Brain-specific glycosylation enzyme GnT-IX maintains levels of protein tyrosine phosphatase receptor PTPRZ, thereby mediating glioma growth.

Gliomas are the most prevalent primary tumor of the central nervous system. Despite advances in imaging technologies, neurosurgical techniques, and radiotherapy, a cure for high-grade glioma remains elusive. Several groups have reported that protein tyrosine phosphatase receptor type Z (PTPRZ) is highly expressed in glioblastoma, and that targeting PTPRZ attenuates tumor growth in mice. PTPRZ is modified with diverse glycan, including the PTPRZ-unique human natural killer-1 capped O-mannosyl core M2 glycans. However, the regulation and function of these unique glycans are unclear. Using CRISPR genome-editing technology, we first demonstrated that disruption of the PTPRZ gene in human glioma LN-229 cells resulted in profoundly reduced tumor growth in xenografted mice, confirming the potential of PTPRZ as a therapeutic target for glioma. Furthermore, multiple glycan analyses revealed that PTPRZ derived from glioma patients and from xenografted glioma expressed abundant levels of human natural killer-1-capped O-Man glycans via extrinsic signals. Finally, since deficiency of O-Man core M2 branching enzyme N-acetylglucosaminyltransferase IX (GnT-IX) was reported to reduce PTPRZ protein levels, we disrupted the GnT-IX gene in LN-229 cells and found a significant reduction of glioma growth both in vitro and in the xenograft model. These results suggest that the PTPR glycosylation enzyme GnT-IX may represent a promising therapeutic target for glioma.

Exo- and endoscopic lateral orbital wall approach for the medial temporal lobe glioma: how I do it.

BACKGROUND: The endoscopic transorbital approach provides a direct access to the medial temporal lobe (MTL). However, when excising a highly vascular tumour, a wider access route that enables the concurrent use of standard neurosurgical instruments with both hands is preferable. METHOD: We described the concept and technique of the lateral orbital wall approach (LOWA), which comprises orbitotomy and mini-craniotomy to treat MTL lesions using an exoscope and endoscope. CONCLUSION: The LOWA provides a safe and natural surgical corridor to the MTL and enables 2- or 3-hand surgery. Hence, LOWA can potentially improve safety and efficiency to treat MTL lesions.

[Selection of Appropriate Approaches to Preserve Brain Function for Deep Seated Brain Tumors:Our Experience of Two Posterior Thalamic Cases].

What is the most important factor to achieve successful surgery for deep-seated brain tumors with preservation of brain functions? Definitely, it is to identify the tumor origin site at which a tumor arose and select appropriate surgical approaches that immediately lead directly to the site in the early stage of surgery, minimizing damages of cortices and important white matter bundles, and controlling main arterial supply to the tumor. For this, neurosurgeons must have thorough knowledge of brain anatomy and function, and tailor the best surgical approach for each patient, based on three-dimensional anatomical simulation. For lesions situated in the posterior and lower part of the thalamus and extending to the lateral part, two "cross-court" approaches; the occipital transtentorial/falcine and infratentorial supracerebellar transtentorial approaches, provide a wide corridor to even the lateral aspect of the thalamus and early access to the posterior choroidal arteries, usually main feeders of this territory tumors, without damaging any cerebral cortices and major white matter bundles. Here, we describe the selection of approaches for two representative cases and demonstrate surgical procedures and postoperative courses.

Loss of social independence in patients with neurofibromatosis type 2: a follow-up study using a national registry in Japan.

BACKGROUND: For patients with neurofibromatosis type 2 (NF2), maintaining an independent state of living is important. The present study aimed to examine the loss of social independence (i.e., a status that patients can work and go to school) and its contributing factors in patients with NF2 using data from a national registry in Japan. METHODS: This longitudinal study used a registry database containing information on patients with NF2 who had submitted initial claims to receive medical expense subsidies between 2004 and 2010. Patients with "employed," "studying," and "housekeeping" categories were classified as "socially independent." Patients who were socially independent at baseline were followed-up for up to nine years. The primary outcome of the present study was the loss of social independence during the follow-up period, which was defined as the change in status from being socially independent to socially dependent. First, we examined longitudinal associations between demographic variables and neurological symptoms at baseline and the loss of social independence. Second, we examined whether the occurrence of neurological symptoms is associated with a loss of social independence in patients. RESULTS: A total of 156 patients were included in the present study. During the follow-up period, 37 (23.7%) patients experienced a loss of social independence. In the first analysis, the multivariate logistic regression model showed that the loss of social independence was significantly more frequent among patients with spinal dysfunction than among patients without. In the second analysis, logistic regression analyses showed that neurological symptoms, including bilateral hearing loss, facial nerve palsy, cerebellar dysfunction, decreased facial sensation, speech dysfunction (dysphagia/dysarthria and aphasia), double vision, blindness, hemiparesis, and seizures, were significantly associated with loss of social independence. CONCLUSIONS: The occurrence of various neurological symptoms of NF2 can hinder social independence in the long term. Medical service providers need to observe patients while considering the risks, and provide appropriate support to address neurological symptoms that can restrict social independence, as this will lead to maintaining social engagement.

[Schwannoma, Neurofibromatosis Type 2, and Schwannomatosis in the 2021 WHO Classification of Tumors of the Central Nervous System].

Schwannomas are benign capsular tumors originating from Schwann cells. Although the majority are sporadic, they also occur within tumor predisposition syndromes, such as neurofibromatosis type 2, schwannomatosis, and Carney complex. Since the 5th edition of the World Health Organization(WHO)Classification of Tumors of the Central Nervous System was published, the description of grades has changed from Roman numerals to Arabic numerals. However, as in the 4th edition, it is still a WHO grade 1 benign tumor. There are several other subtypes of schwannomas in addition to the conventional type, and five subtypes have been specifically described in the 5th edition. "Melanocytic Schwannoma" in the 4th edition is now called "malignant melanotic nerve sheath tumor" in the 5th edition and is classified as a different tumor from schwannoma. Although the 5th edition places greater emphasis on genetic diagnoses, it is not essential for diagnosing schwannomas, and histological and clinical diagnoses remain equally crucial. Furthermore, after publication of the 5th edition in September 2022, an international consensus group renamed "neurofibromatosis type 2" as "NF2-related schwannomatosis." This article describes the shifts between the 4th to the 5th edition of the WHO Classification of Tumors of the Central Nervous System, along with additional clarifications, and offers the latest insights into treatment modalities for schwannomas and NF2.

[Awake surgery for preservation of higher brain functions].

Awake surgery for gliomas has become a widely accepted neurosurgical method worldwide. However, it is applied mainly to restore speech and simple motor functions, and intraoperative applications to restore higher brain functions have not been established yet. Preserving these functions is crucial to restoring the normal social lives of patients postoperatively. In this review article, we focused on preserving spatial attention and higher motor functions, and discussed their neural basis, as well as, the application of awake surgery practices using effective tasks. For spatial attention, the line bisection task is the most popular and reliable; however, other tasks, such as exploratory tasks, can be used, depending on the location of the brain. For higher motor functions, we developed two tasks: 1) the PEG & COIN task, which evaluates grasping and approaching skills, and 2) the sponge-control task, which assesses somatosensory-dependent movement. Although scientific knowledge and evidence are still limited in this field of neurosurgery, we believe that expanding our knowledge about higher brain functions and developing specific and efficient intraoperative tasks to evaluate them will eventually preserve patients'quality of life.

Protein Tyrosine Phosphatase Receptor Type Z in Central Nervous System Disease.

Gliomas are among the most common tumors of the central nervous system and include highly malignant subtypes, such as glioblastoma, which are associated with poor prognosis. Effective treatments are therefore urgently needed. Despite the recent advances in neuroimaging technologies, differentiating gliomas from other brain diseases such as multiple sclerosis remains challenging in some patients, and often requires invasive brain biopsy. Protein tyrosine phosphatase receptor type Z (PTPRZ) is a heavily glycosylated membrane protein that is highly expressed in the central nervous system. Several reports analyzing mouse tumor models suggest that PTPRZ may have potential as a therapeutic target for gliomas. A soluble cleaved form of PTPRZ (sPTPRZ) in the cerebrospinal fluid is markedly upregulated in glioma patients, making it another promising diagnostic biomarker. Intriguingly, PTPRZ is also involved in the process of remyelination in multiple sclerosis. Indeed, lowered PTPRZ glycosylation by deletion of the glycosyltransferase gene leads to reduced astrogliosis and enhanced remyelination in mouse models of demyelination. Here, we review the expression, molecular structure, and biological roles of PTPRZ. We also discuss glioma and demyelinating diseases, as well as the pathological role of PTPRZ and its application as a diagnostic marker and therapeutic target.

[Current Topics on Precision Medicine for Neurofibromatosis Type 2].

Neurofibromatosis type 2(NF2)is a hereditary condition that causes bilateral vestibular schwannomas(VS), multiple schwannomas, and meningiomas. The prognosis is poor because the multiplicity of the tumors leads to a progressive decline in the quality of life, deafness, and death in an early age. NF2 is caused by a disorder in the tumor suppressor gene NF2, which encodes the merlin protein. Although it is an autosomal dominant disease, more than half of cases are presumed to be de novo caused by somatic mosaicism, the diagnosis rate of which has been improved by the recently introduced technology of targeted deep sequencing of DNA from multiple tissues. No chemotherapeutic drugs for treating NF2-related VS are available at present, and surgery and radiotherapy remain the only therapeutic options. Recently, a randomized, double-blind, multicenter clinical trial has started in Japan to verify the efficacy and safety of bevacizumab, a humanized monoclonal antibody that targets vascular endothelial growth factor, in treating NF2-related VS.

Determination of brain tumor recurrence using 11 C-methionine positron emission tomography after radiotherapy.

We conducted a prospective multicenter trial to compare the usefulness of 11 C-methionine (MET) and 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) for identifying tumor recurrence. Patients with clinically suspected tumor recurrence after radiotherapy underwent both 11 C-MET and 18 F-FDG PET. When a lesion showed a visually detected uptake of either tracer, it was surgically resected for histopathological analysis. Patients with a lesion negative to both tracers were revaluated by magnetic resonance imaging (MRI) at 3 months after the PET studies. The primary outcome measure was the sensitivity of each tracer in cases with histopathologically confirmed recurrence, as determined by the McNemar test. Sixty-one cases were enrolled, and 56 cases could be evaluated. The 38 cases where the lesions showed uptake of either 11 C-MET or 18 F-FDG underwent surgery; 32 of these cases were confirmed to be subject to recurrence. Eighteen cases where the lesions showed uptake of neither tracer received follow-up MRI; the lesion size increased in one of these cases. Among the cases with histologically confirmed recurrence, the sensitivities of 11 C-MET PET and 18 F-FDG PET were 0.97 (32/33, 95% confidence interval [CI]: 0.85-0.99) and 0.48 (16/33, 95% CI: 0.33-0.65), respectively, and the difference was statistically significant (P < .0001). The diagnostic accuracy of 11 C-MET PET was significantly better than that of 18 F-FDG PET (87.5% vs. 69.6%, P = .033). No examination-related adverse events were observed. The results of the study demonstrated that 11 C-MET PET was superior to 18 F-FDG PET for discriminating between tumor recurrence and radiation-induced necrosis.

A novel needle electrode for intraoperative fourth cranial nerve neurophysiological mapping.

OBJECTIVES: Trochlear nerve (CN-IV) mapping method has not been confirmed to date. The compound muscle action potential (CMAP) of CN-IV cannot be recorded because of the low mapping sensitivity and anatomical characteristics of the superior oblique muscle (SOM). The aim of this study was to evaluate the effectiveness of a novel needle electrode (NNE), for the intraoperative mapping of CN-IV. MATERIALS AND METHODS: The NNEs were inserted in the target extraocular muscles in 19 patients. We compared the CMAP amplitude of the NNE with that of the conventional needle electrode (CNE). Furthermore, we investigated the dissimilarity between the CMAP of the CN-IV and other extraocular cranial nerves (ECNs) and the correlation between the readings of the CN-IV mapping and its postoperative functional outcome. RESULTS: The CMAP of CN-IV has been measured in nine patients (47.4%). The CMAP of CN-IV was distinguishable from other ECNs. The CMAP of the NNE was found to be three times higher than that of the CNE. Although the NNE has shown the potential to record the CN-IV's CMAP, 4 cases ended up having a CN-IV postoperative dysfunction. CONCLUSIONS: For the first time, we confirmed the possibility of intraoperative mapping the CN-IV using an NNE inserted into the SOM. The NNE can also be useful for other neurophysiological monitoring methods.

[Repair of Spontaneous Cerebrospinal Fluid Leakage due to Multiple Defects in the Skull Base:A Case Report].

Spontaneous cerebrospinal fluid(CSF)rhinorrhea may have multiple leakage sites, and occasionally, may become difficult to manage. A 46-year-old man was admitted to our hospital presenting with bacterial meningitis that occurred after CSF rhinorrhea. The CSF leak had stopped following conservative medical treatment;however, it recurred immediately. The leakage was assumed to be in the left lateral recess of the sphenoid sinus based on the location of fluid accumulation on the CT and MR images and the nasal endoscopic findings. First, we performed an endoscopic endonasal repair of the CSF leakage sites. There were multiple defects in the roof of the sphenoid sinus, including the left lateral sphenoid recess. These bone defects were repaired with abdominal fat;however, this did not stop the CSF leak. Therefore, he underwent a craniotomy and nasal endoscopy, which were performed simultaneously using a galeal flap. The galeal flap was inserted from the middle of the skull base to the sphenoid sinus to cover the bone defects, and the position was adjusted under the guidance of nasal endoscopy. Moreover, intraoperatively, another meningocele with CSF leak was discovered in the cribriform plate and was repaired using abdominal fat. The CSF leak stopped after the second surgery. It is important to be mindful of possible multiple leakage sites when treating cases of idiopathic CSF leakage;moreover, the determination of the leakage sites can be difficult. A repair surgery using a galeal flap is preferable in cases of multiple CSF leakage sites, such as in this case, because it allows for all defects to be covered and repaired simultaneously.

[Coexisting Symptomatic Adrenocorticotropic Hormone- and Growth Hormone-producing Double Pituitary Adenomas with Difficulty in Tumor Localization:A Case Report].

Double functional pituitary adenomas are rare, and only a few cases of excessive clinical symptoms of both adrenocorticotropic hormone(ACTH)and growth hormone(GH)have been reported. We herein report a case of symptomatic ACTH-and GH-producing double pituitary adenomas, which were discretely located within the same pituitary gland. A 38-year-old woman presented with general malaise, facial and lower limb edema, unexplained weight gain, facial redness, acne, and nasal enlargement. Endocrinological findings matched with the diagnostic criteria for both acromegaly and Cushing's disease. Preoperative magnetic resonance imaging showed a 15-mm cyst-like lesion on the right side of the sellae surrounded by what was thought to be the normal contrast-enhancing pituitary gland. We assumed that the cyst-like lesion was an adenoma and performed endoscopic endonasal transsphenoidal surgery. However, the cyst-like lesion was a parenchymal tumor. Furthermore, the region we considered to be a normal pituitary gland was also found to be an adenoma. Both adenomas were completely resected. The postoperative blood analysis showed ACTH<1.0pg/dL, cortisol 1.8µg/dL, and insulin-like growth factor-1 60ng/mL, all of which were below reference levels. The histopathological examination confirmed the coexistence of two adenomas, a GH-producing adenoma and an ACTH-producing adenoma. We concluded that these adenomas were endocrinologically active within the pituitary gland. Thus, a diagnosis of double pituitary adenomas was made. When treating a patient with symptoms caused by hypersecretion of multiple anterior pituitary hormones, the possibility of coexisting multiple pituitary adenomas should be considered.

Secondary brain tumors after cranial radiation therapy: A single-institution study.

AIM: To study the probability of developing secondary brain tumors after cranial radiotherapy.Background Patients treated with cranial radiotherapy are at risk for developing secondary brain tumors. PATIENTS AND METHODS: We planned an institutional survey for secondary brain tumors in survivors after cranial irradiation and reviewed the 30-year duration data. Event analysis and cumulative proportion curves were performed to generally estimate the cumulative proportion of developing secondary brain tumors, cavernoma and meningioma at different periods of time. RESULTS: Secondary brain tumors occurred in 21% of cases: 10% were cavernomas, 6% were meningiomas, 3% were skull osteomas, and 1% were anaplastic astrocytoma. The cumulative proportion of developing secondary brain tumor was 6% at 10 years and 20% at 20 years, while the cumulative proportion for developing cavernomas and meningiomas was 16% and 7% at 20 years, respectively. CONCLUSION: Our study shows that patients who received cranial irradiation were at risk of secondary brain tumors such as cavernomas and meningiomas. Thus, a meticulous follow-up of cancer survivors with history of cranial irradiation by an annual MRI scan is justifiable. This will help clinicians to detect secondary brain tumors early and make its management much easier.

[Corticospinal Tract Mapping by Calculating the Ratio of Subcortical to Cortical Stimulation Intensity:A Technical Note].

OBJECTIVE: Motor evoked potentials(MEPs)have been developed and utilized as safe surgical procedures. A correlation between the threshold intensity of direct stimulation MEPs and the distance of the corticospinal tract(CST)has been already established. However, MEPs are affected by anesthesia and patient-related conditions. Here, we describe a unique technique to avoid these effects. METHOD: When tumors developed in proximity to the CST, the transcortical MEP monitoring was done by placing grid electrodes on the primary motor cortex continuously while direct subcortical MEP mapping was conducted with a monopolar probe. The ratios of the subcortical to the transcortical stimulation intensity were calculated. The point at which the ratios reached 50% was defined as the surgical excision limit. DISCUSSION: MEPs are affected by anesthesia, paralysis, body temperature, and other factors. By measuring the ratio of the cortical stimulation intensity instead of the absolute value of the white matter stimulation intensity, various affecting factors can be avoided, and more accurate monitoring can become possible. CONCLUSION: By calculating the ratio of subcortical to cortical stimulation intensity, the corticospinal tract mapping is less likely to be influenced by the stimulation condition or facility setup, and this warrants further investigation.

＜Editors' Choice＞ Maxillary sinus carcinoma outcomes over 60 years: experience at a single institution.

Advances in the diagnosis and treatment of patients with maxillary sinus carcinoma have improved patient prognosis. This study investigated changes in demographic and clinical characteristics, treatment methods, and outcomes of patients with maxillary sinus carcinomas during three different 10-year periods spanning 60 years at our university hospital. Of the 233 patients with maxillary sinus carcinomas managed at Nagoya University Hospital, 135 were treated between 1951 and 1960 (first period), 35 between 1981 and 1990 (second period), and 63 between 2003 and 2012 (third period). Patient age, sex, TN classifications, treatment methods, and survival rates were compared among patients treated during these time periods. Of the 135, 35, and 63 patients with maxillary sinus carcinomas treated during these time periods, 86 (63.7%), 21 (51.4%), and 48 (76.2%), respectively, were men; 14 (10.4%), six (17.1%), and 14 (22.2%), respectively, were aged ≥70 years; and 135 (100%), 28 (80.0%), and 43 (68.3%), respectively, were treated surgically. The 5-year overall survival rates in patients treated during the first, second, and third periods were 29.7%, 44.3%, and 57.5%, respectively. These findings indicated that advances in the diagnosis and treatment of patients with maxillary sinus carcinoma, including computed tomography and craniofacial resection, have contributed to improvements in patient survival rates.

[Supratentorial-infraoccipital approach supported by navigation and intraoperative magnetic resonance imaging for glioma located at the medial posterior temporal lobe: two case reports].

Resection of posteromedial temporal lobe lesions is challenging because surgical access through standard approaches requires excessive retraction or resection of temporal cortex. The utility of the supratentorial-infraoccipital approach for posteromedial temporal lobe lesions was first reported in 1995. Here, we report two cases of glioma located at the medial posterior temporal lobe. In both, total tumor removal was achieved by a supratentorial-infraoccipital approach using neuronavigation and intraoperative magnetic resonance imaging. Both patients presented with postoperative quadrantanopia because of optic radiation damage, but did not have worsening language, memory, or cognitive functions.

Adipsia increases risk of death in patients with central diabetes insipidus.

Central diabetes insipidus (CDI) is caused by deficiency of arginine vasopressin, an antidiuretic hormone. Patients with CDI manifest polyuria which is usually compensated for by increases in water intake. However, some patients are not able to sense thirst due to the destruction of osmoreceptors in the hypothalamus. These adipsic CDI patients are easily dehydrated and the consequent dehydration could be life-threatening. The objective of this study was to investigate the prognosis of adipsic CDI patients. We have reviewed 149 patients with CDI in three hospitals using databases of the electronic medical recording systems, and examined whether adipsia could affect the morbidity and mortality in CDI patients with multivariable analyses. Twenty-three patients with CDI were adipsic while the remaining 126 patients were non-adipsic. The multivariate analyses showed that the incidence of serious infections which required hospitalization was significantly higher in the adipsic CDI patients compared to that in non-adipsic CDI patients (p <0.001). A total of 6 patients with CDI died during the follow-up (median duration; 60 months, range 1 to 132 months). Four of them were adipsic, three of whom died of infection. The statistical analyses revealed that the risk of death in adipsic CDI patients was significantly higher than in non-adipsic patients (p =0.007). It is thus suggested that adipsic CDI patients were susceptible to serious infections which could be the causes of death.

Papillary glioneuronal tumor with a high proliferative component and minigemistocytes in a child.

Papillary glioneuronal tumor (PGNT) is a rare type of primary brain tumor. Although PGNT has traditionally been defined as a clinically indolent neoplasm, several cases with high proliferative activity and tumor recurrence have recently been reported. We report a case of PGNT in a 12-year-old boy who presented with epilepsy and harbored a 64 mm cystic tumor with a high proliferative component in the right temporal lobe. (11) C-methionine positron emission tomography (PET) showed high uptake in the solid mass. Gross total resection of the tumor mass was achieved and the patient became seizure-free without any neurological deficits. Histologically, the tumor contained two distinct areas of a vasocentric papilliform structure and a desmoplastic component. Minigemistocytic cells and small necrotic regions were observed adjacent to the pseudopapillae. Immunohistochemical analyses revealed both glial and neuronal differentiation. The Ki-67 proliferation index was high (14%) in the area corresponding to the high uptake region in the (11) C-methionine PET. No tumor recurrence was observed 20 months after surgery. High proliferative PGNTs are rare and to our knowledge this is only the third pediatric case of PGNT with atypical features reported in the literature. Hence, we here review the reported cases of PGNT and discuss the clinical, radiological and histological features of this malignancy.

Gender Differences in the Cortical Distribution of Corpus Callosum Fibers.

Introduction Research on gender-based disparities in human brain structure has spanned over a century, yielding conflicting results and ongoing debate. While some studies indicate minimal distinctions, others consistently highlight differences in the corpus callosum (CC), even after accounting for average brain size. Methods Diverging from previous approaches, this study examines the morphology of the entire CC fiber rather than solely focusing on its midsagittal structure. Utilizing advanced neuroimaging techniques and generalized Q-imaging tractography, CC streamlines were constructed to assess gender differences in fractional anisotropy (FA), volume ratio, and cortical distribution. Student's t-test was employed to examine the disparities in FA between gender groups, while gender-based distinctions in the normalized volume of the CC and its segments were assessed using analysis of covariance (ANCOVA), with absolute whole white matter volume serving as a covariate. Results No significant gender-based disparities were found in either FA or normalized CC volume. While females exhibited consistently larger normalized volume CC streamlines than males, these differences lost statistical significance after adjusting for absolute total white matter volume as a covariate. Nonetheless, CC streamlines in females displayed a broader spatial distribution, encompassing various cortical regions, including the bilateral prefrontal cortex (medial and lateral surfaces), as well as medial parietal and temporal regions. Conclusion This study elucidates gender-related variations in the morphology of the brain's white matter pathways, indicating a more widespread cortical distribution of CC fibers in females compared to males. However, the study underscores the need for further investigations into connectivity patterns to fully elucidate these gender-based disparities.