Cerebellopontine Angle Meningioma Research Articles

Gamma Knife stereotactic radiosurgery for cerebellopontine angle meningioma

ObjectiveMeningiomas comprise 6–15 % of cerebellopontine angle (CPA) tumors. Surgical treatment is a real challenge because this area is occupied by several critical neurovascular elements. Currently, surgery is the first choice of treatment, however several factors may be present that necessitate choosing the alternative treatments such as Gamma Knife Stereotactic Radiosurgery (GKS). Patients and MethodsNinety-three patients with CPA meningioma who were treated by GKS for a period of 8 years, were retrospectively reviewed. Factors affecting clinical and radiological improvement were analyzed. ResultsThe median tumor volume was 6 cm3. The mean values for maximal and marginal dose were 20.2 and 13.6 Gy, respectively. The mean follow-up time was 31.5 months. Tumor control (lack of progression) was achieved in 96.8% of the patients and 55.9% of the patients showed tumor regression on follow-up MRI. The actuarial 3-year progression-free survival (PFS) rate was 96%. Clinical improvement was seen in 49.5% of the patients while 11.8% experienced worsening or new-onset symptoms. Adverse radiation effects were seen in 4.3% of the patients. A worse symptomatic outcome, male sex, a lower tumor coverage, and marginal doses <13.5 Gy were associated with worse radiologic outcomes. Worse radiologic outcomes and higher tumor volumes, especially tumor volumes ≥8.5 cc, were associated with worse symptomatic outcomes. The male sex was associated with a lower PFS. ConclusionGamma Knife radiosurgery, either primarily or post- operatively, offers a decent long-term tumor control in CPA meningioma, and is associated with an acceptable complication profile, especially in tumors with lower volumes.

Impact of cochlear modiolus dose on hearing preservation following stereotactic radiosurgery for non-vestibular schwannoma neoplasms of the lateral skull base: a cohort study.

Radiation dose to the cochlea has been proposed as a key prognostic factor in hearing preservation following stereotactic radiosurgery (SRS) for vestibular schwannoma (VS). However, understanding of the predictive value of cochlear dose on hearing outcomes following SRS for patients with non-VS tumors of the lateral skull base (LSB) is incomplete. The authors investigated rates of hearing loss following high-dose SRS in patients with LSB non-VS lesions compared with patients with VS. Patients with LSB meningioma or jugular paraganglioma and serviceable pretreatment hearing who underwent SRS treatment during 2007-2016 and received a modiolus dose > 5 Gy were included in a retrospective cohort study, along with a similarly identified control group of consecutive patients with sporadic VS. Sixteen patients with non-VS tumors and a control group of 43 patients with VS met study criteria. Serviceable hearing, defined as American Academy of Otololaryngology-Head and Neck Surgery class A/B, was maintained in 13 non-VS versus 23 VS patients (81% vs 56%, p = 0.07). All 3 instances of hearing loss in non-VS patients were observed in cerebellopontine angle (CPA) meningiomas. Non-VS with preserved hearing had a median modiolus dose of 6.9 Gy (range 5.7-19.2 Gy), versus 7.4 Gy (range 5.4-7.6 Gy) in those patients with post-SRS hearing loss (p = 0.53). Sporadic VS patients received an overall median modiolus point-dose of 6.8 Gy (range 5.4-11.7 Gy). The modiolus dose threshold of 5 Gy does not predict hearing loss in patients with non-VS tumors undergoing SRS, suggesting that dosimetric parameters derived from VS may not be applicable to this population. Differential rates of hearing loss appear to vary by pathology, with paragangliomas and petroclival meningiomas demonstrating decreased risk of hearing loss compared to CPA meningiomas that may directly compress the cochlear nerve similarly to VS.

Probabilistic Tractography to Predict the Position of Cranial Nerves Displaced by Skull Base Tumors: Value for Surgical Strategy Through a Case Series of 62 Patients

Predicting the displacement of cranial nerves by tumors could make surgery safer and the outcome better. Recent advances in imaging and processing have overcome some of the limits associated with cranial nerve tractography, such as spatial resolution and fiber crossing. Among others, probabilistic algorithms yield to a more accurate depiction of cranial nerve trajectories. To report how cranial nerve probabilistic tractography can help the surgical strategy in a series of various skull base tumors. After distortion correction and region of interest seeding, a probabilistic tractography algorithm used the constrained spherical deconvolution model and attempted the reconstruction of cranial nerve trajectories in both healthy and displaced conditions. Sixty-two patients were included and presented: vestibular schwannomas (n=33); cerebellopontine angle meningiomas (n=15); arachnoid or epidermoid cysts (n=6); cavernous sinus and lower nerves schwannomas (n=4); and other tumors (n=4). For each patient, at least one 'displaced' cranial nerve was not clearly identified on classical anatomical MRI images. All 372 cranial nerves were successfully tracked on each healthy side; among the 175 cranial nerves considered 'displaced' by tumors, 152 (87%) were successfully tracked. Among the 127 displaced nerves of operated patients (n=51), their position was confirmed intraoperatively for 118 (93%) of them. Conditions that led to tractography failure were detailed. On the basis of tractography, the surgical strategy was adjusted for 44 patients (71%). This study reports a cranial nerve probabilistic tractography pipeline that can: predict the position of most cranial nerves displaced by skull base tumors, help the surgical strategy, and thus be a pertinent tool for future routine clinical application.

Tumor Control and Cranial Nerve Outcomes After Adjuvant Radiosurgery for Low-Grade Skull Base Meningiomas

We evaluated the tumor control and cranial nerve (CN) outcomes after adjuvant stereotactic radiosurgery (SRS) for petroclival, cavernous sinus, and cerebellopontine angle meningiomas. From our prospectively maintained database of 2022 patients with meningioma who had undergone Leksell SRS during a 30-year interval, we found 43 patients with petroclival, 94 with cavernous sinus, and 13 patients with cerebellopontine angle meningiomas who had undergone adjuvant SRS after surgical resection of the meningioma. The patients included in the present report had had ≥1 CN deficit at the initial presentation and a minimum follow-up period of 12 months. The median age at SRS was 54 years (range, 22-81). SRS was performed for residual tumor in 104 patients (69%) and recurrent tumor in 46 patients (31%). The median tumor volume treated with SRS was 8.1 cm3 (range, 0.3-42), and the median margin dose was 13 Gy (range, 10-20). Tumor control was achieved in 135 patients (90%) at a median follow-up point of 75 months. The progression-free survival rate after SRS was 99.5% at 1 year, 98% at 3 years, 95% at 5 years, and 90% at 10 years. Overall, 29 of the 150 patients (19%) reported improvement in CN function. Deterioration in CN function after SRS developed in 15 patients (10%). The rate of deterioration was 3.5% at 1 year, 5.5% at 3 years, and 7% at 5 years. Adjuvant SRS provides effective tumor control and a low rate of new or worsening CN deficits.

Retrosigmoid Transmeatal Approach with 360-Degree Drilling of the Internal Auditory Canal for the Resection of Intracanalicular Meningioma.

Introduction Vestibular schwannomas are the most common lesions occupying the internal auditory canal (IAC); however, almost in 4 to 5% of meningiomas, metastases, cysts, lipomas, and cavernous malformations have been found in this location, mimicking schwannomas. Even though cerebellopontine angle (CPA) meningiomas with the involvement of the IAC are frequently encountered, the presence of a primary intracanalicular meningioma is rare. Objective To show the technical nuances of the retrosigmoid-transmeatal approach to successfully achieve gross total resection (GTR) with preservation of facial and auditory function. Case Report We present a left intracanalicular meningioma on a 60-year-old man with history of tinnitus and hearing loss. Magnetic resonance imaging (MRI) showed a left intracanalicular lesion completely obliterating the IAC and with minor extension to the CPA cistern, with the vestibulocochlear complex dislocated posteriorly, initially diagnosed as a Hannover's T2 vestibular schwannoma. The patient underwent a left retrosigmoid approach, and during the exposure of the lesion, the diagnosis of a meningioma became evident. The transmeatal phase of the approach was modified with a wide opening of the canal, including the anterior wall. Closure was performed using a muscle graft, duramater flap, and fibrin glue. Results GTR was achieved and the patient developed a mild facial palsy (House–Brackmann grade III) which completely recovered within 3 months. Conclusions The retrosigmoid transmeatal approach is suitable to achieve GTR in intracanalicular meningiomas. Some modifications of the approach intended for vestibular schwannomas are necessary and may be performed during the procedure. The link to the video can be found at: https://youtu.be/A9OXRFIl1e8 .

Endoscopic Resection of a Cerebellopontine Angle Meningioma via a Retrosigmoid Approach.

A variety of lesions may arise within the cerebellopontine angle (CPA). Schwannomas and meningiomas are most commonly found in this location. Imaging characteristics of meningiomas include hyperdensity on head computed tomography (CT) and avid contrast enhancement on T1-weighted postcontrast magnetic resonance imaging (MRI). Here, we present the case of a 49-year-old woman with enlarging right CPA meningioma. The patient reported mild hearing loss on the right but her neurological exam was otherwise benign. Since the lesion was enlarging and symptomatic, the patient was offered resection of the mass for diagnosis and treatment via an endoscopic retrosigmoid approach. We provide a video that illustrates the steps taken to resect this mass endoscopically. After cerebrospinal fluid (CSF) was drained to achieve brain relaxation, the tumor was visualized. The tumor had a rich vascular supply and had the appearance of a typical meningioma. The bipolar was used to cauterize the tumor's vascular supply. The tumor capsule was then opened with the microscissors. The round knife, suction, and ultrasonic tissue debrider were used to debulk the tumor. After internal debulking of the tumor, the capsule was dissected off the cerebellum and mobilized. A combination of blunt and sharp dissection was done to free the tumor capsule from the adjacent structures. Inferiorly, the lower cranial nerves were visualized. Tissue pathology confirmed a diagnosis of grade I meningioma. A gross total resection was achieved and the patient remained neurologically stable, postoperatively. Furthermore, T1-weighted postcontrast brain MRI, 1 year after surgery, showed no residual. The link to the video can be found at: https://youtu.be/X9c_inLp-So .

Resection of Cerebellopontine Angle Meningioma via Retrosigmoid Approach Aiming for Hearing Improvement.

We present a 71-year-old female case of left cerebellopontine angle (CPA) meningioma who presented with progressive hearing loss. The tumor was 35 mm in maximum diameter, obviously compressed the brain stem and cerebellum, and also displaced cranial nerves 7th and 8th anteriorly ( Fig. 1 ). Retrosigmoid approach was chosen to resect the tumor aiming for hearing improvement. We performed dissection of the tumor from cranial nerves 7th and 8th gently and resection of the tumor except for the part adhesive to these cranial nerves ( Fig. 2 ). Postoperative course was good without any new neurological deficit. Postoperative examination also showed improvement of high-frequency hearing of the left side, and auditory brainstem response demonstrated wave 2 to 5, which was not identify on preoperative examination. These procedures enabled safe and effective resection of the tumor and contributed to hearing improvement. The link to the video can be found at: https://youtu.be/hkRSCxtV3bY .

Microsurgical Resection of Cerebellopontine Angle Meningioma.

Meningiomas of the cerebellopontine angle (CPA) are the second most frequent lesions related to this region (around 10–15%), 1 being the vestibular schwannomas the first (around 85%). This lesions arise from the dura of the petrosal surface of the temporal bone, lateral to the trigeminal nerve ( Fig. 1 ). Variable attachment sites and directions of growth make different clinical presentations and operative challenges. This pathologies can be classified accordingly to they're extension related to the internal acoustic meatus in: postmeatal, premeatal, and large meningiomas with pre- and postmeatal extension ( Fig. 2 ). We present an operative video performed by the senior author (L.A.B.B.). A 64-year-old woman with 3 months of complaint of left facial pain on the V2 territory of the trigeminal nerve and diplopia secondary to VI nerve paresis. Magnetic resonance imaging (MRI) scans demonstrated a large homogeneous enhancing lesion at the left CPA, extending pre- and postmeatal and from the tentorium cerebeli to the jugular foramen region, highly suggestive of CPA meningioma. Surgery was offered to the patient as a first option. In our point of view, neurophysiological monitoring with somatosensory and motor evoked potentials is mandatory while dealing with such large tumors around the CPA. The surgery was performed after a standard retrosigmoid craniotomy, with careful dissection and debulking while devascularizing the tumor from its petrosal attachment. Near-total resection was achieved and the patient had a remarkable postoperative outcome with improvement of the diplopia and facial pain with preservation of VII and VIII nerves function. The pathology demonstrated a grade 1 meningioma. The link to the video can be found at: https://youtu.be/UVVyEhq8Fu0 .

Hearing preservation after Gamma Knife radiosurgery for cerebellopontine angle meningiomas

OBJECTIVEThe objective of this study was to assess hearing function after Gamma Knife treatment of cerebellopontine angle (CPA) meningiomas and assess factors affecting hearing outcome. Additionally, the authors opted to compare these results with those after Gamma Knife treatment of vestibular schwannomas (VSs), because most of the information on hearing outcome after stereotactic radiosurgery (SRS) comes from reports on VS treatment. Hearing preservation, to the best of the authors' knowledge, has never been separately addressed in studies involving Gamma Knife radiosurgery (GKRS) for CPA meningiomas.METHODSThis study included all patients who underwent a single session of GKRS between 2002 and 2014. The patients were divided into two groups. Group A included 66 patients with CPA meningiomas with serviceable hearing and tumor extension into the region centered on the internal auditory meatus. Group B included 144 patients with VSs with serviceable hearing. All patients had serviceable hearing before treatment (Gardner-Robertson [GR] Grades I and II). The median prescription dose was 12 Gy (range 10-12 Gy) in both groups. The median follow-up of groups A and B was 42 months (range 6-149 months) and 49 months (range 6-149 months), respectively.RESULTSAt the last follow-up, the tumor control rate was 97% and 94% in groups A and B, respectively. Hearing preservation was defined as maintained serviceable hearing according to GR hearing score. The hearing preservation rate was 98% and 66% and the 7-year actuarial serviceable hearing preservation rate was 75% and 56%, respectively, between both groups. In group A, the median maximum cochlear dose in the patients with stable and worsened hearing grade was 6.3 Gy and 5.5 Gy, respectively. In group B, factors affecting hearing preservation were cochlear dose ≤ 7 Gy, follow-up duration, and tumor control. The only determinant of hearing preservation between both groups was tumor type.CONCLUSIONSGKRS for CPA meningiomas provides excellent hearing preservation in addition to high tumor control rate. Hearing outcome is better with CPA meningiomas than with VSs. Further long-term prospective studies on determinants of hearing outcome after GKRS for CPA meningiomas should be conducted.

Preservation of cranial nerve function following awake surgery for benign brain tumors in 22 consecutive patients

BackgroundPreservation of cranial nerve function in patients with benign tumors such as meningiomas and vestibular schwannomas remains difficult following microsurgery. MethodsIn this study, awake surgery was performed in 22 consecutive patients with meningiomas or vestibular schwannomas that compressed cranial nerves (I–XII). Improved, unchanged, or deteriorated cranial nerve function after surgery was evaluated. ResultsThe function of 44 cranial nerves in 22 consecutive patients who underwent awake surgery for meningiomas or vestibular schwannomas improved, was unchanged, or deteriorated in eight, 35, and one nerves, respectively. Regarding the function of the olfactory (Ist) nerve, which is difficult to preserve, hyposmia improved after surgery in two patients with olfactory groove meningiomas. Regarding the auditory (VIIIth) nerve, which is also difficult to preserve, the function was improved, unchanged, or deteriorated after surgery in two, 11, and one patients, respectively, with cerebello-pontine angle meningiomas or vestibular schwannomas. In all patients with serviceable auditory function before surgery, function was preserved after surgery. In the same patients, the function of the facial (VIIth) nerve was also preserved after surgery in all patients. ConclusionsThese results suggest that awake surgery for benign brain tumors such as meningiomas and vestibular schwannomas is associated with low patient morbidity regarding cranial nerve function.

Suboccipital Lateral Approach for Resection of Cerebellopontine Angle Meningioma: Operative Video and Technical Nuances.

We present the case of a 34-year-old woman, who presented to our department with a 4 months history of dizziness, hearing loss, and tinnitus on the right side. MRI (magnetic resonance imaging) scan demonstrated a large extra-axial lesion, suggestive of a meningioma, with dural attachments to the petrosal bone surface and tentorium, closely related with the trigeminal, abducens, facial, vestibulocochlear, and lower cranial nerves in the right side. Treatment options were discussed with the patient, and surgical resection was selected to remove the lesion, and decompress the cranial nerves and brainstem. The surgery was performed with a patient in a semi-seated position with head placed in a flexed, nonrotated position. A right lateral suboccipital approach was performed, exposing the right transverse and sigmoid sinuses. After dura opening, microsurgical dissection was used to open the cisterna magna, and obtain cerebellum relaxation. That was followed by identification of cranial nerves VII–XII and then identification of the tumor itself. Tumor debulking was then performed with use of suction and ultrasonic aspirator. After extensive resection, the tumor margins were dissected away from brainstem, cerebellum, and cranial nerves. Finally, the tumor attachment to the tentorium was coagulated and cut and the tumor was completely removed. Postoperative MRI confirmed complete resection of the tumor. The patient was discharged on the 1st week after surgery, with no additional postoperative deficits or complications. The link to the video can be found at: https://youtu.be/aZ3jhZTAeAA .

Gross Total Resection of Large Cerebellopontine Angle Meningioma with a Supratentorial Extension via Retrosigmoid Approach with Suprameatal Drilling and Tentorial Sectioning.

Meningiomas are the second most common neoplasm in the cerebellopontine angle (CPA), and are challenging lesions to treat surgically. With significant refinements in surgical techniques, operative morbidity, and mortality have been substantially reduced. Total or near-total surgical resection can be accomplished in the majority of cases via appropriately selected approaches, and with acceptable morbidity. In this video, we present a 51-year-old woman, who had a 2-year history of vertigo with symptoms that progressed over time. She presented with blurry vision, sensorineural hearing loss, tinnitus, left-sided facial numbness, and double vision. Magnetic resonance imaging (MRI) showed a left-sided homogeneously enhancing mass at CPA with a supratentorial extension. MRI appearance was consistent with a CPA meningioma with supratentorial extension. The patient underwent surgical resection via a retrosigmoid approach. Suprameatal drilling and tentorial sectioning were necessary to achieve gross total resection. The surgery and postoperative course were uneventful. The histopathology was a WHO (world health organization) grade I meningioma. MRI showed gross total resection of the tumor. After a 1.5-year follow-up, the patient is continuing to do well with no residual or recurrent disease. In this video, microsurgical techniques and important steps for the resection of this challenging meningioma of the cerebellopontine angle are demonstrated. The link to the video can be found at: https://youtu.be/CDto52GxrG4 .

Incidence and Risk Factors for Sigmoid Venous Thrombosis Following CPA Tumor Resection.

Our primary aim was to determine the incidence of sigmoid venous thrombosis (SVT) and determine risks factors and sequelae of SVT following cerebellopontine angle tumor resection. Retrospective cohort study. Academic tertiary care hospital. Patients over 18 years of age who underwent resection of cerebellopontine angle meningioma or vestibular schwannoma from January 2005 to April 2016 who had postoperative magnetic resonance imaging. Diagnostic. Incidence of postoperative sigmoid venous thrombosis (SVT) from official radiology reports was compared with retrospective imaging review by our institutional neuroradiologists. Data collected included age, length of stay, body mass index, surgical approach, and postoperative complications. A total of 127 patients were identified. Official radiology reads significantly underreported the incidence of postoperative SVT compared with retrospective review by our institutional neuroradiologist for patients who underwent routine postoperative imaging (n = 4 [3.1%] versus n = 22 [17.3%]; p < 0.001). There was a statistical trend toward increased risk for thrombosis in patients undergoing translabyrinthine and staged resection that did not reach significance (p = 0.068). Cerebrospinal fluid (CSF) leak incidence in patients with thrombosis was significantly increased (n = 9 [37.5%] versus n = 13 [12.6%]; p = 0.007). When controlling for approach, the presence of thrombus was associated with a more then three-fold increase in odds of CSF leak (OR = 3.28, 95% CI: 1.12-9.48, p = 0.030). There was no correlation between SVT and age (p = 0.788), body mass index (p = 0.686), length of stay (p = 0.733), preoperative tumor size (p = 0.555), or increased postoperative ICP (p = 0.645). Only one patient was symptomatic from sigmoid thrombosis compared with 21 who were not. Incidence of SVT is significantly underreported and may predispose patients to increase risk for CSF leak. Staged and translabyrinthine approaches demonstrate an increased trend toward thrombosis risk. Our findings suggest it may not be necessary to treat asymptomatic SVT.

Cranial nerve outcomes after primary stereotactic radiosurgery for symptomatic skull base meningiomas.

To evaluate cranial nerve (CN) outcomes after primary stereotactic radiosurgery (SRS) for petroclival, cavernous sinus, and cerebellopontine angle meningiomas. From our prospectively maintained database of 2022 meningioma patients who underwent Leksell stereotactic radiosurgery (SRS) during a 30-year interval, we found 98 patients with petroclival, 242 with cavernous sinus, and 55 patients with cerebellopontine angle meningiomas. Primary radiosurgery was performed in 245 patients. Patients included in this report had at least one CN deficit at the time of initial presentation and a minimum of 12month follow up. Median age at the time of SRS was 58years. Median follow up was 58months (range 12-300months), Median tumor volume treated with SRS was 5.9cm3 (range 0.5-37.5cm3), and median margin dose was 13Gy (range 9-20Gy). Tumor control was achieved in 229 patients (93.5%) at a median follow up of 58months. Progression free survival rate (PFS) after SRS was 98.7% at 1 year, 96.4% at 3 years, 93.7% at 5 years, and 86.4% at 10years Overall, 114 of the 245 patients (46.5%) reported improvement of CN function. Patients with CP angle meningiomas demonstrated lower rates of CN improvement compared to petroclival and cavernous sinus meningioma patients. Deterioration of CN function after SRS developed in 24 patients (10%). The rate of deterioration was 2.8% at 1 year, 5.2% at 3 years, and 8% at 10years. Primary SRS provides effective tumor control and favorable rate of improvement of preexisting CN deficit.

Extended Retrosigmoid Approach for Cerebellopontine Angle Meningiomas: Operative Technique and Results-A Series of 28 Patients.

Background The purpose of this article is to describe our approach, surgical strategies, and results for resection of meningiomas located at cerebellopontine angle (CPA). Methods We retrospectively identified 28 patients with CPA meningiomas operated by the extended retrosigmoid approach. This approach incorporates a generous mastoidectomy and the sigmoid sinus exposure. Results The mean age was 33.8 years, with a follow-up of 12.5 years. Gross total removal (GTR) was achieved in 22 (78.5%) patients with low surgical mortality, acceptable morbidity, and recurrence rate of 7.1% (2 patients). Conclusion The extended retrosigmoid approach enhances the exposure of the CPA and posterior fossa cisterns and increases the surgical angle of maneuverability. This approach provides adequate access even to extensive CPA meningiomas, enabling, in most of cases, GTR to be safe and effective. The extended retrosigmoid approach used in this group of patients is an alternative to more extensive cranial base approaches.

Hypertensive Brainstem Encephalopathy Mimicking Peritumoral Edema after Gamma Knife Radiosurgery for Cerebellopontine Angle Meningioma: A Case Report

An 83-year-old man presented with hypertensive brainstem encephalopathy manifesting as general weakness, dysarthria, gait disturbance, urinary incontinence, and decreased cognitive function. The patient had a history of gamma knife radiosurgery (GKR) for cerebellopontine angle (CPA) meningioma 10 years prior. Compared with previous magnetic resonance (MR) imaging results, a recent MR image revealed massive brainstem hyperintensity in T2-weighted images, not in the parieto-occipital lobes. The lesions were nearly completely resolved several days after normalization of the blood pressure. Isolated hypertensive brainstem encephalopathy without concomitant typical parieto-occipital abnormalities are unusual and the diagnosis is challenging especially after gamma knife radiosurgery for cerebellopontine angle meningioma. We describe a patient with hypertensive brainstem encephalopathy that was initially confused with peritumoral edema.

The Use of Semitranslucent Rubber Pledgets During Microsurgical Dissection of Cerebellopontine Angle Tumors: Technical Note.

Dissection of cerebellopontine angle (CPA) tumors that abut or adhere to the brainstem or cranial nerves can be a challenging surgical endeavor. We describe the use of semitranslucent latex rubber pledgets in the tumor-brain interface as a method to improve visualization and protection of vital tissue during microsurgical dissection of CPA masses. The rubber pledgets are fashioned by cutting circular discs out of the cuff portion of talc-free, partially opaque latex gloves. These pledgets provide a semitranslucent, nonadherent membrane that can be placed between vital neural tissues and a tumor capsule to minimize trauma during dissection. The semitranslucent latex enables visualization of the underlying anatomical structures while also providing a protective surface onto which a suction device can be rested to facilitate clearance of the surgical field. A 56-yr-old woman with left ear tinnitus presented with a 3-cm CPA meningioma. During microsurgical dissection, rubber pledgets were used to preserve the interface between the brain stem, cranial nerves, and tumor capsule. The use of the rubber pledgets appeared to secure the interface between to tumor and the brain while at the same time protecting the cranial nerves, brainstem, and cerebellum. Semitranslucent rubber pledgets may facilitate microsurgical dissection of CPA tumors.

Level Specific CE-Chirp® BAEP's: A new faster technique in neuromonitoring cochlear nerve during cerebello-pontine angle tumor surgery

Abstract Background Level Specific (LS) CE-Chirp® Brainstem Auditory Evoked Potentials (BAEP's) are the most recent evolution of classical Click BAEP's, performed both in clinical studies and in intraoperative neuromonitoring (IONM) of acoustic pathways during several neurosurgical procedures. LS CE-Chirp® is a new group of acoustic stimuli, latter evolution of Broadband CE-Chirp®, designed by Claus Elberling to provide faster recording of larger amplitude BAEP's V waves in infants. While the original Broadband CE-Chirp® was conceived for optimal response amplitude of V wave at low and medium stimulation intensities, the LS CE-Chirp® provides clearer I–III–V waves at high intensities. Material and method We report a consecutive series of 31 cases in which the new LS CE-Chirp® BAEP's were performed during different skull base surgery procedures during the last 24 months: 25 vestibular schwannomas, 3 cerebello-pontine angle (CPA) meningiomas and 3 CPA epidermoid tumors. Results Using LS-CE-Chirp® BAEP's monitoring, neurosurgeon was alerted in 10–15 s about variation of conduction parameters of acoustic pathways. At the end of surgery, BAEP's were normal in 11 patients, showed deconstructed waves in 14, and elongated waves in 6. At a minimum clinical and BAEP's follow-up of 6 months, hearing function was preserved in 19 cases (61,3%). Conclusions We herein confirm that LS CE-Chirp® BAEP's provide a fast feedback to surgeons regarding acoustic pathways function, helping them during skull base tumor removal in the attempt to hearing preservation when it is socially useful in the preoperative evaluation.

Retrosigmoid transmeatal and suprajugular approach for cerebellopontine angle meningioma: operative video.

Surgical management of cerebellopontine angle meningiomas is challenging due to the intricate neurovascular structures within the limited operative field and the compression of eloquent structures including the brainstem. Surgery on tumors extending into the temporal bone is especially difficult and demands complicated approaches. However, modifications to the retrosigmoid approach utilizing intradural temporal bone drilling enable access to such tumoral extensions without any additional invasive approaches. This video demonstrates the case of a cerebellopontine angle meningioma extending into the internal acoustic meatus and jugular foramen that was surgically treated through the retrosigmoid transmeatal and suprajugular approaches under continuous vagus nerve monitoring. The video can be found here: https://youtu.be/aUD1vr6TbOc .

Cerebellopontine angle meningioma extending into internal auditory canal presenting with unilateral facial weakness and sensorineural hearing loss: Case presentation with review of literature

Tumour types other than schwannomas are uncommonly encountered in the cerebellopontine angle, and unusual lesions extending into the internal auditory canal are even rarer. We herein present a case of a 50-year-old woman with a right cerebellopontine angle meningioma (measuring 34mm x 35mm x 36mm), arising from the posterior surface of the petrous bone or the petrotentorial junction, secondarily involving the internal auditory canal. Contrast enhanced MRI showed typical appearance of a meningioma, with calcifi ed fl at surface against the petrous bone, a hemispheric or ice-cream-cone shape sign, adjacent hyperostosis, and ‘dural tail’ extending from the tumour. Initial clinical evaluation revealed continued presence of a stable neurological defi cit such as unilateral headache, hearing loss, reduced taste sensation, positive corneal and conjunctival refl ex along with right facial weakness (House-Brackmann grade III) signalling towards the involvement of V, VII and VIII cranial nerve. The variation in the anatomy of the faciocochlear nerve bundle in relation to the tumour has to be kept in mind, and preservation of these vital neural structures should be the goal in every case. Tumour resection was performed through a suboccipital-retrosigmoidal approach with a good outcome. Ours is an unusual case report analysing the diagnostic and therapeutic issues, surgical management strategies and treatment outcomes related to this rare disease entity.Journal of Kathmandu Medical College Vol. 5, No. 1, Issue 15, Jan.-Mar., 2016, Page: 34-40