Bo Jespersen

Source localization of rhythmic ictal EEG activity: A study of diagnostic accuracy following STARD criteria

Although precise identification of the seizure‐onset zone is an essential element of presurgical evaluation, source localization of ictal electroencephalography (EEG) signals has received little attention. The aim of our study was to estimate the accuracy of source localization of rhythmic ictal EEG activity using a distributed source model.

Hyperextension injury to the PIP joint or to the MP joint of the thumb--a clinical study.

We present a prospective study of the diagnosis and clinical course of 60 patients with 57 pure hyperextension injuries to the proximal interphalangeal (PIP) joint of the long fingers (fingers 2-5) and seven injuries to the metacarpophalangeal (MP) joint of the thumb. Thirty four of the injuries (57%) were related to ball sports, and the ulnar fingers of the non-dominant hand were usually affected. There were 24 avulsion fractures at the site of the insertion of the volar plate on to the middle phalanx. Twelve (20%) initially presented with hyperextension instability, and this was usually associated with an avulsion fracture. Thirty four of the patients (57%) had symptoms for less than one month, while 10 (17%) complained of symptoms six months after the injury. Severe complications such as daily pain and stiffness were encountered in three cases. The triad sign (pain on extreme flexion and extension) was of no use as a diagnostic or prognostic factor, nor did the radiographic stress-view help to identify acute instability of the joint.

Optogenetic control of human neurons in organotypic brain cultures

Optogenetics is one of the most powerful tools in neuroscience, allowing for selective control of specific neuronal populations in the brain of experimental animals, including mammals. We report, for the first time, the application of optogenetic tools to human brain tissue providing a proof-of-concept for the use of optogenetics in neuromodulation of human cortical and hippocampal neurons as a possible tool to explore network mechanisms and develop future therapeutic strategies.

Subdural to subgaleal EEG signal transmission: The role of distance, leakage and insulating affectors

OBJECTIVE To estimate the area of cortex affecting the extracranial EEG signal. METHODS The coherence between intra- and extracranial EEG channels were evaluated on at least 10 min of spontaneous, awake data from seven patients admitted for epilepsy surgery work up. RESULTS Cortical electrodes showed significant extracranial coherent signals in an area of approximately 150 cm(2) although the field of vision was probably only 31 cm(2) based on spatial averaging of intracranial channels taking into account the influence of the craniotomy and the silastic membrane of intracranial grids. Selecting the best cortical channels, it was possible to increase the coherence values compared to the single intracranial channel with highest coherence. The coherence seemed to increase linearly with an accumulation area up to 31 cm(2), where 50% of the maximal coherence was obtained accumulating from only 2 cm(2) (corresponding to one channel), and 75% when accumulating from 16 cm(2). CONCLUSION The skull is an all frequency spatial averager but dominantly high frequency signal attenuator. SIGNIFICANCE An empirical assessment of the actual area of cerebral sources generating the extracranial EEG provides better opportunities for clinical electroencephalographers to determine the location of origin of particular patterns in the EEG.

Efficacy of the Danish epilepsy surgery programme

Despite optimal medical treatment, approximately one‐third of patients with epilepsy continue to have seizures. Epilepsy surgery is widely accepted as a therapeutic option in the selected subset of patients with drug‐resistant focal epilepsy. Here, we report the results of the Danish epilepsy surgery programme from 2009 to 2014.

Pharmacodynamics of remifentanil. Induced intracranial spike activity in mesial temporal lobe epilepsy

Patients with medically refractory epilepsy may benefit from resective epilepsy surgery. However even the best centers experience surgical failures. It is therefore important to find techniques that may aid in neurosurgical planning of epileptic focus resection. Recordings of electrical brain activity with EEG during seizures reveal abnormal cortical hypersynchronization. Between seizures the EEG often shows interictal depolarizing phenomena such as spikes reflecting an irritable focus of the brain. In the present study we investigated the effect of intravenous remifentanil on the spike activity in the temporal neocortex and hippocampus. We examined 65 patients with mesial temporal lobe epilepsy during surgery, prior to resection. We used a 20-lead grid on the cortex and a 4-lead strip in the lateral ventricle on the hippocampus. At least two 3-min periods of ECoG were recorded - before and after remifentanil injection. In a number of patients we examined the effect of repeated injections in order to estimate the dose-response curve. We describe a significant effect of remifentanil on the average spike activity with an increment from 16 spikes per minute at baseline to 36 spikes per minute after remifentanil injection (p<0.0001). The increase in spike activity was typically seen after 40-50s. When mu-receptors were antagonized with a preceding injection of naloxone, spike activity increased 25% in response to remifentanil as opposed to 80% when remifentanil was preceded by placebo. In only seven out of 59 patients did the injection of remifentanil change the topographic location of the spike focus. Typically administration of remifentanil led to a focus of increased spike count. Activity in other areas was suppressed making the focus stand out from the background. Our observation that remifentanil potentiates spike activity is in agreement with previous findings from smaller studies. Furthermore, we were able to describe the pharmacodynamics of the remifentanil effect on spike activity. Peri-operative provocation with remifentanil may play a future role in guiding neurosurgical intervention during epilepsy resection surgery.

Visual field defects after temporal lobe resection for epilepsy

PURPOSE To determine visual field defects (VFDs) using methods of varying complexity and compare results with subjective symptoms in a population of newly operated temporal lobe epilepsy patients. METHODS Forty patients were included in the study. Two patients failed to perform VFD testing. Humphrey Field Analyzer (HFA) perimetry was used as the gold standard test to detect VFDs. All patients performed a web-based visual field test called Damato Multifixation Campimetry Online (DMCO). A bedside confrontation visual field examination ad modum Donders was extracted from the medical records in 27/38 patients. All participants had a consultation by an ophthalmologist. A questionnaire described the subjective complaints. REULTS A VFD in the upper quadrant was demonstrated with HFA in 29 (76%) of the 38 patients after surgery. In 27 patients tested ad modum Donders, the sensitivity of detecting a VFD was 13%. Eight patients (21%) had a severe VFD similar to a quadrant anopia, thus, questioning their permission to drive a car. In this group of patients, a VFD was demonstrated in one of five (sensitivity=20%) ad modum Donders and in seven of eight (sensitivity=88%) with DMCO. Subjective symptoms were only reported by 28% of the patients with a VFD and in two of eight (sensitivity=25%) with a severe VFD. Most patients (86%) considered VFD information mandatory. CONCLUSION VFD continue to be a frequent adverse event after epilepsy surgery in the medial temporal lobe and may affect the permission to drive a car in at least one in five patients. Subjective symptoms and bedside visual field testing ad modum Donders are not sensitive to detect even a severe VFD. Newly developed web-based visual field test methods appear sensitive to detect a severe VFD but perimetry remains the golden standard for determining if visual standards for driving is fulfilled. Patients consider VFD information as mandatory.

Ictal and interictal electric source imaging in pre-surgical evaluation: a prospective study

Accurate localization of the epileptic focus is essential for surgical treatment of patients with drug‐resistant epilepsy. Electric source imaging (ESI) is increasingly used in pre‐surgical evaluation. However, most previous studies have analysed interictal (II) discharges. Prospective studies comparing the feasibility and accuracy of II and ictal (IC) ESI are lacking.

NPY/Y2 gene therapeutic overexpression in hippocampus of experimental Beagle dogs

people worldwide. Current treatment is only symptomatic and fails to control seizures in about 40% of patients. Gene therapy with NPY overexpression has emerged as an alternative treatment strategy for epilepsy, showing inhibitory effect on seizures in animal models. This effect seems to be mediated mostly via Y2 receptors, while Y1 receptor activation has an opposite outcome. To enhance NPY gene transfer effect on seizures, we additionally overexposed Y2 receipts using AAV vectors in the hippocampus of epileptic rats. We demonstrate that transgene Y2 receptors are functional and even potentiate transgene NPY effect on seizures. These data suggest that combinatorial NPY/Y2 gene therapy could be an alternative strategy to single NPY gene overexertion.

O15: Source localisation of rhythmic ictal activity: a study of diagnostic accuracy following STARD criteria

G. Waterstraat1,2, M. Burghoff2,3, T. Fedele1,2,3, H.J. Scheer3, G. Curio1,2,4 1Charite-University Medicine Berlin, Neurophysics Group, Department of Neurology, Campus Benjamin Franklin, Berlin, Germany; 2Bernstein Focus: Neurotechnology Berlin, Berlin, Germany; 3Physikalisch-Technische Bundesanstalt, Institute Berlin, Berlin, Germany; 4Bernstein Center for Computational Neuroscience Berlin, Berlin, Germany