Paresthesiae or No Paresthesiae? Nerve Lesions after Axillary Blocks

Abstract

Seeking paresthesiae when performing a peripheral nerve block may increase the risk of post-anesthetic neurological sequelae. To test this hypothesis, we prospectively followed two groups of patients who underwent hand surgery with an axillary block. In one group, the axillary plexus was located by actively seeking paresthesiae; in the other, pulsations of the axillary artery indicated an adequate position of the injection needle. Mepivacaine 10 mg/ml, with or without adrenaline, was used. The study included 533 patients, 290 in the paresthesia group and 243 in the artery group. Although unintentional, paresthesiae were elicited in 40% of patients in the artery group. Postanesthetic nerve lesions were seen in ten patients, eight in the paresthesia group and two in the artery group, all of whom had been blocked by mepivacaine with adrenaline. Symptoms varied between light paresthesiae lasting a few weeks, and severe paresthesiae, ache and paresis lasting more than 1 year. The etiology suspected was needle and perhaps injection trauma to the nerves during blocking. We conclude that whenever possible nerve blocks should be performed without searching for paresthesiae.

ASRA Practice Advisory on Neurologic Complications in Regional Anesthesia and Pain Medicine

“…However, several studies have linked selective nerve "rescue blocks" to peripheral nerve injury. 55,56 There is no localization or monitoring device, or approach to the neuraxis, that ensures protection from nerve injury. Some studies have compared paresthesia with peripheral nerve stimulation as indicators of needle-to-nerve contact, 31,32 while another has compared paresthesia or peripheral nerve stimulation with ultrasound-guided nerve localization.…”

Compared with dual nerve stimulation, ultrasound guidance shortens the time for infraclavicular block performance

“…15,16 Therefore, it is not surprising that nearly half of the patients in our stimulation group complained of paresthesiae during block performance compared with only three patients in our ultrasound group. In a similar trial by Sauter et al, it is surprising and rather difficult to explain that 20% of patients in the ultrasound group experienced paresthesiae during block performance compared with only 2.5% of the stimulation group.…”

Bupivacaine crystal deposits after long-term epidural infusion

“…At this point interventional pain therapy, such as epidural analgesia can be introduced with much greater efficacy [12]. Tissue toxicity to LA has been documented in animal studies particularly at higher concentrations [2,3,4,6,7,8,11,13,14,15,16,17,18,19,20,25,29,31,32,33,34,37,38] but seldom observed using the recommended clinical concentrations in humans [1,15,22,23,24,26,28,31].…”

“…It is concluded that the bupivacaine crystalline deposits arose due to precipitation but the clinical significance with regard to sensory level and neuraxial tissue toxicity is unknown. [31] apart from a few case reports [1,15,22,23,24,26,28]. To explain the mechanism of tissue toxicity various pathophysiological pathways of LA or LA mixtures in different human and animal tissues, such as skin, soft tissue, muscle and neurological tissue are discussed but the pathogenesis has not been elucidated in detail [1,13,19,20,29,32,33,34,35,36,37,38].…”