Biomedical subjects

M Seeck

Publications and source records attributed to M Seeck.

At least 19 recordsLinked to original sources

PubMed2007

Epilepsy and cerebellar ataxia associated with anti-glutamic acid decarboxylase antibodies.

Anti-glutamic acid decarboxylase (GAD) antibodies are described in stiff-person syndrome and also in other neurological syndromes, including cerebellar ataxia and epilepsy. This paper reports the case of a patient who had chronic focal epilepsy, upbeat nystagmus and cerebellar ataxia, associated with a polyautoimmune response including anti-GAD antibodies. Both gait and nystagmus improved markedly after immunosuppressive treatment with corticosteroids and azathioprine. After the introduction of benzodiazepines, previously refractory seizures were completely controlled. Anti-GAD antibodies should be actively sought out in pharmacoresistant epilepsy, particularly if other neurological abnormalities are present. Combined treatment with immunosuppressants and gammahydroxybutyric acidergic agents may be highly effective.

Adrenal Cortex Hormones↗

PubMed2006

Bilateral temporal lobe epilepsy in a patient with Turner syndrome mosaicism.

Turner's syndrome (TS), resulting from deletion of one X chromosome in women, is associated with cerebral development abnormalities, particularly in the temporal lobes. Symptomatic epilepsy is described only in cases with extensive malformations. Here, we report the first case of bilateral temporal epilepsy without macroscopic cerebral malformation in a woman with TS mosaicism. Bitemporal dysfunction was confirmed by the ictal and interictal EEG, PET, MR-spectroscopy and the neuropsychological examination, other causes than TS mosaicism were excluded. In rare cases, TS mosaicism may underlie non-lesional temporal lobe epilepsy, probably in relation to microanatomic structural and functional cerebral abnormalities. Further studies are needed to determine the frequency of this association.

Adult↗

PubMed2006

[Status epilepticus and neuronal degeneration: of circuitries and vicious circles].

The relationship between status epilepticus (SE) and neuronal degeneration is quite complex and difficult to investigate. Animal studies suggest that SE induces a progressive neuronal death; however, clinical observations on humans are less uniform: generalized SE may precede the development of hippocampal sclerosis, but other forms (such as simple-partial or complex-partial) seem less ominous. On the other side, SE can be encountered in many patients with neurodegenerative disorders, particularly those with severe forms. It is thus likely that SE represents a sign, rather than an aetiology, of clinical gravity. Therefore, while it is ancillary to treat rapidly any SE form, the therapeutic approach, especially the use of aggressive treatments, should be tailored according to the underlying medical conditions.

Animals↗

PubMed2006

Speech arrest with stimulation may not reliably predict language deficit after epilepsy surgery.

The authors present a patient in whom electrical cortical stimulation of the posterior temporal cortex induced speech arrest, comprehension deficits, and other language-related impairments. This area was ultimately resected because of persistence of a severe seizure disorder. No postoperative aphasia was observed despite the cortical stimulation results, and the patient is since seizure free. These findings question the well-established principle that corticography directly reflects local cortical functions in all patients.

Adult↗

PubMed2006

Extent of preoperative abnormalities and focus lateralization predict postoperative normalization of contralateral 1H-magnetic resonance spectroscopy metabolite levels in patients with temporal lobe epilepsy.

BACKGROUND AND PURPOSE: Magnetic resonance (MR) spectroscopy can be used to determine the side of seizure onset in patients with temporal lobe epilepsy. Some patients with abnormal MR spectroscopy findings also have contralateral abnormalities, which in some cases have been reported to normalize after temporal lobe resection. With the aim of better understanding the mechanisms underlying abnormal MR spectroscopy findings, the current study was performed to define patient features that would predict this postoperative normalization. METHODS: Fifteen patients with temporal lobe epilepsy were subjected to preoperative and postoperative 1H-MR spectroscopy investigations, and the preoperative and postoperative metabolite levels in the contralateral hippocampus and contralateral lateral temporal lobe (CLTL) were determined. RESULTS: In the CLTL, postoperative normalization was more pronounced for patients showing extensive preoperative ipsilateral and contralateral abnormalities on MR spectroscopy. A second factor that influenced the degree to which the metabolite levels changed postoperatively was the focus lateralization. Surgery tended to have a more pronounced effect on the contralateral metabolite levels in patients with a right temporal focus, whereas in patients with left temporal foci, postoperative metabolite levels were virtually unchanged. In the contralateral hippocampal region, neither preoperative abnormalities nor focus side was related to postoperative normalization. CONCLUSIONS: We have thus identified 2 different factors (widespread preoperative MR spectroscopy abnormalities and right-sided focus) that predict postoperative normalization of contralateral MR spectroscopy abnormalities. We suggest that both factors indicate a more generalized epileptic disease (ie, that the patients in whom the MR spectroscopy abnormalities normalize are recovering from a more severe impairment).

Adult↗

PubMed2005

[Current epilepsy treatment in adults].

The prevalence of epilepsy is about 1%. Only two thirds of these patients respond satisfactorily to an antiepileptic drug (AED) treatment. New AED did not clearly improve this overall efficacy, but often show a better tolerability as compared to old AED. This may allow a more targeted choice, especially in some delicate clinical situations, such as for the treatment of women in childbearing age, or patients receiving other drugs with possible pharmacokinetic interactions. Invasive approaches should be considered early in the course of treatment-resistant epilepsy, and may offer a complete seizure remission in selected cases. On the background of recent acquisitions from the literature, the pros and cons of different treatment options are presented. This is followed by the discussion of some clinical relevant situations.

Adult↗

PubMed2005

Orthostatic intolerance and syncope associated with Chiari type I malformation.

The Chiari type I malformation (CM1) is characterized by herniation of cerebellar tonsils to at least 3-5 mm below the plane of foramen magnum and can present with a wide variety of clinical symptoms, frequently including occipital headaches, secondary to bulbar and/or medullary distress. Rarely, syncopal episodes have also been described and attributed to either compression of the midbrain ascending reticular system, or vascular compromise (vertebrobasilar artery compression, hypotension). We report the first case of a CM1 patient with frequently recurring syncope due to postural orthostatic tachycardia syndrome (POTS), a form of orthostatic intolerance, whose symptoms resolved completely after surgical intervention. It is important to stress that it is not clear whether the described association of POTS and CM1 in our patient is a fortuitous finding in an isolated case or a reflection of a more systematic association between the two pathologies.

Adult↗

PubMed2004

Patients with extratemporal lobe epilepsy do not differ from healthy subjects with respect to subcortical volumes.

BACKGROUND: Evidence from previous volumetric magnetic resonance studies has revealed that patients with chronic temporal lobe epilepsy show atrophy of distinct subcortical nuclei, predominantly ipsilateral to the focus side. We were interested to find out if there is also selective subcortical atrophy in patients suffering from long standing extratemporal lobe epilepsy. METHODS: Thirty one patients in whom pre-surgical evaluation unambiguously localised an extratemporal focus were included in this study. Using high resolution magnetic resonance imaging, the volumes of the caudate nuclei, putamen, pallidum, and thalamus were measured bilaterally in both hemispheres and compared with measurements obtained in 15 healthy volunteers. RESULTS: No significant difference in volumes was found between the two subject groups, or in any subgroup of extratemporal lobe epilepsy patients, nor was there any relation to clinical variables such as age of onset, overall seizure frequency, or disease duration. However, patients who had no or only rare generalised tonic-clonic seizures seemed to differ from the other patients and controls in that they had smaller putamen volumes bilaterally (p<0.001). CONCLUSION: We concluded that extratemporal lobe epilepsy in general is not associated with diminished volumes in the studied subcortical structures, which contrasts with findings in temporal lobe epilepsy patients. Thus, both entities differ both cortically and subcortically. However, we found that small putamen volume was bilaterally associated with absent or rare generalised tonic-clonic seizures, implicating the putamen in the control of the most disabling seizure type, independent of the site of neocortical focus.

Adult↗

PubMed2003

Mapping of the neuronal networks of human cortical brain functions.

OBJECTIVE: The principles and methodology of event-related fMRI, electromagnetic source imaging and intracranial evoked potentials will be described along with some examples of the mapping of the neuronal networks of human cortical brain functions with the use of these techniques. INTRODUCTION: Functional brain mapping using PET or fMRI has provided clues on the functioning brain and notably on the functional neuroanatomy of cognitive functions. These mapping possibilities can be used to delineate in an individual patient the brain areas subserving a cerebral function that might be compromised by a surgery in a nearby location, or to target a functional neurosurgical procedure. BACKGROUND: Brain functions and notably "higher brain functions" are served by a complex network of interrelating brain regions. Deeper insights into the functioning of a neuronal network can be gained by adding dynamic, i.e. temporal, information to the functional maps. This will demonstrate the orchestration of the activation of the different brain areas constituting the network, which gives clues to the information processing and therefore to the functioning of the different modules of the network. In order to track the flow of information and the sequential activation of the different brain regions constituting the network, brain activity has to be recorded at the speed of transfer of activation from one neuronal population to the other. The temporal resolution needed to achieve this is not in the range of traditional subtractive or comparative PET or fMRI techniques. NEW DEVELOPMENTS: Novel fMRI methods that record haemodynamic signal changes after single events (event-related fMRI) are now able to determine sequential neural processing by distinguishing the relative onset-time of activity between different areas. The temporal resolution of event-related (ER) fMRI is sufficient to detect changes of mental activity within the order of several hundreds of milliseconds. This allows the exploration of a broad range of cognitive functions. Nevertheless, this technique is currently not rapid enough to observe the transient coordinations and oscillations of neuronal activities occurring across certain cortical areas during the performance of cognitive tasks. The temporal resolution needed for that is within the order of tens or a few milliseconds and is only accessible by EEG or MEG that allow true real-time measurements of the neuronal activity elicited by a stimulus. Surface recordings of multichannel EEG or MEG combined with novel electromagnetic source localisation algorithms allow a relatively precise estimation of the activated areas. A more direct localisation of electric activity is achieved by intracranial recordings in patients having implanted electrodes for diagnostic reasons. In these cases, a high temporal and spatial resolution is achieved but with a limited sampling of brain regions. CONCLUSION: Although the temporal resolution of ER fMRI is due to improve, the temporal measures provided by EEG, MEG or intracranial event-related potentials (ERPs) are absolute, which remains a unique feature of these techniques. Therefore, ER fMRI and electromagnetic source imaging are complementary. The maps obtained with ER fMRI may be refined by electromagnetic ERPs that provide further insights into the temporal coordination or orchestration between the cortical areas already detected by ER fMRI and constituting a neuronal network, and ER fMRI can be used to precisely locate the areas coarsely situated and delineated by electromagnetic source imaging. Thus, the combination of ER fMRI and electromagnetic ERPs is essential in order to produce a mapping method with a millimetre spatial resolution and a millisecond temporal resolution. Future applications should combine these techniques to localise precisely and non-invasively relevant sensory, motor and cognitive processes in order to adequately tailor any brain surgery.

Attention↗

PubMed2003

Ictal bradycardia in a young child with focal cortical dysplasia in the right insular cortex.

We report on a three and a half year old child with episodic sinus bradycardia during habitual seizures and prolonged interictal discharges due to focal cortical dysplasia in the anterior 2/3 of the insula and the inferior frontal cortex. Seizure-induced bradycardia is rarely reported in children. Bradycardia is suspected to be related to sudden death, a rare complication of a chronic seizure disorder. Several well-documented cases in adult patients reveal a high incidence of temporal epilepsy, but MRI and PET studies in healthy subjects suggest a major role of the insular cortex, especially the right, in cardiac regulation. Our finding underlines the predominance of the right insula in cardiac control, which already seems to be present in children.

Bradycardia↗

PubMed2003

Epileptic source localization with high density EEG: how many electrodes are needed?

OBJECTIVE: Electroencephalography (EEG) source reconstruction is becoming recognized as a useful technique to non-invasively localize the epileptic focus. Whereas, large array magnetoencephalography (MEG) systems are available since quite some time, application difficulties have previously prevented multichannel EEG recordings. Recently, however, EEG systems which allow for quick (10-20min) application of, and recording from, up to 125 electrodes have become available. The purpose of the current investigation was to systematically compare the accuracy of epileptic source localization with high electrode density to that obtained with sparser electrode setups. METHODS: Interictal epileptiform activity was recorded with 123 electrodes in 14 epileptic patients undergoing presurgical evaluation. Each single epileptiform potential was down sampled to 63 and 31 electrodes, and a distributed source model (EPIFOCUS) was used to reconstruct the sources with the 3 different electrode configurations. The localization accuracy with the 3 electrode setups was then assessed, by determining the distance from the inverse solution, maximum of each single spike to the epileptogenic lesion. RESULTS: In 9/14 patients, the distance from the EEG source to the lesion was significantly smaller with 63 than with 31 electrodes, and increasing the number of electrodes to 123 increased this number of patients from 9 to 11. Simulations confirmed the relation between the number of electrodes and localization accuracy. CONCLUSIONS: The results illustrate the necessity of multichannel EEG recordings for high source location accuracy in epileptic patients.

Adolescent↗

PubMed2003

Contralateral medial temporal lobe damage in right but not left temporal lobe epilepsy: a (1)H magnetic resonance spectroscopy study.

BACKGROUND: Proton magnetic resonance spectroscopy (MRS) of the hippocampus is useful in lateralising the epileptic focus in temporal lobe epilepsy for subsequent surgical resection. Previous studies have reported abnormal contralateral MRS values in up to 50% of the patients. OBJECTIVE: To identify the contributing factors to contralateral damage, as determined by MRS, and its extension in patients with temporal lobe epilepsy. METHODS: Single voxel MRS was carried out in the hippocampus and lateral temporal neocortex of both hemispheres in 13 patients with left temporal lobe epilepsy (LTLE) and 16 patients with right temporal lobe epilepsy (RTLE). All patients had mesial temporal lobe epilepsy with hippocampal sclerosis. Controls were 21 healthy volunteers of comparable age. RESULTS: Consistent with previous studies, the NAA/(Cho+Cr) ratio was abnormally low in the hippocampus ipsilateral to the focus (p < 0.0001), and there were lower values in both patient groups in the ipsilateral temporal neocortex (p < 0.0001). Patients with RTLE had left hippocampal MRS anomalies (p = 0.0018), whereas the right hippocampus seemed to be undamaged in LTLE patients. CONCLUSIONS: Unilateral mesial temporal lobe epilepsy is associated with widespread metabolic abnormalities which involve contralateral mesial and neocortical temporal lobe structures. These abnormalities appear to be more pronounced in patients with RTLE.

Adult↗

PubMed2002

[Geneva-Lausanne laboratory for presurgical epilepsy diagnosis: experiences with the first 150 patients].

In Switzerland there are approximately 35,000 to 70,000 patients who suffer from epilepsy. In 20% of these patients, seizures cannot be satisfactorily suppressed by medical treatment (so-called pharmacoresistent epilepsy); thus surgical therapy represents an alternative. We report on the first 150 patients who have been investigated in the presurgical epilepsy laboratory Geneva-Lausanne since its foundation in April 1995. Of these patients, 75% were adults and 25% were adolescents or infants. In 87% of all patients, non-invasive methods (phase I) were sufficient for diagnosis. In our laboratory, these methods encompassed the following techniques: prolonged video-EEG monitoring, high resolution MRI, positron-emission-tomography (PET), and neurological and neuropsychological exams during the interictal and postictal periods. In 13% of cases, the epileptic focus was localized by intracranial electrodes as well as differentiated against vital cortex (phase II). Of all operated patients, 78% were seizure-free post-operatively, and another 14% significantly ameliorated, such that more than 90% significantly benefited from the intervention. Psychosocial variables (professional, social integration) as changes were also analysed post-operatively. Although the majority of the patients were seizure-free, only 1/4 to 1/3 of all patients showed an improvement in their psychosocial situation. This is most likely due to the long delay between the onset of epilepsy and surgical treatment, which was found to be approximately 10 to 40 years in our patient population. The necessity to pose the diagnosis "pharmacoresistant epilepsy" as fast as possible is discussed, in order to shorten the delay to a few years until a possible operation.

Adolescent↗

PubMed2002

Temporal lobe epilepsy and postural orthostatic tachycardia syndrome (POTS).

We describe a 20-year-old woman suffering from right temporal epilepsy, behavioral disorder, and a complaint of paroxysmal palpitations accompanied by anxiety. Detailed cardiac evaluation revealed that the palpitations were due to episodes of marked sinus tachycardia secondary to a concomitant postural orthostatic tachycardia syndrome (POTS) and not of psychogenic origin as initially thought. Treatment with a beta-blocker resulted in the disappearance of palpitations and the associated anxiety. This is the first report of the coexistence of partial epilepsy and POTS. The recognition of such a syndrome in epileptic patients is important in order to offer appropriate therapy.

Journal Article↗

PubMed2002

Direction-specific motion blindness induced by focal stimulation of human extrastriate cortex.

Motion blindness (MB) or akinetopsia is the selective disturbance of visual motion perception while other features of the visual scene such as colour and shape are normally perceived. Chronic and transient forms of MB are characterized by a global deficit of direction discrimination (pandirectional), which is generally assumed to result from damage to, or interference with, the motion complex MT+/V5. However, the most characteristic feature of primate MT-neurons is not their motion specificity, but their preference for one direction of motion (direction specificity). Here, we report that focal electrical stimulation in the human posterior temporal lobe selectively impaired the perception of motion in one direction while the perception of motion in other directions was completely normal (unidirectional MB). In addition, the direction of MB was found to depend on the brain area stimulated. It is argued that direction specificity for visual motion is not only represented at the single neuron level, but also in much larger cortical units.

Adult↗

PubMed2001

Volumetric measurements of subcortical nuclei in patients with temporal lobe epilepsy.

OBJECTIVE: To determine the volumes of subcortical nuclei in patients with chronic epilepsy. BACKGROUND: Animal and human data suggest a crucial role for subcortical structures in the modulation of seizure activity, mostly as seizure-suppressing relays. Although cortical epileptogenic foci can vary in localization and extent, it nevertheless appears that these structures subsequently influence seizure propagation in a universal fashion. There is, however, little knowledge about the size of implicated subcortical structures in patients with epilepsy. METHOD: Using high-resolution MRI, the volumes of selected subcortical nuclei, such as the thalamus, caudate nucleus, putamen, and pallidum, were measured in both hemispheres of 27 patients with temporal lobe epilepsy. Fourteen healthy volunteers served as controls. Statistical analysis was done for both normalized volumes (by total brain volume) and unnormalized volumes. RESULTS: Overall, the patient group had smaller thalamic and striatal volumes in both hemispheres, mostly ipsilateral to the epileptic focus. No significant correlations were noted between volume measurements and age, age at onset, duration of epilepsy, or total seizure frequency, including frequency of generalized seizures. The putamen and thalamus seemed to be affected predominantly in patients with a history of febrile convulsions, whereas patients without febrile convulsions had smaller caudate nuclei bilaterally. CONCLUSIONS: Volumetric measurements of subcortical nuclei reveal atrophy of distinct subcortical nuclei in the patient group, predominantly ipsilateral to the focus. This finding probably reflects persistent abnormalities and not secondary change. In addition, the structural differences between patients with and patients without previous febrile convulsions suggest that these conditions may have different causes.

Adult↗

PubMed2001

Functional MRI with simultaneous EEG recording: feasibility and application to motor and visual activation.

The possibility of combining the high spatial resolution of functional magnetic resonance imaging (fMRI) with the high temporal resolution of electroencephalography (EEG) may provide a new tool in cognitive neurophysiology, as well as in clinical applications such as epilepsy. However, the simultaneous recording of EEG and fMRI raises important practical problems: 1) the patients' safety, in particular the risk of skin burns due to electrodes heating; 2) the impairment of the EEG recording by the static magnetic field, as well as by RF and magnetic field gradients used during MRI; and 3) the quality of MR images, which may be affected by the presence of conductors and electronic devices in the MRI bore. Here we present our experiences on 19 normal volunteers who underwent combined fMRI and 16-channel EEG examination. Consistent with previous reports, safety could be assured when performing EEG recordings during fMRI acquisition. Electrophysiological signals recorded with surface EEG were similar inside and outside the 1.5 T magnet. Furthermore, fMRI using motor or visual tasks revealed similar areas of activation when performed with and without 16-channel EEG recording. J. Magn. Reson. Imaging 2001;13:943-948.

Attention↗

PubMed2001

Intracranial Neurophysiological Correlates Related to the Processing of Faces.

Face perception and recognition is an intriguing ability, already present in neonates. Numerous studies in patients with brain lesions identified the temporo-occipital cortex as the crucial structure for this capacity. Analysis of electrical signals (EEG) inside the brain of patients implanted with intracranial electrodes for diagnostic purposes allows researchers to describe the temporal and spatial organization of responses to various aspects of face processing in human subjects. Several findings have emerged and appear relevant for cerebral organization in general: (1) Selective face responses were obtained from the basal temporo-occipital cortex at around 200 ms (N200); however, other structures such as the lateral temporal lobe and frontal cortex also participate in face recognition and perception tasks. (2) Each structure has a distinct "response profile"; that is, with respect to a given task certain structures respond strongly, others less or not at all. This profile might change with a different task, although the physical parameters of the stimuli remain the same. (3) The right hemispheric predominance of face processing, as suggested by patient data and studies in healthy volunteers, seemed to be restricted to its early stages (i.e., before 100-150 ms). (4) Recognition of faces might be associated with differential intracranial responses, despite an incorrect overt response, reflecting neurophysiological correlates of implicit memory. (5) The more the stimulus resembled a complete human face, the earlier and larger the N200 response was found, in particular over the basal temporobasal cortex. Analysis of electrical signals from intracranial electrodes might help to improve our understanding of the underlying physiological and anatomical constraints of cognitive processes.

Journal Article↗