Local anesthetic systemic toxicity induced by penile nerve block: A systematic review

Local anesthetics are widely used by non-anesthesiologists to provide analgesia. Penile nerve blocks are used for analgesia during urological surgery. Local anesthetic systemic toxicity (LAST), which is rare but likely fatal, is often caused by a penile nerve block. However, there has been no analysis of cases of LAST induced by a penile nerve block. This Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant systematic review aimed to analyze case reports involving LAST induced by a penile nerve block, with a particular focus on the presumed causes, local anesthetics, and lipid emulsion treatment. Relevant case reports included in PubMed from inception to December 31, 2024, were retrieved using the keywords "penile nerve block," "dorsal penile nerve block," "penile block," "local anesthetic toxicity," "local anesthetic systemic toxicity," and "local anesthetic overdose." Eleven case reports including 19 patients were obtained. The main presumed causes of penile nerve block-induced LAST were overdose (47.4%) and inadvertent intravascular absorption (47.4%) of local anesthetics. The main local anesthetics associated with overdose and inadvertent intravascular absorption were lidocaine (77.8%) and bupivacaine (88.9%), respectively. Of the patients, 89.5% had risk factors for LAST. Of the patients with LAST, 31.6% received lipid emulsion plus supportive treatment. The age distribution of patients with penile nerve block-induced LAST was as follows: <1 year (73.7%), ≥1 year to <19 years (15.8%), and ≥19 years (10.5%). A penile nerve block was used for circumcision in 84.2% of the cases. The most common symptoms of penile nerve block-induced LAST were cardiovascular symptoms (52.6%) and central nervous system symptoms (42.1%). The negative aspiration technique was used to prevent LAST in 47.4% of patients. All patients recovered from LAST. LAST in infants and neonates receiving a penile nerve block for circumcision is mainly caused by lidocaine overdose or inadvertent intravascular absorption of bupivacaine. The following measures should be considered to prevent LAST: adherence to the maximum recommended dose of local anesthetics; awareness of LAST risk factors; slow injection of the local anesthetic with minimal pressure and negative aspiration; and lipid emulsion preparation.