Cervical Vagal Schwannoma: Anesthetic Concerns.

Schwannomas arising from cervical vagus nerve is an extremely rare benign neoplasm. The majority of patients present with insidiously growing lateral neck mass without neurological deficit. We report a case of symptomatic cervical vagal nerve schwannoma in a 32-year-old female. Complete surgical resection is the treatment of choice. However, anesthetic management of these tumors can be challenging. We describe here the complications experienced during the management of the patient.

INTRODUCTION

Schwannomas are benign nerve sheath neoplasms arising from peripheral or cranial nerves. Cervical vagal nerve schwannoma is an extremely rare, and slow growing tumor.[1] They are reported to occur in patients between 20 and 50 years of age with no sex-related predisposition.[2] To date, there has been no report on the intraoperative anesthetic concerns during excision of cervical vagal nerve schwannoma to the best of our knowledge. We describe here the problems encountered during its excision.

CASE REPORT

A 34-year-old, 50 kg female belonging to American Society of Anesthesiologists-1 (ASA grade 1) Class was posted for cervical vagal nerve schwannoma excision. She presented with a progressive and painless swelling on the left side of the neck since 1 year. History revealed hoarseness of voice for the last 5 months and dizziness associated with vomiting on lying down in left lateral position for since 3 months. On local examination, mass was firm in consistency, nontender, and measuring 5 cm × 4 cm extending superiorly from lower end of pinna to the middle of the neck. The skin over swelling was normal with no local rise of temperature. On palpation of mass, a paradoxical cough was noticed which was diagnostic of vagal nerve schwannoma. Contrast-enhanced computed tomography scan revealed a heterogeneous lesion in left carotid space with mild compression of the left internal jugular vein [Figure 1]. Left adductor palsy was observed on indirect laryngoscopy. Rest of the systemic examination was unremarkable. All blood investigations, X-ray chest and electrocardiogram (ECG) were normal.

Figure 1

Contrast enhanced computed tomography image of tumor compressing and displacing internal jugular vein.

Informed consent was taken. The patient was premedicated with tablet alprazolam 0.25 mg, tablet ranitidine 150 mg and tablet metoclopramide 10 mg night before and on the morning of surgery. Plastic surgeons were informed in view of microvascular surgery for nerve repair. Intensive Care Unit bed was booked keeping in mind any untoward incidence following vagal nerve handling. In the operating room (OR), injection isoprenaline, injection adrenaline, and defibrillator were kept ready in addition to injection atropine. Intravenous (i.v.) cannulation was established after baseline routine monitoring which included ECG, pulse oximetry, noninvasive blood pressure (BP), and end-tidal CO2 (EtCO2). Her baseline heart rate (HR) was 112 b.p.m. and BP was 132/96 mmHg. Standard general anesthesia induction was performed using injection fentanyl, thiopentone, and injection rocuronium. The trachea was intubated with 7.5 mm endotracheal tube. Anesthesia was maintained with N2O: O2 (65:35), isoflurare (0.5–1%) and intermittent doses of rocuronium. The patient remained hemodynamically stable postinduction. Twenty-five minutes following incision, due to manipulation of mass while dissecting it from adjacent structures, the patient developed severe bradycardia of 32/min with an accompanying decrease of BP from 138/87–78/36 mmHg. Surgeons were asked to hold the surgery. Injection atropine 0.5 mg i.v. was given immediately. Patient's HR and BP were restored to 116 b.p.m. and 130/84 mmHg, which remained stable for next 30 min. After that, while excising the mass from the vagus nerve [Figure 2], the patient again experienced bradycardia with HR - 38/min and BP - 86/47 mmHg. Surgeons were asked again to leave the mass. Injection i.v. atropine 0.5 mg was repeated. Patient responded immediately with HR - 122 b.p.m. and BP - 143/100 mmHg. SpO2 and EtCO2 remained normal throughout the surgery. Tumor was dissected very carefully and vagus nerve was repaired by the plastic surgeon by keeping sural nerve graft [Figure 3]. No fresh episode of bradycardia was noted then. The duration of surgery was 1½ h. The patient remained hemodynamically stable therafter. Neuromuscular blockade was reversed successfully at the end of surgery. The right vocal cord was found to be functioning on direct laryngoscopy. Recovery was smooth and uneventful.

Figure 2

Schwannoma on vagus nerve.

Figure 3

Vagal nerve after resection of tumor.

DISCUSSION

Schwannomas are benign nerve sheath tumors. Approximately 25–45% of the reported extracranial schwannomas are present in the head and neck area.[3] Among the cranial nerves, schwannomas, more frequently arise from glossopharyngeal, accessory and hypoglossal nerves. The involvement of vagus nerve is extremely rare and has been reported in 10% of cases.[34] The majority of patients with cervical vagal nerve schwannoma present with asymptomatic, slow growing and painless neck masses.[5] When symptomatic, hoarseness and paroxysmal cough are the most common complaints. Our patient presented with both the symptoms 7 months after the onset of swelling. Cough, elicited on palpation of the mass, is a unique clinical sign of vagal schwannoma.[56] The stimulation of vagal nerve endings due to prominent cystic degeneration of tumor may be responsible for cough.[3] Hoarseness in this case, was explained by adductor palsy of left vocal cord. The incidence of preoperative vocal cord palsy has been reported to be about 12%.[5] In addition, our patient complained of dizziness followed by vomiting in left lateral position which is explainable by the pressure effect on the tumor in that position.

Anesthetic management of vagal nerve schwannoma excision is a challenging task. ECG abnormalities and severe bradycardia leading to hypotension have been reported.[7] Mukherjee et al. experienced cardiac arrest in their patient during excision of a large vagal schwannoma.[8] The probable cause of cardiac arrest was thought to be direct vagal stimulation. We also experienced two episodes of bradycardia accompanied by hypotension in our patient which necessitated the use of injection atropine, as the release of mass by the surgeon was not of much help. The use of anesthetic drugs causing bradycardia was avoided during anesthesia induction as much as possible. No further episode of bradycardia was experienced after removal of the mass. Complete excision including the tumor capsule is important to prevent recurrence.[5] Our patient, however, was complicated by increased hoarseness in postoperative period as per telephonic information since the patient did not come for follow-up. Vocal cord paralysis has been reported in 85% of cases postoperatively while hoarseness in almost all cases.[5] Therefore, assessment of vocal cords mobility preoperatively is of utmost importance. Hence, it is mandatory for the anesthetist as well to inform the patient about possible postoperative neurological complications during preoperative evaluation.

CONCLUSION

Dangerous bradycardia and ECG abnormalities can occur during manipulation and excision of the schwannoma of the vagus nerve. Therefore, the patient should be monitored carefully. Anesthetists should be ready to face such challenges to prevent resultant hemodynamic instability. Communication and cooperation between surgeons and anesthetists are warranted.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.