Biomedical subjects

P Ryvlin

Publications and source records attributed to P Ryvlin.

40 records · Page 3Linked to original sources

PubMed1990

[Contribution of magnetic resonance imaging in 100 cases of refractory partial epilepsy with normal CT scans].

One hundred epileptic patients were included in this study according to the following criteria: intractable partial epilepsy, normal CT scan and focal EEG abnormalities. Eighty-nine patients were suffering from complex partial seizures of temporal or frontal origin, 55 and 34 cases respectively. Eleven patients presented with only simple partial seizures. MRI was abnormal in 31 patients. The abnormalities were: focal T2 increased signal intensity (13 cases) most often temporal (10 cases), cryptic arteriovenous malformation (4 cases), focal T1 and T2 signal abnormality (4 cases), focal atrophy (2 cases) and multiple abnormal T2 signals scattered in the white matter (8 cases). The site of MRI abnormalities was consistent with electroclinical data in 22 patients, of whom 20 had a temporal lobe epilepsy. Thus MRI proved to be more often abnormal in temporal than in frontal lobe epilepsy (36 p. 100 and 5.9 p. 100 respectively) when the CT scan is normal. However MRI data, particularly focal T2 hypersignals should be confronted to electroclinical and metabolic findings whenever functional surgery is considered.

Adolescent↗

PubMedDate not supplied

High signal intensity on T2-weighted MRI correlates with hypoperfusion in temporal lobe epilepsy.

Single-photon emission computed tomography (SPECT) and [99mTc]HMPAO were used to assess the functional significance of nonspecific magnetic resonance imaging (MRI) abnormalities observed in patients with temporal lobe epilepsy and no focal lesion on CT scan. We studied 18 patients whose MRI was normal or showed high signal intensity on T2-weighted images (T2WIs) at the site of the EEG focus in 11 and 7 cases, respectively. EEG was monitored during regional cerebral blood flow (rCBF) study. Lateralized hypoperfusion was present in 7 of 17 interictal (41%) and in one postictal cases; it was located in the temporal lobe on the side of the EEG focus in all, and was significantly more frequent in patients with high signal intensity on T2WI (86%) than in patients with a normal MRI (18%). The degree of temporal perfusion asymmetry measured in each individual was higher in patients whose MRI was abnormal.

Adolescent↗

PubMedDate not supplied

Polyglucosan bodies and temporal lobe epilepsy: an incidental finding or more?

This study reports on histological findings in the temporal lobe of a 36-year-old woman who underwent a right temporal lobectomy for pharmaco-resistant complex partial seizures. Since surgery, the patient has remained seizure-free. The patient had an established diagnosis of right temporal lobe epilepsy, based on video EEG recordings of seizures, MRI hippocampal atrophy, focal interictal hypometabolism on fluoro-desoxyglucose, hypofixation of Cl1-flumazenil in PET studies, and ictal intracerebral recordings. Biopsies were studied under light- and electron microscopy. Histology showed diffuse distribution of a large number of polyglucosan bodies (PBs) in the whole right temporal lobe white matter. PBs were mostly confined to the perivascular areas and in subpial zones rarely and were observed in the most superficial cortical layers. There was some neuronal loss, especially in opercular zone T , but no other histological lesion was found. Ultrastructurally, PBs were made of filamentous and amorphous material, and were found both in intra-astrocytic processes and in axons. The presence of numerous PBs in the temporal lobe of patients with refractory temporal lobe epilepsy has been reported in 3 patients in the literature. It raises the questions whether this histological abnormality could be related to the epileptogenic process as a cause or as a consequence.

Adult↗

PubMedDate not supplied

[Morphological and functional neuro-imaging of surgical partial epilepsies in adults].

This article reviews literature on morphological and functional neuro-imaging data in refractory partial epilepsies of adults including Magnetic Resonance Imaging (MRI); Single Photon Emission Computerised Tomography (SPECT) and Positron Emission Tomography (PET). Except for MRI, which is of unquestionable utility in the diagnosis of epileptogenic lesions, most of these investigations are justified only in the context of pre-operative evaluation of candidates to functional neurosurgery. In terms of interpretation the key issue is that of the relation between the images and the epileptogenic process itself. The specific utility of available techniques is as follows: MRI, in its present state of development, reveals a morphological abnormality in more than 80% of the cases previously considered as cryptogenic on the basis of X ray Computerised Tomography. However, hippocampal atrophy, which has a questionable relation with temporal lobe seizures, represents two thirds of abnormal images. Functional MRI and MR spectroscopy represent potential alternatives respectively to Wada test and interictal SPECT or PET. Ictal blood flow studies during video-EEG monitoring represent the major application of SPECT; showing a focal increase of blood flow in more than 90% of cases. Interictal SPECT is less informative, but necessary for interpreting ictal images. 18F-Deoxyglucose (FDG) PET shows a focal interictal hypometabolism in nearly 90% of patients with refractory temporal lobe epilepsy. The incidence of interictal hypometabolism is less, though more than 50%, in the other types of partial epilepsies. For diagnostic purpose PET studies of benzodiazepine (BZD)-receptors with 11C-Flumazenil are more widely used than those of opiate or mucarinic receptors. The reduced density of BZD receptors is likely to reflect neuronal loss, whereas interictal glucose hypometabolism reflects both the lesional process and secondary deactivation of perilesional areas due to anatomical or functional deafferentation.

Adult↗