Atypical invasion of the temporal bone in vestibular schwannoma

Vestibular schwannomas typically present with erosion of the temporal bone that is limited to the boundaries of the internal auditory canal. Four patients with extensive erosion, excavations, and pseudosatellite defects in the petrous apex are presented. These bony changes extended anteriorly up to the level of the carotid canal. The patients did not have stigmata of neurofibromatosis type 2 and they did not have systemic bony disorders. The tumors did not show any unusual histopathologic changes. Such invasive tumors present an unusual surgical challenge compared to vestibular schwannomas with a more typical pattern of bony erosion. Radiological features and surgical considerations relevant to vestibular schwannomas with this rare presentation are discussed.     

Clinical features of multiple spinal schwannomas without vestibular schwannomas

BackgroundMultiple spinal cord tumors in a single patient are very rare and most often seen in cases of neurofibromatosis and associated disorders. Schwannomatosis, which is characterized by the development of multiple schwannomas without vestibular schwannomas, has been newly defined as a distinct form of neurofibromatosis. The purpose of the present study was to describe and review the clinical and radiological features and the management of patients with multiple spinal schwannomas without vestibular schwannomas.MethodsBetween 1986 and 2016, 19 patients with multiple spinal schwannomas without vestibular schwannoma were diagnosed and treated. Of the 19 patients, 13 were males, and 6 were females. The mean age at the first surgery for spinal schwannoma was 45.2 years old. The mean follow-up period was 123.4 months. The clinical features and radiological findings of the patients with multiple spinal schwannomas were retrospectively reviewed.ResultsAmong the 19 patients, there were more than 140 spinal schwannomas. The most common area of spinal schwannoma was the thoracolumbar-lumbar region. Initial symptoms and chief complaints caused by spinal schwannomas were primarily pain in the trunk or extremities in 17 (89.5%) of 19 patients. More than 60 spinal schwannomas were surgically resected. Multiple spinal surgeries were required in six patients. In all 19 patients, surgical treatment has provided successful relief of symptoms and neurological recovery.ConclusionsSurgical treatment was safe and effective in patients with multiple spinal schwannomas without vestibular schwannomas. After surgery, we recommend that all patients be followed with magnetic resonance imaging to monitor for asymptomatic tumors or detect new tumors early.     

Suboccipital retrosigmoid approach for removal of vestibular schwannomas: facial nerve function and hearing preservation

In this report, we discuss the pertinent bony, arachnoid, and neurovascular anatomy of vestibular schwannomas that has an impact on the surgical technique for removal of these tumors, with the goal of facial nerve and hearing preservation. The surgical technique is described in detail starting with anesthesia, positioning, and neurophysiological monitoring and continuing with the exposure, technical nuances of tumor removal, hemostasis, and closure. Positive prognostic factors for hearing preservation are also highlighted.     

Are Facial Nerve Outcomes Worse Following Surgery for Cystic Vestibular Schwannoma?

Objectives: This study sought to determine explicitly whether postsurgical facial nerve outcomes for patients with a cystic component to a vestibular schwannoma were significantly different from those with a solid tumor. Design: Seventy patients who underwent translabyrinthine surgery for a cystic vestibular schwannoma between May 1981 and the present, and who had complete records in our database, were identified. These were compared with a group of patients with solid tumors matched to the study group on the following parameters: House-Brackmann grade at presentation, tumor size, surgical approach, age. Setting: Regional tertiary referral center. Participants: Adult patients with vestibular schwannomas. Main Outcome Measures: House-Brackmann score 2 years following surgery. Results: No significant difference was found between the two groups. Conclusions: The perceived difference in outcomes between cystic and solid vestibular schwannomas cannot be demonstrated when confounding factors such as tumor size are taken into account.     

Endoscope-controlled removal of intrameatal vestibular schwannomas.

The use of endoscopes for surgery of the cerebellopontine angle tumors is steadily obtaining widespread acceptance. The objective of the present study was a laboratory and clinical evaluation of the safety of the endoscope-controlled microneurosurgical removal of the intrameatal vestibular schwannomas through a retrosigmoid approach. The anatomical investigation was done on formalin-fixed cadaver heads and dry temporal bones. Clinical series included 33 consecutive patients (23 women and 10 men; mean age 50 +/- 15 years). A bayonet-style rigid endoscope with 70 degrees angle of view and 4 mm outer diameter was found to be optimal for observation of the internal auditory canal. Its insertion in the cerebellopontine cistern should be preferably done under control through an operating microscope. Endoscope-controlled manipulations necessitate the use of a special holder system, which provides a stable position of the device and allows bimanual manipulations by the surgeon. A thermographic evaluation did not reveal a significant increase of the local temperature due to use of the endoscope. Use of the endoscope permitted removal of the neoplasm from the most lateral part of the internal auditory canal and identification of the nerve of tumor origin. In total, 28 tumors underwent total removal, and anatomical preservation of the facial nerve was attained in 31 cases. Damage of the facial nerve by the endoscope was met once. In 8 out of 16 patients, who showed serviceable hearing before surgery, this was preserved after tumor removal. In conclusion, endoscope-controlled removal of the intrameatal vestibular schwannomas seems to be a technically feasible, effective and safe procedure. Nevertheless, good equipment and special training are absolutely necessary for attainment of optimal results.     

Recognizing schwannomatosis and distinguishing it from neurofibromatosis type 1 or 2

BACKGROUND DATA: Schwannomatosis has become a newly recognized classification of neurofibromatosis. Although the genetic loci are on chromosome 22, it lacks the classic bilateral vestibular schwannomas as seen in NF-2. We present the surgical treatment of 4 patients with schwannomatosis, including a brother and sister. METHOD: Case 1 presented with multiple progressively enlarging peripheral nerve sheath tumors. Case 4 presented with a trigeminal schwannoma and a vagal nerve schwannoma. Three of 4 patients had spinal intradural, extramedullary nerve sheath tumors. Surgery in all was multistaged and consisted of spinal laminectomies, site-specific explorations, and microsurgical tumor dissection and resection, with intraoperative neurophysiologic monitoring (including somatosensory-evoked and motor-evoked potentials, upper extremity electromyography and intraoperative nerve action potential monitoring, as appropriate). RESULTS: Intraoperatively the schwannomas had cystic and solid features and in all surgical cases the tumors arose from discrete fascicles of sensory nerve roots or sensory peripheral nerve branches. None of the patients experienced neurologic worsening as a result of their resections. Pathologic analysis of specimens from all cases demonstrated schwannoma. CONCLUSIONS: Not all patients with multiple schwannomas of cranial nerve, spinal nerve root, or peripheral nerve origin have NF-1 or NF-2. In schwannomatosis, these lesions are present in the absence of cutaneous stigmata, neurofibromas, vestibular schwannomas, or parenchymal brain tumors. Schwannomas in schwannomatosis can be large, cystic, and multiple. However, the predominant nerve involvement seems to be sensory and discrete fascicular in origin, facilitating microsurgical resection with minimal deficit.     

Management of multiple tumors in neurofibromatosis type 2 patients

Introduction

Neurofibromatosis type 2 is characterized by the presence of bilateral vestibular schwannomas. However, other nervous system tumors may also occur. Therefore, the management of NF2 patients is complex and requires a multidisciplinary discussion in a specialized center.

Management of large and giant vestibular schwannomas

The study was conducted to analyze outcomes following surgical management of large and giant vestibular schwannomas and management options for residual disease. This retrospective case note study includes patients who had undergone microsurgical resection of sporadic, large, or giant vestibular schwannomas from 1986 to 2008. Tumors are classified as large if the largest extracanalicular diameter was 3.5 cm or greater and giant if 4.5 cm or greater. The study included 45 patients (33 large, 12 giant tumors), mean tumor size 4.1 cm. Total excision was achieved in 14 cases (31.1%), near-total in 26 (57.8%), and subtotal in 5 (11.1%). Facial nerve outcome was House-Brackmann Grade I/II in 25 cases (55.6%), III/IV in 16 (35.6%), and V/VI in 4 (8.9%). No recurrence has been detected in those undergoing a complete resection. No residual tumor growth been observed in 15 of 26 who underwent near-total resection (57.7%). Of 11 patients, 10 received further treatment as their residual tumors showed growth. In the subtotal excision group, one patient died, three have demonstrated no growth, and one residual tumor has grown slightly but not required intervention. Optimal management for patients with large or giant vestibular schwannomas has yet to be determined. Management decisions must balance long term function with tumor control.     

Acoustic neuroma

Acoustic neuromas are benign schwannomas that arise from the vestibular portion of the eighth cranial nerve. Small tumors confined to the internal auditory canal may be removed via an extradural subtemporal approach. Tumors that involve the cerebellopontine angle require posterior fossa craniotomy utilizing either the suboccipital or translabyrinthine technique. The choice of surgical approach depends primarily on the size of the tumor, its location, and the status of hearing in the involved ear. Operative mortality is very low. The most common sources of morbidity are hearing loss and facial nerve dysfunction.     

Management of patients with schwannomatosis: report of six cases and review of the literature

BACKGROUND: Schwannomatosis is a rare tumor syndrome characterized by the presence of multiple schwannomas without the stigmata of neurofibromatosis (NF) Type 1 or 2. To better understand the natural history and clinical management of the syndrome, a retrospective review was conducted of patients diagnosed with schwannomatosis over an 11-year period at the University of Pennsylvania Medical Center (UPMC). METHODS: Between 1990 and 2001, 131 patients underwent surgery for resection of spinal or peripheral nerve schwannomas in the Department of Neurosurgery at the University of Pennsylvania Medical Center. Among the 131 patients, there were 6 who had two or more pathologically proven schwannomas without radiographic or clinical evidence of vestibular schwannomas. The hospital charts, clinic notes, radiology films, operative reports, pathology slides, and reports from all 6 patients were retrospectively reviewed. RESULTS: The patient population consisted of 6 patients with a mean age of 48.7 (3 male: 3 female). All patients had enhanced brain magnetic resonance imaging (MRI) scans that were negative for vestibular schwannomas. Ophthalmological and general physical examinations did not reveal any findings suggestive of NF. There was no family history of NF or schwannomatosis. The locations of the schwannomas included intraspinal (multiple sites), paraspinal, brachial plexus, femoral nerve, sciatic nerve, calf, forearm, retroperitoneum, and middle cranial/infratemporal fossa region. The common presenting symptoms included paresthesias, palpable mass, pain, or weakness. All 6 patients underwent surgical resection of symptomatic lesions. CONCLUSIONS: For patients with schwannomatosis, surgery is indicated for symptomatic lesions, while asymptomatic tumors are followed conservatively. Because these patients are at increased risk for developing multiple schwannomas, we recommend regular surveillance and offer genetic counseling even though the pattern of inheritance is unknown.     

Usefulness of Endoscope-Assisted Microsurgery for Removal of Vestibular Schwannomas

The usefulness of endoscope-assisted microsurgical removal of vestibular schwannomas in the internal auditory canal (IAC) was evaluated. Microsurgical removal using the endoscope was done in 28 procedures and microsurgical removal without an endoscope was done in 43 procedures. A retrosigmoid approach was used. The tumor location in the IAC was classified as grade 1 (located up to the mid-portion), 2, 3, or 4 (located up to the fundus with bony destruction) according to the tumor extent, and residual tumor in the IAC was evaluated as grade A (remnant tumor was not observed), B, C, or D (remnant tumor was observed over the mid-portion) according to the extent of remnant tumor. The residual tumor in the IAC was less in the endoscope-assisted group than in the microsurgery group. There was a significant difference only in grade 2, that is, tumor located beyond the mid-portion of the IAC. There was no significant difference in the results of preservation of useful hearing, facial nerve function, and tumor recurrence between the two groups. The benefit of endoscope-assistance microsurgery was shown for those patients whose tumors extended beyond the mid-portion of the IAC but did not reach the fundus.     

Paraspinal plexiform schwannoma of unknown nerve origin: A case report

Introduction and importanceSchwannomas are benign, slow-growing nerve sheath tumors of neoplastic Schwann cells. They are the most common peripheral nerve tumors in adults and are typically discovered incidentally due to their asymptomatic presentation. Despite the fact that most schwannomas are unassociated with a syndrome, their etiology is thought to be related to alterations or loss of the neurofibromatosis type two tumor suppressor gene.Case presentationWe present the case of a fifteen-year-old female who presented with a recurrent lower back/upper buttocks 9 cm mass with imaging suspicious for schwannoma. Needle biopsy revealed an S100 positive cellular schwannoma with patchy Ki-67. During surgical dissection down to the sacrum, no nerve of origin was identified.Clinical discussionSchwannomas have no pathognomonic findings on MRI and may occur at any location that Schwann cells are present; therefore, confirming a diagnosis relies on histopathology. Plexiform schwannomas are defined by a “network-like” intraneural growth pattern and are exceedingly rare in paediatric populations. A location distinct from the spinal canal is also very rare as schwannomas typically originate from the head and neck region.ConclusionPaediatric plexiform schwannomas have been rarely reported. Surgical planning relies on multiple factors such as tumor size, tumor location, pathologic features and symptomatic burden. The distinctive features of this case including an unknown nerve origin and a location outside the spinal canal provide a unique opportunity to discuss the diagnosis and management of paraspinal schwannomas and the impact on operative planning when a nerve of origin is not identified.     

Multiple schwannomas: report of two cases

In this paper authors present two cases of multiple schwannomas without the features of neurofibromatosis (NF). The authors retrospectively reviewed the hospital charts, radiology films, operative notes and pathology slides of these two patients. There was no family history of neurofibromatosis. The two patients had contrast enhanced MRI, which was negative for vestibular schwannomas. Both underwent surgical excision of symptomatic lesions. Histopathology confirmed these lesions as schwannomas. Molecular genetic analysis in case 1 demonstrated two distinct mutations of the NF2 gene in two different schwannomas, with concomitant loss of heterozygosity in both tumours. In contrast peripheral blood lymphocytes did not reveal mutations of NF2. The authors recommend surgery for symptomatic lesions. Asymptomatic tumours can be monitored. Regular follow up is essential as they may develop fresh lesions at any time. The relevant literature is discussed.

     

A parturient with neurofibromatosis type 2: anesthetic and obstetric considerations for delivery

Neurofibromatosis type 2 is an extremely rare form of neurofibromatosis characterized by central nervous system involvement with bilateral vestibular schwannomas and spinal tumors. Anesthetic management of a parturient with neurofibromatosis type 2 has not been fully reported, and the condition is challenging to obstetric anesthesiologists due to the presence of intracranial and intraspinal canal neurofibromas. We present a case of neurofibromatosis type 2 referred for delivery. Because of central neuraxial involvement, regional anesthesia was avoided, and the patient delivered by cesarean section under general anesthesia. The importance of pre-operative diagnosis and multidisciplinary management for neurofibromatosis type 2 is emphasized and anesthetic and obstetric considerations for delivery are presented.     

Trigeminal schwannomas: removal of dumbbell-shaped tumors through the expanded Meckel cave and outcomes of cranial nerve function

OBJECT: As in patients with vestibular schwannomas, advances in surgical procedures have markedly improved outcomes in patients with trigeminal schwannomas. In this article the authors address the function of cranial nerves in a series of patients with trigeminal schwannomas that were treated with gross-total surgical removal. The authors emphasize a technique they use to remove a dumbbell-shaped tumor through the expanded Meckel cave, and discuss the advantage of the extradural zygomatic middle fossa approach for total removal of tumor and preservation or improvement of cranial nerve function. METHODS: Within an 11-year period (1989-2000), 25 patients (14 female and 11 male patients with a mean age of 44.4 years) with benign trigeminal schwannomas were surgically treated by the senior author (O.A.) with the aim of total removal of the tumor. Three patients had undergone previous surgery elsewhere. Trigeminal nerve dysfunction was present in all but two patients. Abducent nerve paresis was present in 40%. The approach in each patient was selected according to the location and size of the lesion. Nineteen tumors were dumbbell shaped and extended into both middle and posterior fossae. All 25 tumors involved the cavernous sinus. The zygomatic middle fossa approach was particularly useful and was used in 14 patients. The mean follow-up period was 33.12 months. In patients who had not undergone previous surgery, the preoperative trigeminal sensory deficit improved in 44%, facial pain decreased in 73%, and trigeminal motor deficit improved in 80%. Among patients with preoperative abducent nerve paresis, recovery was attained in 63%. Three patients (12%) experienced a persistent new or worse cranial nerve function postoperatively. Fifth nerve sensory deficit persisted in one of these patients, sensory and motor dysfunction in another, and motor trigeminal weakness in the third patient. In all patients a good surgical outcome was achieved. One patient died 2 years after treatment from an unrelated cause. In three patients the tumors recurred after an average of 22.3 months. CONCLUSIONS: Preservation or improvement of cranial nerve function can be achieved through total removal of a trigeminal schwannoma, and skull base approaches are better suited to achieving this goal. The zygomatic middle fossa approach is particularly helpful and safe. It allows extradural tumor removal from the cavernous sinus, the infratemporal fossa, and the posterior fossa through the expanded Meckel cave.     

Acoustic intrameatal meningiomas

BACKGROUND: The sporadic finding of an acoustic intrameatal meningioma stimulated the authors to the present study. An analysis of the cases previously reported in the literature aimed to outline a preliminary account about biological, radiological and surgical specific hallmarks of these tumours. METHODS: Eight previous cases of meningiomas, meeting the prerequisite of origin and situation within the internal acoustic canal, have been discovered in the known literature since 1975. A further case was recently observed in our experience. The cases in the series showed no sex prevalence and in most of them the age of incidence was comprised between the fifth and sixth decade of life. Hearing loss was the prevalent symptom, lasting 1 month to 7 years before presentation. Myelocisternography, myelo-CT or high resolution CT/MR revealed no specific radiological features to distinguish small intrameatal meningiomas from the more frequently occurring vestibular schwannomas, while CT scan with bone algorithm could point out valuable indirect details for differential diagnosis. Various surgical approaches, i.e. middle fossa, translabyrinthine and retromastoid, were utilized by the different authors. RESULTS: Basing on apparent individual surgical preference, one of three different surgical routes (translabyrinthine, middle fossa, retromastoid) was chosen for 10 procedures in 9 patients. In all, except two cases the impression at surgery was of complete tumour removal. CONCLUSIONS: The possibility for meningiomas to recur and invade the surrounding bone requires a differential diagnosis from vestibular schwannomas. In the absence of intrinsic distinctive signs, radiological evaluation of peritumoral bone alterations could help diagnosis. Although the various surgical routes have often proved effective, temporal bone invasion justifies more extensive approach even in small tumours.     

Greater petrosal nerve schwannomas—analysis of four cases and review of the literature

Schwannomas arising from the greater petrosal nerve (GPN) are exceedingly rare: only 10 such cases have been reported in the English literature. We report on four cases of GPN schwannomas and discuss the surgical approach for their removal. Four patients with GPN schwannomas underwent surgery at Keio University Hospital. We present the pre- and postoperative clinical findings and describe the structures around the GPN schwannomas as observed during the surgery. Histological sections were performed around the GPN using Masson’s trichrome stain to elucidate the membrane structures. Three patients presented with xerophthalmia, and one with facial palsy, hearing disturbance, and generalized convulsions. Contrast-enhanced magnetic resonance images revealed tumors in the temporal lobe. Bone-window computed tomography showed erosion of the anterior petrous apex. During the operation, the temporal lobe was retracted epidurally. The tumors were visible inside the interdural space and covered with the epineurium. In three cases, the tumors were completely removed, and in one case, the tumor was subtotally removed with intraoperative facial monitoring. In the histological sections, we confirmed that the GPN ran within the interdural space. Approaching epi- and interdurally is suitable for the removal of GPN schwannomas because the GPN is located within the interdural space. The advantage of this approach is that the landmark points can be identified. Moreover, the possibility of injuring the temporal lobe is low because the temporal lobe is not exposed in this approach.     

Long-term outcomes in patients with vestibular schwannomas treated using gamma knife surgery: 10-year follow up

OBJECT: Gamma knife surgery (GKS) has been a safe and effective treatment for vestibular schwannomas in both the short and long term, although less is known about long-term outcomes in the past 10 years. The aim of this study was to clarify long-term outcomes in patients with vestibular schwannomas treated using GKS based on techniques in place in the early 1990s. METHODS: Eighty patients harboring a vestibular schwannoma (excluding neurofibromatosis Type 2) were treated using GKS between May 1991 and December 1993. Among these, 73 patients were assessed; seven were lost to follow up. The median duration of follow up was 135 months. The mean patient age at the time of GKS was 56 years old. The mean tumor volume was 6.3 cm3, and the mean maximal and marginal radiation doses applied to the tumor were 28.4 and 14.6 Gy, respectively. Follow-up magnetic resonance images were obtained in 71 patients. Forty-eight patients demonstrated partial tumor remission, 14 had tumors that remained stable, and nine demonstrated tumor enlargement or radiation-induced edema requiring resection. Patients with larger tumors did not fare as well as those with smaller lesions. The actuarial 10-year progression-free survival rate was 87% overall, and 93% in patients with tumor volumes less than 10 cm3. No patient experienced malignant transformation. CONCLUSIONS: Gamma knife surgery remained an effective treatment for vestibular schwannomas for longer than 10 years. Although treatment failures usually occurred within 3 years after GKS, it is necessary to continue follow up in patients to reveal delayed tumor recurrence.     

Cystic versus solid vestibular schwannomas: a series of 80 grade III–IV patients

Cystic acoustic neuromas are less frequent than solid ones and present different clinical and radiological features. Cystic schwannomas are larger, show a shorter clinical history and a different risk of postoperative complications. This study was designed to compare surgical results and complications of solid and cystic vestibular schwannomas of matching size operated upon via either a retrosygmoid or a translabyrinthine approach. The study included 80 patients presenting with grade III and IV acoustic vestibular schwannomas referred to the Neurosurgical and ENT team in the Department of Neuroscience of Torino, Italy. Twenty-six were cystic and 54 were solid tumours. Clinical history, surgical results and complications were compared between the two groups. In cystic tumors, rapid clinical worsening is common, due to sudden expansion of cystic elements. Tighter adherences are found between cystic tumours and nervous elements (particularly brainstem and possibly facial nerve), once compared to solid ones. Operative morbidity appears to be higher in cystic tumours. A wait and see policy should not to be applied to patients with cystic tumours. Careful technique, possibly sharp dissection, to divide the tumour adherences from the nervous tissue must be employed, in order to avoid lesions on brainstem veins and traction on a thin facial nerve. Severe complications may be caused by the excessive efforts to dissect brainstem adherences.     

Prevention of cerebrospinal fluid leakage and delayed loss of preserved hearing after vestibular schwannoma removal: reconstruction of the internal auditory canal in the suboccipital transmeatal approach--technical note

The suboccipital transmeatal approach uses packing of a muscle or fat graft into the internal auditory canal (IAC) to prevent postoperative cerebrospinal fluid (CSF) leakage. However, preserved hearing after removal of vestibular schwannomas may decline over time because of the progressive constriction of cochlear vascular supply due to scarring of the IAC. We propose a surgical technique for IAC reconstruction, which separates the preserved cochlear nerve and vasculature from the graft, and regains the CSF space in the IAC. Prior to the drilling of the posterior wall of the IAC, the dura mater of the petrous bone forming the posterior wall of the IAC is harvested for IAC reconstruction. After completion of tumor removal, a "roof" of the IAC is reconstructed using the dura mater, and a muscle or fat graft soaked with fibrin glue is placed on the "roof" of the IAC. The IAC was reconstructed using this technique in 26 consecutive patients with vestibular schwannomas who underwent tumor removal via the suboccipital transmeatal approach. Postoperative magnetic resonance imaging confirmed the regained CSF space in the IAC. No delayed hearing loss occurred in four patients with preserved hearing. No CSF leakage occurred after surgery. This new technique of IAC reconstruction may prevent delayed hearing loss as well as postoperative CSF leakage after removal of vestibular schwannomas via the suboccipital transmeatal approach.