Transoral‐transpharyngeal CO2 laser en bloc excision of voluminous left recurrent laryngeal nerve ... .

Otorhinolaryngology

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1 INTRODUCTION

Schwannomas are benign tumors arising from Schwann cells of cranial, peripheral, and autonomic nerves. The 25%‐45% of all schwannomas occur in the head and neck region, but the laryngeal localization is rare.1-3 They usually arise from branches of the superior laryngeal nerve, developing in the supraglottic region.4, 5 Recurrent laryngeal nerve schwannomas are even more uncommon with only eight cases reported in the English literature.6-13

Recurrent laryngeal schwannomas usually present as insidious, slow‐growing, submucosal masses located in the posterior paraglottic space, clinically associated with dysphagia, dysphonia, dyspnea, or stridor. Preoperative diagnosis is possible on the basis of clinical findings and imaging.

Radical surgical excision with minimal injury to uninvolved surrounding areas is considered the treatment of choice, but there are currently no guidelines. The external approach is the most widely described technique for large lesions, while the endoscopic management, with or without laser, is generally proposed for smaller tumors confined in the glottic or supraglottic region.4, 5, 14

The authors report a case of transoral‐transpharyngeal CO2 laser en bloc excision of a voluminous schwannoma of the intralaryngeal portion of the recurrent laryngeal nerve, along with the review of the pertinent literature.

2 CASE REPORT

A 43‐year‐old man was referred to the Research and Clinical Center of Otorhinolaryngology of the Russian Federal Medico‐Biological Agency with an 8‐month history of dysphonia and dysphagia. Fibrolaryngoscopy showed a smooth submucosal swelling of the left pyriform sinus, associated with immobility of the left vocal cord (Figure 1). Computed tomography (CT) of the neck showed a lesion in the left pyriform sinus extending into the ipsilateral paraglottic space (Figure 2). Clinical and radiological features suggested its benign nature, and the patient's anatomy did not contraindicate a favorable endoscopic exposure.

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Endoscopic view showing a large submucosal lesion originating from the left pyriform sinus

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Computed tomography scan of the neck showing an oval mass located in the left pyriform sinus and extending into the ipsilateral paraglottic space

The patient underwent transoral laser excision under general anesthesia.

Surgical steps.
  1. The patient was intubated with a Mallinckrodt laser‐safe tube 5.5.
  2. During direct microlaryngoscopy, with the patient in the “sniffing” Boyce‐Jackson position (neck flexion and head extension), the bivalve laryngoscope offered a wide exposure of the pharyngo‐larynx. A laser dedicated Steiner Distending Operating Laryngoscope was used with the Gottingen Laryngoscope Holder and Chest Support (Karl Storz Se & Co. KG).
  3. CO2 laser AcuPulse 40 ST (Lumenis) was set on 10 Watts, continuous wave in Superpulsed mode/emission, Acu‐Blade 2 mm of length.
  4. Surgery started with the incision of the mucosa of the left pyriform sinus overlying the tumor.
  5. A careful laser resection with blunt dissection from the surrounding structures was performed preserving the capsule, until to achieve the caudal aspect of the tumor.
  6. The ultimate release of the tumor was obtained by the use of a thin cotton loop allowing for the hanging of the mass and its en bloc removal.
  7. Hemostasis was performed by monopolar cautery.

The tumor appeared as an oval mass of 30 mm in greatest dimension (Figure 3). After the excision, the surgical wound of the pyriform sinus was left to heal by secondary intention. Tracheostomy was not performed, but the patient was kept intubated in Intensive Care Unit (ICU) during the first 12 hours after surgery. Naso‐gastric feeding tube (NGT) was used for 4 days after surgery, and then, oral feeding was regained. There were no complications, and the patient was discharged 7 days after surgery. The paralysis of the left vocal cord in median position, already observed at diagnosis, did not improve during the follow‐up, suggesting the origin of the tumor from the intralaryngeal portion of the recurrent nerve. At histology, typical morphologic features of schwannoma (clear capsule, presence of Antoni A and/or B areas and a positive reaction for S‐100 protein) were present15 (Figures 4 and 5). At 4 years of follow‐up, there was no evidence of recurrence.

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Tumor engaged in the Steiner laryngoscope

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5X histological image of the Schwannoma that shows classic variable cellularity: hipercellular areas (Antoni A) with distinctive focal nuclear palisading surrounding aggregates of cellular processes (Verocay bodies) and hypocellular areas (Antoni B)

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5X histological image of the Schwannoma: the tumor cells show strong and diffuse staining for S100 protein

3 DISCUSSION

Supraglottic localization of laryngeal schwannomas is the most frequently reported in literature,5, 14 and it is generally managed by an endoscopic approach.

The nerve of origin is difficult to be identified precisely before and during surgery. The origin from the intralaryngeal portion of the recurrent nerve is extremely rare, probably because of its shortness,16 and, as shown in Table 1, only eight authors theorized the origin of the laryngeal schwannoma from the recurrent nerve.6-13

TABLE 1. Reported cases of laryngeal schwannoma originating from the recurrent nerve
Author (year) Sex/age Location Presenting symptoms Extra‐laryngeal lesions Tumor max dimension Hypothetical nerve of origin Surgical approach Persistent disease or relapse

Jamal

(1994)

M/42 Emilarynx with extralaryngeal extension Dyspnea No 4 cm Recurrent nerve Open approach, tracheostomy No

Plantet

(1995)

M/30 Aryepiglottic fold extending to paraglottic region Cervical mass, dysphagia, dysphonia

Yes

NF2

Recurrent nerve Lateral pharyngotomy

Lone

(2004)

M/80 Subglottic region extending to trachea Hoarseness, dyspnea No 5 cm Recurrent nerve Median thyrotomy, tracheostomy No

Nagato

(2010)

M/38 Aryepiglottic fold extending to arytenoids, cricoid and mediastinum Throat discomfort, dyspnea

Yes

NF2

Recurrent nerve Open approach, tracheostomy Yes

Kharytaniuk

(2014)

M/30 True vocal cord extending to paraglottic space Hoarseness No 2 cm Superior laryngeal nerve or Recurrent nerve Microsurgery No

Wang

(2014)

F/29 Aryepiglottic fold extending to pyriform sinus Hoarseness, dyspnea, dysphagia No 5.8 cm Recurrent nerve Microsurgery Yes

Kennedy

(2015)

F/68 True vocal cord extending to false vocal cord and paraglottic space Hoarseness, dysphagia No 2.4 cm Recurrent nerve Microsurgery Yes

Kamble

(2017)

F/27 Aryepiglottic fold extending to true vocal cord and cricoid Hoarseness, exertional dyspnea No 5 cm Recurrent nerve Total laryngectomy No
Present case M/43 Pyriform sinus extending to the paraglottic space Dysphonia, dysphagia No 3 cm Recurrent nerve Microsurgery (CO2 laser) No
  • Abbreviation: NF2, Neurofibromatosis type 2.

Schwannoma of the recurrent nerve is suspected in patients with a submucosal well capsulated tumor originating from the paraglottic space, especially when associated with vocal cord palsy. However, preoperative vocal cord palsy can be observed both when the tumor causes a compression of the recurrent laryngeal nerve and/or a mass effect to the cricoarytenoid joint (so‐called pseudo‐fixation),2 and when the schwannoma originates from the recurrent laryngeal nerve.14 After surgery, the persistence of the preoperative vocal fold palsy confirms the origin of the tumor from the recurrent nerve, while in case of recovery of the palsy the mass was probably originating from another nerve.

Differential diagnosis includes other benign neoplastic and non‐neoplastic laryngeal lesions that can arise from the paraglottic space (neurofibroma, lipoma, adenoma, chondroma, papilloma, paraganglioma, internal laryngocele, ectopic thyroglossal duct cyst, laryngeal cyst).4

The surgical resection of the mass with minimal injury of uninvolved areas is the treatment of choice because these tumors are radioresistant.2 Surgery can be performed by an open approach or by an endoscopic one. The choice of the surgical approach is based on the tumor's size, the site of origin, patients’ characteristics, and surgeon's skills.

Open approach can be done by median thyrotomy, lateral thyrotomy, and lateral pharyngotomy.14

Five authors6-9, 13 choose this approach because it allows a wide exposure of the lesion for a complete en bloc removal. The morbidity of the open approach varies noticeably. The laryngeal mucosa could be spared minimizing complication and improving the postoperative voice recovery,2, 17 but in one case a total laryngectomy was considered necessary.

Transoral endoscopic microsurgery, with or without the use of laser, is traditionally reserved to small glottic and supraglottic schwannomas, in patients with good pharyngo‐laryngeal exposure.4, 5, 14 The advantages of the technique are less morbidity, the absence of scar in the neck, and shorter hospitalization time. However, some authors believe that the endoscopic approach could be associated with an increased risk of residual disease because of nonoptimal exposure of the mass.14

The endoscopic approach for recurrent nerve laryngeal schwannoma has been previously reported in three cases only.10-12 In two patients, the tumor involved the glottis and the paraglottic space, and in the other case, it involved the aryepiglottic fold and the pyriform sinus.

As shown in Table 1, open and endoscopic approaches showed some difference in the radicalityofresection. Residual disease was observed in one case treated by open approach (20%),9 while persistence of the tumor was reported in two cases treated endoscopically (50%)11, 12 (P‐value of .342782 according to the chi‐square test). Radicality is then related to a wide exposure of the surgical area and the ability to control the inferior aspect of the lesion while working in a narrow lumen. The endoscopic approach should be performed by surgeons with good expertise in both transoral and open procedures since during surgery the surgeon should be able to shift the endoscopy to an open procedure if he/she is not certain about the radicality of the technique, and in case of complications. Although wider lesions could require the external approach, a transoral management could be considered after precise counseling with the patient. In the present case, the transoral laser CO2 assisted excision was performed in avoluminousschwannoma and resulted an optimal treatment in terms of radicality of the resection and low morbidity. The key points of the management were the good transoral exposure of the mass, a meticulous smooth dissection of the capsule avoiding remaining of the tumor, minimal injury to the surrounding areas to reduce the risk of postoperative edema/bleeding, and the ultimate release of the tumor obtained by a cotton loop.

Tracheostomy can be necessary preoperatively in case of airway obstruction,8 and after surgery to avoid life‐threatening complications. In literature, tracheostomy was performed in 60% of the open procedures, while it has never been performed in patients treated endoscopically for recurrent laryngeal nerve schwannomas. In our case, the tracheostomy was not considered necessary, but the patient was kept intubated in ICU during the first postoperative hours under steroid therapy, and the endotracheal tube was removed the day after surgery under endoscopic view.

4 CONCLUSIONS

Recurrent nerve laryngeal schwannoma is a rare benign tumor that should be considered in the differential diagnosis of all submucosal pharyngo‐laryngeal lesions. Although “challenging,” in expert hands transoral CO2 laser enucleation allows for the radical resection with low morbidity even for bigger tumors.

Since the histology of the lesion is benign, a conservative and mini‐invasive approach should be considered as an alternative to open surgery, without excluding the open approach in case of failure to obtain the radical excision or in case of intraoperative complications such uncontrolled bleeding.

ACKNOWLEDGMENTS

None. Published with written consent of the patient.

    CONFLICT OF INTEREST

    The authors declare no conflicts of interest.

    AUTHOR CONTRIBUTIONS

    CM and FC: wrote the manuscript. IIN, IGG, KMM, and NC: involved in patient management. DDS and VM: provided editing and review of the manuscript. RP: involved in patient management and provided editing and review of the manuscript. All authors: reviewed and contributed to the present form of the manuscript.