Simple measurement of spinal cord evoked potential: a valuable data source in the rat spinal cord injury model.

Measurement of spinal cord evoked potentials (SCEPs) is proposed as a means of predicting locomotion outcome in the rat spinal cord injury (SCI) model. Using 55 rats, three reproducible peak waves (waves I, II and III) were observed during stimulation at the C7 level with recording at the L1 epidural space. Hemisection at the T13 level showed three wave loss patterns: wave III loss only, loss of both wave II and III, and loss of all three waves. Defining an ideal SCI model as establishment of stable monoparesis or paraparesis, all animals in the wave II-III loss group showed favorable results. Histological data and electrophysiological properties allowed reasonable assumptions of wave origin: wave I from extrapyramidal tracts, wave II from the ventral corticospinal tract, and wave III from the dorsal corticospinal tract. Complete destruction of pyramidal tracts in both dorsal and ventral fibers was essential for long-term impairment of locomotion.     

Safety of endoscopic endonasal biopsy for the pituitary stalk-hypothalamic lesions

Purpose

The indications for and the optimal biopsy approach in pituitary stalk-hypothalamic (PsH) lesions are controversial. Biopsies through an endoscopic endonasal approach (EEA) for PsH lesions have often been considered to cause the infundibulo-tuberal syndrome. The purpose of this study was to analyze the surgical and endocrinological safety of EEA biopsies for PsH lesions.

Methods

A total of 39 consecutive patients who underwent an EEA biopsy between June 2011 and August 2020 in a single institute were retrospectively analyzed. The ophthalmological and endocrinological outcomes were assessed before and after surgery.

Results

PsH lesions were confirmed to be diverse pathological diagnoses, ranging from lymphocytic hypophysitis to diffuse midline glioma, and the most common pathologic diagnosis was a germinoma (18 patients, 46.2%). No patients developed visual deterioration after the biopsy. In patients without preoperative panhypopituitarism, 13 out of 28 patients (46.4%) developed new anterior pituitary hormonal deficiencies after the biopsy. When the tissue was collected from the stalk, the endocrinological deterioration rate was 100% (6 of 6 patients), while the rate was 31.8% (7 of 22 patients) when tissue could be harvested from an extra-stalk lesion. The rate of newly developed permanent diabetes insipidus after surgery was 40.9% (9 of 22 patients). The median surgery time was 125 min, and there was no postoperative CSF leakage or infections noted.

Conclusions

An EEA biopsy for PsH lesions is a safe and efficient surgical method unless the tissue is collected from the stalk.

     

Preoperative Weakness and Demyelination of the Corticospinal Tract in Meningioma Patients : Changes in Diffusion Parameters Using Diffusion Tensor Imaging

Objective

Differentiation of demyelination in white matter from axonal damage can be determined using diffusion tensor imaging (DTI). In this study using meningioma patients an attempt was made to evaluate the relationship between preoperative weakness and the changes of diffusion parameters in the corticospinal tract (CST) using DTI.

Methods

Twenty-six patients with meningioma were enrolled in this study. Eleven of them suffered from objective motor weakness and were classified as Group 1. The remaining 15 patients did not present motor weakness and were classified as Group 2. Fiber tractography and CST diffusion parameters were obtained using DTIStudio. The ratios (lesion side mean value/contralateral side mean value) of CST diffusion parameters were compared with 1.0 as a test value using a one-sample t-test.

Results

In Group 1, fractional anisotropy (FA), tensor trace (TT), and radial diffusivity (RD, λ2 and λ3) of the CST were significantly different between two hemispheres, but axial diffusivity (AD, λ1) of the CST was not significantly different between two hemispheres. In Group 2, FA and λ3 of CST did not differ significantly between the hemispheres. In Group 2, TT, λ1, and λ2 of CST in the ipsilateral hemisphere were significantly higher than those of the unaffected hemisphere. However, the differences were small.

Conclusion

Motor weakness was related to a low FA and high TT resulting from increased RD of the CST fibers. CST diffusion changes in patients with weakness are similar to those for demyelination.     

Case Report: Intracerebral Hemorrhage After γ-Knife Surgery for Metastatic Brain Tumor

The authors report a case of a 69-year-old man with metastatic brain tumors who died of spontaneous intracerebral hemorrhage 3 days after -knife surgery. He had been suffering from lung cancer with multiple systemic metastasis. Preoperative magnetic resonance images showed two well-defined round lesions with intratumoral hemorrhage in the left frontal and right occipital lobe. There was no bleeding tendency in the hematological examination and the patient was normotensive. -Knife surgery was performed on both lesions in a single session. However, the patient died of massive intracerebral hemorrhage from the left frontal lesion 3 days after the surgery. There have been no previous reports of mortality resulting from spontaneous intracerebral hemorrhage after -knife surgery in metastatic brain tumors documented in the literature. It is likely that the two events, -knife surgery and spontaneous intracerebral hemorrhage, occurred separately and were not associated. However, it is worth noting that there is a possibility of bleeding after -knife surgery, especially in a metastatic brain tumor with preexisting intratumoral hemorrhage as in our case.     

Impact of interim progression during the surgery-to-radiotherapy interval and its predictors in glioblastoma treated with temozolomide-based radiochemotherapy

This study was designed to investigate the impact of interim progression of disease (PD) during the surgery-to-radiotherapy interval (SRI) and its predictors in glioblastoma based on MRIs. A total of 222 patients were planned for radiotherapy (RT) and 166 of them were evaluable for the presence of interim PD by 2 separate MRIs. The size criteria from the updated Response Assessment in Neuro-Oncology criteria was adopted to determine interim PD. 32 (19.3%) patients experienced interim PD, and their median survival (MS) was shorter than patients without PD in univariate (11.3 vs. 19.6 months, p?<?0.001) and multivariate analysis (HR 2.237, 95% CI 1.367–3.660, p?=?0.002). The volume of residual enhancing tumor (p?=?0.003) and prolongation of the SRI (p?=?0.004) were significant predictors of interim PD. Every 1-cc increase in residual enhancing tumor and every 1-day prolongation of the SRI significantly increased the risk of interim PD by 3.9% (p?=?0.003) and 8.1% (p?=?0.004), respectively. A significant portion of patients demonstrate interim PD during SRI and these patients have poor prognosis. The presence of interim PD should be concerned as a significant confounding factor for stratification in future clinical trials. A baseline pre-RT MRI is essential for accurate disease evaluation and RT-target delineation, especially in patients with larger residual disease after surgery and prolonged SRI due to the high risk of interim PD.     

MR imaging findings of extraventricular neurocytoma: a series of ten patients confirmed by immunohistochemistry of IDH1 gene mutation

Background

Extraventricular neurocytomas (EVNs) are rare neuronal tumors included as neoplasms in the 2007 World Health Organization (WHO) classification of tumors of the CNS. Although a few case reports describing EVNs have been published, a systematic analysis of MR imaging findings of EVN has not been reported. Furthermore, imaging findings of IDH1 mutation-negative EVNs have not yet been reported. The aim of our study is to describe the MR imaging findings of IDH1 mutation-negative EVNs.

Methods

MR images of ten patients with pathologically confirmed IDH1 mutation-negative EVNs were retrospectively reviewed. Conventional MR imaging of ten EVNs were reviewed with emphasis on the location, signal intensities, patterns, and grades of enhancement as well as the presence/grade of peritumoral edema, intratumoral cyst, hemorrhage, and calcification. The study also reviewed the results of DWI (b?=?1,000?s/mm², n?=?7).

Results

Seven EVN cases were located in the cerebral hemisphere, and the remaining cases were in the cerebellum and thalamus. Of those in the cerebral hemisphere, five were cortically based tumors. The tumors showed no or mild peritumoral edema. Eight tumors were enhanced on the postcontrast T1WIs. An intratumoral cyst, hemorrhage, and calcification were detected in four, one, and two cases, respectively. On DWI, only one case showed a lower ADC value than the brain parenchyma.

Conclusion

EVNs are usually cortically based infiltrative hemispheric tumors with contrast enhancement, higher ADC value, and sometimes small cystic component, but hardly show peritumoral edema or intratumoral hemorrhage. The differential diagnosis of these findings includes low-grade glioneuronal tumors and low-grade gliomas.     

The role of matrix metalloproteinases and tissue inhibitors of matrix metalloproteinase in microcystic meningiomas

We studied the expression of matrix metalloproteinases (MMP) and tissue inhibitors of matrix metalloproteinase (TIMP) in microcystic meningiomas to investigate a possible underlying mechanism for the development of microcysts and of peritumoral edema, which are frequent characteristics of this rare subtype. Between October 1995 and June 2004, 10 of 19 patients who had histologically confirmed pure microcystic meningiomas were enrolled in the study. Six patients with meningothelial meningiomas, three with atypical meningiomas, and one with a transitional meningioma were included as a control group. Immunohistochemistry with paraffin blocks and real-time RT-PCR analysis for MMP-2, MMP-9, TIMP-1, TIMP-2 and vascular endothelial growth factor (VEGF) were performed using stored frozen tissues. Compared with the control group, MMP-9 was invariably and highly expressed in immunohistochemical staining of microcystic meningiomas. MMP-2, TIMP-1, TIMP-2 and VEGF were weakly expressed or not expressed in both microcystic and non-microcystic meningiomas. Real-time RT-PCR showed increased ratios of MMP-9 to TIMP-1 in microcystic meningiomas compared with the control group (55.855 +/- 106.353 vs. 1.858 +/- 2.575, respectively; p = 0.00). The expression of MMP-2 (0.72 +/- 1.20 vs. 2.54 +/- 3.01, p = 0.01) and TIMP-2 (1.22 +/- 1.67 vs. 1.61 +/- 1.82, p = 0.02) was higher in the control group. The results suggested that the increased ratio of MMP-9 to TIMP-1 might be associated with the formation of microcysts and peritumoral edema in microcystic meningioma.     

Therapeutic strategy for large vestibular schwannomas

Summary Management of large vestibular schwannoma (VS) remains a difficult problem for which the extent of tumor resection and the role of radiosurgery continue to be the subject of debate. To develop an optimal therapeutic strategy for large VS, various treatment options within the avenues of microsurgery and radiosurgery were evaluated and compared. The authors carefully reviewed the clinical data of 50 surgical cases of large VS, defined as tumors with an average diameter over 3 cm in magnetic resonance imaging (MRI). All patients underwent microsurgery as the primary treatment. Gross total removal (GTR) was achieved in nine patients (18%), near total removal (NTR) in 8 (16%), radical subtotal removal (R-STR) in 31 (62%), and subtotal removal (STR) in 2 (4%). Among the 33 patients with R-STR and STR, eight had undergone adjuvant radiosurgery for the residual mass. Average tumor volume and diameter were 26.8 cm³ (13.5–55.1) and 36.4 mm (30.0–47.2), respectively. The mean follow-up duration was 113 months (58–167). The tumor control rate and facial nerve function according to the extent of removal were analyzed. The overall tumor control rate was 82%. Perfect tumor control was achieved after NTR and R-STR with adjuvant radiosurgery. However, 11% (1 of 9) of GTR patients and 32% (8 of 25) of R-STR-only and STR patients showed recurrence or regrowth. Overall favorable outcome of facial nerve function (H-B grade 1 or 2) was achieved in 78% of the patients. The facial nerve preservation rate was inversely proportional to the extent of tumor removal. NTR or R-STR with adjuvant radiosurgery might be acceptable therapeutic options for large VS in terms of achieving good tumor control and functional preservation of facial nerve.     

Optimal extent of resection in vestibular schwannoma surgery: relationship to recurrence and facial nerve preservation

Surgical treatment of vestibular schwannoma is targeted at complete removal with preserved neurological function. Complete removal may cause significant deficits, whereas subtotal tumor removal is associated with a high recurrence rate. The present study assessed the risk of tumor recurrence and postoperative facial nerve function in relation to the extent of surgical resection by reviewing the clinical records and radiological findings of 116 patients with vestibular schwannoma treated between 1990 and 1999. The extent of resection was classified as follows: gross total resection (GTR), near total resection (NTR), and subtotal resection (STR). Facial nerve function was graded using the modified House-Brackmann grade, and patients grouped into good (grades 1-2) and intermediate or poor (grades 3-6). Of the 116 patients, 26 (22%) underwent GTR, 32 (28%) NTR, and 58 (50%) STR. The recurrence rates were 3.8% (1/26 cases), 9.4% (3/32), and 27.6% (16/58) for GTR, NTR, and STR, respectively. GTR and NTR showed no statistically significant difference in terms of recurrence rate (p=0.620). However, recurrence was significantly less after NTR than STR (p=0.043). Immediately postoperative facial nerve function was good in 15.4% of patients after GTR, 40.6% after NTR, and 46.6% after STR. The STR and NTR carried a lower risk of facial nerve palsy than GTR in the immediately postoperative stage (p=0.006 and 0.036, respectively). Nevertheless, no statistical significance was observed in extent of resection and postoperative facial nerve outcome between the groups at last follow up (p=0.227). GTR is the ideal surgical treatment for vestibular schwannoma, but NTR is a good option, with better facial nerve function preservation than GTR without significantly increasing the risk of recurrence.     

Bo Sung Sim (1924-2001): a pioneer of neurosurgery in Korea

Bo Sung Sim (1924-2001) stands as a prominent figure in the history of Korean neurosurgery. His devoted contributions have led to the fruitful development of modern neurosurgery in Korea. Sim practiced advanced neurosurgical techniques, undertook basic research, was passionate about education in the early years of neurosurgery in Korea, and played an essential role in founding the Korean Neurosurgical Society. Sim was a true neurosurgeon-a teacher, a scientist, and a superb pioneer in Korean neurosurgery.