Search PubMed⌕ Search

Biomedical subjects

M Jones-Gotman

Publications and source records attributed to M Jones-Gotman.

53 records · Page 3Linked to original sources
PubMed1992

Pure amnestic seizures in temporal lobe epilepsy. Definition, clinical symptomatology and functional anatomical considerations.

Pure amnestic seizures (PAS) sometimes occur in patients with temporal lobe epilepsy. They never represent the only type of seizures in these patients. Pure amnestic seizures are defined as seizures during which the only clinical manifestation is the patients' inability to retain in memory what occurs during the seizure coupled with the preservation of other cognitive functions and the ability to interact normally with their physical and social environment. It is postulated that PAS result from selective ictal inactivation of mesial temporal (MT) structures without isocortical involvement. This occurs most often in patients with neuropsychological and electroencephalographic (EEG) evidence of bilateral dysfunction of MT structures (six out of eight patients in this study). In the few patients without such evidence as well as in some with bilateral MT dysfunction, PAS may result from seizure discharge limited to the MT structures of both temporal lobes. In the light of current anatomical knowledge, contralateral spread of seizure discharge from the MT structures of one side to those of the other through the dorsal hippocampal commissure is the only likely explanation for this situation. One observation with depth electrode stimulation of MT structures supports this view. In patients with evidence for bilateral MT dysfunction, a unilateral seizure may presumably suffice to induce a PAS, the contralateral MT structures being unable to ensure normal memory function. In most instances PAS can be distinguished from episodes of transient global amnesia on clinical grounds.

Adult↗
PubMed1992

Corticoamygdalectomy in memory-impaired patients.

Sixty-seven patients who underwent resection of the amygdala and temporal neocortex for intractable temporal lobe epilepsy were analyzed. Forty-four of them failed memory tests during the intracarotid sodium amytal procedure or showed severe impairment of contralateral material specific memory. Surgical outcome ratings were seizure-free or rare seizure, 51%; worthwhile improvement, 15%; failure, 34%. The least successful outcome was noted in the group with mandatory corticoamygdalectomy and seizure origin in the dominant hemisphere. There was no postoperative exacerbation of memory deficit, whether preoperative memory was normal or impaired. When hippocampal resection is inadvisable, corticoamygdalectomy may be considered.

Adolescent↗
PubMed1992

Intracranial EEG study of brain structures affected by internal carotid injection of amobarbital.

Hippocampal function, considered critical in memory processing, is supposedly tested in the intracarotid sodium amobarbital (ISA) procedure; however, since the hippocampus is not completely irrigated by the internal carotid artery, some believe the procedure may be invalid for memory testing. We quantified delta activity in intracerebral EEGs during ISA tests. There was increased delta in ipsilateral structures as follows: amygdala (6.4 minutes), anterior hippocampus (7.2), middle hippocampus (7.4), temporal neocortex (9.1), frontal lobe (8.4), central/parietal area (11.0), and occipital lobe (9.7). Contralateral structures usually (> 64%) showed increased delta lasting 4 to 5 minutes. The ipsilateral hippocampus had delta waves in over 90% of injections. We conclude that the hippocampus is clearly affected by the ISA injection. We argue that the slow waves may not be caused by a direct effect of the drug, but rather by a functional deafferentation due to the profound inactivation of structures surrounding the hippocampus. Similarly, slow waves contralateral to injection may be caused by sudden removal of neuronal input from the regions receiving the amobarbital.

Amobarbital↗
PubMed1992

Anatomic basis of amygdaloid and hippocampal volume measurement by magnetic resonance imaging.

Both the amygdala and the hippocampus are involved in the pathogenesis of a number of neurologic conditions, including temporal lobe epilepsy, postanoxic amnesia, and Alzheimer's disease. To enhance the investigation and management of patients with these disorders, we developed a protocol to measure the volumes of the amygdala and as much of the hippocampus as possible (approximately 90 to 95%) using high-resolution MRI. We present the anatomic basis of these two protocols and our results in normal control subjects. These volumetric studies of the amygdala may clarify the role of this structure in the pathogenesis of temporal lobe epilepsy.

Adult↗
PubMed1992

Neuropsychological techniques in the identification of epileptic foci.

Neuropsychological evaluation contributes towards identification of a seizure focus through assessment of function. Tests sample widely among cognitive abilities, usually contrasting language and visuospatial competence. In patients with a temporal-lobe focus, evaluation of memory is crucial and ideally should comprise a variety of tasks tapping different aspects of learning and memory. As a means of predicting and preventing severe postoperative memory impairment, memory is further tested in many cases with the intracarotid sodium amytal (IAP) procedure; hippocampus will be spared in patients who fail IAP memory tests. Performance after temporal lobectomy on three basic memory tests was evaluated in patients who had failed pre-operative IAP memory tests compared to those who had passed. Those who had failed performed significantly worse, confirming fragility of memory function in cases who have been identified as at risk by the IAP procedure.

Amobarbital↗
PubMed1991

Localization of lesions by neuropsychological testing.

Neuropsychological evaluation differs from other methods used to localize cerebral lesions in that it analyzes cognitive function. Tests sample widely among cognitive abilities, contrasting language proficiency with visuospatial skills. A thorough assessment of memory is crucial in the investigation because of the prominence of the temporal lobes in epileptogenesis and their importance in memory. Different aspects of learning and memory are tested, and measures sensitive to hippocampal function should be included. Patients who will undergo elective surgery may also undergo intracarotid sodium amobarbital tests, which provide additional information about the integrity of each hippocampal region. Appraisal of frontal-lobe function is another important part of neuropsychological evaluation. A growing number and variety of neuropsychological tests have proven to be sensitive to lesions in this large and complex cortical area. Frontal-lobe function could be expected to vary according to the function of subregions within the frontal lobes, and some tests appear to be sensitive to specific regions.

Amobarbital↗
PubMed1991

Human olfactory discrimination after unilateral frontal or temporal lobectomy.

Olfactory discrimination and detection was studied in 106 patients with unilateral cerebral excision in the right or left temporal lobe, right or left frontal lobe, left parietal lobe, or right frontal and temporal lobes, and in 20 normal control subjects. Detection thresholds for n-butyl alcohol, measured separately in each nostril, did not differ across subject groups or across nostrils, thus excluding any primary sensory loss. The discrimination task involved monorhinal presentation of repairs of unfamiliar odorants, which the subjects judged as same or different in quality. The results showed a significant deficit in discrimination confined to the nostril ipsilateral to the lesion in patients with temporal lobe removals. Patients with frontal lobe excisions were also impaired and, for patients with right frontal lesions including the orbital cortex, the impairment was found in both nostrils. Patients with left parietal lesions did not demonstrate any significant deficits. Normal subjects showed consistently better performance in the right than in the left nostril. The results are interpreted as reflecting the importance of the orbitofrontal cortex in olfactory discrimination. Temporal lobe lesions may disrupt the input to the orbitofrontal cortex, thereby producing poorer performance. The nostril difference in the normal subjects, together with the birhinal impairment in patients with right orbitofrontal damage, suggest a relative advantage of the right orbital region in olfactory processing.

Adult↗
PubMed1990

Right-nostril advantage for discrimination of odors.

Olfactory discrimination was tested with eight pairs of odors presented to each nostril of each subject. Ninety-nine subjects were tested; there were equal numbers of left- and right-handers, as well as both sexes. Detection thresholds for phenylethyl alcohol were measured separately in each nostril using a forced-choice staircase procedure. In addition, a verbal dichotic listening test known to be sensitive to language lateralization was administered. Results indicated that discrimination performance was significantly better when the stimuli were presented to the right nostril than when they were presented to the left, but no differences between the nostrils in detection thresholds were found. The right-nostril advantage did not vary as a function of sex or handedness, and did not bear any relation to language lateralization as measured via dichotic listening. The asymmetry for olfactory discrimination replicates an earlier study and is interpreted in terms of a possible specialization of function within the right cerebral hemisphere.

Adult↗
PubMed1989

Depth electrode investigations in patients with bitemporal epileptiform abnormalities.

Fifty-seven patients showing bitemporal independent epileptiform abnormalities on extracranial electroencephalograms (EEGs) in whom the epileptogenic zone could not be localized or lateralized by extracranial EEG and other noninvasive tests were investigated with stereotactic depth electrode recordings. In a majority of 44 patients (77%), seizures originated exclusively or with a strong predominance in one temporal lobe only. Of the remaining 13 patients (23%), 8 had seizures originating independently in either temporal lobe without significant lateralized predominance, and 5 had multiple seizure patterns, which were often diffuse. The patterns of seizure onset as recorded by depth electrodes tended to vary even in the same patient. Electrical stimulation studies and the determination of afterdischarge thresholds were of limited utility for lateralization of seizure onset.

Adolescent↗
PubMed1988

Olfactory identification deficits in patients with focal cerebral excision.

The ability to identify common odors using the University of Pennsylvania Smell Identification Test was investigated in 120 patients with a focal surgical brain lesion and 20 normal control subjects. Results showed significant impairment after right or left temporal lobectomy, right or left frontal lobectomy, and right frontotemporal excision. Patients whose excision was confined to the left central, parietal or posterior area showed no significant deficit. The impairment after frontal lobectomy was demonstrated only in patients whose frontal-lobe removal invaded the orbital cortex; that group also showed a significantly greater impairment than did the temporal lobectomy group. All patient groups showed normal detection thresholds for n-butyl alcohol.

Adult↗
PubMed1986

Right hippocampal excision impairs learning and recall of a list of abstract designs.

The role of the temporal lobes and the hippocampus in learning a list of abstract designs was investigated. Variables studied included trials to criterion, 24-hr delayed recall and serial-position effects. Normal control subjects and four groups of patients, classified according to side of temporal lobectomy and extent of excision from the hippocampal zone, were tested. Patients with a right temporal lobectomy that included a large hippocampal excision showed deficient learning and memory, and, on the serial-position analysis, they recalled essentially none of the first items of the list. The other patient groups were unimpaired, except in the number of trials required to reach criterion.

Adolescent↗
PubMed1986

Memory for designs: the hippocampal contribution.

The role of mesial temporal-lobe structures in the recall of designs was examined in two experiments. Normal control subjects and patients with right or left temporal lobectomy that included either a large or small excision from the hippocampal zone were tested. In Experiment 1, subjects copied a complex drawing that was presented piecemeal in an illogical order; in Experiment 2 they copied 18 individual designs. In both cases recall was tested 45 min later. Patients with right temporal lobectomy showed deficient recall in both experiments; in Experiment 1 only, patients with a large right hippocampal removal were also significantly impaired compared to those with a small removal.

Adolescent↗
PubMed1979

Incidental learning of image-mediated or pronounced words after right temporal lobectomy.

The use of visual images in word recall by patients with right temporal lobectomy was studied by testing the incidental learning of 40 (20 abstract, 20 concrete) words that had been either carefully pronounced or the referent visualized. When tested immediately after presentation of the list, the right temporal-lobe group (N = 30) did not differ from a matched normal control group, but in delayed recall 2 hours later the patient group showed impaired recall of concrete words that had been visualized. Recall of visualized abstract words was also poor but not significantly so, while pronounced words, whether abstract or concrete, were recalled normally. Further analysis revealed an impaired recall for visualized concrete words in both immediate and delayed testing in patients having a large right hippocampal removal, indicating an important role of the mesial temporal structures in image recall.

Adolescent↗
PubMedDate not supplied

Duration of sodium amytal effect: behavioral and EEG measures.

In performance of an intracarotid sodium amytal test duration of action is a critical factor since measurements obtained after cessation of action are invalid. Duration of action is often monitored by measuring handstrength contralateral to injection or by visual inspection of amytal-induced EEG slow waves ipsilateral to injection. We describe new objective methods of monitoring drug effect: quantified EEG and sensory discrimination. In a first study of patients with scalp electrodes, the two traditional and the two new measures were compared in 40 injections. Results indicated that the two EEG measures did not differ significantly and estimated a shorter drug effect than the two behavioral measures, which were also not significantly different. The two new measures had a smaller SD, indicating that they may be less erratic. In a second study of 14 patients, using intracerebral electrodes, we showed that slow waves in the frontocentral region lasted as long as the motor and sensory effects, but also that slow waves in the medial temporal region dissipated earlier than the motor and sensory deficits. Our results suggest that motor and sensory measures may overestimate the time in which valid testing can occur if hippocampal function is at issue.

Amobarbital↗
PubMedDate not supplied

EEG slow waves and memory performance during the intracarotid amobarbital test.

During intracarotid sodium amobarbital (ISA) testing, EEG slow waves appear in the injected hemisphere and usually also contralaterally. They are frequently used to estimate duration of drug effect and thus the window of valid memory testing, but the relationship between slow waves and memory performance is not established. In 50 tests, we examined recognition for stimuli presented after amobarbital injection in relation to the quantified EEG. Performance was compared for injection ipsilateral versus contralateral to epileptic focus, with slow waves present bilaterally, unilaterally, or dissipated. Results showed that memory was impaired after injections contralateral to the focus when slow waves were present on the side of the focus (contralateral to injection). Injection contralateral to focus did not interfere with memory if slow waves were not also present, and slow waves contralateral to injection did not interfere with memory if the focus was not also present. This result emphasizes the functional significance of slow waves, which probably reflect decreased neuronal functioning.

Adolescent↗