Parapharyngeal vagal neurilemmoma extending to the jugular foramen

Triggered episodic vestibular syndrome and transient loss of consciousness due to a retrostyloidal vagal schwannoma: a case report

Background

Various conditions may trigger episodic vertigo or dizziness, with positional changes being the most frequently identified condition. In this study, we describe a rare case of triggered episodic vestibular syndrome (EVS) accompanied by transient loss of consciousness (TLOC) linked to retrostyloidal vagal schwannoma.

Case description

A 27-year woman with known vestibular migraine presented with a 19-month history of nausea, dysphagia, and odynophagia triggered by swallowing food and followed by recurrent TLOC. These symptoms occurred independently of her body position, resulting in a weight loss of 10 kg within 1 year and in an inability to work. An extensive cardiologic diagnostic work-up undertaken before she presented to the neurologic department was normal. On the fiberoptic endoscopic evaluation of swallowing, she showed a decreased sensitivity, a slight bulging of the right lateral pharyngeal wall, and a pathological pharyngeal squeeze maneuver without any further functional deficits. Quantitative vestibular testing revealed an intact peripheral-vestibular function, and electroencephalography was read as normal. On the brain MRI, a 16 x 15 x 12 mm lesion in the right retrostyloidal space suspicious of a vagal schwannoma was detected. Radiosurgery was preferred over surgical resection, as resection of tumors in the retrostyloid space bears the risk of intraoperative complications and may result in significant morbidity. A single radiosurgical procedure (stereotactic CyberKnife radiosurgery, 1 x 13Gy) accompanied by oral steroids was performed. On follow-up, a cessation of (pre)syncopes was noted 6 months after treatment. Only residual infrequent episodes of mild nausea were triggered by swallowing solid food remained. Brain MRI after 6 months demonstrated no progression of the lesion. In contrast, migraine headaches associated with dizziness remained frequent.

Discussion

Distinguishing triggered and spontaneous EVS is important, and identifying specific triggers by structured history-taking is essential. Episodes being elicited by swallowing solid foods and accompanied by (near) TLOC should initiate a thorough search for vagal schwannoma, as symptoms are often disabling, and targeted treatment is available. In the case presented here, cessation of (pre)syncopes and significant reduction of nausea triggered by swallowing was noted with a 6-month delay, illustrating the advantages (no surgical complications) and disadvantages (delayed treatment response) of first-line radiotherapy in vagal schwannoma treatment.

Three cases of vagal nerve schwannoma and review of literature

Schwannoma arising from the vagus is an uncommon (2-5%) benign nerve tumour. This tumour most often presents as a slow growing asymptomatic solitary neck mass which rarely undergoes malignant transformation. Definitive pre-operative diagnosis may be difficult and investigations such as FNAC have low specificity. The carotid artery and internal jugular vein may be displaced antero-laterally. Diagnosis is based on clinical suspicion and confirmation is obtained by means of surgical pathology. Surgical excision is the treatment of choice for this tumour, with recurrence being rare. We describe three cases of schwannoma involving the vagus who presented differently to our unit during past 5 years.

Microsurgical management of 53 jugular foramen schwannomas: lessons learned incorporated into a modified grading system

OBJECT

Due to the proximity and involvement of critical neurovascular structures, the resection of jugular foramen schwannomas can pose a formidable challenge. The authors review their experience in the microsurgical management of jugular foramen schwannomas and propose a modified grading scale to guide surgical management.

METHODS

All jugular foramen schwannoma cases treated by the senior author (T.F.) between 1980 and 2004 were retrospectively reviewed. The average age at presentation, surgical approach, tumor characteristics, cranial nerve (CN) deficits, and tumor recurrence rates were assessed. The authors present the following modified grading scale: Type A, intradural tumors; Type B, dumbbell-shaped tumors; and Type C, triple dumbbell tumors with a high cervical extension.

RESULTS

The authors treated jugular foramen tumors in 129 patients during the study period. Of these, 53 patients (41%) had jugular foramen schwannomas. The mean patient age was 52 years (range 14-74 years); there were 12 male and 41 female patients. The mean follow-up period was 8.4 years. Patients presented most commonly with deficits of the vagus nerve, followed by vestibular/cochlear nerve and glossopharyngeal nerve deficits. Gross-total resection of the tumor was achieved in 48 patients (90.5%). New postoperative paresis in a previously normal CN was not seen; however, worsening of preoperative CN deficits was frequently noted. The highest incidence occurred with the glossopharyngeal and vagus nerves (30%), with 26% of the deficits being permanent. There were no deaths related to surgery in this series. Three patients (5.7%) experienced tumor recurrence.

CONCLUSIONS

The microsurgical resection of jugular foramen schwannomas carries a risk of worsening preoperative CN deficits; however, these are often transient. Based on their experience, the authors have formulated a grading scale that predicts the optimal surgical approach to these lesions. Considerable technical training and microneuroanatomical knowledge of the region is required. The modified grading scale presented facilitates preoperative planning.

Schwannoma of vagus nerve masquerading as a parotid tumour

A post-auricular swelling is the most common presentation of a parotid tumour, the majority of which are benign neoplasms like pleomorphic adenoma. This case report discusses a post-styloid parapharyngeal space tumour presenting as a post-auricular mass which, on initial clinical and cytological examination, was diagnosed as pleomorphic adenoma. A cross-sectional radiological examination revealed the true location of the mass, which was histopathologically confirmed to be a vagal schwannoma. A radiological differential diagnosis is also discussed.

Neurogenic tumors of the cervical vagus nerve: report of four cases and review of the literature

OBJECTIVE AND IMPORTANCE

Nerve sheath tumors arising from the cervical vagus nerve are extremely rare. These tumors most often present as asymptomatic, slowly enlarging, lateral neck masses and therefore often come initially to the attention of otolaryngologists and general surgeons. Because they are nerve tumors, however, neurosurgeons must be able to recognize and treat these rare entities. We report three cases of schwannoma and one case of neurofibroma of the cervical vagus nerve that were encountered at our center (Louisiana State University Medical Center) during a 31-year period.

CLINICAL PRESENTATION

The patients ranged from 31 to 61 years of age at the time of presentation to Louisiana State University Medical Center. Presenting complaints included hoarseness, Horner's syndrome, and palpation of an enlarging, asymptomatic, cervical mass. Reviews of systems revealed episodes of aspiration for one patient and frequent respiratory illnesses for two patients. These episodes were possibly related to their tumors. Imaging studies demonstrated well-circumscribed masses in the region of the carotid sheath.

INTERVENTION

Using microsurgical techniques, gross total resection of all four tumors was accomplished. For one patient, the vagus nerve needed to be divided and an end-to-end anastomosis was performed. For the other three patients, resection of the tumor was achieved with the vagus nerve in continuity.

CONCLUSION

Vagal nerve schwannomas and neurofibromas in the neck are rare neoplasms. We present four cases of these benign tumors. The pathological features, epidemiological characteristics, presentation, differential diagnosis, and management are discussed. Gross total resection with preservation of the vagus nerve remains the treatment of choice.