Microsurgical management of hypoglossal schwannomas over 3 decades: a modified grading scale to guide surgical approach

[Accessory nerve meningioma. A case report and literature review]

Meningiomas arising from accessory nerve sheath without dural attachment are rare. To date, only 5 cases are described in the literature. A 53-year-old male presented with long history of occipital pain and headaches. Magnetic resonance imaging revealed a small intradural extramedullary contrast enhanced tumor at the level of foramen magnum. The patient underwent microsurgical resection through minimally invasive midline suboccipital approach. According to intraoperative findings, cystic tumor arose from the left accessory nerve without dural attachment. Gross total resection was achieved without damage to the nerve. Histological analysis revealed angiomatous meningioma. Postoperative period was uneventful without new neurological symptoms. Meningiomas can rarely arise from accessory nerve sheath and mimic schwannoma. These tumors may be totally resected without damage to accessory nerve using minimally invasive surgical approaches.

Stereotactic radiosurgery for the treatment of hypoglossal schwannoma: a multi-institutional retrospective study

BACKGROUND

Surgical removal has been performed as the first line treatment for symptomatic or enlarging hypoglossal schwannomas (HS). Stereotactic radiosurgery (SRS) offers a minimally invasive approach that may afford long-term tumor control for patients with HS particularly those who refuse or are unfit for surgery. This study evaluates outcomes after SRS performed for both newly diagnosed and residual tumors after incomplete resection.

METHODS

This retrospective, multi-institutional study involved patients treated with adjuvant or primary SRS for HS. The study end-points included local tumor response, clinical outcomes, and procedure-related complications. All the patients had Gamma Knife SRS.

RESULTS

The cohort included 12 patients (five females), median age at SRS 49.5 years (range, 37-76)]. The median tumor target volume was 5.9 cm³ (range, 0.7-27.23). At median imaging follow-up of 37 months (range, 6-153), tumor control was achieved in 11 patients. Tumor enlargement that was managed with surgical resection was noted at the 6-month follow-up in one patient. At median clinical follow-up of 30.5 months (range, 6-157), stability, or improvement of all pre-SRS signs and symptoms was noted in nine patients. Two patients experienced worsening of at least one pre-existing symptoms or sign. New-onset trapezius weakness was noted in one patient and tongue atrophy in two patients.

CONCLUSION

Single-fraction SRS appears to be a safe and effective upfront and adjuvant treatment option for HS. SRS may be recommended as an alternative to surgery for patients presenting with HS or as an adjuvant treatment following subtotal resection and at HS recurrence.

Surgical Management of Craniovertebral Junction Schwannomas: A Systematic Review

BACKGROUND

Craniovertebral junction (CVJ) schwannomas are rare, with surgery and stereotactic radiosurgery (SRS) being effective yet challenging options. We systematically reviewed the literature on CVJ schwannomas.

METHODS

PubMed, Scopus, Web-of-Science, and Cochrane were searched following the PRISMA statement to include studies reporting CVJ schwannomas. Clinical features, management, and outcomes were analyzed.

RESULTS

We collected 353 patients from 101 included articles. Presenting symptoms were mostly neck pain (30.3%) and headache (26.3%), with most cranial neuropathies involving the XII (31.2%) and X (24.4%) nerves. Most tumors originated from C2 (30.9%) and XII (29.4%) nerves, being extracranial (45.1%) and intradural-extradural (44.2%). Erosion of C1-C2 vertebrae (37.1%), the hypoglossal canal (28.3%), and/or jugular foramen (20.1%) were noted. All tumors were operated, preferably with the retrosigmoid approach (36.5%), with the far-lateral approach (29.7%) or with the posterior approach and cervical laminectomy (26.9%), far-lateral approaches (14.2%), or suboccipital craniotomy with concurrent cervical laminectomy (14.2%). Complete tumor resection was obtained most frequently (61.5%). Adjuvant post-surgery stereotactic radiosurgery was delivered in 5.9% patients. Median follow-up was 27 months (range, 12-252). Symptom improvement was noted in 88.1% of cases, and cranial neuropathies showed improvement in 10.2%. Post-surgical complications occurred in 83 patients (23.5%), mostly dysphagia (7.4%), new cranial neuropathies (6.2%), and cerebrospinal fluid leak (5.9%). A total of 16 patients (4.5%) had tumor recurrence and 7 died (2%), with median overall survival of 2.7 months (range, 0.1-252).

CONCLUSIONS

Microsurgical resection is safe and effective for CVJ schwannomas. Data on SRS efficacy and indications are still lacking, and its role deserves further evaluation.

Malignant Nerve Sheath Tumor of the Hypoglossal Nerve in a Maltese Dog

A 4 yr old male Maltese dog presented with a 1 wk history of intermittent neck pain and progressive difficulty walking. Neurologic evaluation was consistent with a left-sided brainstem lesion. On oral examination, left lingual hemiatrophy was evident suggesting hypoglossal nerve involvement. A dumbbell-shaped extra-axial mass in the left side of the caudal fossa extending extracranially through the hypoglossal canal was detected by MRI. At postmortem histologic examination, the hypoglossal nerve was diffusely infiltrated by fusiform neoplastic cells arranged in Antoni A and Antoni B patterns. This is the first description of a malignant nerve sheath tumor selectively involving the hypoglossal nerve in a dog.

Management of non-vestibular schwannomas in adult patients: a systematic review and consensus statement on behalf of the EANS skull base section Part III: Lower cranial nerve schwannomas, jugular foramen (CN IX, X, XI) and hypoglossal schwannoma (XII)

BACKGROUND

Non-vestibular schwannomas are relatively rare, with trigeminal and jugular foramen schwannomas being the most common. This is a heterogenous group which requires detailed investigation and careful consideration to management strategy. The optimal management for these tumours remains unclear, and there are several controversies. The aim of this paper is to provide insight into the main principles defining management and surgical strategy, in order to formulate a series of recommendations.

METHODS

A task force was created by the EANS skull base section committee along with its members and other renowned experts in the field to generate recommendations for the surgical management of these tumours on a European perspective. To achieve this, the task force performed an extensive systematic review in this field and had discussions within the group. This article is the third of a three-part series describing non-vestibular schwannomas (IX, X, XI, XII).

RESULTS

A summary of literature evidence was proposed after discussion within the EANS skull base section. The constituted task force dealt with the practice patterns that exist with respect to preoperative radiological investigations, ophthalmological assessments, optimal surgical and radiotherapy strategies and follow-up management.

CONCLUSION

This article represents the consensually derived opinion of the task force with respect to the treatment of non-vestibular schwannomas. For each of these tumours, the management paradigm is shifting towards the compromise between function preservation and progression free survival.

Simplifying the Surgical Classification and Approach to the Posterolateral Skull Base and Jugular Foramen Using Anatomical Triangles

Introduction Lesions of the jugular foramen (JF) and postero-lateral skull base are difficult to expose and exhibit complex neurovascular relationships. Given their rarity and the increasing use of radiosurgery, neurosurgeons are becoming less experienced with their surgical management. Anatomical factors are crucial in designing the approach to achieve a maximal safe resection. Methods and methods Six cadaveric heads (12 sides) were dissected via combined post-auricular infralabyrinthine and distal transcervical approach with additional anterior transstyloid and posterior far lateral exposures. Contiguous surgical triangles were measured, and contents were analyzed. Thirty-one patients (32 lesions) were treated surgically between 2000 and 2016 through different variations of the retro-auricular distal cervical transtemporal approaches. Results We anatomically reviewed the carotid, stylodigastric, jugular, condylar, suboccipital, deep condylar, mastoid, suprajugular, suprahypoglossal (infrajugular), and infrahypoglossal triangles. Tumors included glomus jugulare, lower cranial nerve schwannomas or neurofibromas, meningiomas, chondrosarcoma, adenocystic carcinoma, plasmacytoma of the occipitocervical joint, and a sarcoid lesion. We classified tumors into extracranial, intradural, intraosseous, and dumbbell-shaped, and analyzed the approach selection for each. Conclusion Jugular foramen and posterolateral skull base lesions can be safely resected through a retro-auricular distal cervical lateral skull base approach, which is customizable to anatomical location and tumor extension by tailoring the involved osteo-muscular triangles.

Trends in the Management of Non-Vestibular Skull Base and Intracranial Schwannomas

The aim of this review is to analyze the latest trends in the management of non-vestibular skull base and intracranial schwannomas in order to optimize tumor control and quality of life. Non-vestibular cranial nerve schwannomas are rare lesions, representing 5–10% of cranial nerve schwannomas. Management decisions should be individualized depending on tumor size, location and associated functional deficits. Generally, large sized schwannomas exerting significant mass effect with increased intracranial pressure are treated surgically. In some cases, even after optimal skull base resection, it is not possible to achieve a gross total resection because tumor location and extent and/or to reduce morbidity. Thus, subtotal resection followed by stereotactic radiosurgery or fractioned radiotherapy offers an alternative approach. In certain cases, stereotactic radiosurgery or radiotherapy alone achieves good tumor control rates and less morbidity to gross total resection. Finally, given the slow growth rate of most of these tumors, observation with periodic radiographic follow-up approach is also a reasonable alternative for small tumors with few, if any, symptoms.

[Hypoglossal schwannoma: case report and literature review]

Hypoglossal schwannoma is a rare tumor this frequency approximately less than 5% all non-vestibular schwannomas. Also, it may be sign of neurofibromatosis type 2. Usually, the tong deviation in side of the tumor is the first symptom of the disease. When the tumor size is increased, bulbar disorders and cervico-occipital pain are develop. MRI is the main method of diagnostic. Until the 1970s, mortality after surgical removal reached 50% and was due to bulbar and respiratory dysfunctions. Nowadays, the cause of death remains the same. After introduction stereotactic radiotherapy into clinical practice total removal is not necessary. The purpose of surgery stay is removal of intracranial part of the tumor and decompression of the brainstem (subtotal removal). Radiotherapy or radiosurgery is performed on the intracanal fragment of the tumor. The case of successful surgical treatment of a patient with hypoglossal schwannoma is presented in this article. Subtotal removal was performed via median suboccipital approach. Radiosurgery is planned for residual part of the tumor, located in the hypoglossal nerve channel.

Endoscopic Approach to Remove Intra-extracranial Tumors in Various Skull Base Regions: 10-year Experience of a Single Center

Background:

Some problems have been found in the usually adopted combined approach for the removal of intra-extracranial tumors in skull base. Herein, we described a pure endoscopic transnasal or transoral approach (ETA) for the removal of intra-extracranial tumors in various skull base regions.

Methods:

Retrospectively, clinical data, major surgical complications, pre- and postoperative images, and follow-up information of a series of 85 patients with intra-extracranial tumors in various skull base regions who were treated by surgery via ETA in our skull base center during the past 10 years were reviewed and analyzed.

Results:

Gross total tumor removal was achieved in 80/85 cases (94.1%) in this study. All 37 cases with tumors in anterior skull base and all 14 cases with tumors in jugular foramen received total tumor removal. Thirteen and three cases with tumors in clivus received total and subtotal tumor removal, respectively. Total and subtotal tumor removal was performed for 16 cases and 2 cases in lateral skull base, respectively. The complications in this study included: cerebrospinal fluid leakage (n = 3), meningitis (n = 3), and new cranial nerve deficits (n = 3; recovered in 3 months after surgery). In the follow-up period of 40–151 months (median: 77 months), seven patients (8.8%) out of the 80 cases of total tumor removal experienced recurrence.

Conclusions:

Complete resection of intra-extracranial growing tumors in various skull base regions can be achieved via the pure ETA in one stage in selected cases. Surgical procedure for radical removal of tumors is feasible and safe.

Is Hypoglossal Nerve Palsy Caused by Craniocervical Junction Degenerative Disease an Underrecognized Entity?

Isolated hypoglossal nerve palsy is uncommon, and underlying craniocervical junction degenerative disease has rarely been reported as an underlying cause. To improve understanding of this entity, we present a retrospective series of 18 patients with hypoglossal palsy in whom twelfth cranial nerve compression within the premedullary cistern or hypoglossal canal, or both, was found secondary to craniocervical junction juxta-articular cysts, retro-odontoid fibrous pseudotumors, and osteophytes. The imaging techniques and characteristic craniocervical junction degenerative disease lesion imaging findings presented here might help clinicians interpreting hypoglossal palsy imaging studies avoid perceptual and interpretive errors commonly found in the present series.

Hypofractionated stereotactic radiotherapy for dumbbell-shaped hypoglossal schwannomas: Two cases of long-term follow-up and a review of the literature

Cases of hypoglossal schwannoma are extremely rare. Historically, microsurgical resection has been the standard treatment, but it may not always be feasible; thus, it is crucial to investigate alternative treatments. We herein present the cases of two patients, both of whom presented with tongue deviation and hemiatrophy, accompanied by headaches. Magnetic resonance imaging revealed a dumbbell-shaped tumor originating from the hypoglossal nerve that was adjacent to the cranial base in each patient. Hypofractionated stereotactic radiotherapy was used to treat the tumors, with a total dose of 30 Gy in 3-Gy fractions delivered to the planning target volume. Several months later, the tumors had significantly decreased in size and the symptoms of the two patients had gradually improved.

Spatial Relationship between Hypoglossal Schwannoma and the Vertebral Artery Using the Far-Lateral Approach

In hypoglossal schwannoma removal via the far-lateral approach needs care as the vertebral arteries are usually adjacent to the tumors. Thus, it is important to understand their location respective to schwannoma to conduct a safe surgery. We reviewed the data of eight patients with hypoglossal schwannoma who underwent surgery in Keio University Hospital in 2005–2013. There were five males and three females (mean age at initial presentation was 48.6 years, range 38–72 years). We especially focused on the spatial relationship between the vertebral artery and the tumor, and evaluated their spatial relationship from intraoperative findings. All eight hypoglossal schwannomas included in the current study were type B according to Kaye’s classification. As for spatial relationship between the tumor and the vertebral artery, in six out of eight cases, the vertebral artery was located inside or beneath the tumor; in contrast, in the other two cases, it was pushed out by the tumor and identified just after dural opening. Through the far-lateral approach, we found that the vertebral artery was located inside or beneath in most hypoglossal schwannoma; however, the vertebral artery was occasionally located on the tumor surface. From an anatomical perspective, we speculate this unique location of the vertebral artery in these cases is due to the unusual course of the hypoglossal nerve of tumor origin.

A case of malignant peripheral nerve sheath tumor of the hypoglossal nerve after stereotactic radiosurgery treatment

Objectives Hypoglossal schwannomas are rare. Surgical resection has been the standard treatment modality. Radiosurgery has been increasingly used for treatment. Radiation-associated secondary malignancy/malignant transformation has not been documented in the literature for the treatment of nonvestibular schwannomas. Setting The patient was a 52-year-old man with an enlarging high cervical/skull base lesion 8.5 years after CyberKnife treatment of a presumed vagal schwannoma. A decision was made for surgical resection, and the tumor was found to originate from the hypoglossal nerve intraoperatively. Final pathology diagnosis was malignant peripheral nerve sheath tumor. Results Patient had a gross total resection. Three months after resection, he received fractionated radiation of 50 Gy in 25 fractions and a boost gamma knife radiosurgery of 10 Gy to the 50% isodose surface. He remained tumor free on repeat magnetic resonance imaging 9 months after the resection. Conclusion Although extremely rare, radiation treatment of nonvestibular schwannomas can potentially cause malignant transformation.

Management of hypoglossal schwannomas: single institutional experience of 14 cases

Background Hypoglossal schwannomas are rare intracranial neoplasms. Microsurgical resection with the goal of cure is the aim of management but is associated with a high rate of postoperative morbidity. Objective The objective of the study was to outline the clinical presentation, radiologic characteristics, surgical techniques, postoperative morbidity, and long-term follow-up results for hypoglossal schwannomas. Methods Patients treated for hypoglossal schwannoma at the Department of Neurosurgery of a tertiary-level referral institution from January 2001 until December 2010 were analyzed retrospectively using hospital records. Results There were 14 patients who were treated in the study period. Tongue atrophy and swallowing difficulties were the most common presenting symptoms. Surgery done in 12 patients using a variety of approaches (retromastoid retrosigmoid suboccipital in 9, midline suboccipital in 2, and far lateral in 1). Five patients having small residual tumors received gamma knife (GK) subsequently. two patients received primary GK stereotactic radiosurgery. Three patients had permanent morbidity in the form of cranial nerve paresis. Immediate postoperative complications like cerebrospinal fluid leak and pneumonia were present in three patients. Conclusion Complete microsurgical resection is often associated with a high rate of morbidity. Subtotal and near-total resection followed by stereotactic radiosurgery or observation now offers an alternative approach.

Dumbbell-shaped abducens schwannoma: case report

Schwannomas of the abducens nerve are uncommon. Nineteen cases have been reported in the literature and are classified into two types: Type 1, in the cavernous sinus, and Type 2, in the prepontine area. However, a dumbbell-shaped type has not yet been reported. Here we report the first case of a dumbbell-shaped abducens schwannoma and classify this type into a new category (Type 3). A 36-year-old woman presented with left hearing disturbance for 4 years, dizziness for 2 years, and dysphagia for 6 months. Neurological examination showed left sensorineural hearing impairment, hypesthesia in the distribution of the left first and second branches of the trigeminal nerve, left curtain sign, and gait disturbance. Computed tomography and magnetic resonance imaging revealed a dumbbell-shaped tumor located in the cavernous sinus that extended to the right cerebellopontine angle. She underwent a two-staged operation; the first operation was via ananterior transpetrosal approach for the lesion in the middle fossa and the upper part in the posterior fossa, and the second surgery was via alateral suboccipital approach for the lower part in the posterior fossa. In the first operation, the abducens nerve was sacrificed. Histological examination confirmed schwannoma. Postoperatively, hearing disturbance and ataxia were improved and complete abducens nerve paresis appeared. The dumbbell-shaped abducens schwannoma has novel clinical features, difficulty of sixth nerve preservation, and unique surgical approach.

Hypoglossal schwannoma masquerading as a carotid body tumor

Study Objective. To describe the clinical presentation, evaluation, and treatment of a hypoglossal schwannoma. Methods. We report an unusual case of a hypoglossal schwannoma presenting as a pulsatile level II neck mass at the bifurcation of the external and internal carotid arteries, mimicking a carotid body tumor. Radiologic findings are reviewed in detail. Results. A 59-year-old female presented to a tertiary care medical center with complaints of a pulsatile right-sided neck mass. An MRA of the neck was obtained demonstrating a 5 cm mass located at the carotid artery bifurcation and causing splaying of the internal and external carotids. Based on clinical presentation and imaging, a diagnosis of a carotid body tumor was conferred and the patient scheduled for excision. Intraoperatively, the mass was noted to arise from the hypoglossal nerve, remaining independent of the carotid artery. On histopathologic analysis, the mass was determined to be consistent with hypoglossal schwannoma. Conclusion. Though rare, the hypoglossal schwannoma should remain a consideration in the evaluation of a parapharyngeal space mass. As this report demonstrates, the clinical and radiologic presentation of a hypoglossal schwannoma may closely mimic that of the more common carotid body tumor.