show fewer neurologic com- Aseptic skin prep, drape plications associated with neurostimulation techniques versus paresthesia-seeking techniques.23 Type of needle used, depth to target prior to injection, and if catheter, depth at skin Many publications call into question the sensitivity and specificity of nerve stimulation techniques, and Ultrasound and/or nerve stimulator, with minimum studies demonstrate that intraneural injections (defined
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