Clinical Features

 

 

Case Report 1: Verification of Bilateral Recurrent Laryngeal Nerve Damage and Immediate Tracheal Reintubation

 

A 80-year-old female patient (height 150 cm and weight 69 kg, respectively) presented for elective bilateral thyroid surgery had a medically well-contolled chronic obstructive pulmonary disease and revealed a normal upper airway anatomy at preoperative anesthetic assessment several days prior to admission. The indication for thyroid surgery was a rapidly enlarging, multinodular thyroid gland, particularly at the right side; twenty-four years ago, a left-sided (presumably a subtotal) thyroid lobectomy was performed. Radiographic images documented deviation of the trachea to the left and tracheal compression with narrowing of the transverse lumen by approximately 30 percent) by a right-sided thyroid mass with substernal and retrotracheal expansion. Preoperative indirect laryngoscopy and direct video stroboscopy using a flexible endoscope (performed by a laryngologist) revealed normal vocal cord function. She consented to participate in a study evaluating the Lo Pro Adult GlideScope Video Laryngoscope (LGVL) for orotracheal intubation [see (5)].

 

After induction of general anesthesia (GA) with propofol supplemented by fentanyl and complete rocuronium-induced neuromuscular blockade (monitored by the S/5 Neuromuscular Transmission Module and Mechanosensor, Datex Ohmeda, Instrumentation Corporation, Helsinki, Finland; train-of-four mode with electodes placed over the ulnar nerve), direct laryngoscopy (DL) using a standard Macintosh laryngoscope with gentle lifting force and without external laryngeal manipulation provided visualization of the entire laryngeal aperture. Subsequent LGVL-assisted laryngoscopy provided the same laryngeal view (displayed on a liquid cristal display monitor as color image) and tracheal intubation with a standard tracheal tube (TT) was easy and atraumatic to perform.

 

When performing left-sided residual thyroid lobectomy and right-sided near-total thyroid lobectomy by a surgeon with experience in endocrine surgery, the recurrent laryngeal nerves (RLNs) were identified and exposed under visual control, and protected, although with difficulties, during dissection of the thyroid glands from the trachea in order to minimize accidental nerve damage [a standard procedure also for surgery of benign thyroid diseases at our institution (2)]. Because both RLNs, particularly the RLN on the right side, were at high risk of damage [for more information, see (8)] and neuromonitoring [for intraoperative identification of the RLN and prediction of postoperative vocal cord function (3)] was not used at least prior to ending the surgical procedure, we decided to perform tracheal extubation under videolaryngoscopic view without topical anesthesia.

 

After spontaneous recovery of the neuromuscular blockade, tracheal extubation was performed in the fully awakened and responsive patient with the LGVL partially introduced in the midline into the oral cavity (only depressing the tongue, not advancing the tip of the blade until reaching the vallecula, usually performed for laryngoscopy and tracheal intubation under GA). Despite partial oral introduction of the LGVL, a full view of the laryngeal aperture was obtained (associated with minimal patient discomfort); after confirmation that there was no laryngeal edema formation, the TT was removed. The vocal cords were in close approximation, limiting the glottic opening to less than 2 mm, with no lateral movement (abduction) during inspiration. These video laryngoscopic findings were characteristic for bilateral RLN damage. The video output port of the liquid crystal display monitor was readily connected via an electronic interface (ReceiverSystem TerraTec Synergy 250 USB, TerraTec Electronic, Nettetal, Germany) to a laptop computer. The video images from the LGVL were recorded as video clip using a commercially available software (Pinnacle Studio, Version 8.4, Pinnacle Systems, Braunschweig, Germany); the video record was later viewed by a laryngologist who confirmed the diagnosis of bilateral RLN damage. The patient soon developed severe inspiratory stridor and her trachea was immediately reintubated using the LGVL (again with ease and in an atraumatic fashion). The patient was transfered to the intensive care unit where she received sedation and supported ventilation for four days.

 

We decided to perform the second tracheal extubation attempt in the operating room (with the technique first applied) and provided for the presence of a laryngologist. The trachea was again extubated under videolaryngoscopic view and the procedure was recorded as video clip. Vocal cord function had not improved; a tracheotomy for further treatment was evident and the trachea was reintubated using the LGVL. GA was then induced with propofol and maintained with sevoflurane and fentanyl without muscle relaxation. Before surgical tracheotomy, neuromonitoring of the RLNs (using the Neurosign 100, Indomed, Teningen, Germany) was performed by transligamental placement of the recording electrode into the vocal muscles; the neutral electrode was placed in the sternocleidoimastoid muscle. The left and right RLN could be stimulated by the stimulating probe using high current amplitudes of 1.0 and 1.5 mA, respectively, indicating RLN integrity and the potential of recovery of nerve function (3). A cuffed tracheostomy tube (with spiral-wound wire) was passed through the sutured tracheostomy. After full recovery at the postanesthesia care unit, the patient was transferred to the normal ward.

 

The patient was discharged from the hospital two weeks later and tranferred (with a standard uncuffed tracheostomy tube in place) to a specialized geriatric unit. Informed patient consent was obtained for anonymous use of patient data for publication of this case report. This section will be updated when the surgical update occurs.

 

 

Case Report 2: Verification of Normal Vocal Cord Function at the Operative Site (Preoperative Complete Vocal Cord Palsy at the Non-Operative Site)

 

A 30-year-old female patient (height 166 cm and weight 61 kg, respectively) with medically well-controlled hyperthyroidism presented for elective thyroid surgery revealed a normal upper airway anatomy at preoperative anesthetic assessment several days prior to admission. The indication for thyroid surgery was an enlarged left-sided thyroid gland (suspected immunethyreopathy of type Basedow disease); five years earlier, a right-sided subtotal thyroid lobectomy had been performed at another institution. This was complicated by a right RLN injury. Radiographic images documented deviation of the trachea to the right and tracheal compression with narrowing of the transverse lumen by approximately 20 percent) by a left-sided thyroid mass with substernal expansion. Preoperative indirect laryngoscopy and direct video stroboscopy using a flexible endoscope (performed by a laryngologist) revealed incomplete right-sided vocal cord palsy.

 

The anesthetic technique applied (including easy DL and LGVL-assisted larygoscopy and atraumatic tracheal intubation) was the same as decribed in the first case report. When performing left-sided near-total thyroid lobectomy, the RLN was identified and exposed under visual control and additional neuromonitoring, and protected during dissection of the thyroid gland from the trachea; the RLN on the right side was also identified, although with difficulties. Prior to ending the surgical procedure, the left and right RLNs could be stimulated by current amplitudes of 0.5 and 1.0 mA, respectively. Tracheal extubation under videolaryngoscopic view revealed preserved normal vocal cord function at the operative site and unchanged contralateral incomplete vocal cord palsy. The postoperative course of the patient was uneventful; routine examinations by our laryngological service on the fourth and fourteenth postoperative day certified normal left-sided vocal cord function. Informed patient consent was obtained for anonymous use of patient data for publication of this case report.

 

 

Discussion