Regional anesthesia for carotid endarterectomy is an often-used technique as it avoids cardiorespiratory complications associated with general anesthesia. In addition, an awake patient can provide reliable monitoring of neurological function during cross-clamping of the carotid artery such as speech and participation in motor power as a measure of adequate cerebral perfusion during the procedure [1-8]. Cervical plexus block is relatively easy to perform and provides adequate anesthesia for the surgical procedure in the distribution of C2 to C4, such as required for carotid endarterectomies. Superficial and intermediate cervical plexus block have been successfully used for carotid endarterectomies and are usually not associated with complications and are considered very safe [9,10]. In a review article, Anderson et al. reported that there were no complications arising from superficial cervical plexus block in 2533 patients [9]. It was therefore a surprise when we encountered a patient undergoing carotid endarterectomy and developed hoarseness of voice after ultrasound guided superficial and intermediate cervical plexus block as outlined in this rare case report.

An 85 years old male patient with 75% right internal carotid stenosis was posted for carotid endarterectomy under regional anesthesia. Patient had history of ischemic heart disease, diabetes mellitus, hypertension and dyslipidemia on medications. He was booked for right carotid endarterectomy under superficial and intermediate cervical plexus block. The patient had undergone percutaneous coronary intervention 10 years back, under local anesthesia and sedation. Currently, the patient was on clopidogrel and aspirin that were stopped 3-5 days back. Patient had stable hemodynamic parameters and all his investigations were within acceptable limits.

After informing the patient about the procedure and possible risks, a high-risk consent was obtained. Patient was kept on sliding scale of insulin infusion and nil orally for 6 hours. High dependency and intensive care units were informed about the possibility of shifting the patient, if required. Once inside the radiology suit, standard monitoring was instituted and an 18 G cannula was placed in the right forearm vein and a left radial artery cannula in the left side.

An ultrasound guided right superficial (intermediate) cervical block was done under aseptic technique using insulated needle 50 mm. A total 10 mL of 0.375% of levobupivacaine was used for the procedure after having infiltrated the skin with 5 mL of 2% lidocaine. No immediate complications were noted. On testing the incision site, patient denied any pain. Thereafter, sedation was started with midazolam 2 mg, fentanyl boluses doses 25 mcg up to 100 mcg and propofol 20 mg boluses. Surgery commenced 20 minutes after completion of the block. When surgeon was about to clamp the artery, no sedation was given and communication was started with the patient. It was now noticed that patient had hoarseness of voice which was not there preoperatively. Surgeon was notified and he checked that the vagus nerve was neither trapped nor injured. Patient remained responsive and cooperative throughout the procedure. No carotid shunt was needed.

The operation proceeded uneventfully and was completed within one hour and thirty minutes. Patient was reassured that his voice would return gradually and shifted to post anesthesia care unit fully awake, pain free and with stable vitals.

After 30 min stay in the post anesthesia care unit, patient was shifted to the high dependency ward with no improvement in his voice. However, when the patient was seen in the ward three hours later, he was noted to be pain free and his voice had returned to normal five hours after the block. The patient was discharged from the hospital uneventfully two days later.

The present case highlights that performing even superficial and intermediate cervical plexus blocks are not immune to complications like hoarseness of voice secondary to recurrent laryngeal nerve block. Harris and Benveniste in 2000 reported 2 cases of recurrent laryngeal nerve block in patients undergoing carotid endarterectomy, but these patients had received combination of deep and superficial cervical plexus block [10]. Deep plexus block can anesthetize recurrent laryngeal nerve by diffusion of local anesthetic into the tracheoesophageal groove but is unlikely with superficial and intermediate plexus block.

The probable cause of transient recurrent laryngeal nerve palsy resulting in transient hoarseness of voice in this case may have been caused by anyone of the following factors: First, anatomical variation in the recurrent laryngeal nerve such as extra-laryngeal branches, distorted recurrent laryngeal nerve, or intertwining between branches of the recurrent laryngeal nerve as suggested by Chiang et al. 2010 [11]. Second, the fascia separating the superficial from deep cervical plexus is really thin and there is a possibility of the needle inadvertently penetrating the thin fascia while giving the block that may result in blocking deep cervical plexus and recurrent laryngeal nerve [12]. Third, injury to the vagus or recurrent laryngeal nerve may occur due to physical trauma during carotid endarterectomy that has an incidence of between 1.2 to 35% [13-15]. However, this is unlikely to be the cause of hoarseness of voice in this case as it was transient and recovery was complete. Lastly, local anesthetic seeping across any deficiency in fascia that separates the superficial from deep cervical plexus and blocking recurrent laryngeal nerve or its branches is a possibility.

Superficial/Intermediate cervical plexus block provides satisfactory analgesia for carotid endarterectomy surgery but one should keep in mind that it is not immune from complication, albeit minor.

1. J.J. Pandit et al. "Superficial or deep cervical plexus block for carotid endarterectomy: A systematic review of complications." British Journal of Anaesthesia, vol. 99, no. 2, 2007, pp. 159–169.

2. G. Agrifoglio et al. "The role of regional nerve block anesthesia for carotid endarterectomy: an experimental comparison with previous series with the use of general anesthesia and barbiturates for cerebral protection." International Angiology, vol. 6, 1987, pp. 365–370.

3. G. Agrifoglio et al. "Prediction of cerebral ischaemia using loco-regional anaesthesia." European Journal of Vascular Surgery, vol. 7, suppl. A, 1993, pp. 13–15.

4. B.T. Allen et al. "The influence of anesthetic technique on perioperative complications after carotid endarterectomy." Journal of Vascular Surgery, vol. 19, 1994, pp. 834–842.

5. D.G. Altman et al. "Units of analysis." British Medical Journal, vol. 314, 1997, p. 1874.

6. D.G. Altman et al. Practical Statistics for Medical Research. London: Chapman and Hall, 1990.

7. D.G. Altman et al. "The odds ratio." British Medical Journal, vol. 320, 2000, p. 1468.

8. Anderson, C.A. et al. "Carotid endarterectomy: regional versus general anesthesia." American Surgeon, vol. 46, 1980, pp. 323–327.

9. J.J. Pandit et al. "Efficacy and safety of the superficial cervical plexus block for carotid endarterectomy." British Journal of Anaesthesia, vol. 83, 1993, pp. 970–971.

10. R.J.D. Harris et al. "Recurrent laryngeal nerve blockade in patients undergoing carotid endarterectomy under cervical plexus block." Anaesthesia and Intensive Care, vol. 28, 2000, pp. 431–433.

11. F.Y. Chiang et al. "Anatomical variations of recurrent laryngeal nerve during thyroid surgery: How to identify and handle the variations with intraoperative neuromonitoring." Kaohsiung Journal of Medical Sciences, vol. 26, no. 11, 2010, pp. 575–583.

12. A. Weiss et al. "Acute respiratory failure after deep cervical plexus block for carotid endarterectomy as a result of bilateral recurrent laryngeal nerve paralysis." Acta Anaesthesiologica Scandinavica, vol. 49, no. 5, 2005, pp. 715–719.

13. F.W. Knight et al. "Cranial nerve injuries during carotid endarterectomy." American Journal of Surgery, vol. 154, 1987, pp. 529–532.

14. K. Weiss et al. "Cranial and cervical nerve injuries: local complications of carotid artery surgery." Journal of Cardiovascular Surgery, vol. 28, 1987, pp. 171–175.

15. M.D. Schauber et al. "Cranial/Cervical nerve dysfunction after carotid endarterectomy." Journal of Vascular Surgery, vol. 25, 1997, pp. 481–487.