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D W Loring

Publications and source records attributed to D W Loring.

At least 55 records · Page 3Linked to original sources
PubMed1997

Wada memory and timing of stimulus presentation.

We compared Wada memory performance for stimuli presented at two timing intervals following amobarbital injection in 47 non-lesional patients with complex partial seizures (L = 26; R = 21). A significant interaction between seizure focus and timing of presentation was present (P < 0.03). Memory performance for objects whose presentation began approximately 50-55 s following amobarbital administration differed as a function of ipsilateral vs. contralateral injection at a very high level of statistical significance (P < 0.00001). Items presented approximately 4 min, 30 s post injection were also related to seizure onset literality, but at a lower statistical level (P < 0.01). Presentation of Wada memory stimuli earlier during hemispheric anaesthesia yields results that are more sensitive to lateralized temporal lobe seizure onset than does presentation of items later during the procedure.

Adult↗
PubMed1997

Effect of Wada memory stimulus type in discriminating lateralized temporal lobe impairment.

PURPOSE: To examine the effects of memory stimulus type on Wada memory performance. METHOD: Ninety-six patients (left, 47; right, 49) from four epilepsy centers who were candidates for anterior temporal lobectomy (ATL) and who have subsequently undergone surgery were studied. Patients with atypical cerebral language lateralization or with evidence on magnetic resonance imaging (MRI) to suggest a lesion other than hippocampal sclerosis were excluded. Wada memory performance was obtained by using both real objects and line drawings as memory stimuli. RESULTS: Wada memory laterality scores with either real objects or line drawings as memory stimuli discriminated left from right-ATL groups. However, objects were superior to line drawings in making this differentiation. Further, objects were superior to line drawings in individual patient classification of candidates for left ATL, with no difference in the classification rates using either objects or line drawings in candidates for right ATL. CONCLUSIONS: Type of memory stimuli is an important factor affecting memory results during the Wada test.

Amobarbital↗
PubMed1997

Neuropsychological evaluation in epilepsy surgery.

Neuropsychology has played a prominent role throughout the modern era of epilepsy surgery. Neuropsychology, including the Wada test, has been of benefit in documenting dysfunction associated with a lateralized temporal lobe seizure onset. In addition, neuropsychological results have some predicative power regarding seizure outcome following anterior temporal lobectomy. The current status of neuropsychology in patient evaluation and outcome prediction will be presented. Differences between the Wada test, an inactivation procedure, and functional magnetic resonance imaging, which is an activation procedure, will be discussed. This paper will also present preliminary information about the Wechsler Adult Intelligence Scale-III, the recent revision of the most commonly used test of intellectual function, and its effects on neuropsychological performance results.

Adult↗
PubMed1997

Results of lesional vs. nonlesional frontal lobe epilepsy surgery.

Fifty-three seizure focus resections limited to the frontal lobe were performed. Forty-nine had adequate follow-up. Five of 17 (29%) nonlesional (NL) cases and 21 of 32 (66%) lesional (L) cases were seizure free (SF) at 1 year postoperatively. Eight of 9 (89%) L cases < or = 18 years old vs. 13 of 23 (57%) > 18 years old were SF. Eight of 10 (80%) tumor vs. 13 of 22 (59%) nontumor L cases were SF. Sixteen NL cases were localized by invasive recording. Five (31%) were SF. Ictal localization was obtained in 4 of 32 L cases. Three of 4 (75%) were SF. Eighteen of 24 (64%) L cases without ictal localization were SF. Nine of 12 (75%) lateral resections, 7 of 12 (58%) lobectomies, and 2 of 13 (15%) mesial resections were SF. Three of 20 cases with at least 90% reduction in seizures became SD > or = 2 years postresection. No case with < 90% seizure reduction at one year showed improvement with longer follow-up.

Adolescent↗
PubMed1997

Differential rates of age of seizure onset between sexes and between hemispheres?

In a descriptive analysis of 158 patients with temporal lobe epilepsy, Taylor (1969) reported that the age of first seizure varied systematically as a function of laterality and sex. We conducted inferential analyses of Taylor's original data which (1) provided support for his proposal of disproportionate left hemisphere vulnerability to seizure onset in early life, but (2) failed to provide evidence of sex differences in age of onset of unilateral seizures. Examination of these effects in a larger sample of 844 patients drawn from the Bozeman Epilepsy Consortium provided some additional support for findings from the inferential analysis. Specifically, the left hemisphere appeared more vulnerable to seizure onset in childhood, this increased vulnerability extending to about age 5 years. Age of onset of seizures was not different when males and females were compared. Thus, reanalysis of Taylor's original data as well as examination of data from a larger, more contemporary sample suggest that seizure onset varies as a function of laterality, but not sex.

Adult↗
PubMed1997

The use of figural reproduction tests as measures of nonverbal memory in epilepsy surgery candidates.

The construct of nonverbal memory, as assessed by figural reproduction tests, has recently been questioned by a number of investigators. The purpose of this study was to reexamine this construct and its relationship to right temporal lobe dysfunction. Figural reproduction test scores were examined in 757 epilepsy surgery candidates obtained from 8 epilepsy centers participating in the Bozeman Epilepsy Consortium. All participants exhibited unequivocal evidence of left (LTL) or right (RTL) temporal lobe epilepsy observed in ictal and interictal EEG recordings. All subjects also had IQ scores exceeding 70, right-hand preference, and left hemisphere language dominance confirmed by intracarotid sodium amytal testing. Comparisons of LTL and RTL groups showed no significant differences in scores on the Visual Reproduction subtests from the Wechsler Memory Scale (WMS) or Wechsler Memory Scale-Revised (WMS-R) or on the copy and delayed recall conditions of the Rey-Osterrieth Complex Figure Test (ROCFT). Significant differences were observed among centers on WMS and ROCFT scores, which are likely to be a result of variations in administration and/or scoring procedures. The lack of significant differences between LTL and RTL groups in this large sample raise questions about the nature of nonverbal memory and its relationship to right temporal lobe dysfunction.

Adult↗
PubMed1996

Dementia associated with dorsal midbrain lesion.

Although the dorsal midbrain has been implicated in cognitive processes in animals, its role in humans is unclear. We report the neuropsychological and postmortem neuropathological findings of a 52-yr-old university professor who developed a profound dementia in association with a focal dorsal midbrain lesion. The patient's disorder appeared to result from a tuberculous granuloma based on the clinical course and autopsy results. Neuropsychologically, he exhibited a generalized impairment across most of the cognitive domains assessed. His deficits were not explained by impaired arousal, specific sensory or motor defects, depression, or hydrocephalus. Although there are inherent limitations to a single-case investigation, our observations are consistent with animal studies that have demonstrated that focal dorsal midbrain lesions may result in cognitive impairment. We propose that the dorsal midbrain is involved in cognitive processing via modulation of thalamocortical networks.

Arousal↗
PubMed1996

Amobarbital evaluation of neurobehavioral function prior to therapeutic occlusion of brain arteriovenous malformations: a new neuropsychological procedure.

Because untreated arteriovenous malformations (AVMs) frequently result in some form of permanent neurological complication, treatment of AVMs is aggressively pursued A relatively new treatment consists of sending micropellets into blood vessels supplying the AVM core to block blood flow and "shrink" the AVM When vessels supplying the AVM are thought to also irrigate vital portions of brain, evaluations of neurobehavioral function after injection of amobarbital into intracranial vessels (Wada testing) may be performed to prevent significant complications folIowing embolization This study details our preliminary experience with Wada testing and electroencephalography (EEG) prior to AVM embolization in seven patients Neurobehavioral functions were continuously monitored after injection of 50-75 mg of amobarbital into target cerebral vessels No change in sensorimotor, cognitive, or EEG functions were detected in any of the superselective Wada examinations Embolization was performed following all negative Wada evaluations The only irreversible complication after embolization was a superior quadrantanopia No other permanent neurobehavioral sequelae resulted from embolization These preliminary findings suggest that simultaneous Wada/EEG monitoring may be useful in predicting neurobehavioral complications prior to AVM embolization.

Journal Article↗
PubMed1995

Intraoperative hippocampal cooling and Wada memory testing in the evaluation of amnesia risk following anterior temporal lobectomy.

OBJECTIVE: To determine the efficacy of memory testing following localized thermal inactivation (cooling) of the hippocampus during epilepsy surgery to assess risk for postoperative memory decline. DESIGN: Memory was assessed after intraoperative thermal inactivation of the hippocampus and during the Wada procedure to help determine the clinical utility of each procedure. SETTING: A university hospital, comprehensive epilepsy surgery program. PATIENTS: Individuals undergoing unilateral temporal lobectomy for relief of intractable seizures. PROCEDURE: After temporal tip resection, iced liquid was irrigated into the temporal horn of the lateral ventricle until the hippocampus was "cooled." MAIN OUTCOME MEASURES: Multiple neuropsychological measures of learning and memory. RESULTS: Wada memory testing suggested risk for memory impairment in 15 patients while cooling indicated risk in only five patients. Predictions arising from the two procedures were concordant in 13 patients and discordant in 12 patients. Among the 12 inconsistent predictions, hippocampal cooling suggested adequate contralateral memory support in 11 (92%) of 12 patients, and none of these 11 patients had a postoperative anterograde amnesia. CONCLUSION: Intraoperative hippocampal cooling may be useful in determining the risk of postoperative memory disorder among selected patients undergoing epilepsy surgery.

Adult↗
PubMed1995

Synergistic anticholinergic and antiserotonergic effects in humans.

Animal research suggests an important interactive role for ascending cholinergic and serotonergic systems in modulation of cerebral function. Employing a randomized, double-blind, crossover design, 11 healthy young adults were tested in each of four conditions: (1) placebo, (2) fenfluramine (a serotonin depleting agent), (3) scopolamine (a muscarinic antagonist), and (4) fenfluramine and scopolamine. P3 latency was slowed by the dual drug treatment to an extent greater than the sum of individual drug effects. EEG mean frequency was decreased by behavioral activation, and this decrease was reversed by the combined drug treatment but not by single drugs. In contrast, verbal memory, EEG alpha power, and P3 amplitude were significantly affected only by scopolamine. No drug effects were found for the N1 and P2 potentials. The results provide the first demonstration of combined anticholinergic and antiserotonergic effects in humans, and offer partial support to the concept of an interactive role of cholinergic and serotonergic systems in cerebral mechanisms.

Adult↗
PubMed1995

Intraoperative thermal inactivation of the hippocampus in an effort to prevent global amnesia after temporal lobectomy.

In an effort to assess the risk of amnesia after anterior temporal lobectomy (ATL), we conducted localized thermal inactivation (cooling) of the hippocampus with memory testing. Thirty-three ATL patients whose preoperative evaluation suggested risk for postoperative amnesia underwent hippocampal cooling. Cooling consisted of inserting a catheter in the temporal horn and irrigating it with an iced solution until a stable hippocampal temperature of approximately 20 degrees C was reached. Memory was assessed before and after cooling. In 12 of the 33 patients, memory testing was either aborted or suggested poor contralateral support, and the hippocampus was resected in 2 of these patients. The remaining 21 patients showed evidence of contralateral memory support, and the hippocampus was resected in 18. No patient became amnestic. These results suggest that intraoperative hippocampal cooling may be useful in selected cases. However, even among many patients who could cooperate with testing, discomfort, sedation, attentional deficits, confusion, and anxiety made test interpretation difficult.

Adolescent↗
PubMed1995

Wada memory asymmetries predict verbal memory decline after anterior temporal lobectomy.

We examined Wada memory and neuropsychological memory function in 34 nonlesional patients who underwent anterior temporal lobectomy (ATL) and who were seizure free at 1-year follow-up. Patients who displayed a decline on verbal memory measures that exceeded 1 SD after left ATL had significantly smaller left/right Wada memory asymmetries than left ATL patients without a significant verbal memory decline. When Wada memory asymmetries were used to predict verbal memory decline after left ATL in individual patients, similar statistically significant effects were present. No significant relationship between Wada memory and postoperative memory was present in right ATL patients, and postoperative memory function was not related to Wada memory performance after either left hemisphere or right hemisphere injection alone. We conclude that Wada memory asymmetries provide one measure of the risk to material-specific decline in verbal memory after left ATL.

Analysis of Variance↗
PubMed1995

Comparative cognitive effects of phenobarbital, phenytoin, and valproate in healthy adults.

The relative effects of antiepileptic drugs (AEDs) on cognition are controversial. We compared the cognitive effects of phenobarbital, phenytoin, and valproate in 59 healthy adults using a randomized, double-blind, incomplete-block, crossover design. Cognitive assessments were conducted at baseline, after 1 month on each drug (two AEDs per subject), and at two repeat baselines 11 weeks after each AED treatment. The neuropsychological battery included 12 tests, yielding 22 variables: Choice Reaction Time, P3 Event-Related Potential, Finger Tapping, Lafayette Grooved Pegboard, Selective Reminding Test, Paragraph Memory, Complex Figures, Symbol Digit Modalities Test, Stroop Test, Visual Serial Addition Test, Hopkins Symptom Checklist, and Profile of Mood States. More than one-half of the variables exhibited AED effects when compared with nondrug baselines, and all three AEDs produced some untoward effects. Differential AED effects on cognition were present for approximately one-third of the variables. Phenobarbital produced the worst performance; there was no clinically significant difference between phenytoin and valproate.

Adult↗
PubMed1995

Intracarotid amobarbital procedure. The Wada test.

Wada testing has been a standard part of temporal lobectomy evaluation since the early 1960s. Although the procedure was initially used to lateralize language function, it was soon modified to assess risk for postoperative amnesia. The use of the procedure has now evolved to include prediction of degrees of memory decline. This use has been criticized, but more recent research has better described important parameters of the procedure and supported its validity. The Wada test is effective in lateralizing seizure onset, predicting postoperative seizure control, and predicting degree of verbal memory decline following left temporal lobectomy. The validity of Wada test data has also been supported by correlations between Wada memory performance and hippocampal pyramidal cell loss or MR imaging determined hippocampal volumes. It remains to be seen, however, if Wada memory performance and data from other sources such as MR imaging, ictal SPECT, positron emission tomography, or functional MR imaging are redundant or independently contribute to patient diagnosis and management.

Amobarbital↗
PubMed1994

Stimulus timing effects on Wada memory testing.

OBJECTIVE: To determine the effects of presenting Wada memory stimuli at different times after intracarotid amobarbital injection on Wada memory asymmetries. DESIGN: Wada memory asymmetries from three timing series were related to the laterality of eventual temporal lobectomy. SETTING: Academic institution epilepsy surgery program. PATIENTS: Forty-three patients with complex partial seizures who later underwent anterior temporal lobectomy (left temporal lobectomy, 24 patients; right temporal lobectomy, 19 patients). No patient included had abnormalities on magnetic resonance imaging scans to suggest a lesion other than gliosis. RESULTS: Memory performance for objects whose presentation began approximately 45 seconds after amobarbital administration differentiated laterality of seizure onset. Memory for items presented later and after partial return of language (on average 3 minutes 40 seconds postinjection) also differed as a function of ipsilateral vs contralateral injection, but at a lower level of statistical significance. Memory for items presented last during the procedure (on average 6 minutes postinjection) discriminated seizure groups at a still lower level of statistical significance. When used to predict lateralized temporal lobe impairment in individual patients, early object memory performance was significantly better than memory performance employing either middle (56%) or late (43%) stimulus presentation timings. CONCLUSION: The results of early object memory testing are superior to those obtained from stimulus presentation later in the procedure in documenting temporal lobe dysfunction associated with a lateralized seizure onset.

Adult↗
PubMed1994

Do dichotic word listening asymmetries predict side of temporal lobe seizure onset?

Dichotic word listening asymmetries are thought to be useful in predicting side of temporal lobe dysfunction. However, little direct evidence exists to support this assumption in practice, especially in patients with subtle epileptogenic lesions. To determine if word listening ear asymmetries are valid predictors of side of temporal lobe seizure onset, we examined the preoperative dichotic word listening performance of 80 patients with either left (N = 41) or right (N = 39) temporal lobe (TL) seizure foci. On a group level, patients showed a statistically significant 'lesion effect' as evidenced by a relative deficit in the ear contralateral to the side of lesion. Prediction of side of seizure focus in individual cases, however, was poor: depending upon the criteria used, 61% to 80% of epileptics with unilateral temporal lobe foci did not show the expected contralateral ear deficit. Results suggest that caution be exercised when inferring side of temporal lobe seizure focus through dichotic word listening asymmetries in individual temporal lobe epilepsy cases.

Adult↗
PubMed1994

Wada memory performance predicts seizure outcome following anterior temporal lobectomy.

We examined the ability of Wada memory testing to predict seizure outcome 1 year following anterior temporal lobectomy. Asymmetry scores for Wada memory performance, using amobarbital doses of 125 mg or less, were calculated for 55 patients under the age of 45 years who had no radiologic evidence of structural lesions other than gliosis. Wada memory asymmetries were significantly greater (p < 0.02) in patients who were seizure free compared with those who continued to experience seizures. Furthermore, patients with Wada memory score asymmetries of at least three objects (maximum = 8) were more likely to be seizure free compared with patients with Wada memory asymmetries less than three (p < 0.01). Of the 36 patients who had Wada memory score asymmetries of at least three objects, 32 (89%) were seizure free. In contrast, of the 19 patients whose Wada memory score asymmetries were less than three, only 12 (63%) were seizure free. These data suggest that Wada memory performance is related to seizure outcome following anterior temporal lobectomy.

Adult↗