Extent of resection, molecular signature, and survival in 1p19q-codeleted gliomas

OBJECTIVE

Genomic analysis in neurooncology has underscored the importance of understanding the patterns of survival in different molecular subtypes within gliomas and their responses to treatment. In particular, diffuse gliomas are now principally characterized by their mutation status (IDH1 and 1p/19q codeletion), yet there remains a paucity of information regarding the prognostic value of molecular markers and extent of resection (EOR) on survival. Furthermore, given the modern emphasis on molecular rather than histological diagnosis, it is important to examine the effect of maximal resection on survival in all gliomas with 1p/q19 codeletions, as these will now be classified as oligodendrogliomas under the new WHO guidelines. The objectives of the present study were twofold: 1) to assess the association between EOR and survival for patients with oligodendrogliomas in the National Cancer Database (NCDB), which includes information on mutation status, and 2) to demonstrate the same effect for all patients with 1p/19q codeleted gliomas in the NCDB.

METHODS

The NCDB was queried for all cases of oligodendroglioma between 2004 and 2014, with follow-up dates through 2016. The authors found 2514 cases of histologically confirmed oligodendrogliomas for the final analysis of the effect of EOR on survival. Upon further query, 1067 1p/19q-codeleted tumors were identified in the NCDB. Patients who received subtotal resection (STR) or gross-total resection (GTR) were compared to those who received no tumor debulking surgery. Univariable and multivariable analyses of both overall survival and cause-specific survival were performed.

RESULTS

EOR was associated with increased overall survival for both histologically confirmed oligodendrogliomas and all 1p/19q-codeleted-defined tumors (p < 0.001 and p = 0.002, respectively). Tumor grade, location, and size covaried predictably with EOR. When evaluating tumors by each classification system for predictors of overall survival, facility setting, age, comorbidity index, grade, location, chemotherapy, and radiation therapy were all shown to be significantly associated with overall survival. STR and GTR were independent predictors of improved survival in historically classified oligodendrogliomas (HR 0.83, p = 0.18; HR 0.69, p = 0.01, respectively) and in 1p/19q-codeleted tumors (HR 0.49, p < 0.01; HR 0.43, p < 0.01, respectively).

CONCLUSIONS

By using the NCDB, the authors have demonstrated a side-by-side comparison of the survival benefits of greater EOR in 1p/19q-codeleted gliomas.

Abnormal mitosis in reactive astrocytes

Although abnormal mitosis with disarranged metaphase chromosomes or many micronuclei in astrocytes (named "Alzheimer I type astrocytes" and later "Creutzfeldt-Peters cells") have been known for nearly 100 years, the origin and mechanisms of this pathology remain elusive. In experimental brain insults in rats, we show that abnormal mitoses that are not followed by cytokinesis are typical for reactive astrocytes. The pathology originates due to the inability of the cells to form normal mitotic spindles with subsequent metaphase chromosome congression, which, in turn may be due to shape constraints aggravated by cellular enlargement and to the accumulation of large amounts of cytosolic proteins. Many astrocytes escape from arrested mitosis by producing micronuclei. These polyploid astrocytes can survive for long periods of time and enter into new cell cycles.

Craniotomy and Survival for Primary Central Nervous System Lymphoma

BACKGROUND

Cytoreductive surgery is considered controversial for primary central nervous system lymphoma (PCNSL).

OBJECTIVE

To investigate survival following craniotomy or biopsy for PCNSL.

METHODS

The National Cancer Database-Participant User File (NCDB, n = 8936), Surveillance, Epidemiology, and End Results Program (SEER, n = 4636), and an institutional series (IS, n = 132) were used. We retrospectively investigated the relationship between craniotomy, prognostic factors, and survival for PCNSL using case-control design.

RESULTS

In NCDB, craniotomy was associated with increased median survival over biopsy (19.5 vs 11.0 mo), independent of subsequent radiation and chemotherapy (hazard ratio [HR] 0.80, P < .001). We found a similar trend with survival for craniotomy vs biopsy in the IS (HR 0.68, P = .15). In SEER, gross total resection was associated with increased median survival over biopsy (29 vs 10 mo, HR 0.68, P < .001). The survival benefit associated with craniotomy was greater within recursive partitioning analysis (RPA) class 1 group in NCDB (95.1 vs 29.1 mo, HR 0.66, P < .001), but was smaller for RPA 2-3 (14.9 vs 10.0 mo, HR 0.86, P < .001). A surgical risk category (RC) considering lesion location and number, age, and frailty was developed. Craniotomy was associated with increased survival vs biopsy for patients with low RC (133.4 vs 41.0 mo, HR 0.33, P = .01), but not high RC in the IS.

CONCLUSION

Craniotomy is associated with increased survival over biopsy for PCNSL in 3 retrospective datasets. Prospective studies are necessary to adequately evaluate this relationship. Such studies should evaluate patients most likely to benefit from cytoreductive surgery, ie, those with favorable RPA and RC.

A model for focal seizure onset, propagation, evolution, and progression

We developed a neural network model that can account for major elements common to human focal seizures. These include the tonic-clonic transition, slow advance of clinical semiology and corresponding seizure territory expansion, widespread EEG synchronization, and slowing of the ictal rhythm as the seizure approaches termination. These were reproduced by incorporating usage-dependent exhaustion of inhibition in an adaptive neural network that receives global feedback inhibition in addition to local recurrent projections. Our model proposes mechanisms that may underline common EEG seizure onset patterns and status epilepticus, and postulates a role for synaptic plasticity in the emergence of epileptic foci. Complex patterns of seizure activity and bi-stable seizure end-points arise when stochastic noise is included. With the rapid advancement of clinical and experimental tools, we believe that this model can provide a roadmap and potentially an in silico testbed for future explorations of seizure mechanisms and clinical therapies.

Surgery plus adjuvant radiotherapy for primary central nervous system lymphoma

Objective: Recent studies of primary central nervous system lymphoma (PCNSL) have found a positive association between cytoreductive surgery and survival, challenging the traditional notion that surgery is not beneficial and potentially harmful. However, no studies have examined the potential added benefits of adjuvant treatment in the post-operative setting. Here, we investigate survival in PCNSL patients treated with surgery plus radiation therapy (RT).Methods: The Surveillance, Epidemiology, and End-Results Program was used to identify patients with PCNSL from 1995-2013. We retrospectively analyzed the relationship between treatment, prognostic factors, and survival using case-control design. Treatment categories were compared to biopsy alone.Results: We identified 5417 cases. Median survival times for biopsy alone (n = 1824, 34%), biopsy + RT (n = 1460, 27%), surgery alone (n = 1222, 27%), and surgery + RT (n = 911, 17%) were 7, 8, 20, and 27 months, respectively. On multivariable analysis, surgery + RT was associated with improved survival over surgery alone (hazard ratio [HR] = 0.58 [95% confidence interval = 0.53-0.64] vs. HR = 0.71 [0.65-0.77]). Adjuvant RT was associated with improved survival, regardless of the extent of resection. HR's for subtotal resection, gross-total resection, subtotal resection + RT, and gross-total resection + RT were 0.77 (0.66-0.89), 0.66 (0.57-0.76), 0.62 (0.52-0.72), and 0.54 (0.46-0.63), respectively. Survival improved after adjuvant RT in patients under and over 60 years old. All findings were confirmed by multivariable analysis of cause-specific survival.Conclusion: Adjuvant RT was associated with improved survival in PCNSL patients who underwent surgery. Although these data are hypothesis-generating, additional information on neurotoxicity, dosing, and concurrent chemotherapy will be necessary to validate these findings. Cytoreductive surgery for PCNSL is common in the general population, and more studies are needed to assess optimal treatment in the post-operative setting.

Near real-time intraoperative brain tumor diagnosis using stimulated Raman histology and deep neural networks

Intraoperative diagnosis is essential for providing safe and effective care during cancer surgery1. The existing workflow for intraoperative diagnosis based on hematoxylin and eosin staining of processed tissue is time, resource and labor intensive2,3. Moreover, interpretation of intraoperative histologic images is dependent on a contracting, unevenly distributed, pathology workforce4. In the present study, we report a parallel workflow that combines stimulated Raman histology (SRH)5-7, a label-free optical imaging method and deep convolutional neural networks (CNNs) to predict diagnosis at the bedside in near real-time in an automated fashion. Specifically, our CNNs, trained on over 2.5 million SRH images, predict brain tumor diagnosis in the operating room in under 150 s, an order of magnitude faster than conventional techniques (for example, 20-30 min)2. In a multicenter, prospective clinical trial (n = 278), we demonstrated that CNN-based diagnosis of SRH images was noninferior to pathologist-based interpretation of conventional histologic images (overall accuracy, 94.6% versus 93.9%). Our CNNs learned a hierarchy of recognizable histologic feature representations to classify the major histopathologic classes of brain tumors. In addition, we implemented a semantic segmentation method to identify tumor-infiltrated diagnostic regions within SRH images. These results demonstrate how intraoperative cancer diagnosis can be streamlined, creating a complementary pathway for tissue diagnosis that is independent of a traditional pathology laboratory.

Patterns of seizure prophylaxis after oncologic neurosurgery

BACKGROUND

Evidence supporting routine postoperative antiepileptic drug (AED) prophylaxis following oncologic neurosurgery is limited, and actual practice patterns are largely unknown beyond survey data.

OBJECTIVE

To describe patterns and predictors of postoperative AED prophylaxis following intracranial tumor surgery.

METHODS

The MarketScan Database was used to analyze pharmacy claims data and clinical characteristics in a national sample over a 5-year period.

RESULTS

Among 5895 patients in the cohort, levetiracetam was the most widely used AED for prophylaxis (78.5%) followed by phenytoin (20.5%). Prophylaxis was common but highly variable for patients who underwent open resection of supratentorial intraparenchymal tumors (62.5%, reference) or meningiomas (61.9%). In multivariate analysis, biopsies were less likely to receive prophylaxis (44.8%, OR 0.47, 95% CI 0.33-0.67), and there was near consensus against prophylaxis for infratentorial (9.7%, OR 0.07, CI 0.05-0.09) and transsphenoidal procedures (0.4%, OR 0.003, CI 0.001-0.010). Primary malignancies (52.1%, reference) and secondary metastases (42.2%) were more likely to receive prophylaxis than benign tumors (23.0%, OR 0.63, CI 0.48-0.83), as were patients discharged with home services and patients in the Northeast. There was a large spike in duration of AED use at approximately 30 days.

CONCLUSIONS

Use of seizure prophylaxis following intracranial biopsies and supratentorial resections is highly variable, consistent with a lack of guidelines or consensus. Current practice patterns do not support a clear standard of care and may be driven in part by geographic variation, availability of post-discharge services, and electronic prescribing defaults rather than evidence. Given uncertainty regarding effectiveness, indications, and appropriate duration of AED prophylaxis, well-powered trials are needed.

Ex vivo multi-electrode analysis reveals spatiotemporal dynamics of ictal behavior at the infiltrated margin of glioma

The purpose of this study is to develop a platform in which the cellular and molecular underpinnings of chronic focal neocortical lesional epilepsy can be explored and use it to characterize seizure-like events (SLEs) in an ex vivo model of infiltrating high-grade glioma. Microelectrode arrays were used to study electrophysiologic changes in ex vivo acute brain slices from a PTEN/p53 deleted, PDGF-B driven mouse model of high-grade glioma. Electrode locations were co-registered to the underlying histology to ascertain the influence of the varying histologic landscape on the observed electrophysiologic changes. Peritumoral, infiltrated, and tumor sites were sampled in tumor-bearing slices. Following the addition of zero Mg²⁺ solution, all three histologic regions in tumor-bearing slices showed significantly greater increases in firing rates when compared to the control sites. Tumor-bearing slices demonstrated increased proclivity for SLEs, with 40 events in tumor-bearing slices and 5 events in control slices (p-value = .0105). Observed SLEs were characterized by either low voltage fast (LVF) onset patterns or short bursts of repetitive widespread, high amplitude low frequency discharges. Seizure foci comprised areas from all three histologic regions. The onset electrode was found to be at the infiltrated margin in 50% of cases and in the peritumoral region in 36.9% of cases. These findings reveal a landscape of histopathologic and electrophysiologic alterations associated with ictogenesis and spread of tumor-associated seizures.

Risk of seizures induced by intracranial research stimulation: analysis of 770 stimulation sessions

OBJECTIVE

Patients with medically refractory epilepsy often undergo intracranial electroencephalography (iEEG) monitoring to identify a seizure focus and determine their candidacy for surgical intervention. This clinically necessary monitoring period provides an increasingly utilized research opportunity to study human neurophysiology, however ethical concerns demand a thorough appreciation of the associated risks. We measured the incidence of research stimulation-associated seizures in a large multi-institutional dataset in order to determine whether brain stimulation was statistically associated with seizure incidence and identify potential risk factors for stimulation-associated seizures.

APPROACH

188 subjects undergoing iEEG monitoring across ten institutions participated in 770 research stimulation sessions over 3.5 yr. Seizures within 30 min of a stimulation session were included in our retrospective analysis. We analyzed stimulation parameters, seizure incidence, and typical seizure patterns, to assess the likelihood that recorded seizures were stimulation-induced, rather than events that occurred by chance in epilepsy patients prone to seizing.

MAIN RESULTS

In total, 14 seizures were included in our analysis. All events were single seizures, and no adverse events occurred. The mean amplitude of seizure-associated stimulation did not differ significantly from the mean amplitude delivered in sessions without seizures. In order to determine the likelihood that seizures were stimulation induced, we used three sets of analyses: visual iEEG analysis, statistical frequency, and power analyses. We determined that three of the 14 seizures were likely stimulation-induced, five were possibly stimulation-induced, and six were unlikely stimulation-induced. Overall, we estimate a rate of stimulation-induced seizures between 0.39% and 1.82% of sessions.

SIGNIFICANCE

The rarity of stimulation-associated seizures and the fact that none added morbidity or affected the clinical course of any patient are important findings for understanding the feasibility and safety of intracranial stimulation for research purposes.

Hierarchical Encoding of Attended Auditory Objects in Multi-talker Speech Perception

Humans can easily focus on one speaker in a multi-talker acoustic environment, but how different areas of the human auditory cortex (AC) represent the acoustic components of mixed speech is unknown. We obtained invasive recordings from the primary and nonprimary AC in neurosurgical patients as they listened to multi-talker speech. We found that neural sites in the primary AC responded to individual speakers in the mixture and were relatively unchanged by attention. In contrast, neural sites in the nonprimary AC were less discerning of individual speakers but selectively represented the attended speaker. Moreover, the encoding of the attended speaker in the nonprimary AC was invariant to the degree of acoustic overlap with the unattended speaker. Finally, this emergent representation of attended speech in the nonprimary AC was linearly predictable from the primary AC responses. Our results reveal the neural computations underlying the hierarchical formation of auditory objects in human AC during multi-talker speech perception.

Widespread temporal coding of cognitive control in the human prefrontal cortex

When making decisions we often face the need to adjudicate between conflicting strategies or courses of action. Our ability to understand the neuronal processes underlying conflict processing is limited on the one hand by the spatiotemporal resolution of fMRI and, on the other, by imperfect cross-species homologies in animal model systems. Here we examine responses of single neurons and local field potentials in human neurosurgical patients in two prefrontal regions critical to controlled decision-making, dorsal anterior cingulate cortex (dACC) and dorsolateral prefrontal cortex (dlPFC). While we observe typical modest conflict related firing rate effects, we find a widespread effect of conflict on spike-phase coupling in dACC and on driving spike-field coherence in dlPFC. These results support the hypothesis that a cross-areal rhythmic neuronal coordination is intrinsic to cognitive control in response to conflict, and provide new evidence to support the hypothesis that conflict processing involves modulation of dlPFC by dACC.

Role of paroxysmal depolarization in focal seizure activity

We analyze the role of inhibition in sustaining focal epileptic seizure activity. We review ongoing seizure activity at the mesoscopic scale that can be observed with microelectrode arrays as well as at the macroscale of standard clinical EEG. We provide clinical, experimental, and modeling data to support the hypothesis that paroxysmal depolarization (PD) is a critical component of the ictal machinery. We present dual-patch recordings in cortical cultures showing reduced synaptic transmission associated with presynaptic occurrence of PD, and we find that the PD threshold is cell size related. We further find evidence that optically evoked PD activity in parvalbumin neurons can promote propagation of neuronal excitation in neocortical networks in vitro. Spike sorting results from microelectrode array measurements around ictal wave propagation in human focal seizures demonstrate a strong increase in putative inhibitory firing with an approaching excitatory wave, followed by a sudden reduction of firing at passage. At the macroscopic level, we summarize evidence that this excitatory ictal wave activity is strongly correlated with oscillatory activity across a centimeter-sized cortical network. We summarize Wilson-Cowan-type modeling showing how inhibitory function is crucial for this behavior. Our findings motivated us to develop a network motif of neurons in silico, governed by a reduced version of the Hodgkin-Huxley formalism, to show how feedforward, feedback, PD, and local failure of inhibition contribute to observed dynamics across network scales. The presented multidisciplinary evidence suggests that the PD not only is a cellular marker or epiphenomenon but actively contributes to seizure activity.NEW & NOTEWORTHY We present mechanisms of ongoing focal seizures across meso- and macroscales of microelectrode array and standard clinical recordings, respectively. We find modeling, experimental, and clinical evidence for a dual role of inhibition across these scales: local failure of inhibition allows propagation of a mesoscopic ictal wave, whereas inhibition elsewhere remains intact and sustains macroscopic oscillatory activity. We present evidence for paroxysmal depolarization as a mechanism behind this dual role of inhibition in shaping ictal activity.

Extent of resection and survival for oligodendroglioma: a U.S. population-based study

BACKGROUND

National guidelines recommend maximal safe resection of low-grade and high-grade oligodendrogliomas. However, there is no level 1 evidence to support these guidelines, and recent retrospective studies on the topic have yielded mixed results.

OBJECTIVE

To assess the association between extent of resection (EOR) and survival for oligodendrogliomas in the general U.S.

POPULATION

METHODS

Cases diagnosed between 2004 and 2013 were selected from the Surveillance, Epidemiology, and End-Results (SEER) Program and retrospectively analyzed for treatment, prognostic factors, and survival times. Cases that did not undergo tumor de-bulking surgery (e.g. no surgery or biopsy alone) were compared to subtotal resection (resection) and gross-total resection (GTR). The primary end-points were overall survival (OS) and cause-specific survival (CSS). An external validation cohort with 1p/19q-codeleted tumors was creating using the TCGA and GSE16011 datasets.

RESULTS

3135 Cases were included in the final analysis. The 75% survival time (75ST) and 5-year survival rates were 47 months and 70.8%, respectively. Subtotal resection (STR, 75ST = 50 months) and GTR (75ST = 61 months) were associated with improved survival times compared to cases that did not undergo surgical debulking (75ST = 20 months, P < 0.001 for both), with reduced hazard ratios (HRs) after controlling for other factors (HR 0.81 [0.68-0.97] and HR 0.65 [0.54-0.79], respectively). GTR was associated with improved OS in both low-grade and anaplastic oligodendroglioma subgroups (HR 0.74 [0.58-0.95], HR 0.60 [0.44-0.82], respectively) while STR fell short of significance in the subgroup analysis. All findings were corroborated by multivariable analysis of CSS and externally validated in a cohort of patients with 1p19q-codeleted tumors.

CONCLUSION

Greater EOR is associated with improved survival in oligodendrogliomas. Our findings in this U.S. population-based cohort support national guidelines.

Frameless Stereotactic Radiosurgery on the Gamma Knife Icon: Early Experience From 100 Patients

BACKGROUND

The Gamma Knife (GK) Icon (Elekta AB) uses a cone-beam computed tomography (CBCT) scanner and an infrared camera system to support the delivery of frameless stereotactic radiosurgery (SRS). There are limited data on patients treated with frameless GK radiosurgery (GKRS).

OBJECTIVE

To describe the early experience, process, technical details, and short-term outcomes with frameless GKRS at our institution.

METHODS

We reviewed our patient selection and described the workflow in detail, including image acquisition, treatment planning, mask-based immobilization, stereotactic CBCT localization, registration, treatment, and intrafraction monitoring. Because of the short interval of follow-up, we provide crude rates of local control.

RESULTS

Data from 100 patients are reported. Median age is 67 yr old. 56 patients were treated definitively, 21 postoperatively, and 23 had salvage GKRS for recurrence after surgery. Forty-two patients had brain metastases, 26 meningiomas, 16 vestibular schwannomas, 9 high-grade gliomas, and 7 other histologies. Median doses to metastases were 20 Gy in 1 fraction (range: 14-21), 24 Gy in 3 fractions (range: 19.5-27), and 25 Gy in 5 fractions (range: 25-30 Gy). Thirteen patients underwent repeat SRS to the same area. Median treatment time was 17.7 min (range: 5.8-61.7). We found an improvement in our workflow and a greater number of patients eligible for GKRS because of the ability to fractionate treatments.

CONCLUSION

We report a large cohort of consecutive patients treated with frameless GKRS. We look forward to studies with longer follow-up to provide valuable data on clinical outcomes and to further our understanding of the radiobiology of hypofractionation in the brain.

Cortical naming sites and increasing age in adults with refractory epilepsy: More might be less

OBJECTIVE

Critical decisions regarding resection boundaries for epilepsy surgery are often based on results of electrical stimulation mapping (ESM). Despite the potentially serious implications for postoperative functioning, age-referenced data that might facilitate the procedure are lacking. Age might be particularly relevant, as pediatric ESM studies have shown a paucity of language sites in young children followed by a rapid increase at approximately 8-10 years. Beyond adolescence, it has generally been assumed that the language system remains stable, and therefore, potential age-related changes across the adult age span have not been examined. However, increasing age during adulthood is associated with both positive and negative language-related changes, such as a broadening vocabulary and increased word finding difficulty. Because most patients who undergo ESM are adults, we aimed to determine the potential impact of age on the incidence of ESM-identified naming sites across the adult age span in patients with refractory epilepsy.

METHODS

We analyzed clinical language ESM results from 47 patients, ages 17-64 years, with refractory dominant-hemisphere epilepsy. Patients had comparable location and number of cortical sites tested. The incidence of naming sites was examined as a function of age, and compared between younger and older adults.

RESULTS

Significantly more naming sites were found in older than younger adults, and age was found to be a significant predictor of number of naming sites identified.

SIGNIFICANCE

Unlike the developmental changes that coincide with increased naming sites in children, increased naming sites in older adults might signify greater vulnerability of the language system to disruption. Because preservation of language sites can limit the extent of the resection, and thereby reduce the likelihood of seizure freedom, further work should aim to determine the clinical relevance of increased naming sites in older adults.

Spinal location is prognostic of survival for solitary-fibrous tumor/hemangiopericytoma of the central nervous system

BACKGROUND

Prior studies have highlighted infratentorial tumor location as a prognostic factor for solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) of the central nervous system (CNS), and spinal location is considered a positive prognostic factor for other tumors of the CNS. While SFT/HPC of the CNS is known to frequently arise from the spinal meninges, there are no case series that report outcomes for spinally located CNS tumors, and their prognosis in relation to intracranial and other CNS-located tumors is unknown.

OBJECTIVE

To investigate outcomes for patients with SFT/HPC of the spinal meninges.

METHODS

The Surveillance, Epidemiology, and End-Results Program was used to identify patients with SFT/HPC within the CNS from 1993-2015. We retrospectively analyzed the relationship between tumor location (spinal vs. Brain and other CNS) and survival.

RESULTS

We identified 551 cases of CNS SFT/HPC, 64 (11.6%) of which were primary tumors of the spinal meninges. Spinal tumors were more likely than brain and other CNS tumors to be SFT vs. HPC (37.5 vs. 12%, p < 0.001), benign (42.2 vs. 20.3%, p < 0.001), and less than 5 cm (53.1 vs. 35.7%, p < 0.001). The 10-year survival rates for spinal and brain/other CNS tumors were 85 and 58%, respectively. Median survival time was significantly longer for spinal tumors (median survival not reached vs. 138 months, p = 0.03, HR = 0.41 [95% CI 0.18-0.94]). On multivariable analysis, spinal tumor location was associated with improved survival over tumors located in the brain and other CNS (HR = 0.36 [95% CI 0.15-0.89], p = 0.03).

CONCLUSION

Spinal tumor location is associated with improved survival in patients with SFT/HPC of the CNS. Larger institutional studies are necessary to characterize the relationship between tumor location and other relevant factors such as presentation and amenability to gross-total resection and adjuvant radiotherapy. Future studies exploring optimal management of spinally located tumors are also needed.

Effects of surgical targeting in laser interstitial thermal therapy for mesial temporal lobe epilepsy: A multicenter study of 234 patients

OBJECTIVE

Laser interstitial thermal therapy (LITT) for mesial temporal lobe epilepsy (mTLE) has reported seizure freedom rates between 36% and 78% with at least 1 year of follow-up. Unfortunately, the lack of robust methods capable of incorporating the inherent variability of patient anatomy, the variability of the ablated volumes, and clinical outcomes have limited three-dimensional quantitative analysis of surgical targeting and its impact on seizure outcomes. We therefore aimed to leverage a novel image-based methodology for normalizing surgical therapies across a large multicenter cohort to quantify the effects of surgical targeting on seizure outcomes in LITT for mTLE.

METHODS

This multicenter, retrospective cohort study included 234 patients from 11 centers who underwent LITT for mTLE. To investigate therapy location, all ablation cavities were manually traced on postoperative magnetic resonance imaging (MRI), which were subsequently nonlinearly normalized to a common atlas space. The association of clinical variables and ablation location to seizure outcome was calculated using multivariate regression and Bayesian models, respectively.

RESULTS

Ablations including more anterior, medial, and inferior temporal lobe structures, which involved greater amygdalar volume, were more likely to be associated with Engel class I outcomes. At both 1 and 2 years after LITT, 58.0% achieved Engel I outcomes. A history of bilateral tonic-clonic seizures decreased chances of Engel I outcome. Radiographic hippocampal sclerosis was not associated with seizure outcome.

SIGNIFICANCE

LITT is a viable treatment for mTLE in patients who have been properly evaluated at a comprehensive epilepsy center. Consideration of surgical factors is imperative to the complete assessment of LITT. Based on our model, ablations must prioritize the amygdala and also include the hippocampal head, parahippocampal gyrus, and rhinal cortices to maximize chances of seizure freedom. Extending the ablation posteriorly has diminishing returns. Further work is necessary to refine this analysis and define the minimal zone of ablation necessary for seizure control.

Predicting Cognitive Improvement in Normal Pressure Hydrocephalus Patients Using Preoperative Neuropsychological Testing and Cerebrospinal Fluid Biomarkers

BACKGROUND

Though it is well known that normal pressure hydrocephalus (NPH) patients can cognitively improve after ventriculoperitoneal shunting (VPS), one of the major dilemmas in NPH is the ability to prospectively predict which patients will improve.

OBJECTIVE

To prospectively assess preoperative predictors of postshunt cognitive improvement.

METHODS

This was a prospective observational cohort including 52 consecutive patients with approximately 1-yr follow-up. Patients underwent neuropsychological testing at baseline, postlumbar drainage, and postshunt. Cerebrospinal fluid (CSF) biomarkers and cortical biopsies were also collected to examine their relationship with postshunt cognitive improvement.

RESULTS

Rey Auditory Verbal Learning Test-L (RAVLT-L) was the only neuropsychological test to demonstrate statistically significant improvement both postlumbar drain and postshunt. Improvement on the RAVLT-L postlumbar drain predicted improvement on the RAVLT-L postshunt. Patients with biopsies demonstrating Aβ+ Tau+ had lower ventricular CSF Aβ42 and higher lumbar CSF pTau compared to Aβ– Tau– patients. A receiver operating curve analysis using lumbar pTau predicted Aβ+ Tau+ biopsy status but was not related to neuropsychological test outcome.

CONCLUSION

The RAVLT can be a useful preoperative predictor of postoperative cognitive improvement, and thus, we recommend using the RAVLT to evaluate NPH patients. CSF biomarkers could not be related to neuropsychological test outcome. Future research in a larger patient sample will help determine the prospective utility of CSF biomarkers in the evaluation of NPH patients.

Multiscale recordings reveal the dynamic spatial structure of human seizures

The cellular activity underlying human focal seizures, and its relationship to key signatures in the EEG recordings used for therapeutic purposes, has not been well characterized despite many years of investigation both in laboratory and clinical settings. The increasing use of microelectrodes in epilepsy surgery patients has made it possible to apply principles derived from laboratory research to the problem of mapping the spatiotemporal structure of human focal seizures, and characterizing the corresponding EEG signatures. In this review, we describe results from human microelectrode studies, discuss some data interpretation pitfalls, and explain the current understanding of the key mechanisms of ictogenesis and seizure spread.

Natural history, clinical course and predictors of interval time from initial diagnosis to development of subsequent NSCLC brain metastases

PURPOSE

Non-small cell lung cancer (NSCLC) brain metastases are associated with substantial morbidity and mortality. During recent years, accompanying dramatic improvements in systemic disease control, NSCLC brain metastases have emerged as an increasingly relevant clinical problem. However, optimal surveillance practices remain poorly defined. This purpose of this study was to further characterize the natural history, clinical course and risk factors associated with earlier development of subsequent NSCLC brain metastases to better inform clinical practice and help guide survivorship care.

METHODS

We retrospectively reviewed all institutional NSCLC brain metastasis cases treated with radiotherapy between 1997 and 2015. Exclusion criteria included presence of brain metastases at initial NSCLC diagnosis and incomplete staging information. Interval time to brain metastases and subsequent survival were characterized using Kaplan-Meier and multivariate Cox regression analyses.

RESULTS

Among 105 patients within this cohort, median interval time to development of brain metastases was 16 months. Median interval times were 29, 19, 16 and 13 months for Stage I-IV patients, respectively (P = 0.016). Additional independent predictors for earlier development of NSCLC brain metastases included non-adenocarcinomatous histopathology (HR 3.036, P < 0.001), no prior surgical resection (HR 1.609, P = 0.036) and no prior systemic therapy (HR 3.560, P = 0.004). Median survival following intracranial progression was 16 months. Delayed development of brain metastases was associated with better prognosis (HR 0.970, P < 0.001) but not survival following intracranial disease onset.

CONCLUSIONS

Collectively, our results provide valuable insights into the natural history of NSCLC brain metastases. NSCLC stage, histology, prior surgical resection and prior systemic therapy emerged as independent predictors for interval time to brain metastases.