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J R Gates

Publications and source records attributed to J R Gates.

At least 19 recordsLinked to original sources
PubMed1998

Predicting outcome of anterior temporal lobectomy using simulated neural networks.

PURPOSE: Anterior temporal lobectomy (ATL) is an important option for treatment of medically refractory seizures. Patient selection is not always clear-cut, and there is inherent morbidity and mortality associated with the invasive and expensive surgical protocols. To determine whether patient selection might be facilitated by application of artificial intelligence, we developed a model that predicted seizure outcome after ATL, using a simulated neural network (SNN). METHODS: Predictions of the model were compared with predictions derived from conventional discriminant function analysis. Neural networks and discriminant functions were devised that would predict the occurrence of both Class 1 outcomes (totally seizure-free), and Class 1 or Class 2 outcomes (nearly or totally seizure-free), using data from 87 patients from three surgical centers. The SNNs and discriminant functions were developed using data from a randomly selected subsample of 65 patients, and both models were cross-validated, using the remaining 22 patients. RESULTS: The discriminant functions showed overall predictive accuracy of 78.5% and 72.7%, while the neural networks demonstrated overall accuracy of 81.8% and 95.4%. CONCLUSIONS: Simulated neural networks show promise as adjuncts to decision-making in the selection of epilepsy surgery patients.

Adolescent↗
PubMed1997

A reconsideration of bilateral language representation based on the intracarotid amobarbital procedure.

Hemispheric language dominance was established for 368 epilepsy surgery candidates based on results of objective language performance during the intracarotid amobarbital procedure. Eight-three percent of patients were found to be left hemisphere dominant, while six percent were right dominant, and eleven percent demonstrated some degree of bilateral language representation. Bilateral patients were grouped according to modality-specific patterns of language performance in each hemisphere, with a majority demonstrating left hemisphere superiority in overall language processing. Variables affecting atypical language development are reviewed and results are considered in the context of previous research.

Adolescent↗
PubMed1996

Association of dietary factors and selected plasma variables with sex hormone-binding globulin in rural Chinese women.

Sex hormone-binding globulin (SHBG) is an important regulator of plasma sex steroids as well as a sensitive indicator of insulin resistance. SHBG may be an important diagnostic measure of risk for pathologies associated with insulin resistance syndrome (IRS) such as non-insulin-dependent diabetes mellitus (NIDDM), obesity, hypertension, dyslipidemia, and atherosclerotic cardiovascular disease. In women, SHBG is also implicated in diverse pathologies such as cancers of steroid-sensitive tissues and hirsutism. Data from an ongoing ecological study linking diet and health in rural China were analyzed to determine the relation of selected plasma variables and diet to plasma concentrations of SHBG. All data represent county mean values, pooled by age and sex, to assess the relation between biochemical and lifestyle characteristics and disease-specific mortality rates at the county level. The study sample consisted of 3250 Chinese women between the ages of 35 and 64 y living in 65 widely dispersed rural counties. Consumption patterns for 21 different food groups were derived from a food-frequency questionnaire and a 3-d dietary survey and subsequently compared. Correlation analyses of county mean values demonstrated a significant association between SHBG and insulin, testosterone, triacylglycerols, body mass index, age at menarche, and several foods. In regression analyses, after adjustments, the strongest predictors of SHBG concentrations were the dietary intake of rice (beta = 0.42, P < 0.01), fish (beta = 0.34, P < 0.05), millet (beta = -0.27, P < 0.01), and wheat (beta = -0.34, P < 0.01). When insulin, testosterone, and triacylglycerols were added to the model only triacylglycerols (beta = -0.26, P < 0.05) remained a significant independent predictor of SHBG. Additional analyses suggested that the consumption of green vegetables was modestly positively correlated with SHBG and negatively with insulin values. Consumption of rice and fish in particular appeared to favorably influence the principle plasma variables associated with a reduction in the risk for IRS pathologies.

Adult↗
PubMed1995

Transcranial magnetic stimulation.

Multiple techniques are vying for establishing the new gold standard for functional cortical mapping, displacing that of the currently invasive and risk-prone techniques of subdural electrode arrays and intraoperative electrical stimulation mapping. Transcranial magnetic stimulation holds promise for functional localization of primary motor areas and speech areas, and possibly even other higher cortical functions. The technique is economical, especially when compared with the cost of functional magnetic resonance imaging and positron emission tomography. It can be performed effectively and safely in patients with epilepsy.

Brain↗
PubMed1994

8-12 Hz rhythmic oscillations in human motor cortex during two-dimensional arm movements: evidence for representation of kinematic parameters.

Direct cortical recordings were taken from 12 patients with implanted subdural electrode arrays during performance of a 2-dimensional, multi-joint, visually guided arm movement task. Task-related changes in the amplitude of the motor cortex 8-12 Hz surface local field oscillations were evaluated for the encoding of direction and amplitude of movement in the 6 patients in whom no epileptogenic or ECoG background abnormalities were detected over the motor-sensory cortical areas under the recording electrode array. The topography, time of onset and duration of these responses were evaluated in the context of motor cortex somatotopy, as defined by cortical stimulation delivered through the electrode array. Multi-joint arm movements were accompanied by a decrease in the power of the 8-12 Hz frequency components of the ECoG signal. These power changes were spatially distributed over the upper extremity, motor-sensory representation. Movement amplitude influenced the magnitude, duration, and extent of the spatial distribution of ECoG power changes in the 8-12 Hz band. These effects occurred predominantly over cortical areas corresponding to the upper extremity motor-sensory representations. Direction of movement had a weaker influence on the 8-12 Hz frequency components of the ECoG over the upper extremity motor-sensory representations, but influenced the patterns of 8-12 Hz ECoG response on adjacent cortical regions. These results show that the amplitude of surface electrical oscillations generated over the rolandic cortex are correlated with the kinematics of multi-joint arm movements. These changes in the ECoG signal appear to reflect shifts in the functional state of neuronal ensembles involved in the initiation and execution of motor tasks.

Adult↗
PubMed1994

Language function following subdural grid-directed temporal lobectomy.

The purpose of the study was to determine the extent to which a temporal resection may be undertaken without producing risk to temporal language areas. Patients undergoing craniotomy and placement of a subdural electrode array (SEA) for evaluation of intractable epilepsy were studied to determine the variability of distance of temporal language cortex from the temporal pole. Hemisphere dominance was determined by intracarotid sodium amytal injection. Temporal lobe speech arrest (SA) was mapped with a 64 contact point SEA. Thirty-one patients had left dominant hemisphere SEAs. Thirty had SA 5 cm to 9 cm from the temporal pole (median 7 cm). One had SA at 3 cm. Twenty-one patients subsequently had temporal lobectomy (TL). Mean extent of resection was 5.7 cm (range 3 to 9 cm). In 18 TL patients who had neuropsychometric evaluation of language function pre- and post-surgery, there was no significant deterioration. Thirty-nine patients had right non-dominant SEAs placed. Eighteen had TL. Thirteen of these had pre- and post-surgery language evaluation and there was no significant change. Comparison of preoperative scores showed significant superiority of the right non-dominant group over the left dominant group for naming. TL up to 5 cm without stimulation mapping of language areas would be safe in the majority of cases, but one subject (3%) had SA mapped anterior to this and a small number of cases may therefore be at risk to language function following a 5 cm TL. Extensive lateral resections up to 9 cm are possible with preservation of language function with stimulation cortical mapping.

Adolescent↗
PubMed1991

The prognostic value of residual spikes in the postexcision electrocorticogram after temporal lobectomy.

We correlated the postresection electrocorticograms (ECoGs) of 80 patients who underwent temporal lobectomy under general anesthesia for treatment of intractable complex partial seizures with surgical results in three groups: seizure/aura free (32 patients), auras only (16 patients), and one or more postoperative seizures (32 patients) at mean follow-up times of 34, 31, and 38 months, respectively. Spontaneous "residual spikes," ie, present after all resections, were present in 47% of patients who had no postoperative seizures or auras. However, they occurred in 72% of patients with any postoperative seizures (p less than 0.05). The location (convexity, mesial, or edge of resections) or the distribution (unifocal versus multifocal) of the residual spikes was not of prognostic value. Quantitative studies in 5-minute epochs of the postexcision ECoGs did not reveal a significant difference in the morphology of the residual spikes, ie, the amplitude or firing pattern (single versus polyspike), in the three groups. The group with postoperative seizures showed a higher number of spikes per epoch (greater than or equal to 50), but it was not significant. Although the study shows that patients with residual spikes may have good prognosis, they are at significantly higher risk for postoperative seizures as compared with those without residual spikes. The possibility that intensity of firing of residual spikes may be an additional predictor of outcome warrants further study.

Cerebral Cortex↗
PubMed1991

Induction of speech arrest and counting errors with rapid-rate transcranial magnetic stimulation.

Six adult epileptic patients underwent rapid-rate transcranial magnetic stimulation (rTMS) at stimulation rates of up to 25 Hz with an 11-cm water-cooled round coil held flat on the scalp, centered over 15 different positions on each side of the scalp. The trains of stimuli were for 10 seconds while the patients counted aloud. rTMS centered over D5 or D7 induced reproducible speech arrest in all patients and counting errors in three when applied at lower intensities. There were no such speech disturbances by rTMS centered over the different positions on the right side. Intracarotid amobarbital test (IAT) demonstrated left hemispheric language dominance in all patients. Lateralization of speech arrest induced by rTMS correlated with the IAT results and may be helpful for noninvasive determination of hemispheric language dominance.

Adult↗
PubMed1990

Mesial temporal sclerosis: pathogenesis, diagnosis, and management.

Mesial temporal sclerosis (MTS) is probably the most common symptomatic pathologic entity--alone or mixed with other pathologic features--for seizures of temporal lobe origin. The pathophysiology of MTS, including any genetic influence, needs clarification. A characteristic ictal expression for seizures of MTS origin appears not to exist. The majority of patients (78%) with postresection MTS who are seizure-free have tightly localized interictal abnormalities restricted to F7/F8, Sp1/Sp2, T3/T4, and T5/T6 more than 96% of the time. MRI abnormalities may be seen in 55% of patients with MTS if both "hard" and "soft" criteria are used or in 20% when only "hard" criteria are used. The neuropsychologic evaluation of patients with MTS, which includes intracarotid amobarbital test (IAT), may prove to be increasingly useful in identifying patterns of cognitive deficit that correlate with enhancement of both lateralizing and localizing preoperative information.

Adolescent↗
PubMed1990

Prolonged postictal encephalopathy.

Eleven patients (6 males, 5 females; ages 7.5 to 40 years, mean 27.8) had prolonged postictal confusion lasting from 4 to 10 days. During that time, the EEG showed a typical encephalopathic pattern. Comprehensive evaluation ruled out the possibility of metabolic, toxic, drug-related, or ongoing nonconvulsive status epilepticus. We have designated this syndrome as prolonged postictal encephalopathy (PPIE). Nine of 11 patients were mildly to borderline mentally retarded. Ten had previous episodes of status epilepticus. Nine of 11 had minimal structural abnormalities (mainly diffuse cortical atrophy). Nine patients had multiple recurrent episodes of PPIE. All episodes occurred following a cluster of seizures: in 8 patients after a cluster of generalized tonic-clonic seizures, in 2 after complex partial seizures, and in 1 patient after a cluster of atypical absence seizures. This series suggests that vulnerability to develop PPIE exists in patients with diffuse structural abnormalities, mild to borderline mental retardation, a history of status epilepticus, and a tendency of seizures to cluster.

Adolescent↗
PubMed1989

Malaria in Nicaragua: community-based control efforts and the impact of war.

This descriptive study of temporal trends and geographical distribution examines the effects of prolonged low-intensity warfare on the community-based malaria control efforts. Nicaragua's post-1979 malaria control programme is based on community participation in health education and in mosquito breeding site drainage, expanded case finding, and increased availability of chemotherapy. Mosquito resistance and increasing costs have forced a reduction in the use of residual pesticides. The number of reported malaria cases in the country fell from 25,465 in 1980 to 15,702 in 1984, while the ratio of blood smears to total population increased from 86 to 137 per 1000 people. Malaria incidence in the eight states of the country under heaviest military attack in the current war was compared to incidence in the eight states least affected by the war. In the war zone there was a 17% excess in cases from August 1983-April 1985 above a 1974-82 baseline average, while there was a 62% decline in the number of cases in the non-war zone.

Humans↗
PubMed1989

Supplementation patterns in marathon runners.

The purpose of the present investigation was to study the use of supplements in a large group of endurance runners (no. = 347) who had participated in the 1987 Los Angeles Marathon. Three-day dietary records were analyzed for nutrient content and supplement usage. The runners' supplementation patterns with respect to demographics, dietary quality, training habits, and race performance were investigated. In general, no significant associations were found between supplement use and the aforementioned variables. Use of supplements, especially vitamins C and E, calcium, and zinc, increased with age (p less than .05). Daily use of at least one type of supplement was reported by 29% of the runners; 48% reported use of at least one type of supplement within the 3-day period.

Adult↗
PubMed1987

Valproic acid loading during intensive monitoring.

Of 35 patients who had generalized tonic-clonic seizures during antiepileptic drug therapy withdrawal, "loading" with valproic acid was effective in limiting these seizures in 32 patients. A loading dose of approximately 12.5 mg/kg was used. This dose resulted in valproic acid levels between 284 and 458 mumol/L (41 and 66 mg/L) 1.5 hours after "loading" in six of the eight patients in whom serum concentrations were measured.

Adolescent↗
PubMed1987

Magnetic resonance imaging in the assessment and surgical management of epilepsy and functional neurological disorders.

Magnetic resonance imaging (MRI) offers significant advantages over computerized tomography (CT) and teleradiographic techniques when used for the evaluation and management of epilepsy and functional neurological disorders. Depth recording and radiofrequency electrodes can be more accurately positioned within structures such as the amygdala and hippocampus. The extent of corpus callosum section, lobectomy, topectomy, and radiofrequency stereotactic lesions can now be readily confirmed and related with seizure, neurological, and behavioral outcome. Occult, usually low grade, intraparenchymal neoplasms not visualized on CT scans can be located by MRI and biopsied or excised by MRI stereotactic techniques.

Corpus Callosum↗