Horlocker, Terese T.

Neurologic complications associated with regional anesthesia and pain medicine practice are extremely rare. The ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine addresses the etiology, differential diagnosis, prevention, and treatment of these complications. This Advisory does not focus on hemorrhagic and infectious complications, because they have been addressed by other recent ASRA Practice Advisories. The current Practice Advisory offers recommendations to aid in the understanding and potential limitation of neurologic complications that may arise during the practice of regional anesthesia and pain medicine.

Background and Objectives Successful regional anesthesia involves a three-dimensional visualization of anatomy and an informed approach to needle placement and repositioning. This study trigonometrically examines the relationship between needle insertion angle and resultant needle position. Methods Needle position during advancement of 2-inch (5.1-cm), 3 ½-inch (8.9-cm), and 5-inch (12.7-cm) needles was trigonometrically determined. Starting at 90°, the angle of needle insertion θ (measured from the perpendicular) was decreased in 5° and 10° increments, and the resultant change in needle position was calculated by using a computer model. Needle depths relevant to the three needle lengths were studied and ranged from 0.5 to 11.0 cm. The effects of needle insertion angle, redirection angle, and depth on resultant needle position were evaluated. Results The mean change in needle position was significantly less with a 5° redirection of the needle than with a 10° needle redirection. In addition, the mean change in needle position was highly correlated with increasing needle depth and acute angle of needle insertion. Conclusions Incremental needle redirection of 5° allows a precise survey of neural and adjacent anatomy and results in approximately one half the change in needle position occurring with a 10° angle of redirection. However, a 10° angle of redirection may result in walking over the desired neural structure.