Dec 8, 2015, 14:40 PM by Joseph M. Neal, MD

Note: This article originally appeared in the ASRA News, Volume 15, Issue 4, pp. 27-28 (November, 2015).

Author

Joseph M. Neal, MD
Virginia Mason Medical Center
Seattle, WA

The “Second ASRA Practice Advisory on Neurologic Complications Associated With Regional Anesthesia” was published in the September–October 2015 issue of Regional Anesthesia and Pain Medicine as seven supporting articles,^[1–7] a related case report,^[8] and an executive summary.^[9] This initiative represents an international collaboration of more than two dozen regional anesthesiologists, pain medicine physicians, orthopedic surgeons, neuroanatomists, neurologists, and neuroanesthesiologists. The work is an update of the 2008 ASRA practice advisory on this topic^[10] and presents a compilation of reviewed and new material from the 2012 open forum plus additions through spring 2015. The practice advisory focuses on extremely rare complications; it does not address those “relatively common” neurologic complications related to anticoagulation, infection, and local anesthetic systemic toxicity, all of which are subjects of other ASRA practice advisories. Because data are extremely limited regarding these rare entities, the advisory panel relied primarily on case reports and series, pathophysiology, pharmacokinetics, and expert opinion as the evidence base for its recommendations. Readers are reminded that these recommendations are not intended to define standard of care, that adherence to them does not guarantee an optimal outcome, and that they are subject to modification as knowledge expands.

The focus of the second advisory panel is on new topics and/or previously addressed issues for which substantial new knowledge has evolved. For example, the current advisory contains a series of three articles,^[2,3,6] coauthored by anesthesiologists and orthopedic surgeons, that aim to detail surgery-related nerve injuries associated with common upper and lower extremity elective orthopedic procedures. This is the first time such multidisciplinary knowledge has been described to the anesthesiologist from the orthopedic surgeon’s point of view. Such knowledge should optimize collaborative evaluation and treatment of patients who sustain perioperative nerve injury. Pertinent to this theme, the panel revised algorithmic recommendations for initial evaluation of patients with these injuries, including appropriate imaging and/or neurophysiologic testing. New to the second practice advisory are suggestions for pharmacologic treatment and rehabilitation of those nerve-injured patients who develop neuropathic pain.^[7]

This rendition of the practice advisory delves deeper into the etiology and incidence of perioperative nerve injury, as facilitated by powerful sources of epidemiologic data from new international and/or institutional registries. These data provide valuable insights into causation, focus attention on previously difficult-to-interpret signals of associated injury, and point to varying incidences of the same complication within different patient subsets. The pathophysiology of peripheral nerve injury is reviewed with consideration given to the potential contributions of ultrasound guidance and injection pressure monitoring to injury prevention. The panel addressed evolving knowledge pertaining to needle-to-nerve proximity and recommends using ultrasonography to maintain a respectable distance from neural targets rather than to achieve intentional intraneural injection.^[1]

The appropriateness of performing regional techniques in patients with preexisting neurologic disease is the subject of conjecture, medicolegal fears, and traditional avoidance. Definitive data are as rare as the frequency of patients with these conditions who undergo anesthesia. Although the panel relied primarily on expert opinion and limited case reports or series, it greatly extended discussion of peripheral and neuraxial preexisting conditions and summarized existing literature even when definitive recommendations could not be made. These recommendations emphasize the importance of a deliberate risk-to-benefit analysis when considering the appropriateness of regional anesthesia in individual patients with preexisting neurologic disease. The advisory emphasizes the importance of recognizing postsurgical inflammatory neuropathies.^[4]

The practice advisory offers new, expanded, and potentially controversial recommendations concerning five neuraxial topics. First, medicolegal data since 2008 corroborate our previous recommendation not to routinely perform regional anesthesia in anesthetized or deeply sedated adults. Conversely, voluminous pediatric registry data support our previous opinion that performing regional anesthesia in anesthetized or deeply sedated children does not increase injury rates over what would be expected from historic, adult experience. Second, recommendations regarding transforaminal injections were updated and expanded on the basis of the recent US Food and Drug Administration’s Safe Use Initiative. These recommendations include the use of contrast media before final injection and nonparticulate steroids as first-line therapy for lumbar transforaminal approaches. Third, the advisory considered a collection of neurotoxicity-related conditions and presented a new recommendation to avoid splashed chlorhexidine prep solution (a possible etiologic factor for arachnoiditis), and data that suggest very low risk of transient neurologic symptoms from intrathecal 2-chloroprocaine. With regard to cauda equina syndrome (CES), the panel highlighted signals that associate this condition with previously undiagnosed spinal stenosis, while acknowledging that most CES cases occur after unremarkable neuraxial anesthesia.

The final two neuraxial-related recommendations involve spinal stenosis and blood pressure management. The association of spinal stenosis with neuraxial complications is established from registry signals that record moderate to severe spinal stenosis discovered during workup of spinal hematoma, abscess, or CSE. Additional data and case reports^[8] reveal a slightly increased risk of neurologic complications in patients with known spinal stenosis or spinal canal pathology who undergo spinal anesthesia. Whether these cases represent association or a cause-and-effect relationship is unknown; clearly, neuraxial regional anesthetic and pain medicine techniques are performed daily in patients with known spinal stenosis without frequent injury. Nevertheless, the panel recommends increased anesthesiologist awareness of this association, especially in patients with known spinal stenosis subjected to other than neutral surgical positions or in whom spinal cord perfusion pressure could be compromised. These same conditions, plus others that compromise oxygen carrying capacity, may be particularly worrisome with regard to blood pressure management during neuraxial anesthesia. Evolving evidence suggests that the lower limit of autoregulation of spinal cord blood flow may be higher (60–65 mm Hg) than the traditionally understood lower limit of 50 mm Hg. Isolated case reports of spinal cord ischemic injury and large series involving patients with cerebral stroke suggest that a small subset of humans do not tolerate prolonged periods of previously considered “low normal” blood pressure. The panel recommends that the mean arterial pressure of patients undergoing neuraxial anesthesia not be allowed to drop below 25–30% of baseline, and if it does so, that it not be permitted to persist at those levels.^[5]

ASRA members who desire more information are encouraged to peruse the supporting articles that form the basis of the “Second ASRA Practice Advisory on Neurologic Complications Associated With Regional Anesthesia." The executive summary provides an overall synopsis of the project’s proceedings.

References

1. Brull R, Hadzic A, Reina MA, Barrington MJ. Pathophysiology and etiology of nerve injury following peripheral nerve blockade. Reg Anesth Pain Med 2015;40:479–490. doi:10.1097/AAP.0000000000000125.
2. Dwyer T, Henry PDG, Cholvisudhi P, et al. Neurological complications associated with elective orthopedic surgery: part 1—common shoulder and elbow procedures. Reg Anesth Pain Med 2015;40:431–442. doi:10.1097/AAP.0000000000000178.
3. Dwyer T, Drexler M, Chan VWS, Whelan DB, Brull R. Neurological complications associated with elective orthopedic surgery: part 2—common hip and knee procedures. Reg Anesth Pain Med 2015;40:443–454. doi:10.1097/ AAP.000000000000018.
4. Kopp SL, Jacob AK, Hebl JR. Regional anesthesia in patients with pre-existing neurologic disease. Reg Anesth Pain Med 2015;40:467–478. doi:10.1097/AAP.0000000000000179.
5. Neal JM, Kopp SL, Lanier WL, Pasternak JJ, Rathmell JP. Anatomy and pathophysiology of spinal cord injury associated with regional anesthesia and pain medicine: 2014 update. Reg Anesth Pain Med 2015;40:506–525.
   doi:10.1097/AAP.0000000000000297.
6. Veljkovic A, Dwyer T, Lau J, et al. Neurological complications associated with elective orthopedic surgery: part 3—common foot and ankle procedures. Reg Anesth Pain Med 2015;40:506–525. doi:10.1097/AAP.0000000000000297.
7. Watson JC, Huntoon MA. Neurologic evaluation and management of perioperative nerve injury. Reg Anesth Pain Med 2015;40:491–501. doi:10.1097/AAP.0000000000000185.
8. Kopp SL, Peters SM, Rose PS, Hebl JR, Horlocker TT. Worsening of neurologic symptoms after spinal anesthesia in two patients with spinal stenosis. Reg Anesth Pain Med 2015;40:502–505. doi:10.1097/AAP.0000000000000203.
9. Neal JM, Barrington MJ, Brull R, et al. The Second ASRA Practice Advisory on Neurologic Complications Associated With Regional Anesthesia and Pain Medicine: Executive Summary, 2015. Reg Anesth Pain Med 2015;40:401–430. doi:10.1097/AAP.0000000000000286.
10. Neal JM, Bernards CM, Hadzic A, et al. ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine. Reg Anesth Pain Med 2008;33:404–422.

 

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This advisory was published December 8, 2015, and is currently under review.