Reporte de Caso

Vocal Cords Paralysis Following Infiltration of the Surgical Wound in Thyroid Surgery

Yesid Diaz Ante*, Juan Manuel Gómez**, Mauricio Barbano Hurtado***, Susana Borrero Gutiérrez****

* Médico anestesiólogo, Universidad del Valle, Cali, Colombia.
** Médico. Profesor Titular Departamento de Anestesiología, Universidad del Valle; Anestesiólogo, Centro Médico Imbanaco; Anestesiólogo Clínica Sebastián de Belalcazar. Cali, Colombia, juanmanuel.gomez@imbanaco.com.co.
*** Profesor Departamento de Anestesiología, Universidad del Valle. Cali, Colombia.
**** Médica. Anestesióloga, Centro Médico Imbanaco, Cali, Colombia.

Recibido: agosto 2 de 2010. Enviado para modificaciones: agosto 9 de 2010. Aceptado: agosto 18 de 2010.

SUMMARY

Objective. Two cases of temporary paralysis of the vocal cords are discussed, in which recurrent injury of the laryngeal nerves, edema of the glottis and other common causes were ruled out.

Methodology. Case report

Results. Infiltration of the surgical wound with local anesthetic at the end of the surgical procedure was considered a possible cause. No similar reports were found in the main databases. The decision was made to publish these cases in order to consider another possible cause of vocal cords paralysis following thyroidectomy.

INTRODUCTION

Thyroidectomy is the most frequent endocrine surgical procedure. Surgical treatment of the thyroid gland has evolved significantly in the last few years. The new technologies, improved technique and follow-up of the recurrent laryngeal nerves have all reduced the number of complications (1).

The injuries to the recurrent laryngeal nerve are easily diagnosed following surgery by direct observation of the vocal cords paralyzed at the time of extubation. Different injuries to the external branch of the upper laryngeal nerve can only be observed when the patient vocalizes very high pitch sounds. Up to 87 % of the patients may exhibit voice disorders as measured by acoustic tests, even in the absence of recurrent laryngeal nerve injury (2).

Two branches of the vagus nerve innervate the larynx: the upper laryngeal nerve and the recurrent laryngeal nerve. The upper laryngeal nerve is both motor and sensorial; it divides over the hyoid bone into the internal and external rami. The internal ramus provides sensory innervation to the supraglottis, emits a communicating ramus with the recurrent laryngeal nerve. The external ramus innervates just one intrinsic muscle of the larynx: the cricothyroid that is tensor and adductor of the vocal folds (3).

The recurrent laryngeal nerve innervates all of the intrinsic muscles of the larynx, except for the cricothyroid. It innervates -inter alia- the posterior cricoaritenoid muscle that is very important because it is the only muscle that separates the vocal folds to facilitate breathing. If there is a unilateral injury of the recurrent laryngeal nerve, breathing can still be maintained; however, if the lesion is bilateral, it becomes a life-threatening condition. (4) The incidence of the unilateral lesion of the recurrent laryngeal nerve is 3 to 4 %; the bilateral incidence is less than 1 % (5).

Total Intravenous Anesthesia (TIVA) provides for rapid awakening and monitoring of the recurrent laryngeal nerves, both of which are key in thyroid surgery (5).

It is possible to block the recurrent laryngeal nerve with lidocaine and this approach is used as a surgical option in patients with adductor spasmodic dysphonia, which is a neurogenic condition characterized by continuous hyperadduction of the vocal cords. The surgical treatment is based on sectioning of the recurrent laryngeal nerve. This block of the recurrent laryngeal nerve shall be done prior to surgery to determine any improvements of the patient's voice. The block is done with 2.5 to 5 ml of 1 % lidocaine injected with a needle 27 into the tracheoesophageal sulcus, just under the cricothyroid junction. This is the entry site of the recurrent laryngeal nerve (6).

Two cases with vocal cords paralysis are discussed, in which injury of the recurrent laryn-geal nerve was ruled out. In both patients the surgical wound was infiltrated with local anesthetic and the vocal cords paralysis resolved spontaneously.

Deep infiltration and dissemination of the local anesthetic are considered the possible cause of the vocal cords paralysis in these patients.

CASE DISCUSSION

CASE 1

49-years old female patient admitted for ambulatory thyroidectomy due to a papillary thyroid ca diagnosed with aspiration fine needle biopsy. The only important underlying event was hypothyroidism treated with 50 mcg of sodium levothyroxine per day. The patient had a normal recent TSH, good functionality, normal paraclinical tests and easy intubation predictor.

The induction was done with 100 mcg of fentanyl, 40 mg of lidocaine, 80 mg of Propofol and Remifentanyl dripping at 0.15 mcg/kg/ min, Vecuronium 4 mg. The intubation was uneventful with a 7-gauge orotracheal tube. The anesthesia was maintained with 1 MAC isofluorane associated to remifentanyl dripping. There were no complications during the intraoperative period; the surgical time was 1 hr and 15 min. The patient was then antagonized using 2 mg of prostigmine and 1 mg of atropine. When the patient was awakening, the surgeon infiltrated the surgical wound with 10 cc of 2 % lidocaine in the back of the skin suture.

The patient was extubated awake and relaxed and she said she didn't have any pain or dysphonia. She is then transferred to the post-analgesia care unit but after a few minutes she complained of difficult breathing; the patient's desaturation dropped to 43 %, stridor made her extremely uncomfortable and required positive pressure ventilation with face-mask to recover 100 % saturation. Without ventilatory support the patient is unable to maintain saturation over 90 %, which led to the decision of assessing the vocal folds with the administration of sevorane with facemask. The vocal folds were adducted, free of edema or apparent trauma. The neck didn't show any signs of hematoma or surgical wound disruptions.

The decision was made to intubate and transfer the patient to the ICU. ENT evaluation was required and the ENT specialists determined that there was no recurrent laryngeal nerve injury. A programmed extubation was scheduled 3 days later, upon steroid management. The extuba-tion was successful and the patient is free of any voice sequel.

CASE 2

44-years old female patient admitted to the ambulatory surgery unit for total thyroidectomy and lymphadenectomy. She presented a hardened left thyroid node, which led to the decision to do a total thyroidectomy preceded by a frozen section biopsy that resulted in papillary carcinoma. The patient has good functionality and doesn't exhibit other important pathologies.

The induction was done with an infusion of Propofol remifentanyl, midazolam 3 mg, lidocaine 80 mg, 30 mg of rocuronium, intubation with apnea free of complications. Later, 8 mg of dexametasone, 4 mg of ondansetron and 60 mg of ketorolac were administered.

At the end of the surgical procedure, the surgeon infiltrated the surgical wound with 0.375 % levobupivacaina. The extubation was done free of complications after 1 hour and 40 minutes of surgery. 5 after the patient was admitted to the postanesthesia care unit, the patient experienced breathing difficulties and laryngeal stridor. Laparoscopy showed adduction of the vocal folds and the patient was taken back to the OR for tracheostomy due to suspect injury of the recurrent laryngeal nerve. The procedure was performed free of complications. After 4 hours a nasolaryngoscopy showed normal mobility of the vocal folds, the tracheostomy tube was occluded for three hours with no signs of dyspnea and was then removed. The patient had mild subcutaneous emphysema in the neck with no hematoma and there was no evidence of dysphonia. The patient was discharged the next day.

DISCUSSION

Post-thyroidectomy respiratory obstruction may be due to laryngeal edema. The larynx, the uvula and the vocal folds tend to develop edema quite easily and hinder the airflow. The most frequent causes of this complication are a difficult intubation, inadequate manipulation of the trachea and tracheomalacia. (7) Both patients underwent laryngoscopy, which ruled out any edema of the vocal folds. Therefore this was not the cause of the respiratory complications.

Other less frequent causes of respiratory obstruction are hematomas and bilateral paralysis of the vocal folds due to recurrent laryngeal nerve injury, (4,7) but none of these were present in these two patients; there was no hematoma of the neck and they spoke some time immediately after extubation. Furthermore, their complication -upper airway obstruction- resolved spontaneously and this is not compatible with a permanent bilateral injury of the recurrent laryngeal nerve.

Recurrent laryngeal nerve injury is the most feared complication, both for the surgeon and for the patient. It causes respiratory obstruction due to vocal folds paralysis preceded by stridor. This complication may be transient -resolves in 6 to 8 weeks- or permanent.

In 1938 Lahey published an article about the routine dissection of the recurrent laryngeal nerve in thyroid surgery, with a lower statistically significant rate of recurrent laryngeal nerve palsy in the group that identified the nerve (7). It has been found that the branching of the recurrent laryngeal nerve is a key risk factor for transient paralysis of the vocal folds following thyroidectomy (8). The patients' surgeons said that they identified the recurrent laryngeal nerve and that there was no injury.

A useful therapy for the permanent unilateral injury of the vocal folds is injection laryngoplasty by administering a percutaneous injection in the vocal muscle with a 25G needle passing through the cricothyroid membrane under local anesthesia or directly through the thyroid cartilage, under observation with a trans-nasal flexible fiberscope (9).

The upper laryngeal nerve injury is rarely considered. The inner branch injury may cause aspiration difficulties and the outer branch injury may cause laxity of the vocal folds, which may affect singers and professors. The lesion manifests itself with voice changes, vocal fatigue and inability to produce high pitch notes (7).

Matthias Echternach in his article "Laryngeal Complications After Thyroidectomy - Is It Always the Surgeon?" tried to differentiate whether the cause of the laryngeal dysfunction post-thyroidectomy was a recurrent laryngeal nerve injury or intubation-inflicted vocal fold injury. He studied 761 patients with pre- and post-operatory laryngealestroboscopic examination and the rate of postoperative complications found was of 42 %. Complications due to vocal folds injury occurred in 31.3% of the patients. These data suggested that laryngeal complications following thyroidectomy are mainly due to vocal folds injury, probably as a result of intubation and, to a lesser extent, to injury of the recurrent laryngeal nerve (10).

The complications referred to by the author are hematomas, granulomas, thickening of the mucosa, edema, subluxacion of the aritenoid cartilage and recurrent nerve palsy. None of these complications developed in the patients discussed.

Upon ruling out other causes for post-thyroidectomy respiratory obstruction, consideration should be given to the possible effect of the local anesthetic agent on the recurrent laryngeal nerve when doing a deep infiltration of the surgical wound in thyroid surgery.

REFERENCES

1. Lincoln Santos Souza, Agrício Nubiato Crespo, Jovany Luís Alves de Medeiros. Laryngeal vocal and endoscopic alterations after thyroidectomy under local anesthesia and hypnosedation. Braz. J. Otorhinolaryngol. (Impr.) vol.75 no.4 São Paulo July/ Aug. 2009

2. Sinagra DL, Montesinos M, Tacchi VA, Moreno JC, Falco JE, Mezzadri NA e cols. Voice Changes after thyroidectomy without recurrent laryngeal nerve injury. Journal of the American College of Surgeons. 2004; 199:556-60.

3. Delgado García A. Anatomía humana funcional y Clínica. Editorial univalle, 1996; p 378-379.

4. Claudio R. Cernea, Lenine G. Brandado, Fla'vio C. Hojaij. How to minimize complications in thyroid surgery? Auris Nasus Larynx 37 (2010) 1-5.

5. Alessandro Bacuzzi, Gianlorenzo Dionigi, Andrea Del Bosco, Giovanni Cantone, Tommaso Sansone, Erika Di Losa, Salvatore Cuffari. Anaesthesia for thyroid surgery: Perioperative management. International Journal of Surgery 6 (2008) S82-S85

6. Marshall E. Smith, MD; Nelson Roy, PhD; Cathy Wilson, MS. Lidocaine Block of the Recurrent Laryngeal Nerve in Adductor Spasmodic Dysphonia: A Multidimensional Assessment. Laryngoscope 116: April 2006.

7. S. Sancho Fornos, J. Vaqué Urbaneja, J.L. Ponce Marco, R. Palasí Giménez y C. Herrera Vela. Complicaciones de la cirugía tiroidea. Cirugía española. Vol. 69, Marzo 2001, Número 3 (198-203).

8. J. J. Sancho, M. Pascual-Damieta, J. A. Pereira, M. J. Carrera, J. Fontan'e, A. Sitges-Serra. Risk factors for transient vocal cord palsy after thyroidectomy. British Journal of Surgery 2008; 95: 961-967

9. Seung Won Lee, Jae Wook Kim, Chan Hee Chung, Ji Oh Mok, Sung Shine Shim, Yoon Woo Koh, and Eun Chang Choi. Utility of Injection Laryngoplasty in the Management of Post-Thyroidectomy Vocal Cord Paralysis. Thyroid Surgery. Volume 20, Number 5, 2010

10. Matthias Echternach, Christoph Maurer, Thomas Mencke, Martin Schilling, Thomas Verse, Bernhard Richter. Laryngeal Complications After Thyroidectomy Is It Always the Surgeon? Arch surg/vol 144 (no. 2), Feb 2009.

Conflicto de intereses: ninguno declarado