Other Nerve Sheath Tumors of Brain and Spinal Cord.

The three main types of nerve sheath tumors are schwannomas, neurofibromas and perineuriomas. Multiple neurofibromas throughout the body are the hallmark of Neurofibromatosis type 1 (NF1). Spinal nerve sheath tumors are classified in the group of intradural extramedullary spinal cord tumors, in which they are the most common type (25-30%). Their incidence is 3-4 per 1 million people. Spinal schwannomas are encountered sporadically or in the context of Neurofibromatosis type 2, while neurofibromas are typical for patients with Neurofibromatosis type 1. Neurofibromas are composed predominantly of Schwann cells and fibroblasts, alongside which are also found axons, perineurial cells, mast cells and extracellular matrix. Most of the neurofibromas are asymptomatic. Any increase in the size of a neurofibroma or the presence of pain is an indicator of a possible malignant degeneration. Neurofibromas are treated surgically. Neurofibromas involve the whole nerve and cause its fusiform enlargement which makes it impossible to preserve the nerve's functions if complete tumor removal is performed. Hence, such tumors are initially observed. In case of progressive growth, the options are either resection of the tumor and immediate reconstruction with a peripheral nerve graft (e.g., nerve suralis interposition graft) or subtotal removal and follow-up. Malignant peripheral nerve sheath tumors (MPNST) are very rare tumors with incidence of around 1 per 1,000,000 people. MPNST account for 3-10% of all soft-tissue sarcomas. The most common initial symptom of MPNST is a painless mass. Any rapid increase in a subcutaneous mass or rapid onset of symptoms should raise the suspicion of a malignant tumor. In patients with diagnosed NF1, the recent rapid increase in a known lesion should raise the suspicion of malignant degeneration of the lesion and opt for active treatment. In the case of MPNST a wide surgical excision is advocated. The resectability depends greatly on the location of the tumors and varies from around 20% in paraspinal MPNST and reaches 95% in MPNST localized in the extremities. MPNST are a rare disease and should be managed by a multidisciplinary team of neurosurgeons, radiologists and oncologists.

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.

Changes in Cognitive Functioning After Surgical Resection of Language-related, Eloquent-area, High-grade Gliomas Under Awake Craniotomy.

BACKGROUND: Dominant-hemisphere tumors, especially gliomas, as infiltrative tumors, frequently affect cognitive functioning. Establishing a balance between extensive resection, which is proven to result in longer survival, and less extensive resection, in order to maintain more cognitive abilities, is challenging. OBJECTIVE: To evaluate changes in cognitive functioning before and after surgical resection of language-related, eloquent-area, high-grade gliomas under awake craniotomy. METHOD: We provided individuals with newly diagnosed high-grade gliomas of the language-related eloquent areas with the same standard of care, including surgical resection of the glioma using intraoperative sensory-motor and cognitive mapping under awake craniotomy, and the same protocol for chemoradiotherapy. Cognitive functioning was assessed using Addenbrooke's Cognitive Examination-Revised (ACE-R) at four time points (preoperatively, early after surgery, and 3 and 6 months postoperatively). RESULTS: The preoperative evaluation revealed a range of cognitive impairments in 70.7% of the individuals, affecting all of the cognitive subdomains (mostly attention and visuospatial abilities). Overall cognitive functioning (ie, ACE-R score) dropped by 13.5% (P = 0.169) early postoperatively. At the 3-month evaluation, an average of 15.3% (P = 0.182) recovery in cognitive functioning was observed (mostly in verbal fluency: 39.1%). This recovery improved further, reaching 29% (P < 0.001) at the 6-month evaluation. The greatest improvement occurred in verbal fluency: 68.8%, P = 0.001. CONCLUSION: Extensive resection of eloquent-area gliomas with the aid of modern neuroimaging and neuromonitoring techniques under awake craniotomy is possible without significant long-term cognitive sequela.

Combined endonasal and sublabial endoscopic transmaxillary approach to the pterygopalatine fossa and orbital apex.

BACKGROUND: The pterygopalatine fossa (PPF) and inferomedial orbital apex are difficult regions for open neurosurgical access. The traditional extensive anterior approach (transfacial or transmandibular) and lateral/posterolateral (transcranial) approach were used to access the PPF. The combined endonasal and sublabial transmaxillary approach is a less invasive access route for these lesions. In this study, we present the technical and clinical details of our experience with the combined endoscopic endonasal and transmaxillary approach. METHODS: A retrospective analysis of our patients operated on using a combined endoscopic endonasal and transmaxillary approach was done. The preoperative, intraoperative and postoperative images and all the clinical data were evaluated. The accessibility to the area and extent of surgical resection were reviewed. The surgery-related complications and postoperative morbidities were analyzed. The main items of interest were the exposure of the target area and possibility for safe removal. RESULTS: Five patients with pathologies located in the area of the PPF and orbital apex were operated on using the combined endoscopic sublabial and endonasal transmaxillary approach. The technique provided sufficient exposure of the area and allowed for safe removal of the preoperatively determined target in all of the patients. One patient developed dry eye and a neurotrophic corneal ulcer, and another patient developed temporary postoperative facial numbness. In the follow-up, only one patient with skull base chordoma had an asymptomatic tumor regrowth. The other patients had no recurrence or regrowth. CONCLUSIONS: The combined endoscopic sublabial and endonasal transmaxillary approach is a safe and effective method for resection of lesions in the PPF and inferomedial orbital apex.

Feasibility of cervical intramedullary diffuse glioma resection using intraoperative magnetic resonance imaging.

Intraoperative magnetic resonance imaging (iopMRI) actually has an important role in the surgery of brain tumors, especially gliomas and pituitary adenomas. The aim of our work was to describe the advantages and drawbacks of this tool for the surgical treatment of cervical intramedullary gliomas. We describe two explicative cases including the setup, positioning, and the complete workflow of the surgical approach with intraoperative imaging. Even if the configuration of iopMRI equipment was originally designed for cranial surgery, we have demonstrated the feasibility of cervical intramedullary glioma resection with the aid of high-field iopMRI. This tool was extremely useful to evaluate the extent of tumor removal and to obtain a higher resection rate, but still need some enhancement in the configuration of the headrest coil and surgical table to allow better patient positioning.

Microsurgical or radiosurgical management of intracranial cavernomas.

Cranial cavernous malformations (CCMs) constitute a heterogeneous group of lesions that tend to change dynamically over time with related periods of repeated exacerbation and alternating periods of remission. The decision on their management is based on estimating the inherent risk of further morbidity and the risk/benefit related to the particular treatment mode. Incidentally detected CCMs or lesions in asymptomatic patients presenting without major hemorrhage are best followed up. Complete resection of a CCM is the only healing option and is indicated for symptomatic or hemorrhagic lesions. In the large published series 83-92 % of the patients improved or remained unchanged after surgery, with only 8-11 % showing significant deterioration. For most patients, quality of life is improved. Analysis of the risk/benefit ratio for radiosurgery shows that it should not be regarded as an alternative option: It confers limited protection against bleeding and is related to a certain morbidity risk. In the subgroup of patients with symptomatic or hemorrhagic CCMs in locations that preclude surgical resection with acceptable risks, we recommend follow-up. The senior author is following a group of more than 80 such patients, and the vast majority remain free of hemorrhage and symptoms.

Perioperative seizure in patients undergoing brain mapping under awake craniotomy for language-related eloquent region gliomas: a prospective study.

BACKGROUND: Awake craniotomy (AC) is standard of care for lesions of eloquent brain areas. One important complication during AC is occurrence of intraoperative seizure (IOS), reported to occur among 3.4-20% of the patients. In this study, we report our experience with IOS during AC for resection of gliomas of the language eloquent regions and evaluate the predisposing factors and consequences. METHODS: Patients who underwent AC for language related regions of the dominant hemisphere from August 2018 to June 2021 were enrolled. The rate of IOS during AC and relationship between predisposing factors and IOS were evaluated. RESULTS: Sixty-five patients were enrolled (mean age: 44.4±12.5 years). Among 6 patients with IOS (9.2%), only one needed conversion to general anesthesia (GA) due to repeated seizures; while in the remaining 5, AC accomplished successfully despite one seizure attack in the awake phase. Tumor location (especially premotor cortex lesions, P=0.02, uOR:12.0, CI: 1.20-119.91), higher tumor volume (P=0.008, uOR: 1.9, CI: 1.06-1.12) and a functional tumor margin during surgery (P=0.000, uOR: 3.4, CI: 1.47-12.35) were significantly linked with IOS. CONCLUSIONS: Occurrence of IOS was associated with a longer ICU stay after surgery and worse immediate neurological outcome, but had no impact on the late neurological status. IOS can usually be managed during AC without need to converting to GA. Those with larger tumors, frontal premotor lesions and positive brain mapping are susceptible to IOS. Early neurological deterioration observed after IOS, seems to be transient with no major long-term consequence on the neurological outcome.

Sphenoid sinus pyocele after transsphenoidal approach for pituitary adenoma.

Transsphenoidal pituitary adenoma surgery is related to a low morbidity rate. The complications that can occur are classified as intra- and extracranial. The aim of the study is to discuss one group of these complications involving the sphenoid sinus: mucocele and its possible transformation into pyocele. We evaluate clinical presentation, management strategy and the outcome after long-term follow-up presenting an explicative case and a review of the literature. A patient presented to our outpatient clinic 8 months after transsphenoidal surgery for selective removal of a pituitary adenoma because of an acute onset of frontal headache during an airplane travel, fever and pulsating sensation in left eye and ear. MRI revealed a contrast-enhancing lesion in the left inferior portion of the sphenoid sinus. An endonasal endoscopic revision of the sphenoid sinus was performed. After opening of the scar to enter in the left sinus a pyocele was found and treated with drainage and marsupialisation. Development of sphenoid sinus pyocele is an extremely rare postoperative complication of transsphenoidal surgery. This lesion should be taken in consideration in patients presenting with retroorbital headache of acute onset and fever after pituitary surgery. Diagnosis can be suspected on the MRI studies and confirmed by a targeted flexible endoscope examination. Endoscopic drainage with wide opening of the sphenoid sinus and marsupialisation is the treatment of choice to avoid recurrences.

Restorative neurosurgery of the cortex: resections of pathologies of the central area can improve preexisting motor deficits.

Different pathologies such as tumors or focal dysplasias can be removed from eloquent areas without subsequent functional deficits. What has not yet been established is the removal of structural abnormalities in sensorimotor area associated with substantial neurological deficits performed in order to accomplish functional improvement. Neurosurgical resections in highly eloquent areas thus hold promise to open a new field--achievement of functional restitution even in cases with long-standing deficits. We present four exemplary cases where the removal of different structural abnormalities led to an impressive improvement of motor deficits. One patient had bilateral ischemic lesion resulting from perinatal hypoxia, one cavernoma, and two focal cortical dysplasias. All presented with motor or sensorimotor deficits and three had long-standing therapy refractory focal seizures. The extent of safe lesionectomy was determined using fMRI, fiber tracking, and PET studies and performed with intraoperative functional neuronavigation guidance and cortical stimulation. The achievement of the planned amount of resection was verified with an intraoperative MR examination. New persisting neurological deficits after surgery were not registered. One patient had temporary worsening of the right hand weakness that rapidly resolved. One patient was completely seizure free, and in two patients, the seizures' frequency, duration, and severity were significantly reduced. The preoperatively disturbed motor function improved in all four cases in the course of days or weeks. In summary, pathological processes affecting the sensorimotor area may cause focal seizures and/or compromise sensorimotor functions. Lesionectomy may accomplish not only the amelioration of focal seizures but also substantial functional improvement.

Typical 3-D localization of tumor remnants of WHO grade II hemispheric gliomas--lessons learned from the use of intraoperative high-field MRI control.

BACKGROUND: Complete resection of grade II gliomas might prolong survival but is not always possible. The goal of the study was to evaluate the location of unexpected grade II gliomas remnants after assumed complete removal with intraoperative (iop) MRI and to assess the reason for their non-detection. METHODS: Intraoperative MR images of 35 patients with hemispheric grade II gliomas, acquired after assumed complete removal of preoperatively segmented tumor/tumor part, were studied for existence of unexpected tumor remnants. Remnants location was classified in relation to tumor cavity in axial and vertical planes. The relation of remnants to retractor position and to surgeons' visual axis, and the role of neuronavigational accuracy and brain shift, was assessed. RESULTS: Unexpected remnants were found in 16 patients (46%). In 29.2%, the reason was loss of neuronavigational accuracy. In 21%, remnants were in that part of the resection cavity, where the retractor had been placed initially. In 17%, they were deeply located and hidden by the retractor. In 13%, remnants were hidden by the overlapping brain; and in 21%, the reason was not obvious. In 75% of all temporomesial tumors, remnants were posterolateral to the resection cavity. Remnants detection with iopMRI and update of neuronavigational data allowed further removal in 14 of 16 cases. In two cases, remnant location precluded their removal. CONCLUSIONS: Distribution of tumor remnants of grade II gliomas tends to follow some patterns. Targeted attention to the areas of possible remnants could increase the radicality of surgery, even if intraoperative imaging is not performed.

Two step approach for surgical removal of petroclival meningiomas with large supratentorial extension.

The treatment of petroclival meningiomas is still a matter of controversy in literature. In the last decades, many approaches have been introduced. Our strategy for the treatment of such tumors having large supratentorial extension with encasement of the internal carotid artery or compression of optic and oculomotor nerves has evolved in the attempt to improve the outcome. Currently, we favor a surgical technique consisting of two steps. As first step, we perform a retrosigmoid suprameatal approach in order to resect the posterior part of the tumor and obtain brainstem decompression. In the second step, carried out after patient's recovery from the first surgery, we remove the supratentorial portion of the lesion using a frontotemporal craniotomy to achieve the decompression of the optic nerve, oculomotor nerve, and carotid artery. The retrosigmoid suprameatal approach allows for adequate brainstem decompression: the tumor itself creates a surgical channel increasing the accessibility to the lower and upper petroclival surface. Moreover, this route allows for early visualization of cranial nerves in the posterior fossa and safe tumor removal under direct visual control, reducing the risk of postoperative deficits. Via the simple and safe frontotemporal craniotomy, the supratentorial part of the lesion can be removed thus avoiding the need of invasive approaches. We propose a two-stage surgery for treatment of petroclival meningiomas combining two simple routes such as retrosigmoid suprameatal and frontotemporal craniotomy. This approach reflects our philosophy to use simple and less invasive approaches in order to preserve neurological function and a good quality of life of the patient.

Elderly Patients with Frontobasal and Suprasellar Meningiomas: Safety and Efficacy of Tumor Removal via Frontolateral Approach.

OBJECTIVE: Many neurosurgeons prefer conservative treatments in the elderly because of higher rates of mortality and morbidity after surgery. We aim to evaluate safety and efficacy of surgery in elderly patients with frontobasal and suprasellar meningiomas with a simple operative procedure, the frontolateral approach. METHODS: Retrospective analysis was made in consecutive patients with meningiomas operated via frontolateral approach. They were divided into 2 groups: elderly group (age ≥ 65 years) and young group (age < 65 years). Multivariate logistic regression analysis was performed for postoperative complications and Karnofsky Performance Scale score (KPS). RESULTS: The study comprises 128 patients operated over a 19-year period, of which 35 patients were in the elderly group and 93 patients were in the young group. More elderly patients presented with American Society of Anesthesiology (ASA) class II and III (57.1% vs. 43%). Gross resection was achieved in 31 cases in the elderly and 85 cases in young group (88.6% vs. 90.3%, P = 0.17). Postoperative KPS in both groups was improved (85.7% vs. 91.4%, P = 0.18). One death occurred in elderly group (2.9%, P = 0.27). Approach-related and medical morbidity in the elderly group was slightly higher than in the young group without significant difference (respectively, 11.4% and 14.3% vs. 9.7% and 8.6%, P = 0.18). Multivariate logistic regression showed increasing age was not associated with approach-related morbidity (odds ratio [OR]: 1.39, P = 0.53), medical morbidity (OR: 1.94, P = 0.88), and improvement of KPS (OR: 0.32, P = 0.25). CONCLUSIONS: Frontobasal and suprasellar meningiomas in elderly patients can be treated surgically with acceptably low morbidity and mortality rates via the frontolateral approach. Preoperative KPS score ≤60 and ASA classification ≥III predict an unfavorable postoperative outcome.

Imaging features and classification of peritumoral edema in vestibular schwannoma.

BACKGROUND: Peritumoral edema (PTE) is rarely present in patients with vestibular schwannomas (VS). We studied the correlation between radiological tumor characteristics and the presence of edema, describe its magnetic resonance imaging features and classify the different edema patterns. METHODS: We analysed 605 consecutive patients treated for VS at our Institute. PTE was found in 30 patients, studied on fluid attenuated inversion recovery sequences and categorised as involving the brachium pontis, cerebellum and/or brainstem. Tumor volume, shape, surface, internal structure and axis of growth were evaluated and compared to a matched series of 30 patients without PTE. RESULTS: In our population of patients, 5% showed PTE. Edema involved the brachium pontis in 22 cases (88%), cerebellum in 15 (60%) and brainstem in 3 (12%). PTE was classified as mild (one region involved), moderate (two regions) and severe (three regions). Edema was present not only perpendicular to the major tumor growth axis but also parallel to it (91%). The difference between the two groups in regards to tumor shape and surface was not significant. We found no correlation between tumor and edema volumes. CONCLUSIONS: VS can cause PTE, but its incidence is less frequent than in skull base meningiomas. PTE involves most frequently the brachium pontis, followed by the cerebellum and brainstem. Its occurrence correlates with tumor size but not with other radiological VS features. PTE is not always located perpendicular to the major axis of tumor growth, which indicated that the compressive theory proposed for meningiomas is not plausible explanation for its manifestation.

Reliability of intraoperative high-resolution 2D ultrasound as an alternative to high-field strength MR imaging for tumor resection control: a prospective comparative study.

OBJECT: Ultrasound may be a reliable but simpler alternative to intraoperative MR imaging (iMR imaging) for tumor resection control. However, its reliability in the detection of tumor remnants has not been definitely proven. The aim of the study was to compare high-field iMR imaging (1.5 T) and high-resolution 2D ultrasound in terms of tumor resection control. METHODS: A prospective comparative study of 26 consecutive patients was performed. The following parameters were compared: the existence of tumor remnants after presumed radical removal and the quality of the images. Tumor remnants were categorized as: detectable with both imaging modalities or visible only with 1 modality. RESULTS: Tumor remnants were detected in 21 cases (80.8%) with iMR imaging. All large remnants were demonstrated with both modalities, and their image quality was good. Two-dimensional ultrasound was not as effective in detecting remnants<1 cm. Two remnants detected with iMR imaging were missed by ultrasound. In 2 cases suspicious signals visible only on ultrasound images were misinterpreted as remnants but turned out to be a blood clot and peritumoral parenchyma. The average time for acquisition of an ultrasound image was 2 minutes, whereas that for an iMR image was approximately 10 minutes. Neither modality resulted in any procedure-related complications or morbidity. CONCLUSIONS: Intraoperative MR imaging is more precise in detecting small tumor remnants than 2D ultrasound. Nevertheless, the latter may be used as a less expensive and less time-consuming alternative that provides almost real-time feedback information. Its accuracy is highest in case of more confined, deeply located remnants. In cases of more superficially located remnants, its role is more limited.

Prognostic clinical and radiological parameters for immediate facial nerve function following vestibular schwannoma surgery.

OBJECTIVE: The paper aims to define the parameters available before surgery which could predict immediate facial nerve function after excision of a vestibular schwannoma (VS). METHODS: Ninety-nine patients with VS operated consecutively by a single surgeon using an identical surgical technique have been evaluated retrospectively. Data were collected regarding patients' sex, age at onset of symptoms and at surgery, initial symptoms, neurological status at presentation, early post-operative neurological status and complications. The main radiological parameters included in the study were tumour extension pattern, diameters, shape, and volume, as well as extent of bony changes of the internal auditory canal. RESULTS: As the tumour stage and volume increase, facial nerve function is worse after surgery (p < 0.001 and p < 0.05, respectively). Concomitantly, larger extra-meatal tumour diameters in three dimensions (sagittal, coronal and axial) led to worse function (p < 0.01). Anterior and/or caudal tumour extension (p = 0.001 and p = 0.004, respectively) had more significant correlation than posterior and/or cranial extension (p = 0.022 and p = 0.353, respectively). Polycyclic VS had the worst prognosis, followed by the tumours with oval shape. The extent of intra-meatal tumour growth does not correlate with immediate facial nerve outcome. The different angles, lengths and diameters of the internal auditory channel showed no significant correlation with facial nerve outcome. Patients with headache as an initial symptom and those with gait instability and/or pre-operative poor facial nerve function had significantly worse immediate facial nerve outcome. CONCLUSION: Our data suggests that the analysis of the radiological and neurological patient data prior to surgery could give reliable clues regarding the immediate post-operative facial nerve function.

Radiological factors related to pre-operative hearing levels in patients with vestibular schwannomas.

The pathogenetic mechanism of hearing loss in patients with vestibular schwannomas (VS) remains unclear. Our aim was to determine the radiological and clinical parameters that might be related to hearing. The radiological images and charts of 99 patients were reviewed. Image processing software was used to analyse the maximal tumor diameter in three planes; its volume; its extension cranially, caudally, anteriorly and posteriorly; the width and length of the intrameatal tumor portion, its shape and consistency; and the tumor-fundus distance. These parameters were correlated with the patient's pre-operative hearing range. The degree of hearing correlated significantly with the tumor size, volume and coronal diameter, the degree of intrameatal tumor growth, and the distance between the lateral tumor end and the fundus (p < 0.05). No correlation was found regarding tumor extension, shape and consistency, the presence of hydrocephalus, or the extent of erosion of the internal auditory canal. Loss of hearing in the VS appears to be multifactorial. Determining the radiological parameters related to the hearing level can help to clarify the pathophysiological mechanisms involved.

Clivus chordoma in continuity with a large pontine cyst.

Chordomas are tumors commonly of extradural origin associated with bone destruction; their central nervous system invasion has rarely been reported. The authors describe a rare case of a 37-year-old man presenting with a clivial chordoma invading the brainstem with a large pontine cyst. A median suboccipital approach was selected to remove the tumor.

The Significance of Intraoperative Magnetic Resonance Imaging in Resection of Skull Base Chordomas.

BACKGROUND: Skull base chordoma can be a challenging surgical entity because of its invasive nature. OBJECTIVE: In this study, the role of intraoperative magnetic resonance imaging (iMRI) to optimize the resection of skull base chordomas is evaluated. METHODS: We performed a retrospective analysis of operated patients with skull base chordomas in the setting of iMRI. The clinical records, operative notes, radiologic images, tumor volumetry, location of the residual tumor, and surgical outcome were evaluated. RESULTS: Fifteen patients were operated on for resection of skull base chordomas between 2010 and 2017 in our institution. Gross total resection was planned and achieved in 8 patients and partial resection in 7 patients. In 8 patients (53.3%), the preoperatively planned volume of resection was achieved and confirmed in the first iMRI control. In 7 patients, repeated iMRI controls were required to achieve the surgical target. In 3 patients, the tumor residual requiring further resection was located in the clivus and in 4 patients in the intradural space. The improvement of the preoperative deficits showed a significant statistical association with the resection of the intradural component and decompression of the brainstem. CONCLUSIONS: This study shows that iMRI is a safe method for intraoperative assessment of the degree of resection and the volume and location of residual tumor when resecting skull base chordomas. When gross total resection of the tumor is not feasible, iMRI can be a useful tool for targeted tumor resection.

Bilateral malignant melanoma metastases to the internal auditory canal/cerebellopontine angle: surgical management and preservation of function.

Although intracranial metastases of malignant melanomas are common, localization at the cerebellopontine angle (CPA) or in the internal auditory canal (IAC) is rare, and bilateral presentation especially so. We present the case of a 46-year-old Caucasian woman with bilateral IAC/CPA lesions and a prior history of malignant melanoma on the right leg. During preoperative investigations, the presence of the bilateral IAC/CPA lesions along with several radiologically identified lesions along the neural axis led to the suspicion that she had neurofibromatosis Type 2 despite her history of malignant melanoma and the lack of characteristic skin lesions and family history. Histopathological analysis of the resected lesion confirmed the intraoperative diagnosis of bilateral CPA malignant melanoma metastases. Surgical removal of the tumors via the retrosigmoid approach with preservation of normal bilateral facial nerve function and unilateral serviceable hearing, combined with control of the systemic disease, provided this patient with a near-normal quality of life for at least 42 months after the initial diagnosis of melanoma.