PubMed Health⌕ Search

Biomedical subjects

F G Woermann

Publications and source records attributed to F G Woermann.

At least 19 recordsLinked to original sources

The role of 1H magnetic resonance spectroscopy in pre-operative evaluation for epilepsy surgery. A meta-analysis.

PURPOSE: We aimed to assess the additional pre-operative value of (1)H MRS in identifying the epileptogenic zone (EZ) for epilepsy surgery by performing a meta-analysis considering publications from 1992 to 2003. METHODS: From an extensive computer and hand search 22 studies were included. For inclusion, studies had to report post-operative outcome and detailed diagnostic test results for each individual patient. Studies exclusively reporting on patients with brain tumors or on children were excluded. RESULTS: Great heterogeneity among studies regarding methodological and technical aspects and concerning evaluation and interpretation of data was observed. Only patients with intractable temporal lobe epilepsy were presented. Sixty-four percent of all patients and 72% of patients with good outcome had an ipsilateral MRS abnormality concordant with the EZ. The positive predictive value of all patients with ipsilateral MRS abnormality for good outcome was 82%. An odds ratio weighted by inverse variance showed a 4.891 better chance of seizure free outcome [CI=1.965-12.172; Q=2.748; d.f.=5; critical chi2-value=11.07] in patients with an ipsilateral MRS abnormality when compared to patients with bilateral MRS abnormalities. Data for MRI-negative patients were conflicting. One study stressed a role for MRS in patients with bilateral hippocampal atrophy at MRI. CONCLUSIONS: MRS still remains a research tool with clinical potential. Our findings indicate the connection of ipsilateral MRS abnormality to good outcome. The ability for prediction of post-operative outcome may depend on the assessed population. Prospective studies limited to non-localized ictal scalp EEG or MRI-negative patients are required for validation of these data.

Adolescent↗

Amygdala fMRI lateralizes temporal lobe epilepsy.

OBJECTIVE: To characterize the clinical value of an fMRI task activating the amygdala in controls and patients with mesial temporal lobe epilepsy (MTLE). METHODS: A fearful face fMRI paradigm using video sequences was developed and investigated in 17 patients with epilepsy (12 had MTLE [6 right- and 6 left-sided]) and 17 healthy control subjects. Reproducibility was demonstrated by reimaging 12 of the control subjects. In addition, parahippocampal activation was measured using Roland's Hometown Walking Task within the same session in all patients and in nine of the control subjects. RESULTS: A fearful face paradigm led to significant amygdala activation (p < 0.001) in all subjects. Amygdala activation was bilateral in control subjects and clearly lateralized in patients with MTLE. Dissociated amygdala and parahippocampal activation was found in three MTLE patients. A combination of results from both fMRI paradigms improved the lateralization of the side of seizure onset in patients with MTLE. CONCLUSIONS: fMRI activation of the amygdala evoked by an animated fearful face paradigm is strong, reproducible, and specific in individual subjects. The combination of the fearful face paradigm and Roland's Hometown Walking Task provides a more reliable presurgical mapping of mesial temporal lobe structures.

Adolescent↗

Transient lesion in the splenium of the corpus callosum and antiepileptic drug withdrawal.

OBJECTIVE: To test pathophysiologic hypotheses regarding the occurrence of a splenial lesion in patients with epilepsy. METHODS: The authors studied 16 patients with a splenial lesion and 32 control patients, all of whom had MRI examination immediately after presurgical EEG long-term monitoring (LTM). The authors compared the number of generalized tonic-clonic and partial seizures during LTM, antiepileptic drug (AED) withdrawal, and laboratory results. RESULTS: All of the patients with a splenial lesion had their AEDs stopped completely, vs 47% of the controls (p = 0.001). Patients with SCC lesion had a longer duration of complete withdrawal (median 3.5 vs 2 days, p = 0.03). There was no correlation with seizure frequency or the introduction of new AEDs. CONCLUSION: A lesion of the splenium of the corpus callosum in patients with epilepsy is not associated with toxic drug effects or high seizure frequency, but might be induced by a rapid and relatively long-lasting reduction of antiepileptic drugs. Its frequency might be underestimated as MRI after long-term monitoring is rarely done.

Adolescent↗

Epileptic activity influences the lateralization of mesiotemporal fMRI activity.

OBJECTIVE: To identify clinical factors contributing to the lateralization of mesiotemporal memory functions in epilepsy by using memory-activated fMRI. METHODS: Sixty patients aged 16 to 63 years with mesial temporal lobe epilepsy (MTLE) and 20 patients aged 16 to 60 years with extratemporal epilepsy (ETE) due to circumscribed epileptogenic lesions who consecutively underwent presurgical evaluation including continuous video-EEG monitoring and structural MRI examinations were examined. During memory fMRI, the activation condition consisted of retrieval from long-term memory induced by self-paced performance of an imaginative walk through the patient's hometown. On the basis of a previous study, memory lateralization was defined as typical if larger fMRI activation was in the mesiotemporal structures contralateral to the epileptic focus. RESULTS: There were 45 patients with MTLE who had typical memory lateralization (75%), whereas only 9 patients (45%) with ETE exhibited typical memory lateralization (p = 0.013). In MTLE patients, bilateral independent epileptiform discharges occurred more often in the atypical group than in patients with typical memory lateralization (p = 0.015). CONCLUSIONS: The fMRI lateralization of mesiotemporal visuospatial memory functions in patients with mesiotemporal lobe epilepsy (MTLE) is asymmetric: The larger activation usually appears contralateral to the side of the epileptogenic region. These findings occur more often in MTLE; in patients with extratemporal epilepsy, such type of asymmetry is not characteristic. In MTLE patients with bilateral independent epileptiform discharges, this type of asymmetry is also less frequent.

Adolescent↗

Bilateral mesial temporal lobe epilepsy: comparison of scalp EEG and hippocampal MRI-T2 relaxometry.

OBJECTIVE: Bilateral hippocampal abnormality is frequent in mesial temporal lobe sclerosis and might affect outcome in epilepsy surgery. The objective of this study was to compare the lateralization of interictal and ictal scalp EEG with MRI T2 relaxometry. MATERIAL AND METHODS: Forty-nine consecutive patients with intractable mesial temporal lobe epilepsy (MTLE) were studied with scalp EEG/video monitoring and MRI T2 relaxometry. RESULTS: Bilateral prolongation of hippocampal T2 time was significantly associated with following bitemporal scalp EEG changes: (i) in ictal EEG left and right temporal EEG seizure onsets in different seizures, or, after regionalized EEG onset, evolution of an independent ictal EEG over the contralateral temporal lobe (left and right temporal asynchronous frequencies or lateralization switch; P = 0.002); (ii) in interictal EEG both left and right temporal interictal slowing (P = 0.007). Bitemporal T2 changes were not, however, associated with bitemporal interictal epileptiform discharges (IED). Lateralization of bilateral asymmetric or unilateral abnormal T2 findings were associated with initial regionalization of the ictal EEG in all but one patient (P < 0.005), with lateralization of IED in all patients (P < 0.005), and with scalp EEG slowing in 28 (82,4%) of 34 patients (P = 0.007). CONCLUSION: Our data suggest that EEG seizure propagation is more closely related to hippocampal T2 abnormalities than IED. Interictal and ictal scalp EEG, including the recognition of ictal propagation patterns, and MRI T2 relaxometry can help to identify patients with bitemporal damage in MTLE. Further studies are needed to estimate the impact of bilateral EEG and MRI abnormal findings on the surgical outcome.

Action Potentials↗

Language lateralization by Wada test and fMRI in 100 patients with epilepsy.

Comparing the determination of language dominance using fMRI with results of the Wada test in 100 patients with different localization-related epilepsies, the authors found 91% concordance between both tests. The overall rate of false categorization by fMRI was 9%, ranging from 3% in left-sided temporal lobe epilepsy (TLE) to 25% in left-sided extratemporal epilepsy. Language fMRI might reduce the necessity of the Wada test for language lateralization, especially in TLE.

Adult↗

Epileptic activity influences the speech organization in medial temporal lobe epilepsy.

Factors influencing atypical speech lateralization have theoretical importance in understanding the organization and reorganization of higher cognitive functions, as well as having practical implications, especially in brain surgery and neurorehabilitation. Atypical (right-sided or bilateral) language representation is more frequent in focal epilepsy than in healthy people. This difference is thought to be related to early childhood brain injuries localized in the neighbourhood of speech centres. The effect of epileptic activity on speech lateralization has not been investigated, although much data suggest that epileptic activity may interfere with higher brain functions. It can only be evaluated in a homogeneous human population with epilepsy having the same lesion type in the same localization. For these reasons, we investigated 184 patients with medial temporal lobe epilepsy (MTLE) due to unilateral hippocampal sclerosis (HS), but without other epileptogenic lesions. All patients underwent comprehensive presurgical evaluation. In MTLE, the influence of age at the time of brain damage, i.e. the initial precipitating injury (IPI), could be evaluated separately from the other timing factors. Of 100 patients in whom a Wada test was performed, left-sided speech occurred in 76% of the left-sided and in 100% of the right-sided MTLE patients (P < 0.05). For further evaluation, we included only the 83 left-sided MTLE patients. The mean age at seizure onset was 10.1 +/- 7.8 years (range 1-37 years); the mean age at evaluation was 35.7 +/- 9.8 years. Based on the Wada test, left-sided speech was present in 63 patients, while in 20 (24%) patients the Wada test revealed atypical speech dominance. We found that atypical speech representation in left MTLE was associated with higher spiking frequency (P < 0.05) and with sensory auras representing an ictal involvement of the lateral temporal structures (P < 0.01). Psychic auras suggesting limbic seizure spread showed a significant association with left-sided speech dominance in left MTLE (P < 0.05). Neither age at epilepsy onset, nor age at IPI was associated with atypical speech in left MTLE. Conclusively, we found that in patients with focal epilepsy, not only the known factors, i.e. the age at which the brain injury occurred and its localization, but also the epileptic activity itself, i.e. interictal discharges and seizure spread, may influence speech reorganization. Our findings also suggest that not only structural elements but also functional factors have an effect on the language organization of the brain.

Adult↗

Right hippocampal sclerosis is more common than left after febrile seizures.

Temporal lobe epilepsy (TLE) is frequently associated with hippocampal sclerosis (HS) and a history of febrile convulsions (HFC). The authors investigated 292 patients with TLE due to HS. Left HS occurred more frequently (57%) than right HS (43%, p = 0.01). Forty-seven percent of the patients had HFC. In patients with right HS, HFC occurred in 59.6%, whereas in patients with left HS, HFC was present in 37.5%, showing a highly significant lateralization difference.

Adolescent↗

Measurement of temporal lobe T2 relaxation times using a routine diagnostic MR imaging protocol in epilepsy.

OBJECTIVE: To determine the applicability of a fast spin-echo (FSE) pulse sequence for T2 relaxation time measurements in diagnostic imaging of temporal lobe epilepsy (TLE) and in epilepsy research. To compare FSE T2-relaxometry to the measurements with multi-echo sequence and visual assessment of MR scans. METHODS: MR imaging and T2 relaxometry was performed with widely used 1.5 T scanner only. Fast dual-echo sequence (TE-14/85 ms) and multi-echo pulse sequence were used for T2 measurements. Normal ranges of T2 values in regions of interest in temporal lobe were estimated in 20 healthy controls. Sixty-five patients with intractable focal epilepsy were studied. Fifty-five patients had TLE, three multilobar focal epilepsy and seven extratemporal focal epilepsy. RESULTS: T2 measurements with the FSE showed good reproducibility in the test objects and control subjects. In one TLE case unilateral focal T2 changes were not identified visually. T2-relaxometry was more sensitive than visual inspection of MR scans in assessing bilateral hippocampal changes: there were 15 cases with abnormal bilateral T2 values. Visually bilateral changes were detected in six out of these 15 cases (40%). In six cases (40%) only unilateral changes were diagnosed visually, and in three cases (20%) bilateral changes were classified as probable with qualitative evaluation. T2 relaxation time measurement supplied additional objective data in cases with ambiguous hippocampal changes on visual assessment: T2-relaxometry confirmed hippocampal abnormalities in seven cases judged visually as probable. In four cases with the suspicion of hippocampal changes T2 values appeared to be normal. CONCLUSION: In TLE patients, images constructed from FSE sequences can be used to estimate T2 relaxation times easily and reliably. T2 measurements are an objective method to diagnose structural changes in the temporal lobe. T2-relaxometry is most helpful to assess bilateral hippocampal abnormalities, and thus might have an impact on estimating postsurgical outcome.

Adolescent↗

Amygdala pathology in psychosis of epilepsy: A magnetic resonance imaging study in patients with temporal lobe epilepsy.

Psychosis of epilepsy (POE) has been recognized as a severe complication of chronic intractable epilepsy for more than a century. Most of the clinical symptoms of POE are reminiscent of schizophrenia. Nevertheless, there is general agreement that the phenomenology of POE differs from classical schizophrenia. The temporal lobe hypothesis of schizophrenia put forward in the 1960s notes that episodes with paranoid psychoses are more prevalent in temporal lobe epilepsy (TLE). However, the aetiology and pathogenesis of POE are poorly understood. One of the strongest biological findings in schizophrenia is volume loss of temporal lobe structures and the hippocampus in particular. In order to test the hypothesis that atrophy of the hippocampus and the amygdala is found in patients with TLE and POE, we performed a retrospective study of all patients with TLE who were admitted to the assessment unit of the Chalfont Centre for Epilepsy from 1995 until 1999. Twenty-six (2.6%) of these 1008 patients fulfilled inclusion criteria and were compared with 24 patients with TLE without psychopathology and 20 healthy volunteers. All patients underwent extensive MRI investigations, including volumetric data sets and quantitative T(2 )relaxometry. We found that patients with TLE and POE differed from patients with TLE alone and healthy volunteers in that the total brain volumes were significantly smaller. While there were no differences in hippocampal volumes between the three study groups, there was a significant 16-18% enlargement of the amygdala on both sides in patients with POE. Our findings support the notion that POE is a distinct nosologic entity differing from schizophrenia not only in clinical details but also in neurobiological aspects. The finding of amygdala enlargement agrees with the observation of an association between dysphoric disorders of epilepsy and POE described nearly 100 years ago.

Amygdala↗

Carbamazepine reduces memory induced activation of mesial temporal lobe structures: a pharmacological fMRI-study.

BACKGROUND AND PURPOSE: It is not known whether carbamazepine (CBZ; a drug widely used in neurology and psychiatry) influences the blood oxygenation level dependent (BOLD) contrast changes induced by neuronal activation and measured by functional MRI (fMRI). We aimed to investigate the influence of CBZ on memory induced activation of the mesial temporal lobes in patients with symptomatic temporal lobe epilepsy (TLE). MATERIAL AND METHODS: Twenty-one individual patients with refractory symptomatic TLE with different CBZ serum levels and 20 healthy controls were studied using BOLD fMRI. Mesial temporal lobe (MTL) activation was induced by a task that is based on the retrieval of individually familiar visuo-spatial knowledge. The extent of significant MTL fMRI activation was measured and correlated with the CBZ serum level. RESULTS: In TLE patients, the extent of significant fMRI activation over both MTL was negatively correlated to the CBZ serum level (Spearman r = -0.654, P < 0.001). Activation over the supposedly normal MTL, i.e. contralateral to the seizure onset of TLE patients, was smaller than the averaged MTL activation in healthy controls (P < 0.005). Age, duration of epilepsy, side of seizure onset, and intelligence were not correlated to the extent of the significant BOLD-response over both MTL in patients with TLE. CONCLUSIONS: In TLE patients, carbamazepine reduces the fMRI-detectable changes within the mesial temporal lobes as induced by effortful memory retrieval. FMRI appears to be suitable to study the effects of chronic drug treatment in patients with epilepsy.

Adolescent↗

Memory fMRI lateralizes temporal lobe epilepsy.

BACKGROUND: The assessment of mesial temporal lobe (MTL) function is important for the diagnosis and treatment of temporal lobe epilepsy (TLE) and other brain diseases. Declarative memory depends on the integrity of the MTL region. OBJECTIVE: To investigate hemispheric asymmetries of MTL activity in patients with symptomatic TLE. METHODS: With use of blood oxygenation level-dependent fMRI, hemispheric asymmetries in MTL activation of 30 individual patients with refractory symptomatic TLE and 17 healthy control subjects were studied. Activation was induced by a task employing mental navigation and recall of landmarks based on the retrieval of individually familiar visuospatial knowledge. RESULTS: The study demonstrated that the memory task used reliably activated MTL structures in individual control subjects and patients with refractory TLE including children, older subjects, and patients with low formal IQ. Interhemispheric differences in MTL activation lateralized the side of seizure onset in 90% of patients with symptomatic unilateral TLE. In contrast, healthy control subjects did not show a systematic asymmetry of MTL activation. Correlations between MTL activation and neuropsychological measures suggest that the fMRI-detectable MTL changes were specifically related to memory rather than to memory-independent visuospatial abilities. CONCLUSION: fMRI of memory-induced MTL activation lateralizes the side of seizure onset in patients with refractory symptomatic TLE and may provide complementary information for presurgical evaluation.

Adolescent↗

Cavernous angioma associated with ipsilateral hippocampal sclerosis.

We report two cases with extratemporal cavernous angioma (CA) and coexisting ipsilateral hippocampal sclerosis. Classically dual pathology is defined as the association of hippocampal sclerosis with an extrahippocampal lesion. Subtle changes in hippocampus might be overlooked in the presence of an unequivocal extrahippocampal abnormality. Seizure outcome after epilepsy surgery in cases with dual pathology is less favourable if only one of the lesions is removed. Dual pathology must always be considered in diagnostic imaging of patients with intractable epilepsy and CA.

Adult↗

A fast FLAIR dual-echo technique for hippocampal T2 relaxometry: first experiences in patients with temporal lobe epilepsy.

To evaluate the use of cerebrospinal fluid (CSF) signal nulling in MR T2 measurements of the hippocampus in normal control subjects and patients with temporal lobe epilepsy (TLE), dual-echo acquisitions covering the whole brain were used. T2 relaxation times were estimated in 12 standard Eurospin II MR test objects and in the hippocampi of 10 control subjects, using T2 maps constructed from conventional spin-echo (CSE), fast spin-echo (FSE), and fast FLAIR (FF) dual-echo sequences on a 1.5-T MR scanner. Hippocampal T2 values (HCT2) were measured on contiguous coronal 5-mm slices throughout the antero-posterior extent of each hippocampus in the 10 controls and 12 TLE patients, using both CSE and FF. Scan-rescan reproducibility in Eurospin II standard MR test objects was high for all sequences. There was a good correlation between T2 values from CSE, FF, and FSE sequences in test objects and in control hippocampi. In controls, the coefficient of variation of mean HCT2 values differed between slice positions, but was lowest for FF, followed by CSE data. The intrarater coefficient of reliability between repeated measurements in control subjects was lowest for FF HCT2, at 2.3%. The interrater coefficient of reliability for CSE HCT2 measurements in controls (4.8%) was slightly lower than the interrater coefficient for FF HCT2 (5.4%). HCT2 measurement with both CSE and FF identified abnormal values in the same 10 hippocampi of 12 patients. Hippocampal dual-echo T2 relaxometry using CSF nulling is reliable in control subjects, and identifies the abnormal hippocampi in patients with TLE. The increases in hippocampal T2 signal demonstrated using FF HCT2 measurements are unlikely to be partial volume effects from CSF.

Adult↗

In vivo short echo time 1H-magnetic resonance spectroscopic imaging (MRSI) of the temporal lobes.

Two different methodologies for obtaining PRESS-localized magnetic resonance spectroscopic imaging (MRSI) data from the mesial and lateral temporal lobes were investigated. The study used short echo times (30 ms) and long repetition times (3000 ms) to minimize relaxation effects. Inhomogeneity and spectral distortions from the proximity of the temporal bones precluded the attainment of consistently good-quality data from both temporal lobes at once. Even when the right and left temporal lobes were studied separately, distortions often disturbed spectra from the anterior lateral temporal lobe. Quantitative analysis using LCModel was therefore performed only on the posterior lateral temporal lobe, and the posterior, middle, and anterior mesial temporal lobe. No significant left-right differences in metabolite content were found in a series of 10 controls. Significantly higher concentrations of myoinositol and choline were found in the anterior mesial temporal lobe, even when grey matter content was included as a covariate. The concentration of N-acetyl aspartate plus N-acetyl aspartyl glutamate (NAc) was not found to vary significantly along the length of the hippocampus. The previously observed lower anterior ratios of NAA to creatine plus choline (NAA/(Cr + Cho) may instead have been due to higher anterior choline. Large differences in metabolite concentrations were seen between posterior lateral temporal lobe (predominantly subcortical white matter) and the posterior mesial temporal lobe, most notably lower creatine, glutamate/glutamine, and myo-inositol, and higher NAA/(Cr + Cho) in the lateral than mesial temporal lobe. This pattern was similar to that previously seen for grey/white matter differences in the frontal, parietal and occipital regions.

Adult↗

Ultra-fast low-angle rapid acquisition and relaxation enhancement (UFLARE) in patients with epilepsy.

MRI is an important diagnostic tool in patients with epilepsy, but patient motion during long scans may result in image artefacts. We studied the utility of an ultra-fast MR sequence in patients with epilepsy. Ultra-fast low-angle rapid acquisition and relaxation enhancement (UFLARE) images were acquired for 100 consecutive patients and nine control subjects. Scans were compared with routine T2-weighted spin echo images for signal-to-noise ratio, contrast, and conspicuity, followed by a blind review of lesion detectability. UFLARE scans were also acquired for 15 patients who moved during conventional scans. All UFLARE scans had lower signal-to-noise ratios and lower contrast than the T2-weighted images. Compared with T1- and T2-weighted, PD and FLAIR images, 86% of hippocampal sclerosis (HS), 92% of large but only 24% of small white-matter lesions were detected on the blind review of the UFLARE images. Reduced motion artefacts were seen on the UFLARE images in all 15 patients who moved during the conventional scans, and in three patients UFLARE was the only sequence we were able to obtain. Despite the lower lesion detectability for smaller lesions, the use of an ultra-fast MRI sequence such as UFLARE may be very useful in patients who are not able to co-operate during conventional MRI examinations, if a general anaesthetic is to be avoided.

Adolescent↗

Multiple pterygium syndrome, bilateral periventricular nodular heterotopia and epileptic seizures--a syndrome?

We present the clinical, neurophysiological and radiographic findings in a boy with coexisting multiple pterygium syndrome, bilateral periventricular nodular heterotopia (BPNH), mental retardation and epileptic seizures. This constellation has not been previously reported. We discuss the possibility of a new BPNH syndrome associated with multiple pterygium syndrome in our patient.

Abnormalities, Multiple↗

Quantitative short echo time proton magnetic resonance spectroscopic imaging study of malformations of cortical development causing epilepsy.

In patients with malformations of cortical development (MCD), widespread structural abnormalities of the brain have been demonstrated using volumetric MRI, and associated with poor post-surgical outcome in patients with localization-related epilepsy. Proton magnetic resonance spectroscopic imaging (1H-MRSI) studies permit the non-invasive measurement of concentrations of a variety of cerebral metabolites implicated in cerebral structure and function. There is a dearth of quantitative 1H-MRSI studies of MCD. Ten controls and 10 patients with localization-related epilepsy who were found to have MCD on high resolution MRI underwent 1H-MRSI on a 1.5 T GE Signa scanner [TE (echo time) = 30 ms, TR (repetition time) = 3 s]. In all patients, the axial area studied contained lesional and perilesional tissue. In seven unilaterally affected patients, the area studied contained also apparently normal contralateral grey and white matter; in three patients with bilateral but asymmetrical MCD, it contained visually normal and abnormal tissue from both hemispheres. N-acetyl aspartate + N-acetyl aspartyl glutamate (NAA), creatine + phosphocreatine (Cr), choline-containing compounds (Cho), glutamate + glutamine (Glx) and myo-inositol (Ins) were automatically quantified in voxels covering these different regions. Metabolite concentrations were corrected for CSF content and correlated with the grey and white matter of the MRSI voxels. In control subjects, there were significant positive correlations between grey matter content and concentrations of NAA, Glx, Ins and Cr. Compared with a normal range that took grey matter content into account, defined as the control mean +/- 2 SD, all lesions but one showed metabolic abnormalities. The most common abnormality was a decrease in NAA, but findings were heterogeneous and there was increased NAA in one lesion. Perilesional tissue was abnormal in eight patients, with increased NAA in three. Tissue contralateral to the main MCD was abnormal in all three patients with bilateral but asymmetrical MCD, and in six of the seven apparently unilaterally affected patients. Spectroscopic grey and white matter abnormalities in patients with MCD exceeded the apparently focal abnormality shown by MRI, indicating widespread abnormalities of cerebral function.

Adult↗