Biomedical subjects

W D Gaillard

Publications and source records attributed to W D Gaillard.

45 records · Page 3Linked to original sources

PubMed1995

FDG-PET in children and adolescents with partial seizures: role in epilepsy surgery evaluation.

We used FDG-PET to measure interictal glucose metabolism in 16 children and adolescents (mean age 14.7 years) and complex partial seizures (CPS) (mean seizure onset age 5.0 years). Video-EEG localized the epileptic foci. Glucose metabolism was determined in 14 paired anatomic areas using a standard template. PET hypometabolism was defined as greater than 15% asymmetry. Nine of the 13 (69%) patients with a unilateral EEG focus had regional hypometabolism ipsilateral to the epileptogenic zone. Three subjects had bilateral EEG foci; all had nonfocal PET. MRI (15 patients) concurred with EEG and PET in two, and was normal in seven of nine with focal hypometabolism. One of seven patients with normal PET had a focal MRI abnormality. FDG-PET results are similar to those found in adults, but are present earlier in the natural history of CPS (9.7 vs 22.2 years duration epilepsy) than previously reported. The presence of FDG-PET hypometabolism may be associated with a poor response to drug treatment. PET can identify metabolic abnormalities associated with epileptic foci in children and adolescents and is useful in directing surgical intervention for the control of refractory complex partial epilepsy.

Adolescent↗

PubMed1995

FDG-PET and volumetric MRI in the evaluation of patients with partial epilepsy.

We performed interictal FDG-PET- and MRI-based hippocampal volumetric measurements on 18 adult patients with complex partial epilepsy of temporal lobe origin in whom we had identified their ictal focus by video-telemetry EEG. Sixteen patients (89%) had regional hypometabolism, 11 (61%) had focal 1.5-tesla T2-weighted MRI (two structural abnormalities, nine hippocampal formation [HF] increased T2 signal), and nine (50%) had absolute HF atrophy ipsilateral to the temporal ictal focus. Ten (55%) had abnormal L/R HF ratios, nine ipsilateral to the EEG focus. All patients with abnormal MRI volumetric studies had focal PET abnormalities. Only seven had both abnormal HF volume ratios and T2 MRI (all increased HF T2 signal). There was a significant correlation between hippocampal volume and inferior mesial and lateral temporal lobe cerebral metabolic rate of glucose asymmetry index (p < 0.01), suggesting that hypometabolism may reflect hippocampal atrophy. PET is more sensitive than MRI volumetry in identifying the ictal focus but does not provide additional information when HF atrophy is present.

Adolescent↗

PubMed1995

Interictal metabolism and blood flow are uncoupled in temporal lobe cortex of patients with complex partial epilepsy.

We used positron emission tomography (PET) with 18F-2-deoxyglucose (FDG) and 15O water in 20 patients with complex partial seizures to compare glucose metabolism and blood flow in temporal lobe epileptic foci identified by ictal scalp-sphenoidal video-EEG telemetry. Glucose metabolism was measured 20 minutes after blood flow without moving the patient from the scanner. We also studied 11 patients with 99mTc-HMPAO single-photon emission computed tomography (SPECT). Both local cerebral metabolic rate of glucose (LCMRGlc) and regional cerebral blood flow (rCBF) were significantly decreased in temporal cortex ipsilateral to the EEG focus. However, LCMRGlc was reduced by 11.2% in inferior lateral and 11.1% in inferior mesial temporal cortex and rCBF by only 3.2% and 6.1%. The ratio of LCMRGlc to rCBF was significantly reduced in inferior lateral temporal cortex ipsilateral to the ictal focus (p < 0.009). Moreover, using standardized criteria, blinded raters found that 16 of 20 patients had focal FDG-PET hypometabolism, all in the epileptogenic region; 10 of 20 had focal 15O water PET hypoperfusion, but it was falsely lateralized in two of these 10; and five of 11 had focal 99mTc-HMPAO SPECT hypoperfusion, but it was falsely lateralized in two of these five. Our data suggest that interictal glucose metabolism and blood flow may be uncoupled in epileptogenic cortex.

Adult↗

PubMed1994

Positron emission tomographic measurement of cerebral blood flow and temporal lobectomy.

We used positron emission tomography (PET) and bolus injection of H2(15O) to measure interictal cerebral blood flow (CBF) in 32 patients who had temporal lobectomy for uncontrolled complex partial seizures. Seizure focus localization was confirmed by ictal video-electroencephalographic (video-EEG) telemetry, and patients who had imaging findings suggesting the presence of a tumor were excluded. PET-CBF studies were interpreted using a standard template by raters blinded to EEG and clinical data, and were not used in surgical planning. After surgery, patients were followed for 32 +/- 18 months. Twenty-six patients were seizure free and 6 had persistent seizures. Mean lateral temporal hypoperfusion was 8 +/- 14% in patients who became seizure free and 9 +/- 6% in patients with persistent seizures. Fourteen patients had at least 15%, and 11 at least 20% hypoperfusion, but were not more likely to be seizure free. Three additional patients had 15 to 20% hypoperfusion in the temporal lobe contralateral to their EEG focus. PET measurement of CBF using bolus H2(15O) should not be used to help select patients for temporal lobectomy.

Brain↗

PubMed1994

Seizure control following tumor surgery for childhood cortical low-grade gliomas.

Detailed preoperative electroencephalographic (EEG) studies are now recommended for children with seizures and cortical tumors to define seizure foci prior to surgery. To develop a historical perspective for better evaluation of results from series reporting tumor removal combined with resection of seizure foci, the authors reviewed seizure outcome in 60 children with seizures and low-grade neoplasms treated consecutively since 1981 by surgical resection without concomitant EEG monitoring or electrocortical mapping. Forty-seven of the 60 tumors were totally or near-totally resected; 45 patients were seizure-free and two were significantly improved 1 year following surgery. Of the 50 children in this series with more than five seizures prior to surgery, 36 were seizure-free, two were significantly improved, and 12 were not improved. Factors associated with poor seizure control included a parietal tumor location, a partial tumor resection, and a history of seizures for more than 1 year prior to surgery. The children at highest risk for poor seizure control at 2 years had experienced seizures for more than 1 year prior to surgery and had undergone partial resection of their parietal low-grade glial tumors or gangliogliomas. In contradistinction, the best seizure control was seen in patients with totally resected low-grade gliomas or gangliogliomas who had experienced seizures for less than 1 year (concordance rates for being seizure-free ranged from 78% to 86%). Long-term seizure control remained excellent. These results suggest that seizure control can be obtained 2 years following tumor surgery in the majority of children with presumed tumors after extensive tumor resection without concomitant EEG monitoring or electrocortical mapping.

Adolescent↗

PubMed1993

Measurement of whole temporal lobe and hippocampus for MR volumetry: normative data.

We measured the volumes of the entire length of temporal lobe and hippocampal formation from coronal images in 29 healthy young adults to take into account normal side-to-side variation. Although whole-brain, temporal lobe, and left hippocampal volumes were significantly smaller in women, normalizing measurements for the whole brain eliminated intersex temporal lobe and hippocampal differences. There was a weak but significant inverse correlation between age and normalized hippocampal, but not temporal lobe or whole-brain, volume. In contrast to previous studies, we found no significant side-to-side differences in the sizes of temporal lobes or hippocampi. When performing MR volumetry, it is important to include the entire length of the hippocampal formation.

Adult↗

PubMed1992

Comparison of PET measurements of cerebral blood flow and glucose metabolism for the localization of human epileptic foci.

We compared the relative sensitivity of two interictal PET techniques, bolus injection of [15O] labeled water for estimation of cerebral blood flow (H2(15)O CBF-PET), and 18F 2-deoxyglucose (18FDG-PET) for cerebral glucose metabolism (CMRglc), and T2-weighted magnetic resonance imaging, in 28 patients with medically intractable complex partial seizures undergoing evaluation for surgery. There were statistically significant associations between lateralization by 18FDG-PET, and MRI, but not H2(15)O CBF-PET, and lateralization of the epileptic focus as defined by scalp-sphenoidal ictal EEG. Fifteen patients had surgery or subdural electrodes. 18FDG-PET was more closely associated with a good outcome than H2(15)O CBF-PET, which, in addition, showed hypoperfusion contralateral to the epileptic temporal lobe in several cases. H2(15)O sensitivity may have been reduced by technical factors, but 18FDG-PET appears to be more specific for localization of epileptic zones.

Adult↗

PubMed1986

Spectra of neurotransmitter receptors and ionic responses on cerebral A and B neurons in Aplysia californica.

Receptors to putative transmitters on A and B cells of Aplysia californica were identified and characterized. Neurons within each cluster were similar in responses to transmitters, but the neurons in A and B clusters differed. Both exhibited receptors to acetylcholine, dopamine, gamma-aminobutyric acid, glutamate, histamine and serotonin but not to octopamine or phenylethanolamine. Bi- or multiphasic responses to a single transmitter were common on both cell types. Inhibitory responses were more common on A than B cells where glutamate, histamine and serotonin were all excitatory. Each of these clusters appear homogeneous both in terms of presence of receptors and the ionic channels activated by the receptors.

Acetylcholine↗

PubMed1986

On the transmitter at the A-to-B cell in Aplysia californica.

Cerebral A neurons make excitatory contact with cerebral B cells. While glutamate, histamine and serotonin all have excitatory receptors on B cells, the A-to-B cells synaptic potential was not found sensitive to curare, strychnine, antihistaminergic or antiserotoninergic drugs, nor did bath-perfused glutamate or serotonin cause desensitization of the synaptic response. We conclude that none of these candidates is the transmitter at this synapse.

Animals↗