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Biomedical subjects

F Dubeau

Publications and source records attributed to F Dubeau.

At least 55 records · Page 3Linked to original sources
PubMed2000

Prognostic value of proton magnetic resonance spectroscopic imaging for surgical outcome in patients with intractable temporal lobe epilepsy and bilateral hippocampal atrophy.

The objective of this study was to assess which features of temporal lobe proton magnetic resonance spectroscopic imaging (1H-MRSI) are associated with satisfactory surgical outcome in patients with intractable temporal lobe epilepsy and bilateral hippocampal atrophy. We studied 21 patients with intractable temporal lobe epilepsy and bilateral hippocampal atrophy defined by magnetic resonance imaging volumetric measurements who underwent surgical treatment. 1H-MRSI was used to determine the relative resonance intensity ratio of the neuronal marker N-acetylaspartate to creatine + phosphocreatine (NAA/Cr) for mid and posterior temporal lobe regions of the left and right hemisphere, as well as an asymmetry index. Values lower than 2 SDs below the normal mean were considered abnormal. We used Engel's classification to assess surgical outcome with respect to seizure control. Eleven patients (52%) were in class I-II and 10 (48%) were in class III-IV. All 21 were operated on the side of maximal electroencephalographic (EEG) lateralization. Concordant lateralization of decreases in NAA/Cr to the side of surgery and normal NAA/Cr values in the contralateral posterior-temporal region were significantly associated with good surgical outcome: 11 (69%) of 16 patients with 1H-MRSI abnormalities concordant with EEG lateralization and none of the 5 patients with nonconcordant 1H-MRSI had a good outcome (class I-II); 10 (77%) of 13 patients with normal NAA/Cr contralateral to the EEG lateralization versus 1 (12.5%) of 8 of those with NAA/Cr reduction contralateral to EEG lateralization were in class I-II. Regression correlation analysis showed significant linear correlation between the midtemporal NAA/Cr relative asymmetry ratio and surgical outcome; the greater the asymmetry, the better the outcome. We conclude that discriminant 1H-MRSI features associated with favorable surgical outcome in patients with temporal lobe epilepsy and bilateral hippocampal atrophy were (1) concordant 1H-MRSI lateralization, (2) a greater side-to-side asymmetry of NAA/Cr, and (3) an absence of contralateral posterior NAA/Cr reduction.

Adolescent↗
PubMed2000

Clinical findings, imaging characteristics and outcome in catastrophic post-encephalitic epilepsy.

OBJECTIVES: The aim of this study is to characterize the clinical features and prognostic factors for intractable, post-encephalitic epilepsy. METHODS: We studied retrospectively 42 patients (26 men) evaluated between 1982 and 1999. MRI, neuropsychological findings, interictal and ictal scalp EEG were reviewed for all patients. Fifteen patients had additional stereo EEG (SEEG) studies. RESULTS: The mean age at encephalitis was 17 years (SD = 15.5); etiology was identified in 18 patients. During the acute illness, 79% had status epilepticus (SE) or recurrent seizures and 76% were in coma; mean Glasgow outcome scale (GOS) was 3.6 (SD = 0.8). The mean latency to seizure onset was 0.8 years (SD = 1.9). The majority (72%) presented with complex partial seizures with or without secondary generalization. According to interictal epileptiform findings and the predominant seizure onset pattern as found on scalp EEG, patients were unilateral temporal (UTLE) = 8, bilateral temporal (BTLE) = 12, and extratemporal/multifocal or generalized (ETMFE) = 22 patients. MRI atrophy and/or signal changes were unilateral temporal in 7 (18%), bilateral temporal in 5 (13%), multilobar/diffuse in 20 (51%), and absent in 7 (18%). ANOVA revealed significant differences in mean GOS between UTLE versus BTLE and ETMFE (4.7 versus 3.2 versus 3.6; p < 0.0001), but not in age at encephalitis. Latency to the first unprovoked seizure was shorter in patients with ETMFE compared to UTLE and BTLE (p < 0.01). Surgery was performed in 24 patients. The best outcome was obtained in UTLE (7/8 class I and II). In the others, outcome was poor in the majority (13/16 class III and IV). CONCLUSION: There is a small subgroup of patients with postencephalitic UTLE for whom the outcome is favorable. The majority of our patients had multifocal seizure onset with BTLE and ETMFE, and poor outcome after surgical treatment.

Adolescent↗
PubMed1999

Entorhinal cortex in temporal lobe epilepsy: a quantitative MRI study.

BACKGROUND: The entorhinal cortex (EC) is a distinct anatomic and functional region of the anterior parahippocampal gyrus, which plays a role in seizure generation and propagation in temporal lobe epilepsy (TLE). In tissue resected from TLE patients, cell loss in the EC has been described. OBJECTIVES: To develop a standardized protocol for identifying the anatomic boundaries of the EC using high-resolution MRI and to examine morphologic changes of the EC in TLE. METHODS: We performed T1-weighted MRIs in 20 patients (7 males) with TLE (mean age 34 years) and 18 normal controls (mean age 26 years). Eleven patients had a left and 9 a right epileptic focus as defined by history, video-EEG, and surgical outcome. The volumes of the EC, the hippocampus, and the amygdala were measured using a standardized MRI protocol. Analysis of variance (ANOVA) was used to examine the effect of seizure focus lateralization and hemisphere on these volumes. An asymmetry ratio [A (%) = 100 x (R-L)/(R+L)/2] was also compared between groups using ANOVA. RESULTS: In normal controls the volume of the right EC was 1,247 +/- 127 mm3 (mean +/- standard deviation), and that of the left EC was 1,215 +/- 135 mm3 (p > 0.05). We found a bilateral reduction in the volume of the EC in TLE patients compared with controls (p < 0.05). Examination of the asymmetry ratios showed that the reduction in volume of the EC was greater ipsilateral to the epileptic focus (p < 0.05). The volumes of the hippocampus and the amygdala were smaller on the side of the focus in TLE patients compared with controls (p < 0.05). CONCLUSIONS: With a standardized protocol for the quantitative assessment of the EC, patients with unilateral TLE show bilateral reduction in the volume of the EC. However, this reduction is more severe ipsilateral to the epileptic focus.

Adolescent↗
PubMed1999

Periventricular leukomalacia and epilepsy: incidence and seizure pattern.

OBJECTIVE: To study the incidence and pattern of epilepsy in patients with periventricular leukomalacia (PVLM) in two specialty clinic settings. BACKGROUND: Motor and cognitive deficit as well as epilepsy are common in patients with PVLM. With modern imaging techniques, PVLM is now easily recognized. METHODS: Epileptic seizures and syndromes as well as motor and cognitive deficits were correlated with MRI findings. Two patient populations were studied: Group A-children with cerebral palsy and PVLM presenting to a center for children with motor disability (n = 19); and Group B-epileptic patients with PVLM presenting to a tertiary epilepsy center (n = 12). A single patient with PVLM and epilepsy who underwent extensive investigations, including intracranial EEG telemetry, is reported. RESULTS: In Group A, 47% of patients had epilepsy (9/19). PVLM was found in 1.27% of patients investigated for epilepsy at a tertiary epilepsy center (12/942). The majority of patients in both groups had multiple seizure types, with complex partial seizures being most common. Of patients with seizures (Groups A and B), 85.7% had intractable epilepsy (18/21). Intracranial EEG in the illustrative case demonstrated a multifocal epileptic process with occipitotemporal predominance. CONCLUSIONS: PVLM was an uncommon underlying cause in patients presenting with epilepsy (Group A); however, patients presenting with motor disability and PVLM (Group B) had a high incidence of seizures. PVLM in epileptic patients is associated with multiple seizure types and medically refractory disease.

Cognition Disorders↗
PubMed1999

Neuroimaging evidence of progressive neuronal loss and dysfunction in temporal lobe epilepsy.

Whether temporal lobe epilepsy is the result of an isolated, early injury or whether there is ongoing neuronal dysfunction or loss due to seizures is often debated. We attempt to address this issue by using magnetic resonance techniques. Proton magnetic resonance spectroscopic imaging can detect and quantify focal neuronal dysfunction or loss based on reduced signals from the neuronal marker N-acetylaspartate (NAA), and magnetic resonance imaging (MRI)-based measurements of hippocampal volumes (MRIvol) can quantify the amount of atrophy in this structure. We performed magnetic resonance spectroscopic imaging and MRIvol in 82 consecutive patients with medically intractable temporal lobe epilepsy to determine whether there was a correlation between seizure frequency, or type or duration of epilepsy, with NAA to creatine (Cr) values or hippocampal volumes. Volumes and spectroscopic resonance intensities were categorized as to whether they were measured from the temporal lobe ipsilateral or contralateral to the predominant electroencephalographic focus. Ipsilateral and contralateral NAA/Cr was negatively correlated with duration of epilepsy. Hippocampal volumes were negatively correlated with duration ipsilaterally but not contralaterally. Frequency of complex partial seizures was not correlated with any of the magnetic resonance measures. However, patients with frequent generalized tonic-clonic seizures had lower NAA/Cr bilaterally and smaller hippocampal volumes ipsilaterally than patients with none or rare generalized tonic-clonic seizures. The results suggest that although an early, fixed injury may cause asymmetric temporal lobe damage, generalized seizures may also cause progressive neuronal dysfunction or loss.

Adult↗
PubMed1999

Diagnosis of subtle focal dysplastic lesions: curvilinear reformatting from three-dimensional magnetic resonance imaging.

Focal cortical dysplasia is a frequent cause of medically intractable partial epilepsy. These lesions are being increasingly identified by high quality images provided by magnetic resonance imaging (MRI), resulting in improved seizure control of surgically treated patients. Small dysplastic lesions are often missed by conventional MRI methods. The identification of subtle structural abnormalities by rectilinear slices is often limited by the complex convolutional pattern of the brain. We developed a method of curvilinear reformatting of three-dimensional MRI data that improves the anatomical display of the gyral structure of the hemispheric convexities. It also reduces the asymmetric sampling of gray-white matter that may lead to false-positive results. We present 5 patients in whom conventional two-dimensional and three-dimensional MRI with multiplanar reformatting was initially considered normal. Subsequent studies using curvilinear reformatting identified lesions in all. Four patients underwent surgery with histological diagnosis of focal cortical dysplasia. Three patients are seizure-free and 1 had significant improvement in seizure control. These results indicate that an increase in the detection of subtle focal dysplastic lesions may be accomplished when one improves the anatomical display of the brain gyral structure by performing curvilinear reformatting.

Adolescent↗
PubMed1999

Mapping of a gene determining familial partial epilepsy with variable foci to chromosome 22q11-q12.

We identified two large French-Canadian families segregating a familial partial epilepsy syndrome with variable foci (FPEVF) characterized by mostly nocturnal seizures arising from frontal, temporal, and occasionally occipital epileptic foci. There is no evidence for structural brain damage or permanent neurological dysfunction. The syndrome is inherited as an autosomal dominant trait with incomplete penetrance. We mapped the disease locus to a 3. 8-cM interval on chromosome 22q11-q12, between markers D22S1144 and D22S685. Using the most conservative diagnostic scheme, the maximum cumulative LOD score was 6.53 at recombination fraction (straight theta) 0 with D22S689. The LOD score in the larger family was 5.34 at straight theta=0 with the same marker. The two families share an identical linked haplotype for >/=10 cM, including the candidate interval, indicating a recent founder effect. A severe phenotype in one of the probands may be caused by homozygosity for the causative mutation, as suggested by extensive homozygosity for the linked haplotype and a bilineal family history of epilepsy. An Australian family with a similar phenotype was not found to link to chromosome 22, indicating genetic heterogeneity of FPEVF.

Australia↗
PubMed1999

Surgical outcome in patients with epilepsy and dual pathology.

High-resolution MRI can detect dual pathology (an extrahippocampal lesion plus hippocampal atrophy) in about 5-20% of patients with refractory partial epilepsy referred for surgical evaluation. We report the results of 41 surgical interventions in 38 adults (mean age 31 years, range 14-63 years) with dual pathology. Three patients had two operations. The mean postoperative follow-up was 37 months (range 12-180 months). The extrahippocampal lesions were cortical dysgenesis in 15, tumour in 10, contusion/infarct in eight and vascular malformation in five patients. The surgical approach aimed to remove what was considered to be the most epileptogenic lesion, and the 41 operations were classified into lesionectomy (removal of an extrahippocampal lesion); mesial temporal resection (removal of an atrophic hippocampus); and lesionectomy plus mesial temporal resection (removal of both the lesion and the atrophic hippocampus). Lesionectomy plus mesial temporal resection resulted in complete freedom from seizures in 11/15 (73%) patients, while only 2/10 (20%) patients who had mesial temporal resection alone and 2/16 (12.5%) who had a lesionectomy alone were seizure-free (P < 0.001). When classes I and II were considered together results improved to 86, 30 and 31%, respectively. Our findings indicate that in patients with dual pathology removal of both the lesion and the atrophic hippocampus is the best surgical approach and should be considered whenever possible.

Adolescent↗
PubMed1999

Clinical patterns of patients with temporal lobe epilepsy and pure amygdalar atrophy.

PURPOSE: MRI volumetric measurements (MRIvol) have been proven reliable in determining mesial temporal atrophy in patients with TLE. We attempted to correlate the clinical features with different patterns of hippocampal formation (HF) and amygdala (AM) atrophy in patients with TLE without foreign tissue lesion. METHODS: We studied 65 patients with refractory TLE. They were divided into five groups according to MRIvol results: pure AM atrophy (n = 11, 10 unilateral and one bilateral), unilateral HF atrophy (n = 16), bilateral HF atrophy (n = 12), unilateral AM + HF atrophy (n = 13), and patients with normal volumes of AM and HF (n = 13). MRIvol of AM and HF were performed by using a protocol previously described by Watson et al. (Neurology 1992;42:1743-50). RESULTS: Patients with AM atrophy had later onset of seizures compared with those with unilateral HF atrophy (p < 0.01). History of febrile convulsions (p < 0.0001) and frequent secondarily generalized tonic-clonic seizures (GTCSs) were more often found in patients with HF atrophy compared with those with pure AM atrophy and those with normal volumes (p = 0.04). Prolonged postictal confusion was more often found with AM atrophy (p = 0.05). Memory impairment was more severe in patients with HF atrophy than in those with AM atrophy only or in those with normal volumes (p = 0.03). There were no significant differences among the five groups in the following parameters: age, duration of epilepsy, seizure frequency, and presence and type of aura. CONCLUSIONS: Prolonged postictal confusion appeared to be related to AM atrophy, in keeping with previous clinical observations. These patients also had a lower incidence of early febrile convulsions, older age at epilepsy onset, lower frequency of secondary GTCS, and lesser memory dysfunction compared with patients with hippocampal atrophy.

Adolescent↗
PubMed1999

Intracranial EEG with very low frequency activity fails to demonstrate an advantage over conventional recordings.

PURPOSE: Conventional scalp and intracranial EEG is recorded within a limited band of frequencies (0.3-70 Hz) based on the premise that clinically relevant cerebral activity occurs within this frequency range. Ikeda et al. recently demonstrated focal very low frequency activity (VLFA), <0.3 Hz, at seizure onset for both intra- and extracranial recordings. The purpose of this investigation was prospectively to study VLFA during seizures in intracranial recordings to determine whether activity in this frequency range provides useful information regarding localization of seizure onset and spread. METHODS: Patients undergoing intracranial electrode implantation were studied by using a high-pass filter of 0.01 Hz. The timing, location, and pattern of seizure onset were first determined by using a digital high-pass filter of 0.3 Hz (conventional seizure onset). Seizures were then reviewed without digital filters and the presence of VLFA recorded, along with its timing and location. RESULTS: Forty-seven seizures were recorded in four patients. VLFA was not observed in 29 seizures and, in one other case, VLFA occurred simultaneous with movement. Of seizures with VLFA (n = 17), the timing and location of VLFA were not consistent with those of conventional seizure onset or propagation. CONCLUSIONS: Our study failed to demonstrate any clinical advantage of intracranial telemetry recordings with a high-pass filter of 0.01 Hz over conventional recordings with regard to determining the timing and location of seizure onset and propagation.

Adolescent↗
PubMed1999

Interictal spikes increase cerebral glucose metabolism and blood flow: a PET study.

PURPOSE: In patients with reflex epilepsy, it is sometimes possible to evoke interictal spikes predictably, thus providing an uncommon but important experimental paradigm for examining the physiological changes produced by epileptiform discharges. METHODS: To examine the changes in regional cerebral blood flow (rCBF) and glucose consumption (rCMRglc) produced by interictal spikes, we performed positron emission tomography (PET) scans with the blood-flow tracer [15O]H20 and with [18F]fluorodeoxyglucose in a patient with fixation-off epilepsy. The scans were performed in states of high and low spike frequency produced by eye closure and opening, respectively. RESULTS: The rCBF study revealed a focal increase in blood flow associated with the state of increased interictal spiking. The focus was in the posterior portion of the left superior parietal lobule (Talairach coordinates: x: -36, y: -71, z: 39; t = 4.5; p<0.05) and corresponded to the site of maximal ictal EEG abnormality recorded with implanted electrodes. In a volume of interest of 10-mm diameter centered on the t statistic peak in the rCBF study, the mean rCMRglc was 39.1 micromol/100 g/min with eyes open and 44.1 micromol/100 g/min (13% increase) with eyes closed. An identical activation paradigm was used in six normal subjects studied with functional magnetic resonance imaging. In the normal subjects, no significant activation was observed in the parieto-occipital region, indicating that the changes observed in the patient were due to interictal spiking rather than to task performance alone. CONCLUSIONS: Interictal spiking produces focal increases in cerebral blood flow and glucose metabolism.

Adult↗
PubMed1999

Exceptionally long absence status: multifactorial etiology, drug interactions and complications.

To our knowledge, petit mal status lasting longer than 2-3 days has been documented only once [1]. We report a 66 year-old man with well-documented, idiopathic generalized epilepsy who developed petit mal status lasting 6 weeks. Valproate levels remained low because of interactions with phenytoin. When phenytoin was discontinued, valproate levels increased, and he progressively improved. Chronic ischemic changes in the white matter may have been an additional factor in the causation and, most likely, in the duration of his status. Exceptionally long status and stupor increase the risk of medical complications. Valproate remains the medication of choice for the treatment of petit mal status. Despite the extraordinary course in this patient, complete recovery took place, confirming the benign nature of even such a prolonged episode.

Aged↗
PubMed1998

Morphometric analysis of the temporal lobe in temporal lobe epilepsy.

PURPOSE: Using high-resolution magnetic resonance imaging (MRI), we examined the temporal neocortex and the underlying white matter in patients with unilateral temporal lobe epilepsy (TLE) and in control subjects. METHODS: The images of 27 patients and 42 control subjects were registered into stereotaxic space, corrected for image intensity inhomogeneity, and automatically segmented into gray matter, white matter, and cerebrospinal fluid (CSF) over a predetermined extent of the temporal lobe. The surface between the gray matter and CSF was extracted, indices of curvature (IOC) of the surface were calculated, and a frequency histogram of the IOC was obtained. RESULTS: There was significant bilateral reduction in the total volume of the temporal lobe and in the volume of gray matter. White matter volume was significantly reduced only in the temporal lobe ipsilateral to the seizure focus. There were significant changes in the position and amplitude of peaks in the frequency histogram of the IOC. CONCLUSIONS: The volume of gray matter was negatively correlated with duration of epilepsy, suggesting that neocortical changes may be a consequence of seizures. Changes in the frequency histogram of the IOC suggested an additional alteration in the surface morphology of the temporal lobe in TLE, possibly related to sulcal widening.

Adolescent↗
PubMed1998

Proton magnetic resonance spectroscopic imaging in patients with extratemporal epilepsy.

PURPOSE: Reduced levels of N-acetylaspartate (NAA) in temporal lobes responsible for temporal lobe epilepsy have been observed consistently in proton magnetic resonance spectroscopy (MRS) studies. METHODS: We investigated the potential of proton MRS to detect low NAA outside of the temporal lobes in patients with non-lesional partial extratemporal epilepsy. Proton MR spectroscopic imaging (MRSI) data of both frontal lobes and central/postcentral regions were obtained in 20 such patients and 16 normal control subjects. The epileptogenic region was determined by an extensive clinical-EEG investigation, including the recording of habitual seizures in each patient, and intracranial EEG recordings in 10 patients. RESULTS: The relative NAA resonance intensities (i.e., NAA/phosphocreatine plus creatine (CR(t)), NAA/choline-containing metabolites (Cho(t)) and NAA/Cr(t) + Cho(t)), were all significantly reduced throughout the spectroscopic image as compared with that of the controls. Furthermore, reduction of the NAA ratios was greater in the epileptogenic region as compared with the nonepileptogenic regions, on EEG investigation. CONCLUSIONS: In vivo proton MRSI of patients with nonlesional partial extratemporal epilepsy detected evidence of widespread neuronal damage or dysfunction that was greatest in the region of seizure focus.

Adult↗
PubMed1998

Celiac disease, bilateral occipital calcifications and intractable epilepsy: mechanisms of seizure origin.

PURPOSE: To elucidate the mechanisms of seizure origin in patients with celiac disease and bilateral occipital calcifications (CEBOC). Individuals with CEBOC frequently present with occipital lobe seizures, but additional lesions and additional attack patterns may occur. METHODS: We studied two men and one woman who had CEBOC. Villous atrophy was revealed in the two patients who underwent duodenal biopsy. All had a comprehensive presurgical evaluation, including prolonged video-EEG recordings. Two had magnetic resonance imaging (MRI) with volumetric study of mesial temporal structures (MRIV). One patient had undergone stereotactic intracranial depth electrode studies (SEEG). RESULTS: All patients presented with intractable complex partial seizures. Two had partial simple seizures with visual aura. Neurologic examination was normal; one was of normal intelligence, and two were mildly retarded. Neuroimaging studies showed that each had bilateral occipital calcifications as well as epileptiform abnormalities over temporal lobes. In one, MRI showed an additional right frontal lesion, but SEEG demonstrated right occipital lobe seizure origin with anterior spread; this male patient later underwent a right occipital lobe resection. Another with a history of prolonged febrile convulsions had bilateral hippocampal and amygdalar atrophy demonstrated by MRIV. CONCLUSIONS: In one patient, SEEG confirmed that seizures originated in the occipital lobe. The presence of dual pathology was demonstrated in another, raising the possibility of both occipital and temporal seizure onset. The presence of extraoccipital lesions or of mesial temporal atrophy requires SEEG for clarification of seizure onset. In the absence of confounding factors and when laterality can be demonstrated, surgical treatment may be considered.

Adult↗