Lower Cranial Nerve Research Articles

NCOG-25. STEREOTACTIC RADIOSURGERY VERSUS SURGICAL MICRODISSECTION FOR JUGULAR FORAMEN SCHWANNOMAS: A RETROSPECTIVE COMPARATIVE STUDY

Abstract INTRODUCTION Jugular foramen schwannomas (JFS) are rare, benign tumors arising from lower cranial nerves. Given their delicate location, surgical microdissection carries a substantial risk of neurological morbidity. Stereotactic radiosurgery (SRS) presents an alternative, particularly for smaller or residual tumors. OBJECTIVE This study aims to compare the outcomes and symptomatic improvements between these two treatment modalities. METHODS We conducted a retrospective analysis of 32 patients with JFS who underwent SRS (13 cases [40.6%]) or surgical dissection (19 cases [59.4%]) as their primary management at Stanford Medical Center between 1998 and 2024. Outcomes included progression-free survival (PFS), post-management adverse events based on common terminology criteria for adverse events (CTCAE), symptom improvement, overall survival (OS), and the necessity for secondary interventions. RESULTS Significant differences were observed in baseline characteristics between the SRS and surgery groups, including mean age (62.52 vs. 46.87 years, p<0.001), mean largest diameter (34.38 vs. 53.66 mm, p=0.02), and median total tumor volume (6.50 vs. 19.70 mm3, p=0.009). There were no significant differences in sex or lesion shape (dumbbell vs. non-dumbbell shaped). After adjusting for baseline characteristics, no significant differences were noted in PFS (85.71 vs. 77.77%), OS (92.3 vs 100%), symptom improvement (61.53 vs. 52.63%) or mean CTCAE grade (1.31 vs. 1.58) between the SRS and surgery groups. SRS patients had significantly lower odds of requiring secondary treatment procedures after their primary intervention as compared to those in the surgery group (OR=0.01, 95% CI: 0.0001-0.59, p=0.02). CONCLUSION Both SRS and surgery provide exceptional outcomes for JFS with no significant differences in PFS, OS, CTCAE grades, or symptom improvement between the two groups. However, SRS patients had lower odds of requiring secondary interventions for JFS. This is among the first studies comparing surgical microdissection and SRS for JFS. Future controlled prospective studies are necessary to derive more definitive conclusions.

A Prospective Study of CSF Flow Dynamics Across Foramen Magnum in Adult Chiari Malformation/Syringomyelia Complex and its Clinical Correlation with Outcomes after Surgery

Abstract Introduction Chiari I malformation refers to cerebellar tonsillar descent below the foramen magnum and is frequently associated with syringomyelia. Prior cerebrospinal fluid (CSF) flow studies correlated the clinical severity of these lesions with general flow velocity or bulk flow at the foramen magnum; however, these techniques have not assessed the effect on surgical outcomes. The study aims to present clinical and radiological factors and CSF flow parameters (pre- and postoperative) that affect the surgical outcome. Materials and Methods The institutional ethics committee approved the study. We collected the prospective clinical data, including pre- and postoperative symptoms. Functional grades were determined along with the change in clinical improvement based on clinical examination notes, the change in functional grade was calculated, and the radiologic data were analyzed according to the degree of clinical improvement. The surgical procedure included suboccipital bony decompression with duroplasty. Patients were followed up at 1 month, 3 months, and 1 year. Results There were a total of 25 patients. The mean age of the patients was 45.52 ± 13.37 years, with 40% being males and 60% being females. After the surgery, there was a significant increase in the anterior and posterior CSF flows at the foramen magnum. Most had a resolution in the headache and sensory symptoms, while the lower cranial nerve and motor symptoms had a minor resolution at follow-up. Age, sex, and headache do not correlate with the outcome or syrinx improvement. Motor power in the lower limb (preintervention) and syrinx shape (preintervention) were significantly associated with the variable “anterior flow at the foramen magnum” (preintervention; p < 0.05). Average flow, cervicomedullary angle (postintervention), sensory symptom progression, and CSF flow change anterior to the foramen magnum were significantly associated with the variable “anterior flow at the foramen magnum” (postintervention; p < 0.05). Conclusion Even after surgery, persistent foramen magnum CSF outflow obstruction has a robust negative correlation with the outcome. The Chiari outcome predictability index has shown a significant correlation with patient outcomes and can be used to inform patients about the expected outcome. The results of the present study will be helpful in stratifying patients according to their desired outcomes.

Clinical Features and Surgical Outcomes of Jugulotympanic Paraganglioma

Introduction: Jugulotympanic paraganglioma (JTP) refers to paraganglioma arising from jugular bulb, which can invade surrounding structures such as the bones, blood vessels, meninges, and cranial nerves. The authors conducted a study to find surgical indications to avoid a serious cranial nerve complications by analyzing the medical records of patients who underwent surgical management for JTP. Methods: We performed a single-institution, retrospective review of patients who underwent resection of JTP from 2004 to 2022. Patients underwent either Fisch infratemporal fossa approach type A (ITFA-A) or modification of ITFA-A with partial rerouting of the facial nerve. Preoperative and postoperative lower cranial nerve (LCN) function and facial function using the House-Brackmann (H-B) grade were evaluated. Results: The study included 19 patients with a mean age of 43.1 years (standard deviation [SD], 16.1 years). The average tumor size was 28.6 mm (SD 12.6 mm). In patients with Fisch classes C1 and C2 tumors, there were 3 and 11 patients, respectively. Gross total tumor removal (GTR) was performed in all patients with classes C1 and C2. GTR was achieved in 2 out of the 5 patients with class C3 tumor. Seventeen patients underwent ITFA-A and 2 patients underwent partial rerouting. Facial function before surgery was normal in all but 3 cases. Among 16 patients with preoperative normal facial function, 13 had H-B grade I to II and 3 had H-B grade III at 1 year after surgery. Total and partial rerouting did not significantly affect facial function immediately after surgery or at the postoperative 1-year evaluation (p = 1.00). Preoperative LCN function was normal in all patients. LCN palsy lasting more than 1 year occurred in 7 patients after surgery. Patients with Fisch class C1 tumor did not develop postoperative LCN palsy. Among the patients with class C2 tumor, none of 5 patients with medial invasion depth less than 9.5 mm developed LCN palsy, whereas 5 of 6 patients (83.3%) with invasion depth of 9.5 mm or greater developed LCN palsy (p = 0.02). Conclusion: JTPs with deep medial invasion should be managed conservatively to prevent LCN palsy.

The surgical outcomes in management of jugular foramen paragangliomas with tension free anterior rerouting of the facial never and tunnel packing of the inferior petrous sinus

Objective:The aim of this study is to evaluate the safety and efficacy of surgical interventions ofjugular foramen paragangliomas（JFP） utilizing modified surgical techniques, tensionfree anterior rerouting of the facial nerve and tunnel-packing or push-packing of the inferior petrous sinus. Methods:A retrospective analysis was conducted on a cohort of 88 patients diagnosed with JFP and treated at the Eye Ear Nose and Throat Hospital of Fudan University（in Shanghai, China） from October 2010 to June 2021. The surgical outcomes were analyzed for tumor classification, intraoperative conditions, and function of the postoperative facial nerve（FN） and lower cranial nerve（LCN）. Results:The study included a total of 88 patients, gross total resection was achieved in 70 patients（79.5%）, near total resection was obtained in 17 patients（19.3%）, and one patient undergoing subtotal resection. The average of intraoperative blood loss was 448.3 mL. Additionally, 24 patients underwent surgical total anterior rerouting（TAR）, 18 patients underwent surgical total FN tension free anterior rerouting（TF-TAR）, and 18 patients underwent surgical FN partial FN tension free anterior rerouting（TF-PAR）. Good postoperative FN function（House-Brackmann Ⅰ-Ⅱ） was achieved in 62.5% of TAR group. In the TF-TAR and PF_TAR groups, good postoperative FN function was demonstrated in 88.9% patients. It showed a significantly improvement of the FN function following application of tension-free FN anterior rerouting technique（P=0.007）. Twenty patients（22.7%） suffered from at least one LCN deficit in the preoperative evaluation. The postoperative LCN deficits was correlated with the Fisch classification of tumors, which showed a lower incidence of LCN dysfunction in classes C1-C2（4.9%, 2/41cases） and poorer outcomes of LCN dysfunction in classes C3-D（8.5%,4/47cases ）, it was likely less impacted the LCN function in the early stage tumor. Conclusion:The application of modified surgical techniques of FN tension-free anterior rerouting and tunnel-packing of the inferior petrous sinus has been shown to effectively preserve the function of the FN and LCN, decrease intraoperative blood loss, and ultimately improve patients' postoperative quality of life.

The intrabulbar or extrabulbar growth pattern and its surgical outcomes of jugular foramen paragangliomas.

This study is to define a subclassification system of jugular foramen paragangliomas (JFPs) and to demonstrate corresponding microsurgical outcomes of JFPs. Retrospective study. A single-center study. We conducted a retrospective review of the clinical data of 44 patients with JFPs who underwent surgical management. Extrabulbar(Be) tumor and intrabulbar(Bi) tumor are defined based on the growth patterns, receiver operating characteristic (ROC) curves of the imaging profile were generated and was confirmed based on intraoperative findings. Area Under Curve (AUC), accuracy, sensitivity, and specificity for diagnostic imaging were revealed. We also compared the correlation between the two growth patterns with Fisch's classification, blood loss, lower cranial nerves (LCNs) deficit. There are 27 (69%) cases of Bi tumor and 17 (39%) cases of Be tumor. Significant radiomics features between the two growth patterns were demonstrated, ROC curves achieved excellent AUCs for MRI sequences (T1W1 MRI, MR contrast-enhanced sequence, MR complex sequences and MR complex + DSA by 0.833, 0.833, 0.875, 0.944) and had statistically significant in diagnosis of two growth patterns (P<0.05). There was no statistical correlation between growth patterns of JFPs and intra-operative blood loss. Preoperative LCNs deficits and Fisch's classification of tumors were correlated with the growth patterns of JFPs (P < 0.05). We proposetd two growth patterns of JFPs in term of the inferior petrous sinus involvement. Identification of Bi or Be growth patterns preoperatively is helpful to design optimal surgical strategies and minimize postoperative complications.

Sleep-disordered breathing in children with Chiari type I malformation.

The objective was to identify clinical and radiological factors associated with sleep-disordered breathing (SDB) in children with Chiari type I malformation (CIM) and to evaluate the efficacy of foramen magnum decompression (FMD) in resolving SDB. A retrospective chart review was conducted for all children evaluated for CIM at a single institution from 2002 to 2022, identifying all children who had undergone nocturnal polysomnography (PSG). Apnea-hypopnea index (AHI) score, sleep apnea type (obstructive, central, mixed, and unspecified), clinical manifestations, and radiological measurements were recorded. SDB was considered present when officially diagnosed in the PSG report. Logistic regression was performed to identify factors correlating with the presence of SDB. For children with SDB who underwent FMD, the Wilcoxon signed-rank test was used to assess AHI improvement. Of the 997 children referred for CIM, 310 completed PSG. SDB was diagnosed in 147 patients (overall prevalence 14.7%, 95% CI 12.7%-17.1%; prevalence among children with PSG 47.4%, 95% CI 41.9%-53%). Specific SDB diagnosis consisted of 33% of patients with central sleep apnea, 27% with obstructive sleep apnea, 9% mixed, and 31% unspecified. Lower cranial nerve (CN) dysfunction (OR 3.891, p = 0.009), tonsillar position (OR 1.049, p = 0.017), Chiari type 1.5 malformation (OR 1.862, p = 0.044), and BMI (OR 1.039, p = 0.036) were significantly associated with presence of SDB. Of the 310 patients who underwent PSG, 47 were originally categorized as asymptomatic: 27 (57%) of these asymptomatic patients were diagnosed with SDB on PSG. Of children diagnosed with SDB, 34 completed PSG before and after FMD. Median AHI score decreased from 6.5 preoperatively to 1.8 postoperatively, with a median (IQR) difference of -2.3 (-11.9 to 0.1) (p = 0.001). Twelve (35%) had resolution of SDB. The authors' findings suggest that the prevalence of SDB in children with CIM is high (15%-47%). Furthermore, lower CN dysfunction, Chiari type 1.5, lower tonsillar position, and higher BMI may be risk factors. Notably, SDB can be present even in the absence of clinical symptoms. This study also demonstrates that surgical intervention has the potential to reduce the severity of SDB. These results could help clinicians identify CIM patients at risk for SDB and those who may benefit from surgical decompression.

Combined Deficit of the Four Lower Cranial Nerves also Known as the Syndrome of Collet-Sicard: A Systematic Review and Meta-analysis.

Combined deficit of the four lower cranial nerves (CN IX, X, XI, and XII) was originally described by French physicians Collet (1915) and Sicard (1917) during World War I. To date though, this rare neurological clinical picture lacks systematic evidence regarding its epidemiology, clinical presentation, treatment strategies, and outcome. We conducted a systematic review and meta-analysis concerning Collet-Sicard syndrome (CSS) on Medline database in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The research yielded 84 articles among which 73 individual case reports were eventually retained. Mean age was 53.7 (± 16) years old and the male-to-female ratio was 1.8/1. CSS was firstly caused by tumors (38.4%), following by vascular etiologies (28.8%), trauma (16.4%), and infection (6.8%), among others. Temporary enteral nutrition was required for 17 patients (23.3%). The four CN presented significant chances of complete or partial recovery: 52.1% for CN IX ( p < 0.001), 46.6% for CN X and CN XII ( p < 0.001), and 39.7% for CN XI ( p = 0.002). Tumoral causes presented significantly lower chances of favorable CN recovery (7.1%) compared to infection (60%), vascular (52.4%), and trauma (41.7%) ( p < 0.001). Older age (> 53 years old) was not associated with a dismal CN prognostic ( p = 0.763). Most patients (71.2%) presented a favorable outcome (Glasgow Outcome Scale score ≥ 4). All the patients who died (6.8%) suffered from skull base tumors. CSS is a rare condition requiring prompt clinical and radiologic diagnostic and multidisciplinary management. Vascular or infectious-related CSS seem to present a rather good prognostic, closely followed by trauma, whereas tumoral-related CSS seem to suffer from a more dismal prognostic.

Surgical management of large lower cranial nerves schwannomas: long term results of a less aggressive resection strategy.

In an effort to reduce the high morbidity and life-threatening complications after radical resection in large schwannoma surgery, alternative strategies of nontotal resections have emerged. To evaluate the long term clinical and oncological outcome after lower cranial nerves (LCN) schwannoma surgery operated on with a cranial nerve-sparing technique. Single center retrospective cohort study of 8 consecutive patients harboring LCN schwannomas operated on between March 2005 and October 2021. The mean LCN schwannoma diameter was 33mm (range 26-51). Seven patients (87,5%) underwent a modified retrosigmoid approach. Three patients underwent gross total resection (37,5%), 3 had received neartotal resection (mean tumor residue 0,25cc) and subtotal resection in 2 patients who presented with an extracranial extension of the tumor (mean tumor residue 2,44cc). Both patients had received upfront additional GKRS. The three patients who presented with preoperative CN IX & X injuries recovered within 6months after surgery. All of the five patients freed from any preoperative CNs IX & X symptoms experienced transient (80%) or definitive (one patient) disturbances after surgery. They all improved within 6months but one who required long term gastrostomy feeding tube. This patient harbored a schwannoma originating from the glossopharyngeal nerve, which could not be anatomically preserved during surgery. Tumor control was achieved in 100% of cases with a mean follow-up of 91months. LCN schwannomas could be surgically removed through a less aggressive non-radical resection strategy with acceptable functional results and excellent tumor control.

End-to-end revascularization between the occipital Artery(OA) and the p1 segment of posterior inferior cerebellar Artery(PICA) for a patient with posterior circulation ischemia via a far-lateral approach:2-Dimensional Operative video

Vertebral artery （VA）Aneurysms involving the origin of the posterior inferior cerebellar artery (PICA) ,occasionally, induce cerebellum and brainstem infarction due to intraluminal thrombus and calcific VA stenosis. At times, vessel occlusion and revascularization is necessary for successful obliteration of these aneurysms.2 The occipital artery (OA) is often the preferred donor graft for lesions of the posterior fossa. Although most OA-PICA bypasses can be performed using the p3 segment as the recipient site for an end-to-side anastomosis, a more feasible alternative to conventional OA-p3 PICA bypass in cases of high-riding caudal loops , aberrant anatomy or p3 multiple perforators is to free the p1 PICA, transpose it away from the lower cranial nerves, and perform an end-to-end OA-p1 PICA bypass instead. This video captures the dissection of the OA using an orientational anterograde harvesting technique and the end-to-end anastomosis of the OA to the PICA at the p1 segment. This was performed in a 56-year-old man who presented with posterior circulation ischemia from a fusiform aneurysm with calcific vertebral artery stenosis located at the origin of the right PICA. The patient tolerated the procedure well and suffered no major complications related to the operation. He did experience some mild, posterior neck rigidity at the time of his 6-month follow-up, likely due to nerve injury that occurred while harvesting the OA. Overall, the patient remains in good neurologic status 1 year after the operation. The operation proved the feasibility of end-to-end bypass in OA-p1 PICA.

Microsurgical anatomy of the glossopharyngeal nerve.

The glossopharyngeal nerve is a complicated and mixed nerve including sensory, motor, parasympathetic, and visceral fibers. It mediates taste, salivation, and swallowing. The low cranial nerves, including IXth, Xth, and XIth, are closely related, sharing some nuclei in the brainstem. The glossopharyngeal nerve arises from the spinal trigeminal nucleus and tract, solitary tract and nucleus, nucleus ambiguous, and inferior salivatory nucleus in the brainstem. There are communicating branches forming a neural anastomotic network between low cranial nerves. Comprehensive knowledge of the anatomy of the glossopharyngeal nerve is crucial for performing surgical procedures without significant complications. This review describes the microsurgical anatomy of the glossopharyngeal nerve and illustrates some pictures involving the glossopharyngeal nerve and its connective and neurovascular structures.

Thrombosed Posterior Inferior Cerebellar Artery Aneurysm Mimicking a Medulla Oblongata Cavernous Malformation: 2-Dimensional Operative Video.

The incidence of posterior inferior cerebellar artery (PICA) aneurysms is estimated to be between 0.5% and 3% of total aneurysm cases.1 Most patients with these aneurysms typically present with subarachnoid hemorrhage, although there are instances in which patients may present with symptoms resulting from mass effect exerted on the brain stem or lower cranial nerves.1,2 Treatment options for PICA aneurysms include endovascular procedures, surgical clipping, or bypass techniques.2 Surgical treatment is considered more effective for partially thrombosed aneurysms compared with endovascular approaches.3 In addition, endovascular coiling of these aneurysms carries the potential risk of coil migration and subsequent reopening of the aneurysm lumen.4 In certain instances, thrombosed PICA aneurysms have the potential to simulate the radiological characteristics of alternative pathologies, such as cavernous malformations or brainstem tumors.5-7 This situation can result in misdiagnosis and inappropriate management. We present the case of a patient who exhibited symptoms of imbalance and dysfunction in the lower cranial nerves. Magnetic resonance imaging findings indicated a possible cavernous malformation in the medulla oblongata. However, further investigation revealed that the underlying cause was a thrombosed PICA aneurysm. The patient was successfully treated through surgical clipping. The patient consented to the procedure and to the publication of his/her image.

Giant Invasive Schwannomas of C1 Root – Technical Challenges and Report of the First Two Cases in Literature

Abstract Giant invasive schwannomas (GISs) have been defined as different from other spinal schwannomas. C1 schwannomas are rare and often described with other high cervical tumors. GISs of C1 have not been previously described. Two cases of GIS are reported. In both patients, presenting with myelopathy, the lesions were extradural and intradural with posterior, lateral, and anterior extensions, compressing the cervicomedullary junction (CMJ) and displacing it. The V3-4 segments of the vertebral artery (VA) were closely associated. A posterolateral approach was used to initially expose and debulk the extradural portion of the lesion, which allowed access to the intradural component. The latter was followed anterior and/or posterior to the CMJ and excised completely. The tumors were dissected at the VA. Bleeding from the perivertebral venous plexus was controlled using topical hemostats. A small bit of tumor was left in a blind area anterior to the C1 arch in one patient. There were no complications and both patients improved in the postoperative period. GIS of the C1 are rare lesions in a difficult location. Complex relationships to the CMJ, lower cranial nerves, VA, and bony spine need a careful preoperative understanding of the anatomy and planning of surgery.

10259-NQPC-9 CONTROVERSY ON INVASIVE AIRWAY MANAGEMENT IN PATIENTS WITH BRAIN STEM MALIGNANT GLIOMA.

Abstract INTRODUCTION The prognosis for patients with malignant gliomas of the brainstem is poor. As the tumor progresses into the medulla oblongata, the lower cranial nerves are affected, resulting in dysphagia and eventually respiratory paralysis. On the other hand, higher cerebral function is often preserved, making it a palliative medical issue whether to perform invasive procedures to secure the airway. We report here three characteristic cases treated at our hospital. CASE 1 A-60-year-old male patient with diffuse midline glioma of the medulla oblongata was admitted to our hospital for radiation therapy and concomitant temozolomide. His consciousness level was clear, but dysphagia was noted. Although he was at risk for aspiration and choking, he did not wish to undergo surgery to prevent aspiration. After treatment was started, he died of choking. CASE 2 A-50-year-old male patient with recurrent astrocytoma in the brainstem was admitted for bevacizumab monotherapy. Despite the treatment, his dysphagia gradually worsened, and he developed respiratory failure due to aspiration pneumonia, resulting in tracheal intubation. Subsequently, he underwent glottis closure, and as a result, he lost his speech but recurrence of aspiration pneumonia and choking were prevented. CASE 3 A-50-year-old male patient with cerebellar glioma invading brainstem was admitted due to aspiration pneumonia. He was disoriented and required heavy care. He did not wish to undergo surgery to prevent aspiration, but with antimicrobial therapy and frequent oral suctioning, his aspiration pneumonia was cured. DISCUSSION Although invasive procedures are generally avoided in terminal-stage cancer patients, anti-aspiration procedures such as tracheostomy and glottis closure may be considered for the conscious patients with malignant glioma in the brainstem. These procedures might be an option at the end of life to avoid painful death due to choking and to prevent deterioration of the patient's condition due to repeated aspiration pneumonia.

Topohistology of the cranial nerves IX-XII at the cranial base and upper parapharyngeal space: A histological study using human fetuses.

The topographical relationships among the lower cranial nerves, internal carotid artery (ICA), and internal jugular vein (IJV) in the upper parapharyngeal neurovascular bundle remain obscure. Thus, details of the anatomy were examined in human fetus histology. We observed the horizontal histological sections from 20 midterm (9-18 weeks) and 12 near-term (28-40 weeks) fetuses. At the external skull base, the glossopharyngeal nerve crosses the anterior aspect of the IJV to reach the medially located Hyrtl's fissure in the petrous temporal bone. The nerve crossed the anterior aspect of the ICA medially near or below the first cervical nerve root. Below the hypoglossal nerve canal, the accessory nerve crosses the anterior or posterior aspects of the IJV and moves laterally. During the half-spiral course, the hypoglossal nerve was tightly attached to the posterolateral-anterior aspects of the vagus nerve and surrounded by a common nerve sheath. The glossopharyngeal ganglia sometimes extended inferiorly to the level of the hypoglossal nerve canal but were absent along the inferior course. The inferior vagal ganglion rarely extends above the occipital condyle. The superior cervical sympathetic ganglion occasionally extends above the first cervical nerve root. The IJV (or ICA) descends to the lateral (or medial) margins of the parapharyngeal neurovascular bundle. The glossopharyngeal (or accessory) nerve crosses the ICA (or IJV) to exit the bundle at the base of the skull (or below the hypoglossal nerve canal). The glossopharyngeal and vagus inferior ganglia differ at each site.

Analysis of Nonvestibular Cranial Nerve Schwannomas

Background and Aim: Cranial nerve (CN) schwannomas other than the eighth nerve schwannoma are called nonvestibular cranial nerve schwannomas (NVCNS). This study aims to analyze the clinical profile, distribution, and surgical outcome of the NVCNS. Methods and Materials/Patients: This is a retrospective study analyzing the NVCNS conducted between January 2007 and December 2021. VIIIth cranial nerve schwannomas and conservatively managed NVCNS were excluded from the study. Results: This study included 25 patients with NVCNS. Ten patients (40%) had trigeminal schwannomas, 3(12%) facial nerve schwannomas, 9 (36%) lower cranial nerve (LCN) schwannomas, 1 (4%) vagal schwannoma in neck and 2(8%) hypoglossal schwannomas. Eight patients (32%) were male and 17(68%) were female. The age of the patients ranges from 13 to 62 years (mean 39 years +/- 14 SD). Findings of cerebellar involvement, VIIIth CN involvement, and headache are the most common clinical features. The posterior cranial fossa is the most common location of the tumors. Thirteen patients (52%) underwent gross total resection (GTR), 7(28%) underwent neartotal resection (NTR) and 5(20%) underwent subtotal resection (STR). All the patients improved in the postoperative period. Facial nerve palsy is the most common cranial nerve palsy occurring in the postoperative period. Conclusion: Trigeminal and lower cranial nerve (LCN) schwannomas are the most common NVCNS. The retrosigmoid suboccipital approach is the most commonly used surgical approach for tumors located in the posterior cranial fossa. Since NVCNS are benign lesions, postoperative clinical improvement along with decreased complications should be the goal of the surgery. Hence, gross total resection is the most commonly achieved extent of resection, near-total or subtotal resection can be done wherever gross total resection (GTR) is not possible in NVCNS.

Transmastoid/Infralabyrinthine Approach to the Jugular Foramen: 2-Dimensional Operative Video.

This approach is intended for tumors centered in the jugular foramen with extensions between intracranial and extracranial spaces, possible spread to the middle ear, and variable bony destruction. 1,2. Jugular foramen paragangliomas are complex lesions that usually invade and fill related venous structures. They present complex relationships with skull base neurovascular structures as internal carotid artery, lower cranial nerves (CNs), middle ear, and mastoid segment of facial nerve. In this way, it is essential to perform an adequate preoperative vascular study to evaluate sinus patency and the tumor blood supply, besides a computed tomography scan to depict bone erosion. Mastoidectomy through an infralabyrinthine route up to open the lateral border of jugular foramen, allowing exposure from the sigmoid sinus to internal jugular vein. Skeletonization of facial canal without exposure of facial nerve is performed and opening of facial recess to give access to the middle ear in way of a fallopian bridge technique. 2-10. If there is preoperative preservation of lower CN function, it is important to not remove the anteromedial wall of the internal jugular vein and jugular bulb. In addition, facial nerve should be exposed just in case of preoperative facial palsy to decompress or reconstruct the nerve. Variations are related mainly with temporal bone drilling depending on the extensions of the lesion, its source of blood supply, and preoperative preservation of CN function.Informed consent was obtained from the patient for the procedure and publication of his image.Anatomy images were used with permission from:• Ceccato GHW, Candido DNC, and Borba LAB. Infratemporal fossa approach to the jugular foramen. In: Borba LAB and de Oliveira JG. Microsurgical and Endoscopic Approaches to the Skull Base. Thieme Medical Publishers. 2021.• Ceccato GHW, Candido DNC, de Oliveira JG, and Borba LAB. Microsurgical Anatomy of the Jugular Foramen. In: Borba LAB and de Oliveira JG. Microsurgical and Endoscopic Approaches to the Skull Base. Thieme Medical Publishers. 2021.

Lower Four Cranial Nerves in the Management of Glomus Jugulare: Anatomical Study.

Introduction The surgical management that achieves minimal morbidity and mortality for patients with glomus and non-glomus tumors involving the jugular foramen (JF) region requires a comprehensive understanding of the complex anatomy, anatomic variability, and pathological anatomy of this region. Objective The aim of this study is to propose a rational guideline to expose and preserve the lower cranial nerves (CNs) in the lateral approach of the JF. Methods The technique utilized is the gross and microdissection of 4 fixed cadaveric heads to revise the JF's surgical anatomy and high part of the carotid sheath compared with surgical cases to understand and preserve the integrity of lower CNs. The method involves radical mastoidectomy, microdissection of the JF, facial nerve, and high neck just below the carotid canal and the JF. The CNs IX, X, XI, and XII are microscopically dissected and kept in sight up to the JF. Results This study realized well the surgical and applied anatomy of the lower CNs with relation to the facial nerve and JF. Conclusions The JF anatomy is complicated, and the key to safely operate on it and preserving the lower CNs is to find the posterior belly of the digastric muscle, to skeletonize the facial nerve, to remove the mastoid tip preserving the stylomastoid foramen, to skeletonize the sigmoid sinus and posterior fossa dura not only anterior but also posteroinferior to reach and drill the jugular tubercle.

Dysautonomia and related outcomes in Guillain-Barre syndrome

Guillain-Barre syndrome (GBS) presents an annual incidence of 1.2-2.3 per 100,000. Sympathetic and parasympathetic nervous systems' peripheral control of visceral organs is affected by GBS aberrant immune response. Associated cardiovascular, gastrointestinal, sudomotor, pupillary, and other systems disturbances cause significant morbidity and mortality. This study aims to evaluate the dysautonomia spectrum in GBS patients, its relationship with patient outcomes, and compare it with those without autonomic disturbances. We performed an ambispective review study of patients with GBS and dysautonomia admitted to the Institute of Neurology from 2017 to 2021. We recorded demographics, comorbidities, nerve conduction studies, clinical course, hospital complications, and functional outcomes. We included 214 patients, mean age 46.44±16.49years, 51 (31%) presented dysautonomia, hypertension in most of the patients 39 (84.8%), hypotension 35 (76.1%), tachycardia 35 (76.1%), enteric dysmotility 35 (76.1%), and need for vasopressor 27 (58.7%) were common characteristics. Twenty (39.2%) with a demyelinating form and twenty (39.2%) with an axonal motor form. The bivariate analysis report factors associated with dysautonomia, were lower cranial nerves (VII, IX, X) involvement (p=0.002), need for mechanical ventilation (p=0.0001) and intensive care (p=0.0001), higher mEGOS (p=0.05), EGRIS (p=0.004), GBS disability score (p=0.004), and delirium presence (p=0.001). Kaplan-Meier survival analysis showed that dysautonomic patients needed more days for the independent walk (p=0.004). There was no associated mortality. Autonomic dysfunction in GBS significantly affects the peripheral nervous system. With consequently worse functional results. Further investigation needs to clarify whether more aggressive treatment is beneficial in this category of GBS.

Posterior Fossa Midline Epidermoid Tumors: Role of the Inferior Medullary Velum and a Proposed New Imaging Classification.

Posterior fossa midline epidermoid tumors (PFMETs) include the epidermoid tumors of the cisterna magna (CM) and fourth ventricle (FV). To report tumor epicenter-based classification of PFMETs and its clinical and surgical implications with outcome. On retrospective analysis of operated cases of intracranial epidermoid tumors, 19 (N = 19) patients having tumor epicenter within FV, CM, or both were included. Cerebellopontine and prepontine cistern epidermoid were excluded. Tumor location was decided based on preoperative MRI and intraoperative findings. Major complication was defined as new onset or worsening of cranial nerve (CN) deficit, sensory motor impairment, or tracheostomy. The mean (±SD) age of the patients was 42.0 ± 11.6 years (range 25-61 years), with no sex predilection (male:female: 1:0.9). The most common symptoms were cerebellar dysfunction, headache, vomiting, and diplopia. Common CNs affected were VII, V, lower cranial nerve, and VI. The PFMETs were classified based on tumor epicenter as type 1 (tumor epicenter in CM, n = 4/21.1%), type 2 (FV, n = 5/26.3%), and type 3 (involved CM and FV, n = 10/52.6%). Type 2 tumors had a higher incidence of raised intracranial pressure and only facial nerve palsy as preoperative CN deficit. Type 1 tumors had the least incidence of postoperative major complications. Type 3 tumors were the largest and had a greater incidence of brainstem adhesion and postoperative complications. The tumor size, duration of symptoms, and patient age were higher in patients with brainstem adhesion (5.3 ± 1.0 cm, 21 ± 16 months, 44.1 ± 9.2 years) as against its absence (4.8 ± 1.3 cm, 11.2 ± 7.3 months, 38.2 ± 11.7 years). Inferior medullary velum and tela choroidea have a critical role in tumorogenesis, tumor extension, and brainstem adhesion. PFMETs can be classified into 3 subtypes based on tumor epicenter having clinical and surgical implications. Less aggressive dissection and near total excision in the presence of brainstem adhesion yield favorable outcomes.

Long-Term Hearing Outcome After Radiosurgery for Vestibular Schwannoma: A Systematic Review and Meta-Analysis.

Stereotactic radiosurgery (SRS) is one of the main treatment options in the management of small to medium size vestibular schwannomas (VSs), because of high tumor control rate and low cranial nerves morbidity. Series reporting long-term hearing outcome (>3 years) are scarce. To perform a systematic review of the literature and meta-analysis, with the aim of focusing on long-term hearing preservation after SRS. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we reviewed articles published between January 1990 and October 2020 and referenced in PubMed or Embase. Inclusion criteria were peer-reviewed clinical study or case series of VSs treated with SRS (single dose), reporting hearing outcome after SRS with a median or mean audiometric follow-up of at least 5 years. Hearing preservation, cranial nerves outcomes, and tumor control were evaluated. Twenty-three studies were included. Hearing preservation was found in 59.4% of cases (median follow-up 6.7 years, 1409 patients). Main favorable prognostic factors were young age, good hearing status, early treatment after diagnosis, small tumor volume, low marginal irradiation dose, and maximal dose to the cochlea. Tumor control was achieved in 96.1%. Facial nerve deficit and trigeminal neuropathy were found in 1.3% and 3.2% of patients, respectively, both significantly higher in Linear Accelerator series than Gamma Knife series ( P < .05). Long-term hearing preservation remains one of the main issues after SRS, with a major impact on health-related quality of life. Our meta-analysis suggests that hearing preservation can be achieved in almost 60% of patients after a median follow-up of 6.7 years, irrespective of the technique.