How coupled slow oscillations, spindles and ripples coordinate neuronal processing and communication during human sleep

Learning and plasticity rely on fine-tuned regulation of neuronal circuits during offline periods. An unresolved puzzle is how the sleeping brain, in the absence of external stimulation or conscious effort, coordinates neuronal firing rates (FRs) and communication within and across circuits to support synaptic and systems consolidation. Using intracranial electroencephalography combined with multiunit activity recordings from the human hippocampus and surrounding medial temporal lobe (MTL) areas, we show that, governed by slow oscillation (SO) up-states, sleep spindles set a timeframe for ripples to occur. This sequential coupling leads to a stepwise increase in (1) neuronal FRs, (2) short-latency cross-correlations among local neuronal assemblies and (3) cross-regional MTL interactions. Triggered by SOs and spindles, ripples thus establish optimal conditions for spike-timing-dependent plasticity and systems consolidation. These results unveil how the sequential coupling of specific sleep rhythms orchestrates neuronal processing and communication during human sleep

Post-Surgical Outcome and Its Determining Factors in Patients Operated on With Focal Cortical Dysplasia Type II—A Retrospective Monocenter Study

Purpose: Focal cortical dysplasias (FCDs) are a frequent cause of drug-resistant focal epilepsies. These lesions are in many cases amenable to epilepsy surgery. We examined 12-month and long-term post-surgical outcomes and its predictors including positive family history of epilepsy.Methods: Twelve-month and long-term outcomes regarding seizure control after epilepsy surgery in patients operated on with FCD type II between 2002 and 2019 in the Epilepsy Center of Bonn were evaluated based on patient records and telephone interviews.Results: Overall, 102 patients fulfilled the inclusion criteria. Seventy-one percent of patients at 12 months of follow-up (FU) and 54% of patients at the last available FU (63 ± 5.00 months, median 46.5 months) achieved complete seizure freedom (Engel class IA), and 84 and 69% of patients, respectively, displayed Engel class I outcome. From the examined variables [histopathology: FCD IIA vs. IIB, lobar lesion location: frontal vs. non-frontal, family history for epilepsy, focal to bilateral tonic–clonic seizures (FTBTCS) in case history, completeness of resection, age at epilepsy onset, age at surgery, duration of epilepsy], outcomes at 12 months were determined by interactions of age at onset, duration of epilepsy, age at surgery, extent of resection, and lesion location. Long-term post-surgical outcome was primarily influenced by the extent of resection and history of FTBTCS. Positive family history for epilepsy had a marginal influence on long-term outcomes only.Conclusion: Resective epilepsy surgery in patients with FCD II yields very good outcomes both at 12-month and long-term follow-ups. Complete lesion resection and the absence of FTBTCS prior to surgery are associated with a better outcome

Long-term seizure outcome after epilepsy surgery of neuroglial tumors

PurposeNeuroglial tumors are frequently associated with pharmacorefractory epilepsies. However, comprehensive knowledge about long-term outcomes after epilepsy surgery and the main prognostic factors for outcome is still limited. We sought to evaluate long-term outcomes and potential influencing factors in a large cohort of patients who underwent surgery for neuroglial tumors in a single-center setting.MethodsThe study analyzed the outcomes of 107 patients who underwent epilepsy surgery for neuroglial tumors between 2001 and 2020 at the Department of Epileptology, University Hospital Bonn, in Germany. The outcomes were evaluated using Engel classification. Differences in outcome related to potential prognostic factors were examined using the Chi2-test, Fisher’s exact test and sign test. Additionally, stepwise logistic regression analysis was employed to identify independent prognostic factors.ResultsComplete seizure freedom (Engel Class IA) was achieved in 75% of the operated patients at 12 months, and 56% at the last follow-up visit (70.4 ± 6.2 months, median: 40 months). Completeness of resection was a crucial factor for both 12-month follow-up outcomes and the longest available outcomes, whereas lobar tumor localization, histology (ganglioglioma vs. dysembryoplastic neuroepithelial tumor), history of bilateral tonic–clonic seizures prior to surgery, invasive diagnostics, side of surgery (dominant vs. non-dominant hemisphere), age at epilepsy onset, age at surgery, and epilepsy duration did not consistently impact postsurgical outcomes. Among temporal lobe surgeries, patients who underwent lesionectomy and lesionectomy, including hippocampal resection, demonstrated similar outcomes.ConclusionNeuroglial tumors present as excellent surgical substrates in treating structural epilepsy. To achieve an optimal postsurgical outcome, a complete lesion resection should be pursued whenever possible

Artificial Intelligence for the Detection of Focal Cortical Dysplasia: Challenges in Translating Algorithms into Clinical Practice

Focal cortical dysplasias (FCDs) are malformations of cortical development and one of the most common pathologies causing pharmacoresistant focal epilepsy. Resective neurosurgery yields high success rates, especially if the full extent of the lesion is correctly identified and completely removed. The visual assessment of magnetic resonance imaging does not pinpoint the FCD in 30%–50% of cases, and half of all patients with FCD are not amenable to epilepsy surgery, partly because the FCD could not be sufficiently localized. Computational approaches to FCD detection are an active area of research, benefitting from advancements in computer vision. Automatic FCD detection is a significant challenge and one of the first clinical grounds where the application of artificial intelligence may translate into an advance for patients' health. The emergence of new methods from the combination of health and computer sciences creates novel challenges. Imaging data need to be organized into structured, well-annotated datasets and combined with other clinical information, such as histopathological subtypes or neuroimaging characteristics. Algorithmic output, that is, model prediction, requires a technically correct evaluation with adequate metrics that are understandable and usable for clinicians. Publication of code and data is necessary to make research accessible and reproducible. This critical review introduces the field of automatic FCD detection, explaining underlying medical and technical concepts, highlighting its challenges and current limitations, and providing a perspective for a novel research environment

Rapid closure technique in suboccipital decompression

Objective!#!Suboccipital decompression has been established as standard therapeutic procedure for raised intracranial pressure caused by mass-effect associated pathologies in posterior fossa. Several different surgical techniques of dural closure have been postulated to achieve safe decompression. The aim of this study was to examine the differences between fibrin sealant patch (FSP) and dural reconstruction (DR) in suboccipital decompression for acute mass-effect lesions.!##!Methods!#!We retrospectively analyzed our institutional data of patients who underwent suboccipital decompression due to spontaneous intracerebellar hemorrhage, cerebellar infarction and acute traumatic subdural hematoma between 2010 and 2019. Two different dural reconstruction techniques were performed according to the attending neurosurgeon: (1) fibrin sealant patch (FSP), and (2) dural reconstruction (DR) including the use of dural patch. Complications, operative time, functional outcome and the necessity of a ventriculoperitoneal shunt (VP Shunt) were assessed and further analyzed.!##!Results!#!Overall, 87 patients were treated at the authors' institution (44 in FSP group, 43 in DR group). Glasgow coma scale on admission and preoperative coagulation state did not differ between the groups. Postoperatively, we found no difference in cerebrospinal fluid leakage or chronic hydrocephalus between the groups (p = 0.47). Revision rates were 2.27% (1/44 patients) in the FSP group, compared to 16.27% (7/43) in the DR group (p < 0.023). Operative time was significantly shorter in the FSP group (90.3 ± 31.0 min vs. 199.0 ± 48.8 min, p < 0.0001).!##!Conclusion!#!Rapid closure technique in suboccipital decompression is feasible and safe. Operative time is hereby reduced, without increasing complication rates

Complete hemispheric exposure vs. superior sagittal sinus sparing craniectomy: incidence of shear-bleeding and shunt-dependency

Purpose!#!Decompressive hemicraniectomy (DC) has been established as a standard therapeutical procedure for raised intracranial pressure. However, the size of the DC remains unspecified. The aim of this study was to analyze size related complications following DC.!##!Methods!#!Between 2013 and 2019, 306 patients underwent DC for elevated intracranial pressure at author´s institution. Anteroposterior and craniocaudal DC size was measured according to the postoperative CT scans. Patients were divided into two groups with (1) exposed superior sagittal sinus (SE) and (2) without superior sagittal sinus exposure (SC). DC related complications e.g. shear-bleeding at the margins of craniectomy and secondary hydrocephalus were evaluated and compared.!##!Results!#!Craniectomy size according to anteroposterior diameter and surface was larger in the SE group; 14.1 ± 1 cm vs. 13.7 ± 1.2 cm, p = 0.003, resp. 222.5 ± 40 cm!##!Conclusions!#!Complete hemispheric exposure in terms of DC with SE was associated with significantly lower levels of iatrogenic shear-bleedings compared to a SC-surgical regime. Although we did not find significant outcome difference, our findings suggest aggressive craniectomy regimes including SE to constitute the surgical treatment strategy of choice for malignant intracranial pressure

Postoperative Hematoma Expansion in Patients Undergoing Decompressive Hemicraniectomy for Spontaneous Intracerebral Hemorrhage

Introduction: The aim of the study was to analyze risk factors for hematoma expansion (HE) in patients undergoing decompressive hemicraniectomy (DC) in patients with elevated intracranial pressure due to spontaneous intracerebral hematoma (ICH). Methods: We retrospectively evaluated 72 patients with spontaneous ICH who underwent DC at our institution. We compared the pre- and postoperative volumes of ICH and divided the patients into two groups: first, patients with postoperative HE > 6 cm3 (group 1), and second, patients without HE (group 2). Additionally, we screened the medical history for anticoagulant and antiplatelet medication (AC/AP), bleeding-related comorbidities, age, admission Glasgow coma scale and laboratory parameters. Results: The rate of AC/AP medication was higher in group 1 versus group 2 (15/16 vs. 5/38, p < 0.00001), and patients were significantly older in group 1 versus group 2 (65.1 ± 16.2 years vs. 54.4 ± 14.3 years, p = 0.02). Furthermore, preoperative laboratory tests showed lower rates of hematocrit (34.1 ± 5.4% vs. 38.1 ± 5.1%, p = 0.01) and hemoglobin (11.5 ± 1.6 g/dL vs. 13.13 ± 1.8 g/dL, p = 0.0028) in group 1 versus group 2. In multivariate analysis, the history of AC/AP medication was the only independent predictor of HE (p < 0.0001, OR 0.015, CI 95% 0.001–0.153). Conclusion: We presented a comprehensive evaluation of risk factors for hematoma epansion by patients undergoing DC due to ICH

Single-neuron mechanisms of neural adaptation in the human temporal lobe

Abstract A central function of the human brain is to adapt to new situations based on past experience. Adaptation is reflected behaviorally by shorter reaction times to repeating or similar stimuli, and neurophysiologically by reduced neural activity in bulk-tissue measurements with fMRI or EEG. Several potential single-neuron mechanisms have been hypothesized to cause this reduction of activity at the macroscopic level. We here explore these mechanisms using an adaptation paradigm with visual stimuli bearing abstract semantic similarity. We recorded intracranial EEG (iEEG) simultaneously with spiking activity of single neurons in the medial temporal lobes of 25 neurosurgical patients. Recording from 4917 single neurons, we demonstrate that reduced event-related potentials in the macroscopic iEEG signal are associated with a sharpening of single-neuron tuning curves in the amygdala, but with an overall reduction of single-neuron activity in the hippocampus, entorhinal cortex, and parahippocampal cortex, consistent with fatiguing in these areas

Dehydration Status at Admission Predicts Recurrence in Patients with Traumatic Chronic Subdural Hematoma

Objective: There remains a significant risk of chronic subdural hematoma (CSDH) recurring after treatment. Patient-related predictors and surgical procedures have been investigated in many studies. In contrast, the literature remains scant on reports of the potential impact of dehydration on the admission of affected patients and on the CSDH recurrence rate. Methods: All consecutively admitted patients with CSDH and surgical treatment at the authors’ institution between 2015 and 2019 were retrospectively identified. Dehydration was assessed as a blood urea/creatinine (U/Cr) ratio > 80. The association between dehydration on admission and postoperative complication rates, in-hospital mortality, and recurrence of CSDH, with the need for additional surgical treatment, was further analyzed. Results: A total of 265 patients with CSDH requiring surgery were identified. In 32 patients (12%), further surgery was necessary due to the recurrence of CSDH. It was found that 9 of the 265 patients with CSDH (3%) suffered from dehydration at the time of admission. Multivariate analysis revealed diabetes mellitus (p = 0.02, OR 2.7, 95% CI 1.2–6.5), a preoperative midline shift > 5 mm (p = 0.003, OR 3.3, 95% CI 1.5–7.5) and dehydration on admission (p = 0.002, OR 10.3, 95% CI 2.4–44.1) as significant and independent predictors for the development of CSDH recurrence that requires surgery. Conclusion: the present findings indicate that dehydration on admission appears to be an independent predictor for CSDH recurrence that requires surgery

Auditory beat stimulation modulates memory-related single-neuron activity in the human medial temporal lobe

Auditory beats are amplitude-modulated signals (monaural beats) or signals that subjectively cause the perception of an amplitude modulation (binaural beats). We investigated the effects of monaural and binaural 5 Hz beat stimulation on neural activity and memory performance in neurosurgical patients performing an associative recognition task. Previously, we had reported that these beat stimulation conditions modulated memory performance in opposite directions. Here, we analyzed data from a patient subgroup, in which microwires were implanted in the amygdala, hippocampus, entorhinal cortex and parahippocampal cortex. We identified neurons responding with firing rate changes to binaural versus monaural 5 Hz beat stimulation. In these neurons, we correlated the differences in firing rates for binaural versus monaural beats to the memory-related differences for remembered versus forgotten items and associations. In the left hemisphere, we detected statistically significant negative correlations between firing rate differences for binaural versus monaural beats and remembered versus forgotten items/associations. Importantly, such negative correlations were also observed between beat stimulation-related firing rate differences in the pre-stimulus window and memory-related firing rate differences in the post-stimulus windows. In line with concepts of homeostatic plasticity, our findings suggest that beat stimulation is linked to memory performance via shifting baseline firing levels