Dumbbell-shaped hypoglossal neurinoma: surgical removal via a dorsolateral transcondylar approach. A case report and review of the literature

Schwannomas of Brain and Spinal Cord

Schwannomas are benign tumors originating from the Schwann cells of cranial or spinal nerves. The most common cranial schwannomas originate from the eight cranial nervevestibular schwannomas (VS). VS account for 6-8% of all intracranial tumors, 25-33% of the tumors localized in the posterior cranial fossa, and 80-94% of the tumors in the cerebellopontine angle (CPA). Schwannomas of other cranial nerves/trigeminal, facial, and schwannomas of the lower cranial nerves/are much less frequent. According to the World Health Organization (WHO), intracranial and intraspinal schwannomas are classified as Grade I. Some VS are found incidentally, but most present with hearing loss (95%), tinnitus (63%), disequilibrium (61%), or headache (32%). The neurological symptoms of VSs are mainly due to compression on the surrounding structures, such as the cranial nerves and vessels, or the brainstem. The gold standard for the imaging diagnosis of VS is MRI scan. The optimal management of VSs remains controversial. There are three main management options-conservative treatment or "watch-and-wait" policy, surgical treatment, and radiotherapy in all its variations. Currently, surgery of VS is not merely a life-saving procedure. The functional outcome of surgery and the quality of life become issues of major importance. The most appropriate surgical approach for each patient should be considered according to some criteria including indications, risk-benefit ratio, and prognosis of each patient. The approaches to the CPA and VS removal are generally divided in posterior and lateral. The retrosigmoid suboccipital approach is a safe and simple approach, and it is favored for VS surgery in most neurosurgical centers. Radiosurgery is becoming more and more available nowadays and is established as one of the main treatment modalities in VS management. Radiosurgery (SRS) is performed with either Gamma knife, Cyber knife, or linear accelerator. Larger tumors are being increasingly frequently managed with combined surgery and radiosurgery. The main goal of VS management is preservation of neurological function - facial nerve function, hearing, etc. The reported recurrence rate after microsurgical tumor removal is 0.5-5%. Postoperative follow-up imaging is essential to diagnose any recurrence.

Excision of hypoglossal neurinoma by condyle sparing suboccipital keyhole approach

Hypoglossal neurinomas are rare tumors that present with gradually worsening unilateral wasting of the tongue. The tumors often attain large size prior to detection and often extend into the hypoglossal canal. Large tumors can distort the brainstem and cerebellum. Preoperative diagnosis can often be made by magnetic resonance imaging (MRI) with contrast enhancement. Traditionally, surgery for these tumors has entailed large transcondylar approaches, often necessitating occipitocervical stabilization. We managed one 23-year-old female patient with a large hypoglossal neurinoma. The tumor could be excised completely by a condyle-sparing minimally invasive suboccipital keyhole approach.

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

BACKGROUND

Schwannomas originating from the hypoglossal nerve are extremely rare. Microsurgical resection with the goal for cure has traditionally been associated with a high risk of postoperative deficits.

OBJECTIVE

To summarize our clinical experience using tailored cranial base approaches for these formidable lesions.

METHODS

The clinical records of 13 patients were retrospectively reviewed. In addition, all reported patients in the literature were reviewed. The extreme lateral infrajugular transcondylar-transtubercular exposure approach was used in all of our patients. Based on our experience and literature analysis, we propose the following modified grading scale to facilitate surgical planning: type A, intradural tumors; type B, dumbbell-shaped tumors; type C, extracranial tumors; and type D, peripheral tumors.

RESULTS

All 13 patients underwent total, near-total, or subtotal tumor resection. Eight patients were men, 5 were women (mean age, 41.7 years). Sural nerve graft reconstruction for the hypoglossal nerve was performed in 4 patients. Three of the 4 patients in whom nerve reconstruction was performed regained satisfactory movement of their tongue. In the review of the literature, the mean patient age was 45.8 years. Patients presented with tongue atrophy (91.6%), headache (60.9%), and dysphagia (31.8%). The tumors were categorized as type A in 31.7% of these patients, type B in 38.6%, type C in 6.2%, and type D in 23.4%.

CONCLUSION

The extreme lateral infrajugular transcondylar-transtubercular exposure approach, which is a modification of the extreme lateral suboccipital approach, provides sufficient exposure for most intracranial dumbbell-shaped hypoglossal schwannomas. Hypoglossal nerve reconstruction using a sural nerve graft improves tongue atrophy and movement for patients with resected nerves.

Surgical treatment of dumbbell-shaped hypoglossal schwannoma via a pure endoscopic transoral approach

BACKGROUND

Dumbbell-shaped hypoglossal schwannomas with intradural and extradural extension are extremely rare, and complete removal of these tumors is very difficult. This report describes such lesions in three patients that were completely removed via a purely endoscopic transoral approach.

METHOD

Three patients with intradural and extradural growth hypoglossal schwannomas (three women, aged 16, 42 and 43 years) were treated by direct surgery via a purely endoscopic transoral approach to the posterior fossa.

RESULTS

In this series, radical resections of the dumbbell-shaped hypoglossal schwannomas were achieved in all three patients via a purely endoscopic transoral approach without creating additional cranial nerve deficits but temporary left vagus palsy in one case and a temporary left hypoglossal palsy in one case. The postoperative vagus and hypoglossal palsy had recovered in 3 months after surgery. No patient experienced complications such as postoperative cerebrospinal fluid leak, meningitis and cerebrovascular evidence. At the time of this review, the preoperative lingual motor function and muscular bulk had recovered but hemiatrophy of the tongue was still detectable. The preoperative vagus palsy had recovered by the 10th day after surgery. The hearing loss and facial palsy before surgery had completely recovered in 3 months postoperatively. No patient in our series has experienced a recurrence for the follow-up period (3-11 months).

CONCLUSIONS

Dumbbell-shaped hypoglossal schwannomas tend to cause lower cranial nerve deficits, facial paralysis and hearing loss. With appropriate preoperative evaluation and careful planning of the perioperative period, complete tumor resection can be achieved via the purely endoscopic transoral approach. The endoscopic transoral approach is an effectice choice for management of dumbbell-shaped hypoglossal schwannomas.

Endoscopic endonasal clipping of a ruptured vertebral-posterior inferior cerebellar artery aneurysm: technical case report

BACKGROUND AND IMPORTANCE

Aneurysms arising from the vertebral and posterior inferior cerebellar artery complex account for only 0.5 to 3% of all aneurysms. Surgery for these aneurysms is technically challenging because of the deep location and intimate relation with the medulla and lower cranial nerves. The authors report the case of a patient with a right vertebral-posterior inferior cerebellar artery complex (VA-PICA) aneurysm that was successfully clipped via an extended endoscopic endonasal transclival approach.

CLINICAL PRESENTATION

A 74-year-old woman with the sudden onset of severe headache, nausea, and vomiting was admitted to our hospital. A computed tomography (CT) of the brain revealed diffuse subarachnoid hemorrhage associated with intraventricular hemorrhage and incipient hydrocephalus. Cerebral angiography revealed a 1.2-mm aneurysm arising at the origin of the right PICA. The aneurysm was considered unsuitable for selective coil embolization, so neck clipping was performed. With the use of an extended endoscopic endonasal transclival approach, the aneurysm was accurately reached endoscopically and successfully clipped from the parent artery. The patient was discharged neurologically intact.

CONCLUSION

To the best of the authors' knowledge, this is the first report of a successfully treated VA-PICA ruptured aneurysm using a pure endoscopic endonasal transclival approach. Endoscopic surgery may be added to the armamentarium of procedures for the treatment of posterior circulation aneurysms.

Endoscopic transoral approach for extracranial hypoglossal schwannoma

OBJECTIVE

Hypoglossal nerve schwannoma, especially when inside the extracranial region, is extremely rare. This report describes a new endoscopic transoral approach for the removal of extracranial hypoglossal schwannoma.

PATIENTS AND METHODS

Three patients (1 male and 2 females, aged 58-63 years) with extracranial hypoglossal schwannoma in the paroccipital condyle and the jugular foramen were treated solely by an endoscopic transoral approach. All patients presented signs of hypoglossal nerve paresis with hemiatrophy of the tongue. In addition, one of them had glossopharyngeal nerve paresis, and vagus nerve paresis was found in another patient.

RESULTS

In all patients, tumors underwent successful radical intracapsular removal by the endoscopic transoral approach, as confirmed by the postoperative examinations and MRI. No complications occurred during or after surgery, except that 1 patient had swallowing difficulties and a temporary right vagus palsy during the first day after surgery. All patients were followed up for 6 months, and the lack of any recurrence has been confirmed. Muscle bulk, motor and swallowing functions, and the vagus palsy improved in all patients.

CONCLUSION

The endoscopic transoral approach is a safe and useful surgical technique for the removal of intracapsular tumors, including extracranial hypoglossal schwannomas, which involves minimal invasion.

Hypoglossal schwannoma presenting only with headache

Hypoglossal schwannoma is a rarely encountered skull base lesion that has generally both intracranial and extracranial parts. This article reports a case of hypoglossal schwannoma that is purely extracranial and presents itself only with persistent headache. Magnetic resonance imaging delineated a mass at the skull base that consisted of both cystic and solid components, consistent with a nerve sheath tumor. Cervical approach was chosen, and the mass was completely removed. Postoperatively, the patient developed hypoglossal nerve palsy because the hypoglossal nerve was sacrificed. Hypoglossal schwannomas are briefly discussed with a literature review.

A cylindrical extracranial cranial base neurinoma of the hypoglossal nerve: a rare tumor with a rare localization: case report

OBJECTIVE

Neurinomas of the hypoglossal nerve are very rare. They are mostly located intracranially or combined intra- and extracranially, resulting in the so-called dumbbell shape. The isolated extracranial localization of the neurinoma of the hypoglossal nerve adjacent to the cranial base as described in this case report is extremely rare.

CLINICAL PRESENTATION

The 23-year-old patient presented with recurring headaches. She had right-sided hypoglossal nerve palsy for approximately 5 to 6 years. Magnetic resonance imaging revealed an extracranial tumor with contact to the cranial base originating from the hypoglossal nerve.

INTERVENTION

The tumor was extirpated surgically and verified histologically as a schwannoma of the hypoglossal nerve.

CONCLUSION

Pathologies of the hypoglossal nerve as such are very rare within the clinical landscape. When a tumor occurs, its shape and location must be analyzed to establish whether, or by which approach, surgical removal is feasible. Although very unusual, the mere extracranial occurrence of a hypoglossal neurinoma at the cranial base should be considered a differential diagnosis.

Hypoglossal schwannoma-successful reinnervation and functional recovery of the tongue following tumour removal and nerve grafting

OBJECTIVE

Hypoglossal nerve schwannomas are rare tumours that usually cause ipsilateral hypoglossal palsy. This report describes such lesions in two patients and suggests nerve grafting as part of the treatment regimen.

METHOD

Two patients with intra- and extra-dural hypoglossal schwannomas respectively were treated by direct surgery via a postero-lateral approach to the posterior fossa, hypoglossal canal and carotid sheath. Following tumour removal, sural nerve grafting was used to reconstruct the nerves. Unexpectedly, muscle bulk and motor function returned within 6 months in both patients.

CONCLUSION

Nerve grafting was highly successful in achieving functional recovery following surgery for hypoglossal nerve schwannomas.

Surgical approach for hypoglossal schwannomas to prevent deformity of the atlanto-occipital joint

BACKGROUND

Hypoglossal schwannomas are very rare tumors that often enlarge the hypoglossal canal and jugular foramen, and erode the bone bridge of the occipital condyle. We compared pre- and postoperative 3D bone CT images and discussed the ideal craniotomy to prevent fracture formation.

METHOD

Seven patients with hypoglossal schwannomas underwent surgery in our department. Six cases were type B and 1 case was type C. All patients complained of hypoglossal nerve paresis and nuchal pain.

FINDINGS

We used the condylar fossa approach for four cases of type B, the lateral suboccipital approach with C1 laminectomy for two cases of type B and extradural transjugular approach for one case of type C. In all cases, the lateral rim of the foramen magnum or the posterior rim of the jugular foramen was not resected at the same time. The intracranial part of the tumor was removed in all type B cases. Radiotherapy was added for the residual tumor. No patient had deformity or fracture of the joint.

CONCLUSIONS

Opening the hypoglossal canal and dural incision toward the hypoglossal canal are important for high radicality. However, preservation of the lateral rim of the foramen magnum must be noted to prevent consecutive deformity or fracture of the atlanto-occipital joint.

Dumbbell-shaped jugular foramen schwannomas: surgical management, outcome and complications on a series of 16 patients

Schwannomas of the lower cranial nerves are very rare and the dumbbell-shaped ones are even rarer. The authors report their experience in managing such lesions, usually presenting either with intra- and/or extra-cranial extension through an enlarged jugular foramen. The juxtacondylar approach without sacrificing the labyrinth was used; clinical, radiological and complication features are discussed and analysed. This is a case series study on 16 consecutive patients with lower cranial nerves schwannomas surgically managed during a 14-year period using the juxtacondylar approach. In 13 cases, a complete resection has been achieved whereas in three, the excision was near total. The tumour nerve origin has been identified only in ten cases (62.5%). No death or additional post-operative cranial nerve deficits occurred. Aspiration pneumonia developed in one patient and cerebrospinal fluid leak in another. Pre-operative lower cranial nerve deficits improved in all patients. At a mean follow-up of 6.6 years (range 2-14 years), no radiological tumour recurrence was recorded amongst the patients having complete resection as well as no tumour progression in the group of near total removal. Jugular foramen schwannomas can be radically and safely resected with no additional neurological deficit if a careful pre-operative evaluation and the appropriate surgical approach is implemented. Finally, full cranial nerve functional recovery may be expected after complete resection.

Extradural dumbbell schwannoma of the hypoglossal nerve: a case report with review of the literature

BACKGROUND

Dumbbell-shaped schwannomas of the hypoglossal nerve are very rare. This report concerns a case with an extradural, dumbbell-shaped hypoglossal schwannoma extending both intra- and extracranially.

CASE DESCRIPTION

A 25-year-old woman presented with a right hypoglossal palsy. Imaging revealed a dumbbell-shaped tumor with considerable compression and medial displacement of the medulla oblongata, diagnosed as a hypoglossal schwannoma. The tumor mass extended extracranially to the parapharyngeal space through the enlarged hypoglossal canal. The tumor was partially excised by a right far-lateral suboccipital approach and the tumor was found to be predominantly extradural with minimal intradural extension. A histopathologic diagnosis of schwannoma was made.

CONCLUSIONS

This case emphasizes the importance of recognizing this extradural variant of schwannoma. Staged extracranial and intracranial approaches to these tumors may be necessary.

Neurinoma of the hypoglossal nerve in the submandibular space: case report and review of the literature

Neurinomas of the hypoglossal nerve extending extra-cranially are rare; a schwannoma in a 63-year-old woman causing nerve palsy is reported. The tumour presented as a slow-growing mass in the right submandibular space; a surgical approach with transcervical exploration was performed. The post-operative course was uneventful.

The midline suboccipital subtonsillar approach to the hypoglossal canal: surgical anatomy and clinical application

Primary lesions of the hypoglossal canal, such as hypoglossal schwannomas, are rare. No consensus exists with regard to the surgical approach of choice for treatment of these lesions. Usually, lateral transcondylar approaches have been used. The authors describe the surgical anatomy of the midline subtonsillar approach to the hypoglossal canal. This approach includes a midline suboccipital craniotomy, dorsal opening of the foramen magnum and elevation of ipsilateral cerebellar tonsil to expose the hypoglossal nerve and its canal. The midline subtonsillar approach permits a straight primary intradural view to the hypoglossal canal. There is no necessity of condylar resections. The surgical anatomy of the subtonsillar approach is described and illustrated by an example of a case.

Navigated dorsolateral suboccipital transcondylar (NADOSTA) approach for treatment of hypoglossal schwannoma

Hypoglossal schwannoma is a rare skull base neoplasm, which lies in the midst of extremely complex anatomical structures. We report a 39-year-old man who presented with a history of right glossal hemiatrophy, dysesthesia and weakness of the left extremities. These symptoms were caused by a unilateral hypoglossal schwannoma located at the cranial base. This lesion was exposed through a dorsolateral suboccipital transcondylar approach, which was navigated with the frameless stereotaxy (NADOSTA). We also describe the epidemiology, symptomatology and the diagnosis of hypoglossal schwannoma as well as literature review of the operative approach. By introducing this minimally invasive dorsal surgical approach with neuronavigation in treating hypoglossal schwannoma, we believe that safe exposure and complete tumor resection can be achieved with minimal rate of morbidity.

Dumbbell-shaped hypoglossal schwannoma. A case report

Dumbbell-shaped neuromas of the 12th cranial nerve extending intra- and extracranially are extremely rare. The present paper reports on a 32-year-old patient who presented with hypoglossal nerve palsy and a two-year history of headache. MRI showed inhomogeneous contrast agent enhancement in a tumor that was partly cystic, partly solid, in the cerebellopontine cistern. The tumor, with its main lesion mass located in the parapharyngeal space, extended along the canal of the hypoglossal nerve. The tumor was excised by two-stage suboccipital osteoclastic craniotomy and later through a cervical approach. Pathohistology showed a grade I schwannoma and the patient was discharged symptom-free without any further therapy.

Hypoglossal neurinoma presenting with intratumoral hemorrhage

Focal or microscopic hemorrhage in a neurinoma is common, but tumor origin from the hypoglossal nerve and extensive symptomatic intratumoral hemorrhage are both rare. A 59-year-old male presented with severe neck pain, nausea and vomiting of 1-day duration, accompanied by right hypoglossal nerve palsy. Neuroimaging disclosed a tumor located in the right cerebellomedullary fissure and containing a hematoma. The right hypoglossal canal was slightly dilated. The intracranial tumor was resected via a suboccipital approach. Histological examination demonstrated spindle-shaped tumor cells with nuclear palisading and also relative hypervascularity with hyaline degeneration of the vessels. Extensive hemorrhage was present, as was necrosis. Thickening and hyalinization of arterial walls, a common occurrence in neurinomas, may have contributed to symptomatic intratumoral hemorrhage.

Diagnosis and radiologic manifestations of malignant dumbbell tumors of the parotid gland: review and 2 case reports

Primary malignant dumbbell tumors represent a special growth type of deep-lobe parotid neoplasm. Because they are located in an anatomically limited space between the skull base and the mandibular ramus, they do not cause any but a few nonspecific symptoms and may metastasize into the neck or distant organs before the primary tumor has ever been diagnosed. This article describes 2 cases that first presented as asymptomatic carcinoma unknown primary syndrome and were later discovered to be malignant dumbbell tumors of the parotid gland. Because adequate evaluation is essential for the subsequent management, several diagnostic methods available for the differential diagnosis of this tumor are discussed; we compare these according to their relevance to the therapeutic procedure. Magnetic resonance imaging was found to be the most appropriate imaging technique because of its ability to help us better differentiate between tumor and surrounding tissue. Computed tomography and single photon emission computed tomography can help us identify involvement of the skull base and mandibular ramus.

Nonvestibular schwannomas of the brain: a 7-year experience

OBJECTIVE

Nonvestibular schwannomas are uncommon tumors of the brain. Trigeminal nerve schwannomas are the most common of this group, followed by glossopharyngeal, vagal, facial, accessory, hypoglossal, oculomotor, trochlear, and abducens nerve schwannomas, in descending order of frequency. We present a series of nonvestibular schwannomas that were surgically treated during a 7-year period.

METHODS

Forty-six patients with schwannomas of Cranial Nerves V (26 cases), VII (7 cases), IX, X, and XI (9 cases), XII (3 cases), and III (1 case) were microsurgically treated by the senior author (LNS) during a 7-year period, from 1993 to 2000. The clinical presentations, operative approaches, complications, and results were studied.

RESULTS

Forty-five patients underwent gross total tumor resection in the first operation. One patient who had undergone subtotal tumor resection in the initial operation experienced a large recurrence after 4 years, and gross total tumor resection was achieved in the second operation. There were no postoperative deaths. Postoperative morbidity consisted of cerebrospinal fluid leaks for 5 patients (3 patients required a second operation to repair the leak, and 2 patients responded to lumbar drain placement), meningitis for 3 patients (2 cases were aseptic and 1 involved bacterial meningitis, which resolved with antibiotic therapy), vasospasm requiring angioplasty for 1 patient, temporary hemiparesis for 2 patients (who experienced good recoveries), and permanent hemiparesis for 1 patient. New cranial nerve deficits were observed for 24% of patients but were usually partial. The mean follow-up period was 33.3 months (range, 0.2-93 mo). No patient experienced tumor recurrence after complete tumor removal. The patient who experienced regrowth of the tumor did not exhibit recurrence after the second operation. The Karnofsky Performance Scale scores at the latest follow-up examination were 80 or more for 45 patients (98%) and 70 for 1 patient.

CONCLUSION

Nonvestibular schwannomas can be treated via microsurgical excision, with excellent functional results. Recurrence is rare after total tumor excision, although much longer follow-up monitoring is required.