Local anesthetic resistance in a pregnant patient with lumbosacral plexopathy

Abstract

BackgroundWe report a case of a patient with apparent resistance to local anesthetics. While similar cases of failure of regional anesthetics are often attributed to technical failure, the overall clinical presentation and history of this patient suggests a true resistance to local anesthetics.Case PresentationThis patient presented for elective cesarean section and the decision for regional anesthesia was made. While attempting to place an epidural, the patient failed to achieve adequate skin analgesia despite multiple attempts at local infiltration. When a spinal was ultimately placed, sensory or motor blockade was not obtained despite no evidence of technical problems with technique. Further questioning revealed multiple prior episodes of local anesthetic failure in this patient.ConclusionsWhile the failure rate of spinal anesthesia has been shown range from 4–13% and is often attributed to technical failure, elements of this particular case suggest a true resistance to local anesthetics.

Complete failure of spinal anaesthesia in obstetrics

“…In one case the patient had reported numbness and weakness in her right thigh during both her pregnancies. 36 Before an elective caesarean section, infiltration of the skin with a total of 6 mL of 1% lidocaine produced no analgesia or anaesthesia and the planned combined spinalepidural was abandoned in favour of a single-shot spinal technique which was performed uneventfully; CSF was easily aspirated (to a volume of 2 mL) before injection of 1.2 mL of 0.75% bupivacaine, 50 lg fentanyl and 250 lg of preservative-free morphine. Apart from a sensation of warmth in the buttocks, there was no demonstrable sensory or motor block after 20 min and the procedure was abandoned in favour of general anaesthesia.…”

Large intrathecal volume: a cause of true failed spinal anesthesia

“…Physiologic resistance to an intrathecal local anesthetic as an explanation for failed spinal anesthesia has been included among the etiologies for a true failed spinal [2,4]; however, as "resistant" sodium channel conformations to local anesthetics have yet to be discovered in the Caucasian population, it should not be seriously considered in the etiology of failed spinal anesthesia. One case of true failed spinal anesthesia in 2004 describes failed spinal anesthesia in a parturient following an intrathecal bupivacaine injection.…”

“…One case of true failed spinal anesthesia in 2004 describes failed spinal anesthesia in a parturient following an intrathecal bupivacaine injection. Unfortunately, these authors assumed the failure to be due to physiologic resistance, and did not image her lumbosacral spine [15].…”

“…Reports of true failures of intrathecal analgesia have been largely associated with spinal catheter use rather than with single-injection spinals; the catheter-related failures are believed to be secondary to malposition of the catheter (caudad placement) with maldistribution of local anesthetic. Although there are different theories to explain true failures of spinal anesthesia, most failures are actually due to technical mishaps with failure to actually introduce the local anesthetic into the cerebrospinal fl uid (CSF) [2][3][4][5]. Anatomic malformations and enlarged thecal volumes, that lead to sacral restriction and spinal failure, are rarely observed or reported.…”

Development of Resistance to the Effect of Local Anesthetic Agents Administered Via Various Routes Due to Single or Multiple, Previous Scorpion Bites: A Proposed Hypothesis and Reporting a Yet Unrecognized Phenomenon

“…Resistance to the effect of local anesthetic agents is an uncommon but not an unknown phenomenon. The multifactorial etiology has been well documented [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In spite of many of these available case reports and series, the ambiguity persists and authenticity of this phenomenon is still not very well established.…”