Vagal schwannoma

Jugular foramen schwannomas: surgical approaches and outcome of treatment

Twelve cases of schwannomas of the jugular foramen that involved surgery in our department between 1983 and 1997 are described. Eight were women and 4 were men (mean age, 40 years), and the duration of their symptoms, the most predominant of which were hearing loss and tinnitus, ranged from 1 month to 20 years (median, 8.5 months). Depending on their radiological and surgical features, tumors were classified as type A, a tumor primarily at the cerebellopontine angle with minimal enlargement of the jugular foramen (n = 5); type B, a tumor primarily at the jugular foramen with or without intracranial extension (n = 4); type C, a primarily extracranial tumor with extension into the jugular foramen (n = 0); or type D, a dumbbell tumor with both intracranial and extracranial components (n = 3). A retrosigmoid suboccipital craniectomy (RSSOC) was performed for type A tumors; for types B and D, the RSSOC or staged infratemporal fossa approach (ITFA)/RSSOC was used. Total removal was achieved in 6 cases, near total removal in 3, and subtotal removal in 3. The most common complication was lower cranial nerve dysfunction (n = 5). The follow-up period ranged from 6 to 173 (mean, 48) months, and there was no recurrence. Two patients showed regrowth of the tumor after subtotal resection, however. In 1 of these, the residual tumor had progressed within 12 months of initial surgery, it was again resected and linac radiosurgery was successful. In the other, the residual mass had progressed within 8 months of initial surgery, and the pathological report indicated malignant peripheral nerve sheath tumor. Conclusively, type A tumors could be totally resected with the retrosigmoid approach alone. For type B and D tumors, however, combined ITFA and retrosigmoid approach showed the better results. In spite of our limited data, cases showing adhesion to critical structures can be managed by subtotal or near total resection followed by radiosurgery to reduce postoperative complications.

Expected neurologic outcomes for surgical treatment of cervical neurilemomas

OBJECTIVE

Neurilemomas are classically described as fusiform tumors that eccentrically displace the undisturbed neural fascicles. The authors seek to clarify the relationship of cervical neurilemomas to their nerve of origin and assess the functional outcome of surgical extirpation.

STUDY DESIGN

A retrospective review of clinical, intraoperative, and histopathologic data of six patients with cervical extracranial neurilemomas.

METHODS

Additional histochemical staining of the pathologic specimens was performed to evaluate the tumor for neurites. A comprehensive literature review of cervical neurilemoma cases and meta-analysis of clinical outcomes in these cases were performed.

RESULTS

In the series of five consecutive cervical neurilemomas, only one was an eccentric mass pushing the undisturbed nerve aside. In the five other cases, excision of the neurilemoma required complete nerve excision. Neural elements traveling through the central portions of the tumor were clearly demonstrated histologically. Collective analysis of the literature on cervical neurilemomas revealed that although some cases allow nerve preservation, preservation of function is frequently poor.

CONCLUSIONS

This experience and that reported in the literature suggest that it is frequently impossible to preserve the function of the nerve of origin with surgical treatment of cervical neurilemomas.

Parapharyngeal vagal neurilemmoma extending to the jugular foramen

A large vagal neurilemmoma in a 33-year-old man is reported. He complained of slowly progressive palsy of the tongue on the left side. Weakness of soft palate movement was also noted. Magnetic resonance imaging (MRI) revealed a tumour in the left parapharyngeal space with partial extension to the posterior cranial fossa through the jugular foramen. Carotid angiography revealed avascularity of the tumour and anterior shift of the left internal carotid artery. The venous phase showed no blood flow in the internal jugular vein. The tumour was successfully extirpated via a transmandibular transpterygoid approach. Although vagus nerve dysfunction was not observed pre-operatively, the tumour was identified as a neurilemmoma arising from the vagus nerve. The surgical approach should be selected according to the lesion in individual patients. Since neurilemmoma is benign in nature, minimal post-operative sequelae should be expected.