Karl Lothard Schaller

Electroencephalographic source imaging: a prospective study of 152 operated epileptic patients

Electroencephalography is mandatory to determine the epilepsy syndrome. However, for the precise localization of the irritative zone in patients with focal epilepsy, costly and sometimes cumbersome imaging techniques are used. Recent small studies using electric source imaging suggest that electroencephalography itself could be used to localize the focus. However, a large prospective validation study is missing. This study presents a cohort of 152 operated patients where electric source imaging was applied as part of the pre-surgical work-up allowing a comparison with the results from other methods. Patients (n = 152) with >1 year postoperative follow-up were studied prospectively. The sensitivity and specificity of each imaging method was defined by comparing the localization of the source maximum with the resected zone and surgical outcome. Electric source imaging had a sensitivity of 84% and a specificity of 88% if the electroencephalogram was recorded with a large number of electrodes (128–256 channels) and the individual magnetic resonance image was used as head model. These values compared favourably with those of structural magnetic resonance imaging (76% sensitivity, 53% specificity), positron emission tomography (69% sensitivity, 44% specificity) and ictal/interictal single-photon emission-computed tomography (58% sensitivity, 47% specificity). The sensitivity and specificity of electric source imaging decreased to 57% and 59%, respectively, with low number of electrodes (<32 channels) and a template head model. This study demonstrated the validity and clinical utility of electric source imaging in a large prospective study. Given the low cost and high flexibility of electroencephalographic systems even with high channel counts, we conclude that electric source imaging is a highly valuable tool in pre-surgical epilepsy evaluation.

Transvenous embolization of a ruptured deep cerebral arteriovenous malformation. A technical note.

Ruptured cerebral arteriovenous malformations (AVMs) usually require treatment to avoid re-bleeding. Depending on the angioarchitecture and center strategy, the treatment can be surgical, endovascular, radiosurgical or combined methods. The classic endovascular approach is transarterial, but sometimes it is not always applicable. The transvenous approach has been described as an alternative for the endovascular treatment of small AVMs when arterial access or another therapeutic method is not possible. This approach can be considered when the nidus is small and if there is a single draining vein. We present a technical note on a transvenous approach for the treatment of a ruptured AVM in a young patient.

With or without spikes: localization of focal epileptic activity by simultaneous electroencephalography and functional magnetic resonance imaging

In patients with medically refractory focal epilepsy who are candidates for epilepsy surgery, concordant non-invasive neuroimaging data are useful to guide invasive electroencephalographic recordings or surgical resection. Simultaneous electroencephalography and functional magnetic resonance imaging recordings can reveal regions of haemodynamic fluctuations related to epileptic activity and help localize its generators. However, many of these studies (40-70%) remain inconclusive, principally due to the absence of interictal epileptiform discharges during simultaneous recordings, or lack of haemodynamic changes correlated to interictal epileptiform discharges. We investigated whether the presence of epilepsy-specific voltage maps on scalp electroencephalography correlated with haemodynamic changes and could help localize the epileptic focus. In 23 patients with focal epilepsy, we built epilepsy-specific electroencephalographic voltage maps using averaged interictal epileptiform discharges recorded during long-term clinical monitoring outside the scanner and computed the correlation of this map with the electroencephalographic recordings in the scanner for each time frame. The time course of this correlation coefficient was used as a regressor for functional magnetic resonance imaging analysis to map haemodynamic changes related to these epilepsy-specific maps (topography-related haemodynamic changes). The method was first validated in five patients with significant haemodynamic changes correlated to interictal epileptiform discharges on conventional analysis. We then applied the method to 18 patients who had inconclusive simultaneous electroencephalography and functional magnetic resonance imaging studies due to the absence of interictal epileptiform discharges or absence of significant correlated haemodynamic changes. The concordance of the results with subsequent intracranial electroencephalography and/or resection area in patients who were seizure free after surgery was assessed. In the validation group, haemodynamic changes correlated to voltage maps were similar to those obtained with conventional analysis in 5/5 patients. In 14/18 patients (78%) with previously inconclusive studies, scalp maps related to epileptic activity had haemodynamic correlates even when no interictal epileptiform discharges were detected during simultaneous recordings. Haemodynamic changes correlated to voltage maps were spatially concordant with intracranial electroencephalography or with the resection area. We found better concordance in patients with lateral temporal and extratemporal neocortical epilepsy compared to medial/polar temporal lobe epilepsy, probably due to the fact that electroencephalographic voltage maps specific to lateral temporal and extratemporal epileptic activity are more dissimilar to maps of physiological activity. Our approach significantly increases the yield of simultaneous electroencephalography and functional magnetic resonance imaging to localize the epileptic focus non-invasively, allowing better targeting for surgical resection or implantation of intracranial electrode arrays.

Decompressive Hemicraniectomy in Patients With Supratentorial Intracerebral Hemorrhage

Background and Purpose— Decompressive craniectomy (DC) lowers intracranial pressure and improves outcome in patients with malignant middle cerebral artery stroke. Its usefulness in intracerebral hemorrhage (ICH) is unclear. The aim of this study was to analyze feasibility and safety of DC without clot evacuation in ICH. Methods— We compared consecutive patients (November 2010–January 2012) with supratentorial ICH treated with DC without hematoma evacuation and matched controls treated by best medical treatment. DC measured at least 150mm and included opening of the dura. We analyzed clinical (age, sex, pathogenesis, Glasgow Coma Scale, National Institutes of Health Stroke Scale), radiological (signs of herniation, side and size of hematoma, midline shift, hematoma expansion, distance to surface), and surgical (time to and indication for surgery) characteristics. Outcome at 6 months was dichotomized into good (modified Rankin Scale 0–4) and poor (modified Rankin Scale 5–6). Results— Twelve patients (median age 48 years; interquartile range 35–58) with ICH were treated by DC. Median hematoma volume was 61.3mL (interquartile range 37–83.5mL) and median preoperative Glasgow Coma Scale was 8 (interquartile range 4.3–10). Four patients showed signs of herniation. Nine patients had good and 3 had poor outcomes. Three patients (25%) of the treatment group died versus 8 of 15 (53%) of the control group. There were 3 manageable complications related to DC. Conclusions— DC is feasible in patients with ICH. Based on this small cohort, DC may reduce mortality. Larger prospective cohorts are warranted to assess safety and efficacy.

Common variant near the endothelin receptor type A (EDNRA) gene is associated with intracranial aneurysm risk

The pathogenesis of intracranial aneurysm (IA) formation and rupture is complex, with significant contribution from genetic factors. We previously reported genome-wide association studies based on European discovery and Japanese replication cohorts of 5,891 cases and 14,181 controls that identified five disease-related loci. These studies were based on testing replication of genomic regions that contained SNPs with posterior probability of association (PPA) greater than 0.5 in the discovery cohort. To identify additional IA risk loci, we pursued 14 loci with PPAs in the discovery cohort between 0.1 and 0.5. Twenty-five SNPs from these loci were genotyped using two independent Japanese cohorts, and the results from discovery and replication cohorts were combined by meta-analysis. The results demonstrated significant association of IA with rs6841581 on chromosome 4q31.23, immediately 5′ of the endothelin receptor type A with P = 2.2 × 10−8 [odds ratio (OR) = 1.22, PPA = 0.986]. We also observed substantially increased evidence of association for two other regions on chromosomes 12q22 (OR = 1.16, P = 1.1 × 10−7, PPA = 0.934) and 20p12.1 (OR = 1.20, P = 6.9 × 10−7, PPA = 0.728). Although endothelin signaling has been hypothesized to play a role in various cardiovascular disorders for over two decades, our results are unique in providing genetic evidence for a significant association with IA and suggest that manipulation of the endothelin pathway may have important implications for the prevention and treatment of IA.

Electrical source imaging for presurgical focus localization in epilepsy patients with normal MRI.

Purpose:  Patients with magnetic resonance (MR)–negative focal epilepsy (MRN‐E) have less favorable surgical outcomes (between 40% and 70%) compared to those in whom an MRI lesion guides the site of surgical intervention (60–90%). Patients with extratemporal MRN‐E have the worst outcome (around 50% chance of seizure freedom). We studied whether electroencephalography (EEG) source imaging (ESI) of interictal epileptic activity can contribute to the identification of the epileptic focus in patients with normal MRI.

The C-reactive protein for detection of early infections after lumbar microdiscectomy

SummaryThe tendency for short hospitalization after lumbar microdiscectomy implies the need for early confirmation or disproval of serious postoperative infections such as spondylodiscitis or deep wound infections. The C-reactive protein (CRP) is a well-known screening parameter for monitoring postoperative infectious complications in other fields. Our objective was to establish the diagnostic significance of CRP-in comparison with ESR and WBC-for monitoring infectious complications after lumbar microdiscectomy. Over a 15 months period we studied prospectively a homogeneous group of N = 400 patients with lumbar disc herniations who were operated on a single level for the first time. CRP, ESR and WBC values were determined in all patients pre-operatively, and on postoperative days 1 and 5. Clinical and laboratory findings were correlated and the diagnostic significance of CRP, ESR and WBC calcualted. N = 385 (96%) patients had an uneventful postoperative course. N = 15 (4%) patients developed infectious complications, of which N = 6 (1.5%) were unrelated and N = 9 (2.5%) related to surgery. Evaluation of the laboratory values showed: The CRP baseline is a very individual value of no prognostic relevance. A high postaggression peak is typical and essential as a reference value for only the future time course will disclose any infection. We found 0% false negative and 4% false positive results on day 5. The sensitivity for serial CRP testing was calculated as 100% and specificity as 95.8%. ESR (sensitivity: 78.1%/specificity: 38.1%) and WBC (sensitivity: 21.4%/specificity: 76.8%) both failed to reach such distinct diagnostic significance on day 5. The C-reactive protein has thus proved to be a reliable, simple and economical screening test for infectious complications after lumbar microdiscectomy, superior to classical laboratory parameters.

Flow-diverting stent for ruptured intracranial dissecting aneurysm of vertebral artery

BACKGROUND: The treatment of ruptured dissecting aneurysms of the intracranial vertebral artery (VA) with parent vessel preservation is a challenge for neurosurgeons and interventional neuroradiologists. OBJECTIVE: To propose an indication for flow-diverting treatment for reconstruction of a dissecting VA with acute subarachnoid hemorrhage. METHODS: Two male patients transferred after acute subarachnoid hemorrhage and dissecting aneurysm on the V4 segment of the dominant VA. An occlusion test was not performed because of their poor clinical state. A flow-diverting stent represented by the Pipeline embolization device was suggested to both patients. RESULTS: Three Pipeline embolization devices were deployed in each VA. One dissecting aneurysm was excluded immediately after 3 stents, and 1 patient had complete exclusion demonstrated at the 48-hour control. No morbidity directly related to the procedure was observed. No recanalization and no rebleeding occurred during the 3 months of follow-up. CONCLUSION: A flow-diverting stent may be considered an option to treat ruptured dissecting aneurysms of the VA, providing remodeling of the parent vessel and complete exclusion of the aneurysm.

Blood blister-like aneurysms: single center experience and systematic literature review.

Blood blister-like aneurysms (BBAs) are a controversial entity. They arise from non-branching sites on the supraclinoid internal carotid artery (ICA) and are suspected to originate from a dissection. Our aim is to describe the BBA cases seen in our center and to present a systematic review of the literature on BBAs. We analyzed the eleven cases of BBA admitted to our center from 2003 to 2012. We assessed the medical history, treatment modality (endovascular and/or surgery), complications and clinical outcome. The cohort included 8 women and 4 men with a mean age of 53.16 years. Treatment of the BBA consisted of stenting and coiling in 5 patients, stenting only in 4 patients, coiling and clipping in 1 patient, clipping only in 1 patient, and conservative treatment in 1 patient. A good outcome was found in 10 patients, as defined by a modified Rankin Scale (mRS) less than or equal to two at three months. A systematic review of the literature was performed, and 314 reported patients were found: 221 patients were treated with a primarily surgical approach, and 87 patients were treated with a primarily endovascular approach. A rescue or second treatment was required in 46 patients (21%). The overall estimated treatment morbidity rate was 17%, and the mortality rate was 15%. BBAs exhibit more aggressive behavior compared to saccular aneurysms, and more intra-operative complications occur with BBAs, independent of the treatment type offered. They are also significantly more likely to relapse and rebleed after treatment. Endovascular treatment offers a lower morbidity-mortality compared with surgical approaches. Multilayer flow-diverting stents appear to be a promising strategy.

Incidence and relative survival of chordomas: the standardized mortality ratio and the impact of chordomas on a population.

Chordomas are rare bone tumors arising from remnants of the embryonic notochord.