Prevention of Cerebrospinal Fluid Leakage in the Anterior Transpetrosal Approach.

Background: The anterior transpetrosal approach (ATPA) is effective for reaching petroclival lesions, and it allows for complications such as impaired venous return and neuropathy to be resolved. However, there is still room for improvement regarding cerebrospinal fluid (CSF) leakage. Here, we aim to focus on describing specific preoperative, intraoperative, and postoperative countermeasures for preventing CSF leakage when using the ATPA. Methods: Eleven patients treated using the ATPA, who were treated at our hospital from June 2019 to February 2023, were included in this descriptive study. Preoperatively, we performed a 3D simulation of the opened air cells. Then, we classified patterns of dural closure into three types based on intradural manipulation and whether it involved opened air cells or not. Intraoperatively, we performed a dural closure that included the use of more-watertight sutures (DuraGen®) and an endoscope. Furthermore, temporal bone air cell volume measurements were performed to confirm the correlation between the volume and factors related to CSF leakage. Results: No postoperative CSF leakage was observed in any patient. The temporal bone air cell volumes significantly corelated with the air cells of the petrous apex, the high-risk tract in the petrous apex, and postoperative fluid collection in mastoid air cells. Conclusions: We have described countermeasures for preventing CSF leakage when using the ATPA. Preoperative simulations and the use of multiple-layered dural reconstructions with endoscopes could be considered more reliable methods for preventing CSF leakage when using the ATPA.

The historical adventures of Takeshi Kawase: the mountaineer who explored the "no man's land" with love for art, nature, and humankind.

The anterior petrosal approach, or Kawase's approach, is a commonly used technique in skull base surgery to access the brainstem in the posterior fossa from the middle fossa, and has the advantages of minimizing brain retraction and preserving hearing. It was first successfully performed by the legendary Japanese neurosurgeon, Takeshi Kawase, for the clipping of a basilar artery aneurysm in 1981. To date, no historical article has shed light on Kawase's intriguing personal history. In this historical vignette, the authors depict Kawase's unique background, talent, passion, as well as struggles that ultimately shaped his career. By sharing Kawase's personal story from the hospital where he first successfully performed his original approach, the authors hope to pass on to future generations Kawase's spirit and philosophy that have impacted the global neurosurgical community.

Anterior transpetrosal approach and the tumor removal rate, postoperative neurological changes, and complications: experience in 274 cases over 33 years.

OBJECTIVE: The authors report on the anterior transpetrosal approach (ATPA) and the results of surgeries performed over a 33-year period for petroclival tumors, including meningioma, trigeminal schwannoma, chordoma, and epidermoid tumor. They analyze early postoperative neurological changes, surgical complications, and trends over the decades. METHODS: A retrospective analysis of 274 surgical cases that had undergone the ATPA from January 1984 to March 2017 was conducted. Data were collected from charts, clinical summaries, operative records, and operative videos. The analyzed parameters included patient diagnosis, tumor size, disease location, operation date, tumor removal rate, pre- and postoperative neurological symptoms (consciousness level, motor and sensory deficits of the limbs, sensory aphasia, and cranial nerve III-VIII injuries), surgical deaths, and radiologically recognized brain injuries after the operation (contusion, infarction, hemorrhage). RESULTS: Gross-total resection (GTR) was achieved in 53.5% of the 243 tumors with available data. The GTR rate for meningiomas (148 cases) was 54.1%. Trigeminal schwannomas had a high GTR rate of 87.1%, whereas chordomas had a low GTR rate of 14.3%. The rate of early neurological deterioration immediately after the ATPA, referred to as "early neurological change," was as follows: consciousness disturbance in 1.9% of cases (5 cases), improvement of hemiparesis in 45.0% of cases but deterioration in 8.1% of cases, sensory aphasia in 2.3% of cases due to temporal lobe injury, improvement of cerebellar symptoms in 39.3% of cases with rare deterioration (1.9% of cases), worsening of preoperative diplopia in 49.4% of patients and rarely improving, improvement of trigeminal symptoms in 19.1% of cases (mostly trigeminal neuralgia) among the 43.7% of patients who had them preoperatively, and deterioration of facial hypesthesia and/or paresthesia in 27.4% of cases. Early neurological deterioration was monitored in 183 patients for 6 months to determine the surgical complications of ATPA. Consciousness disturbance recovered in half of the cases but persisted in 3 (1.5%). Hemiparesis fully recovered in 63.2% of cases, resulting in a complication rate of 3.0%. The most frequent complication was diplopia (36.4%), with a complete remission rate of 26.4%. The second most frequent complication was facial hypesthesia (24.0%), with a recovery rate of 16.1%. Facial nerve palsy improved in 63.0% of cases and had a complication rate of 4.9%. Cerebellar symptoms showed complete recovery in all cases. CONCLUSIONS: The ATPA allows the removal of petroclival tumors extending into Meckel's cave and the middle fossa, making it preferred for dumbbell trigeminal schwannomas and meningiomas. However, the ATPA's aggressive tumor removal can risk a lower recovery of cranial nerve IV-VI deficits. For benign meningiomas, initial observation with regular follow-up is recommended. Surgery is appropriate for high-growth cases aiming for total removal, accompanied by a thorough explanation of the risks. If the risks are not accepted, subtotal removal can be considered, and radiosurgery is suggested for residual tumor.

Simplified anterior transpetrosal approach without superior petrosal sinus and tentorial incision for lesions centered in Meckel's cave.

OBJECTIVE: The anterior transpetrosal approach (ATPA) is an effective method to reach lesions in the petroclival region. This approach involves many steps, including superior petrosal sinus (SPS) ligation and tentorial cutting. It is sometimes unnecessary to perform all procedures in the ATPA for certain lesions, especially those centered in the Meckel's cave. Here, we present a simplified anterior transpetrosal approach (SATPA) without superior petrosal sinus and tentorial incision for lesions centered in the Meckel's cave as a modified ATPA. METHODS: This study included 13 patients treated with SATPA. The initial steps of SATPA are similar to ATPA, excluding a middle cranial fossa dural incision, SPS dissection, or tentorial incision. Histological examination was performed to understand the membrane structure of the trigeminal nerve, which runs through the Meckel's cave. RESULTS: Pathology revealed trigeminal schwannoma (n=11), extraventricular central neurocytoma (n=1), and a metastatic tumor (n=1). The average tumor size was 2.4 cm. The total removal rate was 76.9% (10/13). Permanent complications included trigeminal neuropathy in four cases and cerebrospinal fluid leakage in one case. Histological examination revealed the trigeminal nerve traverses the subarachnoid space from the posterior fossa subdural space to the Meckel's cave and is covered with the epineurium in the inner reticular layer. CONCLUSIONS: We used SATPA for lesions located in the Meckel's cave identified using histological examination. This approach may be considered for small- to medium-sized lesions centered in the Meckel space. CLINICAL TRIAL REGISTRATION NUMBER: None.

A case of subarachnoid and intracerebral hemorrhages complicated by trichosporonosis.

Background: Trichosporonosis has an extremely poor prognosis. In this report, we describe a case of subarachnoid hemorrhage and intracerebral hemorrhage due to a fungal aneurysm caused by Trichosporon. Case Description: A 71-year-old woman who experienced subcortical hemorrhage developed a subarachnoid hemorrhage. Endovascular parent artery occlusion was performed for a fungal aneurysm in the left posterior cerebral artery caused by Trichosporon. After surgery, voriconazole and liposomal amphotericin B were administered. The patient died of massive left putamen hemorrhage. Conclusion: Effective treatment for intracranial hemorrhage due to trichosporonosis has not yet been established and an accumulation of cases is required.

Meningiomas Involving the Hypoglossal Canal: A Case Report and Literature Review.

We report a rare case of hypoglossal canal meningioma in a 65-year-old woman who presented with dysphagia. Neurological examination revealed left hypoglossal nerve palsy. Head computed tomography and magnetic resonance imaging revealed a lesion around the left hypoglossal canal. She underwent a total resection with a midline suboccipital transcondylar approach. There were no postoperative complications, and the hypoglossal nerve palsy improved. There was no recurrence nine months after the surgery. Choosing a surgical approach that considers the site of origin and extent of tumor extension is important.

Descending musculospinal branch of the ascending pharyngeal artery as a feeder of carotid body tumors: Angio-architecture and embryological consideration.

INTRODUCTION: Although the ascending pharyngeal artery (APhA) is known as a main feeder of carotid body tumors (CBTs), its detailed architecture and embryological consideration have not been described. The objective of this study was to describe the architecture of a descending feeder of the APhA and to consider its origin embryologically through a review of our CBT embolizations. METHODS: We retrospectively analyzed data from patients with CBTs who underwent transarterial embolization or angiographic examination-only between July 2010 and February 2017. The arterial supply of the tumors, the number of feeder pedicles, the mean tumor size, embolization materials, complication of embolization, and extent of tumor removal were assessed. The embryological origin of feeding artery was considered based on the literature. RESULTS: Eighteen patients with 20 CBTs underwent preoperative embolization or angiographic examination. The number of feeder pedicles was significantly related to the size of the CBT (P = 0.0002). The main feeding artery was the descending branch of APhA, which was hypertrophied and tortuous (18/20, 90%). Embryologically, this artery originated from the musculospinal branch and is termed the "descending musculospinal branch". CONCLUSION: The main feeder of the CBTs was the "descending musculospinal branch" of the APhA and needs special consideration such as dangerous anastomosis for embolization.

Bridging vein and tentorial sinus in the subtemporal corridor during the anterior transpetrosal approach.

BACKGROUND: The bridging vein (BV) and the tentorial sinus (TenS) are important venous structures in neurological surgery. These venous structures during the anterior transpetrosal approach (ATPA) have not been reported. The objective of this study is to examine the BV and the TenS in the subtemporal corridor during the ATPA and propose a technique to identify the BV preoperatively. METHODS: This study included 126 patients treated via the ATPA. The BV and the TenS located in the operative fields were analyzed. Furthermore, in the preoperative evaluation, the cross-sectional shapes of the intradural vein and the interdural sinus were analyzed by curved planar reconstruction (CPR), and the flattening rate was calculated. Flattening rate = (a-b)/a = 1-b/a (a: long radius, b: short radius). RESULTS: Seventeen BVs and 18 TenS were identified. The bridging site was divided into two groups: tentorial and middle fossa. The middle fossa group was divided into three subgroups: cavernous sinus, middle fossa dural sinus, and middle fossa dural adherence. Five isolated TenS were sacrificed and no venous complications were observed. The mean flattening rate was 0.13 in the intradural vein and 0.51 in the interdural sinus, respectively (P = 0.0003). CONCLUSIONS: We showed classification of the BV, and preservation of the BV and TenS during the ATPA. Furthermore, we found that the interdural sinus was significantly flatter than the intradural veins. Measuring the flattening rate by CPR may be useful to identify BVs preoperatively.

A Pilot Study of Vaccine Therapy with Multiple Glioma Oncoantigen/Glioma Angiogenesis-Associated Antigen Peptides for Patients with Recurrent/Progressive High-Grade Glioma.

High-grade gliomas (HGGs) carry a dismal prognosis despite current treatments. We previously confirmed the safety and immunogenicity of a vaccine treatment targeting tumor angiogenesis with synthetic peptides, for vascular endothelial growth factor receptor (VEGFR) epitopes in recurrent HGG patients. In this study, we evaluated a novel vaccine therapy targeting not only tumor vasculature but also tumor cells, using multiple glioma oncoantigen (GOA)/glioma angiogenesis-associated antigen (GAAA) peptides in HLA-A2402+ recurrent/progressive HGG patients. The vaccine included peptide epitopes from four GOAs (LY6K, DEPDC1, KIF20A, and FOXM1) and two GAAAs (VEGFR1 and VEGFR2). Ten patients received subcutaneous vaccinations. The primary endpoint was the safety of the treatment. T-lymphocyte responses against GOA/GAAA epitopes and treatment response were evaluated secondarily. The treatment was well tolerated without any severe systemic adverse events. The vaccinations induced immunoreactivity to at least three vaccine-targeted GOA/GAAA in all six evaluable patients. The median overall survival time in all patients was 9.2 months. Five achieved progression-free status lasting at least six months. Two recurrent glioblastoma patients demonstrated stable disease. One patient with anaplastic oligoastrocytoma achieved complete response nine months after the vaccination. Taken together, this regimen was well tolerated and induced robust GOA/GAAA-specific T-lymphocyte responses in recurrent/progressive HGG patients.

A pilot study of peptide vaccines for VEGF receptor 1 and 2 in patients with recurrent/progressive high grade glioma.

OBJECT: Early-phase clinical studies of glioma vaccines have shown feasibility and encouraging preliminary clinical activity. A vaccine that targets tumor angiogenesis factors in glioma microenvironment has not been reported. Therefore, we performed a pilot study to evaluate the safety and immunogenicity of a novel vaccination targeting tumor angiogenesis with synthetic peptides for vascular endothelial growth factor (VEGF) receptor epitopes in patients with recurrent/progressive high grade gliomas. METHODS: Eight patients received intranodal vaccinations weekly at a dose of 2mg/kg bodyweight 8 times. T-lymphocyte responses against VEGF receptor (VEGFR) epitopes were assessed by enzyme linked immunosorbent spot assays. RESULTS: This treatment was well-tolerated in patients. The first four vaccines induced positive immune responses against at least one of the targeted VEGFR epitopes in the peripheral blood mononuclear cells in 87.5% of patients. The median overall survival time in all patients was 15.9 months. Two achieved progression-free status lasting at least 6 months. Two patients with recurrent GBM demonstrated stable disease. Plasma IL-8 level was negatively correlated with overall survival. CONCLUSION: These data demonstrate the safety and immunogenicity of VEGFR peptide vaccines targeting tumor vasculatures in high grade gliomas.

Metabolic heterogeneity and plasticity of glioma stem cells in a mouse glioblastoma model.

Background: Glioblastomas have been shown to rely on glycolysis as an energy source. However, recent evidence suggests that at least a subset of glioma cells with stem cell-like properties can thrive on oxidative phosphorylation. It remains unclear whether both metabolic phenotypes support tumor propagation, if they are independent, and how stable they are. The present study investigated these questions with the use of isogenic murine glioma stem cells (GSCs). Methods: GSCs were established from tumors formed by Ink4a/Arf-null, H-RasV12-expressing glioma-initiating cells that differed in extracellular acidification potential. Metabolic characteristics of GSCs were determined by measurement of glucose, oxygen, and glutamine uptake, ATP content, and lactate production. Effects of metabolic inhibitors and changes in oxygen or nutrient availability on lactate production and tumorsphere growth were also determined. Results: GSCs were found either to consume more glucose and produce more lactate or to consume more oxygen and maintain a higher ATP content depending on the metabolic characteristics of the tumor cells of origin. The latter, mitochondrial-type GSCs increased lactate production after treatment with the oxidative phosphorylation inhibitor oligomycin or phenformin. Exposure to hypoxia also increased lactate production and expression of glycolysis-related enzymes and metabolites in mitochondrial-type GSCs in a reversible manner. Conclusions: Both glycolytic and mitochondrial-type energy production can sustain tumor propagation by isogenic GSCs. Whereas both phenotypes can be independent and stable, cells that rely on oxidative phosphorylation can also switch to a more glycolytic phenotype in response to metabolic stress, suggesting that plasticity is a further characteristic of GSC metabolism.

Organotypic brain explant culture as a drug evaluation system for malignant brain tumors.

Therapeutic options for malignant brain tumors are limited, with new drugs being continuously evaluated. Organotypic brain slice culture has been adopted for neuroscience studies as a system that preserves brain architecture, cellular function, and the vascular network. However, the suitability of brain explants for anticancer drug evaluation has been unclear. We here adopted a mouse model of malignant glioma based on expression of H-RasV12 in Ink4a/Arf-/- neural stem/progenitor cells to establish tumor-bearing brain explants from adult mice. We treated the slices with cisplatin, temozolomide, paclitaxel, or tranilast and investigated the minimal assays required to assess drug effects. Serial fluorescence-based tumor imaging was sufficient for evaluation of cisplatin, a drug with a pronounced cytotoxic action, whereas immunostaining of cleaved caspase 3 (a marker of apoptosis) and of Ki67 (a marker of cell proliferation) was necessary for the assessment of temozolomide action and immunostaining for phosphorylated histone H3 (a marker of mitosis) allowed visualization of paclitaxel-specific effects. Staining for cleaved caspase 3 was also informative in the assessment of drug toxicity for normal brain tissue. Incubation of explants with fluorescently labeled antibodies to CD31 allowed real-time imaging of the microvascular network and complemented time-lapse imaging of tumor cell invasion into surrounding tissue. Our results suggest that a combination of fluorescence imaging and immunohistological staining allows a unified assessment of the effects of various classes of drug on the survival, proliferation, and invasion of glioma cells, and that organotypic brain slice culture is therefore a useful tool for evaluation of antiglioma drugs.

Intraspinosum Middle Meningeal Artery Ligation: A Simple Technique to Control Bleeding in the Middle Fossa During the Anterior Transpetrosal Approach.

BACKGROUND: Although the greater superficial petrosal nerve (GSPN) is an important landmark of the anterior transpetrosal approach (ATPA), bleeding from the interdural space around the foramen spinosum (FS), the GSPN, and the foramen ovale impedes the identification of the GSPN, during epidural dissection in the ATPA. OBJECTIVE: To describe the technique of intraspinosum middle meningeal artery (MMA) ligation, which enables us to control bleeding from the interdural space. METHODS: During epidural dissection, we identified the FS and partially drilled the lateral side of the FS. Next, we cut the convergence site of the neurovascular structures such as the MMA, middle meningeal vein, and the meningeal branch of the mandibular nerve with the periosteal dura within the FS and continued dural detachment epidurally to expose the petrous apex. Bleeding control around the FS and postoperative facial nerve paresis were assessed for 96 patients treated with the ATPA. Additionally, histological study was performed around the FS using Masson's trichrome stain. RESULTS: In all cases, in which this technique was used, bleeding from the interdural space was well controlled and no persistent facial nerve paresis was identified. In the histological study, we confirmed that the MMA, the middle meningeal vein, and the meningeal branch of the mandibular nerve converged into the FS and many venous channels existed in the interdural space around the FS and the foramen ovale. CONCLUSION: Intra-FS MMA ligation is an effective method for control of bleeding from the interdural space of the middle fossa during the ATPA.

Chronic Encapsulated Intracerebral Hematoma: Endoscopic Removal as Minimally Invasive Surgery for a Patient with Alcoholic Cirrhosis.

Chronic encapsulated intracerebral hematoma (CEIH) is a rare cerebrovascular disease. Here, we describe a case of a patient with alcoholic cirrhosis and an abnormal coagulation state that was treated with minimally invasive endoscopic hematoma removal. A 54-year-old man presented with a 2-week history of incoherent speech, incontinence, and repeated stumbling. Laboratory analysis showed thrombocytopenia and the prolongation of prothrombin time due to alcoholic cirrhosis. Computed tomography and magnetic resonance imaging showed a large mass in the left parieto-occipital lobe suggesting a hematoma. Minimally invasive endoscopic hematoma removal was then performed. CEIH was diagnosed from the intraoperative findings of serous hematoma, a thin yellowish capsule, and old clots. The postoperative course was uneventful and there was no hematoma recurrence. In conclusion, endoscopic hematoma removal may be one of the options for the treatment of CEIH in patients with cirrhosis and an abnormal coagulation state.

The Trigeminocardiac Reflex During the Anterior Transpetrosal Approach.

OBJECTIVE: The anterior transpetrosal approach (ATPA), during which the trigeminal nerve (TN) is manipulated, has a risk of eliciting the trigeminocardiac reflex (TCR). The aim of this study was to assess the risk of TCR during ATPA. METHODS: Surgical records of 92 patients who had surgical treatment via ATPA at the Keio University Hospital between December 2005 and June 2015 were retrospectively analyzed. Patients were divided into 2 groups on the basis of the occurrence of TCR during surgery, and clinical and tumor characteristics were compared. Tumor characteristics were evaluated based on preoperative images and intraoperative findings and included the side of the lesion, size of the lesion, tumor size in Meckel cave, pathology of the disease, cavernous sinus invasion, extension into Meckel cave, and adhesion of lesion to TN. RESULTS: TCR was observed in 14 of 92 patients (15.2%). TCR occurrence was significantly related to Meckel cave tumor size (P = 0.0264) and adhesion of the lesion to TN (P = 0.0002). CONCLUSIONS: This study suggests that TCR is related to Meckel cave tumor size and tumor adhesion to TN in ATPA. To our knowledge, this is the first report describing TCR during ATPA.

Delayed and isolated oculomotor nerve palsy following minor head trauma.

BACKGROUND: The purpose of this study was to consider the mechanism of isolated oculomotor nerve palsy after minor head trauma. CASE DESCRIPTION: We report a rare case of delayed and isolated oculomotor nerve palsy following minor head trauma. A 19-year-old boy complained of double vision 1 day after a minor head trauma. Neuro-ophthalmic examination showed isolated left oculomotor nerve palsy. Computed tomography and magnetic resonance imaging examination revealed no abnormal findings and steroid therapy was administered for a week. Three months after the injury, the ptosis and extraocular movements had fully resolved, although the pupillary light reflex was still abnormal. CONCLUSIONS: Delayed and isolated oculomotor nerve palsy may be caused by an injury at the point where the oculomotor nerve runs over the posterior petroclinoid ligament. Because edema of the damaged oculomotor nerve might result in constriction at the point where the nerve pierces the dura of the cavernous sinus, symptoms of oculomotor nerve palsy appeared late after trauma. Steroid treatment reducing edema could be effective for delayed and isolated oculomotor nerve palsy following minor head trauma.

Prechiasmatic transection of the optic nerve in optic nerve glioma: technical description and surgical outcome.

Optic pathway glioma (OPG) encompasses a spectrum of findings ranging from lesions confined to the optic nerve only, lesions affecting the optic chiasm and hypothalamus, and lesions with diffuse involvement of a large part of the optic pathway and neighboring structures. The majority of pediatric low-grade astrocytomas in the optic/chiasmatic region are typical pilocytic astrocytoma. The rest of them (10 %) may be other gliomas such as fibrillary pilomyxoid astrocytoma (grade 2 WHO). The postsurgical local recurrence rate of 55 to 76 % has been reported in some histological subtypes such as pilomyxoid astrocytoma (grade 2). Performing a prechiasmatic transection might offer a new surgical option to avoid further tumor growth toward the chiasm in the optic nerve glioma with predominantly orbital manifestations. In this retrospective study, four patients (three children, two without neurofibromatosis type 1 (NF1), and one with NF1 and one adult without NF1) with optic nerve glioma without involvement of the chiasm but blindness, disfiguring proptosis, and pain of the affected eye were included. The surgical approach was performed as a combined approach from pterional extradural and intradural. Without any exceptions, vision of the contralateral eye could be preserved and did not show any deterioration after surgery or during the follow-up time between 17 and 106 months. Furthermore, in all patients, gross total tumor resection could be achieved. During follow-up observation in all patients, no further tumor progress or recurrences could be observed. None of the patients were treated postoperatively by radiotherapy or chemotherapy. Prechiasmatic transection of the optic nerve in optic nerve glioma without affecting the chiasm might offer a surgical treatment option to control tumor growth and to preserve vision of the contralateral eye.

Pathological Location of Cranial Nerves in Petroclival Lesions: How to Avoid Their Injury during Anterior Petrosal Approach.

Objectives Numerous surgical approaches have been developed to access the petroclival region. The Kawase approach, through the middle fossa, is a well-described option for addressing cranial base lesions of the petroclival region. Our aim was to gather data about the variation of cranial nerve locations in diverse petroclival pathologies and clarify the most common pathologic variations confirmed during the anterior petrosal approach. Method A retrospective analysis was made of both videos and operative and histologic records of 40 petroclival tumors from January 2009 to September 2013 in which the Kawase approach was used. The anatomical variations of cranial nerves IV-VI related to the tumor were divided into several location categories: superior lateral (SL), inferior lateral (IL), superior medial (SM), inferior medial (IM), and encased (E). These data were then analyzed taking into consideration pathologic subgroups of meningioma, epidermoid, and schwannoma. Results In 41% of meningiomas, the trigeminal nerve is encased by the tumor. In 38% of the meningiomas, the trigeminal nerve is in the SL part of the tumor, and it is in 20% of the IL portion of the tumor. In 38% of the meningiomas, the trochlear nerve is encased by the tumor. The abducens nerve is not always visible (35%). The pathologic nerve pattern differs from that of meningiomas for epidermoid and trigeminal schwannomas. Conclusion The pattern of cranial nerves IV-VI is linked to the type of petroclival tumor. In a meningioma, tumor origin (cavernous, upper clival, tentorial, and petrous apex) is the most important predictor of the location of cranial nerves IV-VI. Classification of four subtypes of petroclival meningiomas using magnetic resonance imaging is very useful to predict the location of deviated cranial nerves IV-VI intraoperatively.