Leptomeningeal Metastasis in Gliomas : Clinical Characteristics and Risk Factors

Objective@#: Our objective is to analyze the occurrence, clinical course and risk factors for glioma patients with leptomeningeal metastasis (LM) according to different metastasis patterns and clinical variables. @*Methods@#: We retrospectively reviewed data from 376 World Health Organization (WHO) grade II–IV adult glioma patients who were treated in the National Cancer Center from 2001 to 2020. Patients who underwent surgery at other institutions, those without initial images or those with pathologically unconfirmed cases were excluded. LM was diagnosed based on magnetic resonance imaging (MRI) findings or cerebrospinal fluid (CSF) cytology. The metastasis pattern was categorized as nodular or linear according to the enhancement pattern. Tumor proximity to the CSF space was classified as involved or separated, whereas location of the tumor was dichotomized as midline, for tumors residing in the thalamus, basal ganglia and brainstem, or lateral, for tumors residing in the cerebral and cerebellar hemispheres. @*Results@#: A total of 138 patients were enrolled in the study. A total of 44 patients (38%) were diagnosed with LM during a median follow-up of 9 months (range, 0–60). Among the clinical variables, tumor proximity to CSF space, the location of the tumor and the WHO grade were significant factors for LM development in univariate analysis. In multivariate analysis, the midline location of the tumor and WHO grade IV gliomas were the most significant factor for LM development. The hazard ratio was 2.624 for midline located gliomas (95% confidence interval [CI], 1.384–4.974; p=0.003) and 3.008 for WHO grade IV gliomas (95% CI, 1.379–6.561; p=0.006). @*Conclusion@#: Midline location and histological grading are an important factor for LM in glioma patients. The proximity to the CSF circulation pathway is also an important factor for WHO grade IV glioma LM. Patients carrying high risks should be followed up more thoroughly.

Disorders of Secondary Neurulation : Mainly Focused on Pathoembryogenesis

Recent advancements in basic research on the process of secondary neurulation and increased clinical experience with caudal spinal anomalies with associated abnormalities in the surrounding and distal structures shed light on further understanding of the pathoembryogenesis of the lesions and led to the new classification of these dysraphic entities. We summarized the changing concepts of lesions developed from the disordered secondary neurulation shown during the last decade. In addition, we suggested our new pathoembryogenetic explanations for a few entities based on the literature and the data from our previous animal research. Disordered secondary neurulation at each phase of development may cause corresponding lesions, such as failed junction with the primary neural tube (junctional neural tube defect and segmental spinal dysgenesis), dysgenesis or duplication of the caudal cell mass associated with disturbed activity of caudal mesenchymal tissue (caudal agenesis and caudal duplication syndrome), failed ingression of the primitive streak to the caudal cell mass (myelomeningocele), focal limited dorsal neuro-cutaneous nondisjunction (limited dorsal myeloschisis and congenital dermal sinus), neuro-mesenchymal adhesion (lumbosacral lipomatous malformation), and regression failure spectrum of the medullary cord (thickened filum and filar cyst, low-lying conus, retained medullary cord, terminal myelocele and terminal myelocystocele). It seems that almost every anomalous entity of the primary neural tube may occur in the area of secondary neurulation. Furthermore, the close association with the activity of caudal mesenchymal tissue in secondary neurulation involves a wider range of surrounding structures than in primary neurulation. Although the majority of the data are from animals, not from humans and many theories are still conjectural, these changing concepts of normal and disordered secondary neurulation will provoke further advancements in our management strategies as well as in the pathoembryogenetic understanding of anomalous lesions in this area.

Disorders of Secondary Neurulation : Mainly Focused on Pathoembryogenesis

Recent advancements in basic research on the process of secondary neurulation and increased clinical experience with caudal spinal anomalies with associated abnormalities in the surrounding and distal structures shed light on further understanding of the pathoembryogenesis of the lesions and led to the new classification of these dysraphic entities. We summarized the changing concepts of lesions developed from the disordered secondary neurulation shown during the last decade. In addition, we suggested our new pathoembryogenetic explanations for a few entities based on the literature and the data from our previous animal research. Disordered secondary neurulation at each phase of development may cause corresponding lesions, such as failed junction with the primary neural tube (junctional neural tube defect and segmental spinal dysgenesis), dysgenesis or duplication of the caudal cell mass associated with disturbed activity of caudal mesenchymal tissue (caudal agenesis and caudal duplication syndrome), failed ingression of the primitive streak to the caudal cell mass (myelomeningocele), focal limited dorsal neuro-cutaneous nondisjunction (limited dorsal myeloschisis and congenital dermal sinus), neuro-mesenchymal adhesion (lumbosacral lipomatous malformation), and regression failure spectrum of the medullary cord (thickened filum and filar cyst, low-lying conus, retained medullary cord, terminal myelocele and terminal myelocystocele). It seems that almost every anomalous entity of the primary neural tube may occur in the area of secondary neurulation. Furthermore, the close association with the activity of caudal mesenchymal tissue in secondary neurulation involves a wider range of surrounding structures than in primary neurulation. Although the majority of the data are from animals, not from humans and many theories are still conjectural, these changing concepts of normal and disordered secondary neurulation will provoke further advancements in our management strategies as well as in the pathoembryogenetic understanding of anomalous lesions in this area.

The Present and Future of Vagus Nerve Stimulation

Epilepsy is one of the major chronic neurological diseases affecting many patients. Resection surgery is the most effective therapy for medically intractable epilepsy, but it is not feasible in all patients. Vagus nerve stimulation (VNS) is an adjunctive neuromodulation therapy that was approved in 1997 for the alleviation of seizures; however, efforts to control epilepsy by stimulating the vagus nerve have been studied for over 100 years. Although its exact mechanism is still under investigation, VNS is thought to affect various brain areas. Hence, VNS has a wide indication for various intractable epileptic syndromes and epilepsy-related comorbidities. Moreover, recent studies have shown anti-inflammatory effects of VNS, and the indication is expanding beyond epilepsy to rheumatoid arthritis, chronic headaches, and depression. VNS yields a more than 50% reduction in seizures in approximately 60% of recipients, with an increase in reduction rates as the follow-up duration increases. The complication rate of VNS is 3–6%, and infection is the most important complication to consider. However, revision surgery was reported to be feasible and safe with appropriate measures. Recently, noninvasive VNS (nVNS) has been introduced, which can be performed transcutaneously without implantation surgery. Although more clinical trials are being conducted, nVNS can reduce the risk of infection and subsequent device failure. In conclusion, VNS has been demonstrated to be beneficial and effective in the treatment of epilepsy and various diseases, and more development is expected in the future.

The Present and Future of Vagus Nerve Stimulation

Epilepsy is one of the major chronic neurological diseases affecting many patients. Resection surgery is the most effective therapy for medically intractable epilepsy, but it is not feasible in all patients. Vagus nerve stimulation (VNS) is an adjunctive neuromodulation therapy that was approved in 1997 for the alleviation of seizures; however, efforts to control epilepsy by stimulating the vagus nerve have been studied for over 100 years. Although its exact mechanism is still under investigation, VNS is thought to affect various brain areas. Hence, VNS has a wide indication for various intractable epileptic syndromes and epilepsy-related comorbidities. Moreover, recent studies have shown anti-inflammatory effects of VNS, and the indication is expanding beyond epilepsy to rheumatoid arthritis, chronic headaches, and depression. VNS yields a more than 50% reduction in seizures in approximately 60% of recipients, with an increase in reduction rates as the follow-up duration increases. The complication rate of VNS is 3–6%, and infection is the most important complication to consider. However, revision surgery was reported to be feasible and safe with appropriate measures. Recently, noninvasive VNS (nVNS) has been introduced, which can be performed transcutaneously without implantation surgery. Although more clinical trials are being conducted, nVNS can reduce the risk of infection and subsequent device failure. In conclusion, VNS has been demonstrated to be beneficial and effective in the treatment of epilepsy and various diseases, and more development is expected in the future.

The Usefulness of the Frontolateral Approach as a Minimally Invasive Corridor for Clipping of Anterior Circulation Aneurysm

OBJECTIVE: Several studies have reported on the effectiveness of fronto-lateral craniotomy in reducing the operating time and post-operative complications. However, no study has practically evaluated this method from the cosmetic point of view. MATERIALS AND METHODS: We designed this study for comparison of the clinical differences and cosmetic outcomes between the frontolateral craniotomy and the conventional pterional craniotomy for clipping of unruptured intracranial aneurysms. We performed a retrospective analysis of the two groups based on their medical records and radiologic findings juxtaposed with their length of hospital stay, intensive care unit day and operation time, and the emergence of postoperative complication, mean size of aneurysm, and temporal depression. RESULTS: After careful comparison of the thickness of temporalis muscle between the craniotomy side and the contralateral side, the results clearly showed that the conventional pterional craniotomy group was asymmetric by a p value of 0.152 and the frontolateral craniotomy group was symmetric by a p value of 0.002. CONCLUSION: Frontolateral craniotomy could be a practical alternative for patients with an unruptured intracranial aneurysm in the anterior circulation including the posterior communicating artery, particularly those who are in a medically poor state or who highly demand minimal aesthetic mutilation.

Clinicoepidemiological Features of Asymptomatic Moyamoya Disease in Adult Patients

OBJECTIVE: The aim of this study was to document the natural course of asymptomatic adult moyamoya disease (MMD) and the factors related to disease progression to aid in treatment decisions. MATERIALS AND METHODS: Among 459 adult MMD patients (aged > or = 20 years), 42 patients were included in this retrospective cohort study. Clinical records of adult asymptomatic MMD patients (n = 42) and follow-up data from September 2013 were reviewed to determine the factors related to disease progression. RESULTS: The mean age of patients at the time of diagnosis was 41.2 years (range, 23-64 years), and the mean follow-up period was 37.3 months (range, 7.4-108.7 months). Of the 42 patients and 75 hemispheres, there were 12 patients (28.6%) and 13 hemispheres (17.3%) with disease progression. There were four hemispheres (5.3%) with symptomatic progression (three hemorrhage, one transient ischemic attack) and nine hemispheres (12.0%) with asymptomatic radiographic progression. There were no relationships with sex, diabetes, hypertension, thyroid disease, family history of MMD, or family history of stroke. However, reduced initial cerebrovascular reserve capacity was observed in seven hemispheres (9.3%) in patients with disease progression. A relationship was found between disease progression and initial cerebrovascular reserve capacity (p = 0.05). None of the patients underwent bypass surgery during the follow-up period. CONCLUSION: It appears that asymptomatic adult MMD is not a permanent stable disease. In particular, reduced cerebrovascular reserve capacity is an indication of MMD progression, so close regular observation is needed.