Guidance for the preparation of neurological management guidelines by EFNS scientific task forces - revised recommendations 2012

This paper is meant to provide guidance to anyone wishing to write a neurological guideline for diagnosis or treatment, and is directed at the Scientist Panels and task forces of the European Federation of Neurological Societies (EFNS). It substitutes the previous guidance paper from 2004. It contains several new aspects: the guidance is now based on a change of the grading system for evidence and for the resulting recommendations, and has adopted The Grading of Recommendations, Assessment, Development and Evaluation system (GRADE). The process of grading the quality of evidence and strength of recommendations can now be improved and made more transparent. The task forces embarking on the development of a guideline must now make clearer and more transparent choices about outcomes considered most relevant when searching the literature and evaluating their findings. Thus, the outcomes chosen will be more critical, more patient-oriented and easier to translate into simple recommendations. This paper also provides updated practical recommendations for planning a guideline task force within the framework of the EFNS. Finally, this paper hopes to find the approval also by the relevant bodies of our future organization, the European Academy of Neurology.

Cognitive effects of interictal epileptiform discharges in children

Frequent interictal epileptiform discharges (IEDs) may have effects on cognition. We analysed a group of 182 children with different epilepsy syndromes as well as children with IEDs without observed seizures [corrected], with 24-h ambulatory EEG and cognitive tests. The IED index was estimated, in wakefulness and in sleep, as percentage of time in five categories (0%, <1%, 1-10%, ≥10-50% and ≥50%). IEDs were defined as spikes or spike-wave complexes, isolated or occurring serially (in runs) without evident clinical signs of a seizure. The IED categories were correlated to cognitive test results and epilepsy characteristics. The group of patients with diurnal IEDs in ≥10% of the EEG record showed impaired central information processing speed, short-term verbal memory and visual-motor integration. This effect was seen independently from other EEG-related and epilepsy-related characteristics, and independently from epilepsy syndrome diagnosis. The impact of the nocturnal IEDs was of less importance; only contributing partially to the slowing of central information processing speed. We conclude that frequent IEDs (in more than 10% of the record) in the awake EEG can impair cognitive performance in children. Whether children with a high diurnal spike frequency and low seizure frequency can benefit from antiepileptic treatment should be examined in controlled trials.

Surgical successes and failures of invasive video-EEG monitoring in the presurgical evaluation of epilepsy

Invasive monitoring with intracranial electrodes continues to play a critical role in the presurgical evaluation of patients with medically intractable epilepsy. Intracranial monitoring helps in localizing the epileptogenic zone and can be used to delineate eloquent cortical areas adjacent to this zone. In this review we analyzed surgical successes and failures of invasive video-electroencephalography (EEG) monitoring. Thorough understanding of all potential complications is of paramount importance not only for detection and successful management of intractable epilepsy but also for medicolegal purposes, as patients and their relatives need to be fully informed about the possible risks associated with invasive monitoring. A mortality rate between 0.5% and 2.8% has been reported. Cerebrospinal fluid (CSF) leaks and infections are the most frequent complications, with an incidence ranging from 0-31.3% and from 0-17.4%, respectively. The incidence of intracranial hemorrhage is reported to be up to 14% with subdural hematomas being the most prevalent. Epidural hematomas are less frequent and encountered in up to 2.6% of cases. Intraparenchymal hematomas are even less frequent and are typically associated with the placement of depth electrodes. In 47-98% of cases, invasive video-EEG monitoring results into resective surgery. Invasive video-EEG monitoring is a reasonably safe and effective method to help delineate the epileptogenic zone and its relation to eloquent cortex.

Modulation of seizure threshold by vagus nerve stimulation in an animal model for motor seizures

OBJECTIVE

The precise mechanism of action of vagus nerve stimulation (VNS) in suppressing epileptic seizures remains to be elucidated. This study investigates whether VNS modulates cortical excitability by determining the threshold for provoking focal motor seizures by cortical electrical stimulation before and after VNS.

MATERIAL AND METHODS

Male Wistar rats (n = 8) were implanted with a cuff-electrode around the left vagus nerve and with stimulation electrodes placed bilaterally on the rat motor cortex. Motor seizure threshold (MST) was assessed for each rat before and immediately after 1 h of VNS with standard stimulation parameters, during two to three sessions on different days.

RESULTS

An overall significant increase of the MST was observed following 1 h of VNS compared to the baseline value (1420 microA and 1072 microA, respectively; P < 0.01). The effect was reproducible over time with an increase in MST in each experimental session.

CONCLUSIONS

VNS significantly increases the MST in a cortical stimulation model for motor seizures. These data indicate that VNS is capable of modulating cortical excitability.

Progressive myoclonic epilepsy as an adult-onset manifestation of Leigh syndrome due to m.14487T>C

BACKGROUND

m.14487T>C, a missense mutation (p.M63V) affecting the ND6 subunit of complex I of the mitochondrial respiratory chain, has been reported in isolated childhood cases with Leigh syndrome (LS) and progressive dystonia. Adult-onset phenotypes have not been reported.

OBJECTIVES

To determine the clinical-neurological spectrum and associated mutation loads in an extended m.14487T>C family.

METHODS

A genotype-phenotype correlation study of a Belgian five-generation family with 12 affected family members segregating m.14487T>C was carried out. Clinical and mutation load data were available for nine family members. Biochemical analysis of the respiratory chain was performed in three muscle biopsies.

RESULTS

Heteroplasmic m.14487T>C levels (36-52% in leucocytes, 97-99% in muscle) were found in patients with progressive myoclonic epilepsy (PME) and dystonia or progressive hypokinetic-rigid syndrome. Patients with infantile LS were homoplasmic (99-100% in leucocytes, 100% in muscle). We found lower mutation loads (between 8 and 35% in blood) in adult patients with clinical features including migraine with aura, Leber hereditary optic neuropathy, sensorineural hearing loss and diabetes mellitus type 2. Despite homoplasmic mutation loads, complex I catalytic activity was only moderately decreased in muscle tissue.

INTERPRETATION

m.14487T>C resulted in a broad spectrum of phenotypes in our family. Depending on the mutation load, it caused severe encephalopathies ranging from infantile LS to adult-onset PME with dystonia. This is the first report of PME as an important neurological manifestation of an isolated mitochondrial complex I defect.

Opinion of Belgian neurologists on antiepileptic drug treatment in 2006: Belgian study on epilepsy treatment (BESET-2)

OBJECTIVES

(i) To describe the medical treatment of epilepsy in Belgium in 2006, (ii) to detect the presence or absence of consensus in epilepsy treatment and (iii) to analyze the evolution of the neurologists' opinion between 2003 and 2006.

MATERIALS AND METHODS

In December 2006, 100 neurologists were interviewed with a structured questionnaire, based on ordinal four-point scales. The questionnaire contained questions on treatment choices in adult patients with epilepsy. The results of this survey were compared with results of a previous one done in 2003.

RESULTS

Initial monotherapy was the preferred treatment strategy. Valproate was first choice in idiopathic generalized epilepsy. Carbamazepine and oxcarbazepine were first choice in focal epilepsy with partial seizures. Valproate was also first choice in focal epilepsy with secondarily generalized seizures. New antiepileptic drugs were recommended in second line. However, in special treatment situations, they were considered first-line, e.g. lamotrigine in case of women in childbearing age. In comparison with 2003, there was a trend of using earlier the new antiepileptic drugs.

CONCLUSIONS

In end 2006, carbamazepine, valproate and oxcarbazepine were considered to be first choice drugs, whereas other newer drugs, like lamotrigine, levetiracetam and topiramate were predominantly prescribed in second line.

Ischemic stroke and hyperhomocysteinemia: truth or myth?

Hyperhomocysteinemia is generally acknowledged as a treatable risk factor for atherotrombotic diseases, but a causal relationship between both is not yet definitively established. Hyperhomocysteinemia originates from a deviation in the methionine-homocysteine metabolism including disturbances of enzymes, vitamin deficiencies and different other factors. Observational studies, genetic polymorphism studies and several meta-analyses implicate already a causal relation between homocysteine and cerebrovascular diseases. It is useful to determine homocysteine levels for stroke who present no clue for vascular disease and thrombosis, who have an ischemic stroke at a young age and who have a family history of premature atherosclerosis. Because of the low cost and safety of the therapy, the American Heart and Stroke Association advises to treat patients with a stroke and hyperhomocysteinemia daily with 0,4 mg folic acid, 2,4 microg vitamin B12 and 1,7 mg vitamin B6. A significant benefit in secondary prevention is not yet proven. The results of larger follow-up trials have to be published.

Deep brain stimulation for epilepsy: knowledge gained from experimental animal models

Since the development of Deep Brain Stimulation (DBS) for Parkinson's Disease, DBS has been suggested as a treatment option for various other neurological disorders. Stimulation of deep brain structures for refractory epilepsy appears to be a safe treatment option with promising results. As research on the evaluation and optimization of DBS for refractory epilepsy may be difficult and unethical in patients, studies on animal models of epilepsy are indispensable. Various brain structures and specific nuclei such as the basal ganglia, the cerebellum, the locus coeruleus and temporal lobe structures have been investigated as target areas for DBS. Additionally, a wide variety of stimulation parameters are available, with a range of stimulation frequencies, pulse widths and stimulation intensities. This review provides an overview of the relevant literature on experimental animal studies of DBS for epilepsy. Knowledge gained from animal studies can be used to answer questions regarding the optimal brain targets and stimulation parameters in human applications.

Seizures in the intrahippocampal kainic acid epilepsy model: characterization using long-term video-EEG monitoring in the rat

OBJECTIVE

Intrahippocampal injection of kainic acid (KA) in rats evokes a status epilepticus (SE) and leads to spontaneous seizures. However to date, precise electroencephalographic (EEG) and clinical characterization of spontaneous seizures in this epilepsy model using long-term video-EEG monitoring has not been performed.

MATERIALS AND METHODS

Rats were implanted with bipolar hippocampal depth electrodes and a cannula for the injection of KA (0.4 lg /0.2 ll) in the right hippocampus. Video-EEG monitoring was used to determine habitual parameters of spontaneous seizures such as seizure frequency, severity, progression and day-night rhythms.

RESULTS

Spontaneous seizures were detected in all rats with 13 out of 15 animals displaying seizures during the first eight weeks after SE. A considerable fraction (35%) of the spontaneous seizures did not generalize secondarily. Seizure frequency was quite variable and the majority of the KA treated animals had less than one seizure per day. A circadian rhythm was observed in all rats that showed sufficient seizures per day.

CONCLUSIONS

This study shows that the characteristics of spontaneous seizures in the intrahippocampal KA model display many similarities to other SE models and human temporal lobe epilepsy.

Vagal nerve stimulation--a 15-year survey of an established treatment modality in epilepsy surgery

Neurostimulation is an emerging treatment for neurological diseases. Electrical stimulation of the tenth cranial nerve or vagus nerve stimulation (VNS) has become a valuable option in the therapeutic armamentarium for patients with refractory epilepsy. It is indicated in patients with refractory epilepsy who are unsuitable candidates for epilepsy surgery or who have had insufficient benefit from such a treatment. Vagus nerve stimulation reduces seizure frequency with > 50% in 1/3 of patients and has a mild side effects profile. Research to elucidate the mechanism of action of vagus nerve stimulation has shown that effective stimulation in humans is primarily mediated by afferent vagal A- and B-fibers. Crucial brainstem and intracranial structures include the locus coeruleus, the nucleus of the solitary tract, the thalamus and limbic structures. Neurotransmitters playing a role may involve the major inhibitory neurotransmitter GABA but also serotoninergic and adrenergic systems. This manuscript reviews the clinical studies investigating efficacy and side effects in patients and the experimental studies aiming to elucidate the mechanims of action.

Contribution of magnetic source imaging to the presurgical work-up of patients with refractory partial epilepsy

Magnetoencephalography (MEG) is a functional cerebral imaging technique that non-invasively records extracranial magnetic fields generated by the electrical activity of the brain. Magnetic source imaging (MSI) is a combination of MEG and coregistered magnetic resonance imaging (MRI) that is increasingly being used in the non-invasive presurgical evaluation of patients with refractory partial epilepsy to localize the magnetic correlate of interictal epileptiform discharges. This paper reviews the basics of MEG and MSI, briefly describes the characteristics of the MEG system installed at the ULB-Hôpital Erasme and then summarises the available data on the contribution of MSI to the presurgical work-up of refractory partial epilepsy.