Exploration of postural effects on the external jugular and diploic venous system using upright computed tomography scanning.

PURPOSE: Few studies have investigated the influence of posture on the external jugular and diploic venous systems in the head and cranial region. In this study, we aimed to investigate the effects of posture on these systems using upright computed tomography (CT) scanning. METHODS: This study retrospectively analysed an upright CT dataset from a previous prospective study. In each patient, the diameters of the vessels in three external jugular tributaries and four diploic veins were measured using CT digital subtraction venography in both supine and sitting positions. RESULTS: Amongst the 20 cases in the original dataset, we eventually investigated 19 cases due to motion artifacts in 1 case. Compared with the supine position, most of the external jugular tributaries collapsed, and the average size significantly decreased in the sitting position (decreased by 22-49% on average). In contrast, most of the diploic veins, except the occipital diploic veins, tended to increase or remain unchanged (increased by 12-101% on average) in size in the sitting position compared with the supine position. However, the changes in the veins associated with this positional shift were not uniform; in approximately 5-30% of the cases, depending on each vein, an opposite trend was observed. CONCLUSION: Compared to the supine position, the contribution of external jugular tributaries to head venous drainage decreased in the sitting position, whilst most diploic veins maintained their contribution. These results could enhance our understanding of the physiology and pathophysiology of the head region in upright and sitting positions.

The Long-Term Natural History of Fibrous Dysplasia.

Fibrous dysplasia (FD), a developmental, nonfamilial, benign anomaly of bone development, is characterized by the replacement of normal bone by proliferating fibro-osseous tissue. Marked craniofacial deformities, functional disturbances, and emotional stress are major indications for treatment, and various surgical procedures have been performed; however, excision and regrowth issues have also been reported. While several treatment options are available, no studies have reported the natural history of untreated FD. Here, we report 2 patients, aged 73 and 50 years, respectively, who had not received treatment. Both patients presented to the hospital complaining of noise when moving their heads. Computed tomography scans showed niveau with honeycomb cavities in both patients, indicating abscess formation, and resection was performed. Relatively large cranial FD leads to the development of central necrosis over time. In such cases, surgical intervention should be performed at an early disease stage.

Activation of ventral CA1 hippocampal neurons projecting to the lateral septum during feeding.

A number of studies have reported the involvement of the ventral hippocampus (vHip) and the lateral septum (LS) in negative emotional responses. Besides these well-documented functions, they are also thought to control feeding behavior. In particular, optogenetic and pharmacogenetic interventions to LS-projecting vHip neurons have demonstrated that the vHip→LS neural circuit exerts an inhibition on feeding behavior. However, there have been no reports of vHip neuronal activity during feeding. Here, we focused on LS-projecting vCA1 neurons (vCA1→LS ) and monitored their activity during feeding behaviors in mice. vCA1→LS neurons were retrogradely labeled with adeno-associated virus carrying a ratiometric Ca2+ indicator and measured compound Ca2+ dynamics by fiber photometry. We first examined vCA1→LS activity in random food-exploring behavior and found that vCA1→LS activation seemed to coincide with food intake; however, our ability to visually confirm this during freely moving behaviors was not sufficiently reliable. We next examined vCA1→LS activity in a goal-directed, food-seeking lever-press task which temporally divided the mouse state into preparatory, effort, and consummatory phases. We observed vCA1→LS activation in the postprandial period during the consummatory phase. Such timing- and pathway-specific activation was not observed from pan-vCA1 neurons. In contrast, reward omission eliminated this activity, indicating that vCA1→LS activation is contingent on the food reward. Sated mice pressed the lever significantly fewer times but still ate food; however, vCA1→LS neurons were not activated, suggesting that vCA1→LS neurons did not respond to habitual behavior. Combined, these results suggest that gastrointestinal interoception rather than food-intake motions or external sensations are likely to coincide with vCA1→LS activity. Accordingly, we propose that vCA1→LS neurons discriminate between matched or unmatched predictive bodily states in which incoming food will satisfy an appetite. We also demonstrate that vCA1→LS neurons are activated in aversive/anxious situations in an elevated plus maze and tail suspension test. Future behavioral tests utilizing anxious conflict and food intake may reconcile the multiple functions of vCA1→LS neurons.

Correction to: Clinical and histopathological analyses of VEGF receptors peptide vaccine in patients with primary glioblastoma - a case series.

Following publication of the original article [1], the authors reported an error in the author group.

Clinical and histopathological analyses of VEGF receptors peptide vaccine in patients with primary glioblastoma - a case series.

BACKGROUND: The expression of vascular endothelial growth factor (VEGF)-A/ VAGF receptors (VEGFRs) signaling plays a pivotal role in the tumor angiogenesis and the development of the immunosuppressive tumor microenvironment in glioblastomas. We have previously conducted exploratory clinical studies investigating VEGFRs peptide vaccination with and without multiple glioma oncoantigens in patients with recurrent high-grade gliomas. Recently, an exploratory clinical investigation of VEGFRs peptide vaccination was conducted in patients with progressive neurofibromatosis type 2. Those studies suggested that cytotoxic T lymphocytes (CTLs) induced by the vaccination can directly kill a wide variety of cells associated with tumor growth, including tumor vessels, tumor cells, and immunosuppressive cells expressing VEGFR1 and/or 2. In the present study, synergistic activity of the combination of VEGFRs peptide vaccination with chemotherapy was evaluated. METHODS: We performed the first clinical trial to assess VEGFR1 and 2 vaccination along with temozolomide (TMZ) -based chemoradiotherapy for the patients with primary glioblastomas. Furthermore, histopathological changes after the vaccination were evaluated using paired pre- and post- vaccination specimens. RESULTS: The disappearance of radiographically enhanced lesion was observed in 2 patients after the vaccination, including one in which the methylation of the O6-methylguanine-DNA methyltransferase (MGMT) promoter was not observed. The histopathological findings of pre- and post-vaccination specimens demonstrated that tumor vessels showed negative or slight VEGFRs expressions after the vaccination and most endothelial cells were covered with PDGFR-ß-positive pericytes. Notably, CTLs induced by VEGFRs peptide vaccination attacked not only tumor vessels but also tumor cells and regulatory T cells expressing VEGFRs even in recurrent tumors. CONCLUSIONS: VEGFR1 and 2 vaccination may have a preliminary synergistic effect when administered with TMZ. The limitation of the present study was the paucity of the number of the samples. Further studies involving more patients are warranted to confirm the findings of this study. TRIAL REGISTRATION: This study was registered as UMIN000013381 (University Hospital Medical Information Network-Clinical Trial Registry: UMIN-CTR) on 5 March, 2014 and with the Japan Registry of Clinical Trials (jRCT) as jRCTs031180170 on 1 March, 2019.

Difference in the hypoxic immunosuppressive microenvironment of patients with neurofibromatosis type 2 schwannomas and sporadic schwannomas.

BACKGROUND: Neurofibromatosis type 2 (NF2) patients uniformly develop multiple schwannomas. The tumor-microenvironment (TME) is associated with hypoxia and consists of immunosuppressive cells, including regulatory T cells (Tregs) and tumor-associated macrophages (TAMs). The hypoxic TME of NF2 schwannomas remains unclear. In addition, no comparative study has investigated immunosuppressive cells in NF2 and sporadic schwannomas. METHODS: In 22 NF2 and 21 sporadic schwannomas, we analyzed the immunohistochemistry for Ki-67, hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor receptor 1 (VEGFR1) and VEGFR2, platelet derived growth factor receptor-beta (PDGFR-ß), programmed cell death-1 (PD-1)/ programmed cell death ligand-1 (PD-L1), Foxp3, CD163, CD3, and CD8 to assess the immunosuppressive TME. RESULTS: Most vessels in sporadic schwannomas exhibited slight or negative VEGFR1 and 2 expressions with pericytes coverage. In contrast, large vessels in NF2 schwannomas exhibited strong VEGFR1 and 2 expressions without pericytes. The number of CD3+, CD8+, and CD163+ cells was significantly higher in NF2 schwannomas than in sporadic ones. The expression of PD-L1 and nestin positive cell ratio was higher in NF2 schwannomas than that in sporadic ones. The number of CD163+ cells, nestin positive cell ratio, and HIF-1α expression were significantly associated with shorter progression-free survival in NF2 schwannomas. CONCLUSIONS: This study presents the clinicopathological features of the differences in immunosuppressive cells and the expression of immune checkpoint molecules between NF2 and sporadic schwannomas. Hypoxic TME was first detected in NF2-schwannomas, which was associated with the tumor progression.

Quantitative assessment and clinical relevance of VEGFRs-positive tumor cells in refractory brain tumors.

Vascular endothelial growth factor (VEGF)/VEGF receptor (VEGFR)1 and 2 signaling is a potent activator of tumor angiogenesis. Although the expressions of VEGFR1 and VEGFR2 were initially thought to be limited to the endothelial cells, it is now known that both the receptors are expressed in tumor cells. This is the first study wherein VEGFRs-positive tumor cells are quantitatively evaluated for brain tumors with upregulated VEGF/VEGFR signaling. The percentage of VEGFRs-positive tumor cells was quantitatively evaluated in various brain tumors (10 glioblastomas, 22 neurofibromatosis type 2 [NF2]-related schwannomas, 21 sporadic schwannomas, 27 chordomas, 36 meningiomas, 29 hemangioblastomas, 11 hemangiopericytoma, and 13 ependymomas) using immunohistochemistry. VEGF-A expression was also analyzed using quantitative real-time polymerase chain reaction. Double immunofluorescence staining using anti-PDGFR-ß and anti-CD34 antibody, microvessel density, and vessel diameter were analyzed to evaluate the vascular characteristics. Chordomas demonstrated an extremely higher percentage of VEGFR1 and VEGFR2-positive tumor cells than other tumors. In contrast, meningiomas and hemangiopericytomas showed few VEGFRs-positive tumor cells. The percentage of positive tumor cells in chordomas, hemangioblastomas, and NF2 schwannomas was associated with clinical courses, such as shorter progression free survival, and growth speed. Glioblastomas and NF2 schwannomas showed larger tumor vessels without pericyte coverage. The present study is the first to quantitatively analyze VEGFR1- and VEGFR2- positive tumor cells in various types of refractory brain tumors. This novel parameter significantly correlated with the progressive clinical courses.

Surgical outcomes of anterior cerebellopontine angle meningiomas using the anterior transpetrosal approach compared with the lateral suboccipital approach.

BACKGROUND: Anterior transpetrosal approach (ATPA) and lateral suboccipital approach (LSO) are the major surgical approaches for cerebellopontine angle (CPA) meningiomas. Particularly, anterior CPA meningiomas are challenging lesions to be treated surgically. To date, only a few studies have directly compared the outcomes of both approaches focusing on the anterior CPA meningiomas. METHODS: For the comparative analysis, anterior CPA meningiomas that were eligible for both APTA and LSO were collected in our hospital from April 2005 to March 2017. Anterior CPA meningiomas targeted for this study were defined as follows: (1) without cavernous sinus, clivus, and middle cranial fossa extension, (2) the posterior edge is 1 cm behind the posterior wall of the internal auditory canal, and (3) the inferior edge is above the jugular tuberculum. Based on these criteria, the operative outcomes of 17 patients and 13 patients who were operated via ATPA and LSO were evaluated. RESULTS: The complication rate of the LSO group was significantly higher than that of the ATPA group (30.7% vs. 0%, p = 0.033). The removal rate did not differ between the ATPA and LSO groups (97.35% vs. 99.23%, p = 0.12). The operative time was significantly shorter in the LSO group than in the ATPA group (304.3 min vs. 405.8 min, p = 0.036). CONCLUSIONS: Although the LSO is more widely used for CPA meningiomas, ATPA is also considered for these anterior CPA meningiomas.

Sinking skin flap syndrome visualized by upright computed tomography.

Sinking skin flap syndrome is a craniectomy complication characterized by new neurological dysfunction that typically worsens in the upright position and improves after cranioplasty. We present a 33-year-old man who experienced hemiparesis in the upright position after craniectomy. Upright computed tomography (CT) before cranioplasty showed a remarkable shift of the brain compared to supine CT. After cranioplasty, both symptoms and brain shift on CT resolved. Upright CT enables detection and objective evaluation of paradoxical herniation and midline shift that is not obvious on supine imaging modalities. Clinicians need to be aware of positional brain shift in postcraniectomy patients.

Prognostic significance of VEGF receptors expression on the tumor cells in skull base chordoma.

BACKGROUND: Chordoma is a rare refractory neoplasm that arises from the embryological remnants of the notochord, which is incurable using any multimodality therapy. Vascular endothelial growth factor (VEGF) is a potent activator of angiogenesis that is strongly associated with the tumor-immune microenvironment. These factors have not been elucidated for chordomas. METHODS: To evaluate the characteristics of vascular and tumor cells in chordoma, we first analyzed the expression of VEGF receptor (VEGFR) 1, VEGFR2, CD34, and Brachyury in a cell line and 54 tumor tissues. Patients with primary skull base chordomas were divided into the following two groups as per the tumor growth rate: patients with slow progression (SP: < 3 mm/year) and those with rapid progression (RP: ≥ 3 mm/year). Thus, the expressions of VEGF-A, VEGFR 1, and VEGFR2 on tumor cells; tumor infiltrative immune cells, including regulatory T cells (Tregs) and tumor-associated macrophages (TAMs); and immune-checkpoint molecules (PD-1/PD-L1) were analyzed with the clinical courses, especially in a comparison between the two groups. RESULTS: In chordomas, both VEGFR1 and VEGFR2 were strongly expressed not only on vascular endothelial cells, but also on tumor cells. The recurrent cases showed significantly higher VEGFR1 expressions on tumor cells than the primary cases. The expression of VEGF-A was significantly higher in RP than that in SP group. The numbers of CD163+ TAMs and Foxp3+ Tregs were higher in RP than that in SP group. CONCLUSIONS: Expression of VEGFR1 and VEGFR2 on tumor cells and immunosuppressive tumor-microenvironment were related to tumor growth in patients with chordomas.

Optimizing perampanel monotherapy for surgically resected brain tumors.

Perampanel (PER) is an antiseizure medication (ASM) with a unique mechanism of action, which was approved in Japan for use in combination therapy in 2016 and as a monotherapy in 2020. It has exerted antitumor effects against several types of tumors in vitro. However, the efficacy of PER monotherapy for seizure control is not well-established in patients with brain tumor. In the present study, 25 patients with brain tumor treated using PER monotherapy at our institution were analyzed and compared with 45 patients treated using the most commonly prescribed ASM, levetiracetam (LEV). The PER group was younger and had a higher frequency of glioma cases. During drug administration, seizures were observed in two patients from the PER group (8.0%) and five patients from the LEV group (11.1%); however, the difference was not significant. The incidence of adverse effects did not significantly differ between the groups (12.0 and 2.2%, respectively). In the PER group, mild liver dysfunction was observed in two patients and drug rash in one. In the LEV group, a drug-induced rash was observed in one patient. PER monotherapy may be safe and effective for seizure treatment or prophylaxis in patients with brain tumor. Further large-scale clinical studies are warranted.

Upright CT-based evaluation of the effects of posture on skull-base reconstruction after endoscopic endonasal surgery.

Cerebrospinal fluid (CSF) leakage is a common complication associated with endoscopic endonasal skull-base surgery (EESBS). Postoperative mobilization-associated postural changes are considered to cause CSF leakage. However, no study has demonstrated a robust relationship between postural changes and CSF leakage. We used upright computed tomography (CT) to clarify the effects of postural changes on the reconstructed skull base (RSB) after EESBS. Thirty patients who underwent EESBS at our institution were prospectively included, and their upright and supine CTs were compared to measure morphological changes in the RSB. Patient clinical data were also collected from medical charts and surgical videos, and their relationships with morphological changes were assessed. In upright CTs, the RSB shifted intracranially by 0.94 (0.0-2.9) mm on average. This shift was larger in cases with lesions extending to the sphenoid sinus, dural defects, intraoperative pulsation of the RSB, and large bone windows. The direction of the change was opposite to intuitive movement driven by gravity because of reduced intracranial pressure in the sitting position. Thus, these shifts can be directly associated with postoperative CSF leakage caused by reconstruction material displacement. Skull-base reconstruction and postoperative postural management accounting for these morphological changes may be necessary for preventing CSF leakage.

Awake Surgery for Right Frontal Lobe Glioma: Preserving Emotional Recognition and Facilitating Early Return to Work.

BACKGROUND/AIM: Many glioma patients struggle to return to work after surgery because of higher brain dysfunction. Although the right frontal lobe has historically been considered functionally silent, reports of performing awake surgery to evaluate higher brain functions in patients with tumors in this area have increased. We present two cases of patients who underwent awake surgery for malignant glioma in the right frontal lobe to preserve emotional recognition and facilitate an early return to work. CASE REPORT: Case 1 was a 48-year-old right-handed woman employed as a nursery school teacher and case 2 was a 21-year-old right-handed man employed in sales. Both had contrast-enhancing right frontal lobe tumors exhibiting high signal intensity on fluid attenuated inversion recovery imaging and underwent awake surgery. During the operation, cortical mapping was performed using the Reading the Mind in the Eyes, calculation, and motor tasks. Resection of sites involved in motor and emotional recognition functions was avoided. In case 1, all regions of high signal intensity were completely resected; in case 2, all regions exhibiting enhancement were resected. Both patients were discharged home without neurological deficits and returned to work within 21 days after surgery. CONCLUSION: It may be important to focus not only on overall survival and progression-free survival in glioma patients, but also on factors associated with life satisfaction, such as time to return to work after surgery and time until work becomes difficult. Awake surgery aimed at preserving higher brain functions is useful and may also improve life satisfaction.

Intraventricular hemorrhage volume and younger age at surgery may be risk factors for postoperative hydrocephalus after hemispherotomy in children.

OBJECTIVE: Hemispherotomy is an effective treatment for intractable hemispheric epilepsy; however, hydrocephalus remains a common complication of the procedure. The causes of hydrocephalus following hemispherotomy have not been fully elucidated; therefore, the purpose of this study was to identify the risk factors associated with the condition. METHODS: The authors investigated the records of all patients aged < 18 years who underwent hemispherotomy at their institution between 2003 and 2020 and were monitored for hydrocephalus for at least 1 year after the procedure. To identify the risk factors for hydrocephalus, the following information about each patient was collected: sex, corrected age at surgery, body weight at surgery, previous intracranial surgery, etiology of epilepsy, results of PET for hypermetabolism, side of surgery, type of operation (vertical or horizontal approach), operation time, blood loss during surgery, use of intraventricular drainage, occurrence of intraventricular hemorrhage (IVH) on the 1st postoperative day, duration of postoperative fever of > 38°C, and maximum C-reactive protein level after the operation. Multivariate logistic regression analyses were performed. RESULTS: This study included 51 children who underwent hemispherotomies for drug-resistant epilepsy at our hospital. Seven patients (13.7%) experienced hydrocephalus and were treated with ventricular or subdural peritoneal shunts or fenestration. Multivariate logistic analysis using the Bayesian information criterion revealed that 3 factors were associated with the occurrence of hydrocephalus: age at surgery, postoperative IVH volume, and duration of postoperative fever of > 38°C. CONCLUSIONS: This study showed that younger age at surgery, postoperative IVH volume, and duration of postoperative fever of > 38°C might be risk factors for hydrocephalus after hemispherotomy. The risk of hydrocephalus should be considered in cases of early surgical indication in children. Intraoperative hemostasis and postoperative use of anti-inflammatory measures may reduce the risk of hydrocephalus.

Safety, Feasibility, and Efficacy of Additional Extraventricular Anterior Commissurotomy With Corpus Callosotomy.

BACKGROUND: Corpus callosotomy (CC) is a palliative neurosurgical procedure for patients with intractable epilepsy and without resectable focal epileptogenic lesions. Anterior commissurotomy (AC) has been historically performed with CC. However, the efficacy and safety of adding AC to CC remain unknown. OBJECTIVE: To describe the surgical technique of extraventricular AC and retrospectively investigate its clinical efficacy and safety by assessing patients who underwent CC with and without AC. METHODS: AC has been added to CC at our institution since 2018. Fifty-five consecutive patients who received total callosotomy from 2016 to 2020 were included and categorized into 2 groups: 26 patients with additional AC and 29 patients without additional AC. Seizure outcome 1 year after surgery were compared between groups for assessing the efficacy of adding AC. The perioperative factors were compared for assessing the safety and feasibility. RESULTS: Seizure reduction rate (50% and 60%; P = .60) and disappearance of drop attacks (42% and 58%; P = .25) were not significantly different between CC and CC + AC groups. No statistical group differences were found in intraoperative estimated blood loss, number of days to first oral intake, duration of postoperative intravenous hydration, and length of hospital stay. CONCLUSION: Disconnection of the anterior commissure is a feasible and relatively safe procedure. This study failed to show the significant efficacy of adding AC to CC. However, further investigation is needed to prove its efficacy in ameliorating epilepsy.

Probable Sporadic Creutzfeldt-Jakob Disease Presenting as Refractory Status Epilepticus in a Poststroke Epilepsy Patient: A Case Report.

In this study, we report on a case of probable sporadic Creutzfeldt-Jakob disease (sCJD) diagnosed after a difficult course of status epilepticus (SE) in a patient with poststroke epilepsy. The patient was admitted with progressive cognitive decline and convulsive SE; therefore, it was initially thought that the patient had developed SE due to nonadherence to antiseizure medication (ASM) use, but despite treatment with ASMs after admission, no improvement was noted in consciousness disturbance or lateralized periodic discharges (LPDs) on electroencephalogram (EEG) examination. After a refractory course, the progression of LPDs to generalized periodic discharges (GPDs) on EEG and abnormal magnetic resonance imaging (MRI) findings met the diagnostic criteria of sCJD. Even if the patient had epilepsy, such as poststroke epilepsy, as in this case, it is essential to consider other underlying causes, including CJD in cases of superrefractory SE.

Surgical Planning and Simulation of Endonasal Endoscopic Surgery for Pituitary Adenoma With Cavernous Sinus Invasion.

BACKGROUND: Transsphenoidal endoscopic endonasal surgery (EES) provides effective treatment for patients with lesions of the sella turcica. The endoscopic technique requires different instrumentation, which depends on the gross anatomy of the nasal cavity. The treatment of lateral lesions is more challenging in EES. OBJECTIVE: To evaluate the effect of preoperative simulation using multiple anatomic landmarks. METHODS: Pre- and postoperative tumor volumes were analyzed in 33 patients with nonfunctioning pituitary adenomas who underwent EES (Knosp grades 3 and 4). The surgical working angle and space were three-dimensionally simulated at the plane of the anterior/posterior surgical field (tuberculum sellae/posterior clinoid process) using multiple anatomic landmarks of high-resolution computed tomography scans, such as nasal piriform aperture (proximal surgical corridor), and the width of bilateral vidian canals or lamina perpendicularis of palatine bone (distal surgical corridor). Receiver operating characteristic curves for the removed tumor volume were used to determine the cutoff value for the simulated working angle and space. RESULTS: Simulated working space at the plane of tuberculum sellae using piriform aperture and lamina perpendicularis of palatine bone was associated with the removed tumor volume in the cavernous sinus. Patients with a larger working space (≥42.7 mm) significantly showed a higher removed tumor volume ( P = .023). There was no relationship between other parameters and the removed tumor volume. CONCLUSION: A new method to predict the surgical field for cavernous sinus lesions around sella turcica was successfully established. Further studies are needed to define and expand applications of this simulation method.

[Vagus Nerve Stimulation Therapy for Drug-Resistant Epilepsy].

Epilepsy is a neurological disorder with abnormal brain activity. It causes convulsions or periods of unusual behavior, sensations, and sometimes loss of awareness. Drug-resistant epilepsy (DRE) affects an estimated 15%-20% of patients with epilepsy. Vagus nerve stimulation (VNS) is a type of neuromodulation. VNS therapy is an adjunctive neurostimulation treatment for DRE patients who are unsuitable for respective surgery or have experienced unsuccessful surgery. VNS involves the use of a device to stimulate the vagus nerve with electrical impulses. VNS is not a cure for epilepsy, and most epilepsy patients can still experience seizures or use epilepsy medication after the procedure. However, 60%-70% of patients can have over 50% reduction in seizures 5 years after the VNS procedure. Seizure intensity may also reduce. VNS is safe with tolerable side effects in most cases. The mechanism of VNS action against epilepsy is still not accurately verified. Some people believe that VNS therapy improves their mood, memory, or alertness and may also help reduce depression. VNS therapy is also expected to work in other indications, including psychiatric, gastrointestinal, endocrinological, and immunological disorders.

Low EEG Gamma Entropy and Glucose Hypometabolism After Corpus Callosotomy Predicts Seizure Outcome After Subsequent Surgery.

Background: Patients with generalized epilepsy who had lateralized EEG abnormalities after corpus callosotomy (CC) occasionally undergo subsequent surgeries to control intractable epilepsy. Objectives: This study evaluated retrospectively the combination of EEG multiscale entropy (MSE) and FDG-PET for identifying lateralization of the epileptogenic zone after CC. Methods: This study included 14 patients with pharmacoresistant epilepsy who underwent curative epilepsy surgery after CC. Interictal scalp EEG and FDG-PET obtained after CC were investigated to determine (1) whether the MSE calculated from the EEG and FDG-PET findings was lateralized to the surgical side, and (2) whether the lateralization was associated with seizure outcomes. Results: Seizure reduction rate was higher in patients with lateralized findings to the surgical side than those without (MSE: p < 0.05, FDG-PET: p < 0.05, both: p < 0.01). Seizure free rate was higher in patients with lateralized findings in both MSE and FDG-PET than in those without (p < 0.05). Conclusions: This study demonstrated that patients with lateralization of MSE and FDG-PET to the surgical side had better seizure outcomes. The combination of MSE and conventional FDG-PET may help to select surgical candidates for additional surgery after CC with good postoperative seizure outcomes.

Is Hippocampal Resection Necessary for Low-Grade Epilepsy-Associated Tumors in the Temporal Lobe?

Low-grade epilepsy-associated tumors (LEATs) are common in the temporal lobe and can cause drug-resistant epilepsy. Complete resection of LEATs is sufficient for seizure relief. However, hippocampal resection might result in postoperative cognitive impairment. This study aimed to clarify the necessity of hippocampal resection for seizure and cognitive outcomes in patients with temporal lobe LEATs and a normal hippocampus. The study included 32 patients with temporal lobe LEATs and without hippocampal abnormalities. All patients underwent gross total resection as treatment for drug-resistant epilepsy at our tertiary epilepsy center from 2005 to 2020, followed by at least a 12-month follow-up period. Seizure and cognitive outcomes were compared between patients who underwent additional hippocampal resection (Resected group) and those who did not (Preserved group). Among the participants, 14 underwent additional hippocampal resection and 28 (87.5%) achieved seizure freedom irrespective of hippocampal resection. The seizure-free periods were not different between the two groups. Additional hippocampal resection resulted in a significantly negative impact on the postoperative verbal index. In conclusion, additional hippocampal resection in patients with temporal lobe LEATs without hippocampal abnormalities is unnecessary because lesionectomy alone results in good seizure control. Additional hippocampal resection may instead adversely affect the postoperative language function.