Laryngocardiac Reflex: A Case Report and Review of the Literature

Hemodynamic Changes Associated With Transcervical Laryngeal Injection of Botulinum Toxin

PURPOSE

Laryngeal dystonia is a chronic neurologic disorder characterized by intention-induced spasms of the vocal folds driven by aberrant central motor processing. The use of in-office transcervical botulinum toxin injection for the treatment of laryngeal disorders, such as laryngeal dystonia, has been deemed safe and efficacious. There is, however, no available data outlining the hemodynamic changes experienced by patients undergoing this frequently performed procedure.

METHODS

One hundred and one patients diagnosed with laryngeal dystonia were enrolled in this prospective study. These patients underwent transcervical laryngeal botulinum toxin injection to address their dysphonia. Vital signs where acquired prior to, and at the time of injection. Alterations in these parameters were then evaluated for statistical significance.

RESULTS

Statistically significant increases in mean heart rate (5.8 ± 10.8 bpm, P < 0.0001), systolic blood pressure and diastolic blood pressure (7.0 ± 9.5 mm Hg, P < 0.0001; 8.7 ± 14.7 mm Hg, P < 0.0001) were discovered. No statistically significant difference in oxygen saturation was noted and no patients in the study faced major adverse outcomes.

CONCLUSIONS

Though these findings may not have related to clinically significant complication, our study demonstrates the importance of understanding potential stressors in a procedure routinely performed by laryngologists. This may result in more careful patient selection, alterations in procedure, and improved safety by acting in a timely fashion if alarming changes in hemodynamic parameters are noted.

Sinus pause during nerve integrity monitoring tube insertion following anesthetic induction with a low-dose neuromuscular blocking agent: A CARE-compliant case report

RATIONALE

Nerve integrity monitoring (NIM) tubes are commonly used in thyroid surgery to prevent recurrent laryngeal nerve injury. To achieve the optimal electromyographic signal for NIM as intraoperative neural monitoring (IONM), the neuromuscular blocking agent (NMBA) dose should be low. The use of a low-dose NMBA increases the anesthetic and analgesic agent dose required to attenuate the laryngeal reflex during intubation. In addition, since the NMBA onset time is delayed, depending on the situation, anesthesia may become excessively deep or shallow before intubation.

PATIENTS CONCERN

A 51-year-old woman scheduled for thyroid lobectomy received 0.3 mg/kg of rocuronium. Three minutes later, when the NIM tube was inserted through the vocal cord, the patient's heart rate (HR) was undetectable for 2 seconds.

DIAGNOSIS

We suspected that the use of a high-dose anesthetic agent and remifentanil or the laryngocardiac reflex induced the sinus pause.

INTERVENTIONS

To maintain the anesthetic depth, we administered 6 vol% of desflurane. Because the patient's systolic blood pressure was 70 mmHg and HR was 30 beats/min, we discontinued the remifentanil infusion and administered 8 mg of ephedrine.

OUTCOMES

The patient's vital signs recovered to normal levels. Subsequently, there were no episodes of bradycardia or arrhythmia.

CONCLUSION

Sinus pause or severe bradycardia may occur due to the laryngocardiac reflex or the administration of a high-dose anesthetic and analgesic agent during tracheal intubation in patients who received a low-dose NMBA for IONM induction using an NIM tube. Anesthesiologists should be aware of these risks and take precautions to maintain adequate anesthesia, be prepared to administer vasoactive drugs to increase the blood pressure and HR if needed, and, if possible, intravenously administer lidocaine to attenuate the laryngeal reflex during intubation.