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Query: UMLS:C0014547 (focal epilepsy)
 1,627 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The most important causes of focal epilepsy are hippocampal sclerosis, circumscribed tumors, vascular malformations, trauma and perinatal damage. At the moment MRI is the best radiological imaging modality for localizing and characterizing a focus. In many cases, however, even MRI is negative. Especially in hippocampal sclerosis the diagnostic role of MRI is still not well established. Diagnostic criteria are side differences with hippocampal atrophy and circumscribed signal increase on T2-weighted images of the affected temporal lobe. Circumscribed lesions caused by tumors or vascular malformations are demonstrated very reliably by paracoronal T2-weighted sequences. Routine administration of the paramagnetic contrast material Gd-DTPA is not necessary.
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PMID:[Magnetic resonance tomography in epilepsy]. 850 4

1. The regional cerebral blood flow was studied by SPECT in patients with partial epilepsy before and after 30 days of monotherapy with carbamazepine (CBZ). 2. Both a qualitative visual interpretation and a semiquantitative analysis of SPECT was performed. All patients underwent EEG, CT scan, and MRI studies. The CBZ serum concentrations were assayed. 3. After therapy, in three patients with focal epilepsy, both a crossed cerebral and cerebellar diaschisis were observed, with respect to the side of the epileptic focus in the opposite hemisphere. No morphologic changes were detected at MRI in the cerebral or cerebellar remote hypometabolic areas found at SPECT. 4. CBZ may have a depressant action on the corticopontocerebellar pathways and on the corticocallosal connections.
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PMID:Cerebral and cerebellar diaschisis following carbamazepine therapy. 853 26

This study compared the efficacy and tolerability of vigabatrin 3/day as add-on therapy with that of placebo in patients with focal epilepsy whose complex partial seizures were difficult to control with established antiepilepsy drug therapy. We enrolled 203 patients; 182 (90 placebo; 92 vigabatrin) received drug therapy under double-blind conditions. We increased the daily dosage to 2.5 g/day during a 4-week titration segment and maintained it at 3 g/day during the 12-week maintenance segment. By analyses we found a statistically significant lower frequency of seizures (complex seizures plus partial seizures secondarily generalized) at the end of the study for patients receiving vigabatrin than for those receiving placebo. The median monthly frequency was reduced by three seizures per 28 days in the placebo group (baseline, 8.3; end of study, 7.5) (p = 0.0002). Therapeutic success (a 50% reduction from baseline in mean monthly seizure frequency) was attained in 40 of the vigabatrin patients (43%) compared with 17 of those treated with placebo (19%) (p < 0.001). Vigabatrin significantly increased the mean number of seizure-free days per 28 days (2.2 days) compared with placebo (0.5 days) (p = 0.0024). Mean trough serum vigabatrin concentration during therapy was 8.6 +/- 7.7 micrograms/ml. The oral clearance of vigabatrin was determined to be 7.8 L/hr, and the elimination half-life was 8.4 hours. No clinically important changes in MRI, evoked potential, or other laboratory tests were noted during vigabatrin treatment. The results of this study indicate that 3 g/day vigabatrin is more effective than placebo as add-on therapy. Vigabatrin was well tolerated, compliance was high with twice-daily administration, and therapy did not result in clinically relevant drug interactions.
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PMID:A double-blind, placebo-controlled study of vigabatrin three g/day in patients with uncontrolled complex partial seizures. Vigabatrin Protocol 024 Investigative Cohort. 855 21

Volumetric measurement of the hippocampus is of use in localisation of lesions causing focal epilepsy and in lateralisation of epilepsy due to mesial temporal sclerosis. However, it is time consuming and requires specialised equipment. Hence, we compared volumetric measurement with visual detection of hippocampal asymmetry by five trained observers. MRI studies of 19 neurologically normal subjects and of 34 consecutive patients with epilepsy and hippocampal volume ratios below the lowest normal value were employed. Agreement between visual and quantitative diagnoses was 59% for all subjects (kappa = 0.38) and 65% for those with volumetric hippocampal asymmetry. Disagreements in visual and volumetric lateralisation of hippocampal asymmetry were relatively uncommon. Visual estimates of the extent of hippocampal involvement and the observers' confidence in the diagnosis influenced the accuracy of visual inspection. However, discordance in diagnoses occurred even when confidence in the visual diagnosis was high. Reliable visual detection occurred for hippocampal volume ratios below 0.7, suggesting that visual determination of hippocampal asymmetry is of greatest clinical value in the lateralisation of seizure foci in patients already selected for the presence of intractable temporal lobe epilepsy. Volumetric measurements are particularly important if hippocampal asymmetry is used for seizure localisation in groups of patients with temporal or extratemporal epilepsy.
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PMID:Reliability of visual inspection for detection of volumetric hippocampal asymmetry. 874 Nov 91

20% of patients with focal epilepsy suffer from medically refractory seizures. Many of these patients can be cured by a surgical intervention removing the brain area where the seizures are originating (epileptogenic zone). 6000 patients in Austria would benefit from epilepsy surgery with an additional 150-200 new patients appearing each year. Potential candidates have to undergo an extensive presurgical work-up. During the non-invasive Phase I each patient is evaluated with an intensive video-EEG monitoring with scalp-EEG, a high resolution MRI, a SPECT and/or PET, a neuropsychological evaluation and a Wada-test. If the epileptogenic zone cannot be localized adequately with these methods, invasive electrophysiological techniques (epidural Peg-electrodes, Foramen-ovale electrodes, depth electrodes, subdural strip and grid electrodes) have to be applied. Operative strategies for temporal lobe epilepsies include antero-mesial temporal lobe resections and selective amygdala-hippocampectomies. Extratemporal epilepsies are treated by cortical resections guided by structural and electrophysiological parameters. The new technique of multiple subpial transections facilitates treatment of seizures originating in essential brain regions. Catastrophic epilepsies of early childhood often are caused by extensive pathologies affecting one hemisphere and can be treated successfully by large multilobar resections or hemispherectomies. Epilepsy surgery renders 70-80% of patients seizure free and thus can be regarded as an effective and safe treatment option for patients with medically refractory focal epilepsies.
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PMID:[Presurgical diagnosis of epilepsy and surgical epilepsy treatment]. 917 67

We compare the localisation of epileptic foci by means of (1) EEG, (2) magnetoencephalography (MEG) and (3) combined EEG/MEG data in a group of patients suffering from pharmaco-resistant focal epilepsy. Individual epileptic events were localised by means of a moving dipole model in a 4-shell spherical head approximation. A patient's epileptic activity was summarised by calculating the spatial density distribution (DD) of all localised events, and the centre of gravity of DD was considered the most likely locus of seizure generation. To verify these loci a subgroup of 6 patients was selected, in which seizures could be related to a clearly identifiable lesion in MRI. On average, the combined EEG/MEG approach resulted in the smallest error (1.8 cm distance between calculated locus and the nearest lesion border); using only MEG yielded the largest error (2.4 cm), while EEG resulted in an intermediate value (2.2 cm). In the individual patients, EEG/MEG would also rank intermediate, but never worst. In summary, combining EEG/MEG appears to be a more robust approach to localisation than using only EEG or only MEG. Finally, we also report on the use of the barbiturate methohexital as a safe method of increasing the number of spike events during an EEG/MEG recording session.
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PMID:Localisation of epileptic foci with electric, magnetic and combined electromagnetic models. 974 58

EEG has been used to trigger functional MRI of patients with focal epilepsy, but EEG can be obscured by artifacts during MR data acquisition, and no continuous correlation of EEG and MRI has been possible without limiting the image time. Artifacts caused by an MRI sequence were investigated in five healthy subjects, and an EEG of five patients with epileptic discharges was recorded during echo-planar imaging. All interfering frequencies in the EEG were discrete and defined by loop structures in the MRI sequence. In post-processing of the EEG interfering frequencies were automatically detected by comparing the frequency spectra of the EEG recorded before and during imaging. After elimination of interfering frequencies by filters in the time domain or by Fourier transform, reliable spike detection in the EEG recorded during MR data acquisition became feasible, without loss of EEG quality.
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PMID:Electroencephalography during functional echo-planar imaging: detection of epileptic spikes using post-processing methods. 1106 14

The successful surgical treatment of medically refractory epilepsy is based on one of three different principles: (1) elimination of the epileptic focus, (2) interruption of the pathways of neural propagation, and (3) increasing the seizure threshold through cerebral lesions or electrical stimulation. Temporal lobe epilepsy, being the most common focal epilepsy, may ultimately require temporal lobectomy. This is a case report of a 36-year-old male with drug-resistant right mesial temporal lobe epilepsy who failed to obtain seizure control after stereotactic radiosurgery to the seizure focus. Complex-partial seizures occurred 6-7 times monthly, and consisted of a loss of awareness followed by involuntary movements of the right arm. EEG/CC TV monitoring indicated a right mesial temporal lobe focus, which was corroborated by decreased uptake in the right temporal lobe by FDG-PET and by MRI findings of right hippocampal sclerosis. Stereotactic radiosurgery was performed with a 4MV linac, utilizing three isocenters with collimator sizes of 10, 10, and 7 mm respectively. A dose of 1500 cGy (max dose 2535 cGy) was delivered in a single fraction to the patient's right amygdala and hippocampus. There were no acute complications. Following radiosurgery the patient's seizures were improved in both frequency and intensity for approximately 3 months. Antiepileptic medications were continued. Thereafter, seizures increased in both frequency and intensity, occurring 10-20 times monthly. At 1 year post radiosurgery, standard right temporal lobectomy including amygdalohippocampectomy was performed with subsequent resolution of complex-partial seizures. Histopathology of the resected temporal lobe revealed hippocampal cell loss and fibrillary astrocytosis, consistent with hippocampal sclerosis. No radiation-induced histopathologic changes were seen. We conclude that low-dose radiosurgery doses temporarily changed the intensity and character of seizure activity, but actually increased seizure activity long-term. If radiosurgery is to be an effective alternative to temporal lobectomy for medically intractable temporal lobe epilepsy, higher radiosurgery doses will be required. The toxicity and efficacy of higher-dose radiosurgery is currently under investigation.
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PMID:Low-dose stereotactic radiosurgery is inadequate for medically intractable mesial temporal lobe epilepsy: a case report. 1170 Oct

Functional mapping of the human brain has made tremendous progress in the past years thanks to new technical developments. Imaging methods are now available; they allow to study brain functions with high spatial and temporal resolution. Single photon emission computer tomography (SPECT), positron emission tomography (PET), functional magnetic resonance imaging (fMRI) and high resolution electro- and magnetoencephalography (EEG and MEG) are currently intensively applied techniques to functional studies, each one having specific properties concerning spatial and temporal resolution. The success of these methods in basic neuroscience research has led to the demand for applying them to clinical questions. Diseases of the central nervous system that lead to brain dysfunction can be ideally explored using these techniques. Of particular importance are those diseases in which a focal neuronal dysfunction is the primary cause and where surgical resection of this focus might be the cure. This is often the case for epilepsy, where a discrete primary focus might exist from which pathological rhythms evolve and propagate throughout the brain, leading to seizures that severely handicap the patient. Surgical resection of the primary focus is only possible if the focus can be exactly localized and adequately separated from functionally important areas. This is where these new functional imaging tools become important. The use of SPECT and PET for focus localization has been most extensively studied and their specificity and sensitivity are intensively discussed. In the last few years functional MRI has evolved as a new interesting tool in epileptic focus localization. The most important limitation of these techniques, however, is the temporal resolution. Since epileptic activity can propagate very fast, several hyper- or hypoactive regions are seen in the images and primary areas cannot be distinguished from regions of propagation. The only methods that have sufficient temporal resolution to follow neuronal activity in real time are the electrophysiological measures, i.e. the EEG and the MEG. Localization of the sources in the brain that produced a given surface electromagnetic field has become possible through algorithms that solve the so-called "inverse problem". Several different algorithms exist and many groups begun to apply them to epileptic data with the aim to localize the focus of the pathological electrical discharges. This review article discusses the use of distributed EEG source localization procedures in the presurgical evaluation of patients with intractable focal epilepsy. In contrast to equivalent dipole models, distributed localization methods do not localize one active point in the brain but rather assume extended active areas, which is generally the case in epileptic activity. The methods shown here are based on linear numerical methods and are therefore less prone to errors when working with scattered solution spaces such as the one defined by anatomical constraints. Solutions constraint to the gray matter determined in the individual MRI are shown here. We illustrate three methods to increase the spatial resolution of the source localization procedures: One is to increase the number of recording channels to more than 100, the second to use linear methods of high precision to detect focal sources (EPIFOCUS), and the third to combine EEG source localization with EEG-triggered functional magnetic resonance imaging. The importance of EEG source localization for the interpretation of fMRI data will be particularly discussed in view of the important difference of the temporal resolution by the two methods. The localization methods can be applied to interictal as well as to ictal activity. In case of analysis of ictal EEG we propose to use full scalp frequency analysis to determine the time period of seizure onset and to localize the sources of the initial dominant frequency.
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PMID:Localization of distributed sources and comparison with functional MRI. 1178 Dec

In this paper, we describe a case of an immunocompetent patient with cerebral nocardiosis. The onset was with loss of strength, paresthesia and focal epilepsy of the left arm. MRI showed on T2-weighted sequences a hyperintense central area of pus surrounded by a well-defined hypointense capsule and surrounding edema; on T1-weighted sequences a hypointense necrotic cavity with ring enhancement following administration of intravenous gadolinium. The patient underwent surgical excision of the abscess but culture from the specimen was negative. After 40 days of empirical antimicrobial therapy he developed neurological deterioration with focal epilepsy. A new MRI documented an enlargement of the hypointense lesion in the right frontal-parietal region. A second craniotomy with drainage of the abscess was performed; cultures yielded Nocardia farcinica. Therapy with trimethoprim/sulfamethoxazole, amikacin and meropenem was given for 35 days, and clinical and radiological improvement was observed. Home therapy was done with oral trimethoprim/sulfamethoxazole. Currently, 5 months from the second surgery, the patient can walk with support and no new episodes of epilepsy occurred. Side effects were absent from therapy. The MRI appearance of the brain lesion has improved, with a decrease in size, surrounding edema and ring enhancement.
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PMID:Primary brain abscess with Nocardia farcinica in an immunocompetent patient. 1193 43


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