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PubMed1993

Intracarotid amobarbital injection produces hippocampal EEG changes in patients with temporal lobe epilepsy.

EEGs of hippocampi of both sides were analyzed during intracarotid amobarbital tests in 12 patients with temporal lobe epilepsy. The number of paroxysms occurring 1 min before the injection ipsilaterally and contralaterally was compared with that occurring 1 min after the injection. The hippocampal EEG ipsilateral to the injection showed an increase in paroxysms irrespective of the laterality of the epileptogenic side. Contralateral to the amobarbital injection an increase in paroxysms was observed in the epileptogenic hippocampus only.

Adult↗
PubMed2004

Effects of topiramate on memory performance on the intracarotid amobarbital (Wada) test.

We evaluated the effects of topiramate (TPM) on memory function in the intracarotid amobarbital (Wada) test in nine patients with mesial temporal lobe epilepsy (MTLE) whose antiepileptic drugs (AEDs) included TPM and compared their scores with those of 16 patients with MTLE on AEDs not including TPM. Sodium amobarbital was injected first into the hemisphere ipsilateral to the seizure focus and then into a contralateral site, and the patients were tested for naming and memorization. There was no statistical difference in percentage memory scores between the two patient groups following the contralateral injection. After the ipsilateral injection, however, TPM patients had significantly lower percentage memory scores compared with non-TPM patients (P < 0.02). We conclude that a possible adverse effect of TPM on memory performance should be considered when evaluating the Wada test memory scores of patients on TPM therapy.

Adolescent↗
PubMed1980

The emergency amobarbital interview.

Patients infrequently present to the general emergency department with what appears to be a severe psychiatric condition needing rapid differentiation from urgent and emergency medical problems for proper initial disposition and treatment. These include patients with both acute conversion reactions and those in acute catatonic or pseudocatatonic states. Fifteen consecutive patients (11 women and four men ranging in age from 17 to 62) with these symptoms underwent interviews under intravenous amobarbital in the emergency department. Five of these patients presented with acute paralysis of extremities. Ten presented in a state of vigilant awareness similar to, or identical with, catatonia. Using this technique, all 15 patients had the presumptive psychiatric nature of their underlying condition quickly confirmed. The five patients with conversion reactions have no recurrence to date. Four of the 10 catatonia-type patients had resolution of their symptoms without recurrence. All 15 patients responded to 500 mg or less of amobarbital. There were no complications. Two cases are discussed.

Adult↗
PubMed2000

Beyond speech lateralization: a review of the variability, reliability, and validity of the intracarotid amobarbital procedure and its nonlanguage uses in epilepsy surgery candidates.

While the intracarotid amobarbital procedure (IAP) was originally utilized to lateralize speech functions as an aid in the surgical treatment of epilepsy, additional uses for the IAP have emerged including: (1) the use of the IAP to predict post-surgical memory changes, including both global amnesia and smaller, yet significant, material-specific memory deficits; (2) the use of the IAP to provide confirmatory evidence of lateralization of seizure focus; and (3) the use of the IAP to predict post-surgical relief from seizures. While the literature on the IAP is extensive and growing, its utility is marred by the wide variability associated with the procedure itself from epilepsy center to center. This variability renders comparisons among IAP studies problematic and conclusions about IAP efficacy difficult. The variability associated with the amobarbital procedures, as well as the reliability and the validity of the IAP in its nonlanguage uses is reviewed here. A special emphasis is devoted to research conducted in the last decade. Also discussed is the future of the IAP including anticipated research directions.

Amobarbital↗
PubMed1983

Variation in amobarbital metabolism: evaluation of a simplified population study.

Kinetic constants of amobarbital metabolism were established for 52 subjects on the basis of urinary analysis extending over several days, usually 96 hr. There was no evidence of effect of age or sex on any of the constants. C-Hydroxylation was induced by cigarette smoking as much as 100%, but glucosidation was not affected. A factor influencing the constants was ethnicity of subjects (Caucasian or Oriental). This study confirms ethnic differences in amobarbital metabolism that were reported after measuring the concentration of metabolites in single samples of urine, that is, urine specimens voided during the postdistributive phase after oral drug intake. It appears that extreme simplification of sampling methods may be contemplated in the design of metabolic investigations of populations.

Adult↗
PubMed1997

Use of the intracarotid amobarbital procedure in the evaluation of memory.

The intracarotid amobarbital procedure (IAP) involves the temporary inactivation of one cerebral hemisphere by the injection of sodium amobarbital, which allows independent testing of the contralateral hemisphere. Initially used for lateralization of language, IAP later found a role in the evaluation of memory function in patients with intractable temporal lobe epilepsy being considered for resective surgery. IAP technique varies widely across centers, but, in general, memory is assessed by presenting the patient with a number of items during the period of hemispheric inactivation and testing recall or recognition of these items after the effect of the drug has worn off. Because the medial temporal lobe is not directly perfused by the internal carotid artery, concerns have been raised about the ability of the IAP to test hippocampal memory function. Consequently, a variety of selective procedures have been devised. Findings on both intracranial EEG recordings and pathologic and neuroimaging studies support the association of IAP memory results with hippocampal function. The IAP memory test was originally designed to predict the risk for development of global amnesia following unilateral temporal lobectomy. More recently, it also has been used as an adjunct in lateralizing the seizure focus and for predicting postoperative selective memory deficits and seizure outcome.

Adult↗
PubMed2005

Reduced anesthetization during the intracarotid amobarbital (Wada) test in patients taking carbonic anhydrase-inhibiting medications.

PURPOSE: Failure to show adequate anesthetization during the intracarotid amobarbital procedure (IAP or "Wada test") is a rare complication. After an unusually high rate of recent anesthetization failures, we sought to determine the frequency of reduced anesthetization and any common factors underlying these failures. METHODS: We reviewed the records of all patients who underwent IAP tests through the UCLA Seizure Disorder Center between September 1999 and May 2002. Age, date, epileptogenic focus, radiologist, and current medications were all considered. RESULTS: Of a total of 56 patients who underwent our intracarotid amobarbital examination, 11 (19.6%) showed either very rapid recovery ( /=8 weeks after discontinuation of such medications.

Amobarbital↗
PubMedDate not supplied

Factors in children that predict performance on the intracarotid amobarbital procedure.

The intracarotid amobarbital procedure (IAP) is frequently used to determine hemispheric language dominance and memory competence in individuals with intractable epilepsy before surgical intervention. The present study focused on outcome results concerning use of this technique in children. The IAP was an effective tool in determining their hemispheric language dominance. Seven characteristics, including age, gender, dose level of sodium amobarbital, Full-Scale I.Q., hemispheric side of injection (left or right), language dominance of hemisphere injected, and order of injection (first or second) were examined as possible factors predictive of memory performance on the IAP. Results suggest that after injection of the hemisphere suspected of containing the primary seizure origin, children aged < 13 years who had the left language-dominant hemisphere injected were significantly less likely to pass IAP memory tasks than were older children or younger children who had the nondominant hemisphere injected. These findings suggest that the IAP is a reliable indicator of hemispheric memory competence in children aged > 13 years or younger children whose suspected seizure focus is located in the nondominant language hemisphere.

Adolescent↗
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↗
PubMed1996

Relation between intracarotid amobarbital memory asymmetry scores and hippocampal sclerosis in patients undergoing anterior temporal lobe resections.

The intracarotid amobarbital procedure (IAP) is used to evaluate memory function preoperatively in candidates for anterior temporal lobe resections (ATL). We examined IAP memory asymmetry scores in 30 patients undergoing ATL (17 R, 13 L), as a function of the presence (HS+) or absence (HS-) of hippocampal sclerosis. Ictal onset zones were determined by extraoperative recording with subdural strip electrodes in all but 3 patients in whom magnetic resonance imaging (MRI) scan showed HS. MRI scans were otherwise normal. All patients were left hemisphere dominant for language except 1, in whom language was represented bilaterally. IAP memory testing involved presentation of eight subjects during anesthesia of each hemisphere, followed by recognition testing after patients recovered from amobarbital effects. A score of 1 was given for each correctly recognized object, and 0.5 was deducted for each false-positive identification. There were 16 foils. A total asymmetry score was calculated, which was positive if there was agreement between the direction of the symmetry and side of operation and negative if reversed. The mean asymmetry score for HS- (n = 8) was 0.9; that for HS+ (n = 22) was 4.1 (p < 0.01). IAP memory performance provided lateralizing information (asymmetry score > or = + or -2) in 73% of cases; among these, the lateralization was correct in 91%. Our data indicate that IAP memory asymmetry predicts both laterality of ictal onset and the presence of HS.

Adolescent↗
PubMed1997

Electrocerebral recovery during the intracarotid amobarbital procedure: influence of interval between injections.

PURPOSE AND METHODS: During the intracarotid amobarbital procedure (IAP) at the University of Michigan, continuous scalp EEG monitoring guides the timing for presentation of memory items and postinjection testing. Most of our patients have undergone bilateral injections. The interval between injections varied from 22 to 60 min, depending on the test and recovery time, as well as the time to catheterize the second side. After noting a trend toward prolonged electrographic recovery following the second injection, we tested our clinical impression that recovery of the second hemisphere may be influenced by (a) the time between injections and (b) which hemisphere is injected first (epileptogenic or nonepileptogenic). To study these questions, we analyzed EEG recovery data from 48 consecutive IAPs. Approximately half the patients had the epileptogenic side injected first. RESULTS: We found that (a) electrographic recovery after the second injection is prolonged if the interval between bilateral injections is less than 40 minutes and (b) electrographic recovery is more rapid after injection of the epileptogenic hemisphere. CONCLUSIONS: We now recommend waiting at least 45 min between injections. The pathophysiology of more prolonged amobarbital effect on the nonepileptogenic hemisphere than on the epileptogenic hemisphere remains unclear.

Amobarbital↗
PubMed1997

Asymmetries in the effect of side of seizure onset on recognition memory following intracarotid amobarbital injection.

PURPOSE: To assess interhemispheric differences in recognition memory for objects during the intracarotid amobarbital sodium procedure (IAP). METHODS: The recognition memory for real objects of patients with either right (RTLE; n = 28) or left (LTLE; n = 22) temporal lobe epilepsy was assessed at baseline, and after left and right intracarotid amobarbital sodium injection. RESULTS: There were no differences between groups on baseline performance. Performance following injection ipsilateral to the side of seizure focus was relatively lower for the LTLE as compared with the RTLE group, but this difference did not reach statistical significance. However, performance following injection contralateral to the side of seizure focus was significantly lower for the RTLE as compared with the LTLE group. Within-group differences in performance after ipsilateral as compared with contralateral injection were significant for the RTLE but not the LTLE group. The difference in interhemispheric asymmetry in IAP memory performance between RTLE and LTLE groups was reflected in decreased ability to classify LTLE patients as compared with RTLE patients about side of seizure onset, using a clinically applicable decision rule. CONCLUSIONS: Recognition memory during the IAP for real objects, simultaneously named and presented visually during encoding, is mediated effectively by both the left and right hemisphere when there is no seizure focus present. However, memory appears to be more vulnerable to the presence of a seizure focus in the right as compared with the left hemisphere.

Adolescent↗
PubMed2000

Risk factors for unsuccessful testing during the intracarotid amobarbital procedure in preadolescent children.

PURPOSE: Identification of risk factors for unsuccessful testing during intracarotid amobarbital procedure (IAP) in preadolescent children. METHODS: A pediatric IAP protocol was attempted in 42 candidates for epilepsy surgery (5-12 years old; mean, 10 years) based on the ability to pass a practice test. Language dominance was defined by marked asymmetry until first verbal response and paraphasic errors. Intact hemispheric memory was defined by recall of >/=60% of test items. The odds ratios of baseline variables (age at IAP, Full-Scale IQ, side of disease, age at seizure onset, amobarbital dose) were calculated for various IAP outcomes. RESULTS: IAPs were accomplished in 40 children. Language dominance was established in 25 (62.5%) of 40 patients: all 21 focal resection candidates were left language dominant; four hemispherectomy candidates had intact language after injection of the damaged hemisphere. In 12 (30%) of 40 patients, language testing failed because of agitation or obtundation. Compared with the 21 children with language dominance established by bilateral IAP, these 12 children had lower mean Full-Scale IQ (66.4 vs. 87.9; p = 0.014), and more frequently, the epileptogenic lesion in the left hemisphere (presumed dominant by right-handedness; 78 vs. 33%; p = 0.04). Excluding hemispherectomy candidates (intentionally only one injection), memory testing could not be completed in 13 (36%) of 36 children because of obtundation or agitation. These children were significantly younger than the 23 (64%) of 36 with successful bilateral memory testing (mean age, 107.6 vs. 128.7 months; p = 0. 006). The eight (25%) of 32 children with failing retention scores after ipsilateral injection had lower Full-Scale IQ than did the 24 (75%) patients who passed (mean, 59.6 vs. 81.7 months; p = 0.03). CONCLUSIONS: The IAP successfully established hemispheric language dominance and memory representation for just under two thirds of the preselected preadolescent children. Risk factors for unsuccessful testing included low Full-Scale IQ (especially <80), young age (especially <10 years), and seizures arising from the left hemisphere presumed dominant by right-handedness.

Age Factors↗
PubMed1978

Age-dependent disposition of amobarbital: analog computer evaluation.

Previously published observations on 4-hour and 24-hour amobarbital blood levels in two groups of subjects (ages 20--40 and over-65) were analyzed with use of an analog computer and literature data for the rate constants of absorption, distribution and metabolism. It was found that the volume of distribution did not change with age, and the increase in biologic half-life from 22.8 hours in the young subjects to 86.62 in the elderly subjects was due to a decreased rate of metabolism. When the one-point method is used, the size of the nightly dose of amobarbital should be reduced in elderly subjects from 200 mg to 50 mg in order to maintain the same steady-state blood levels found in younger subjects.

Adult↗
PubMed2002

Transcranial Doppler ultrasound: a new method of monitoring hemispheric anesthetization during the intracarotid amobarbital procedure.

BACKGROUND: Electroencephalography (EEG) is traditionally used to assess the duration of hemispheric anesthetization and to monitor return of function in the anesthetized hemisphere during the intracarotid amobarbital procedure (IAP), but EEG changes are not consistently seen. The authors evaluated the role of continuous transcranial Doppler (TCD) monitoring as an alternative to EEG. METHODS: The authors performed both continuous TCD monitoring and EEG during the IAP in 10 patients with medically intractable partial epilepsy. Mean velocities were monitored continuously in both middle cerebral arteries (MCAs), and changes in MCA velocities on continuous TCD monitoring were time locked with the EEG changes. RESULTS: The average mean MCA velocities were within normal limits bilaterally (50-85 cm/s) in all patients at baseline. Mean MCA velocites increased in all patients to 95-115 cm/s at the start of the test when the patients were asked to raise their hands and start counting. After injection of sodium amobarbital, mean MCA velocities in all patients dropped dramatically on the ipsilateral side to values of 12-39 cm/s and returned to the baseline average value when the hemiparesis recovered. In 8 patients, the duration of delta activity on EEG coincided with the time interval during which the mean MCA velocities were low on TCD monitoring. In 2 patients, despite the presence of hemiparesis clinically and a drop in mean MCA velocities on the ipsilateral side on continuous TCD monitoring, EEG remained normal on the ipsilateral side. CONCLUSIONS: Continuous TCD monitoring may be a more sensitive method than EEG in determining the duration of hemispheric anesthetization during IAP. Because the items for assessment of memory are presented during the period of hemispheric anesthetization, TCD may be useful in more precisely defining the time window for memory testing.

Amobarbital↗
PubMed1984

Effects of amobarbital and methohexital on epileptic activity in mesial temporal structures in epileptic patients. An EEG study with depth electrodes.

Bilateral intracarotidal Amytal (amobarbital) tests for evaluation of speech and memory function were performed during preoperative evaluation of 30 patients with drug-resistant epilepsy. In 8 of these patients (16 tests), having partial complex epilepsy, EEG was recorded with depth electrodes, implanted bilaterally in anterior mesial temporal structures. The EEGs during 13 tests could be quantified with regard to spike activity. A rapid increase in spike frequency was observed ipsilateral to the injection in all tests but one. No seizure activity or clinical seizures were provoked. This previously unnoticed effect of amobarbital could be due to a direct excitatory effect of the drug on epileptic temporal neurones or, alternatively, to a release of interictal inhibition, exerted upon these neurons by other structures. In 4 patients, the effect was compared with that of methohexital, another barbiturate known to have excitatory effects upon epileptic activity.

Action Potentials↗
PubMed1970

Frequency-specific relation between hippocampal theta rhythm, behavior, and amobarbital action.

The frequency of the hippocampal theta rhythm in freely moving rats varies predictably in relation to behavior in a simple learning situation. The theta rhythm may be driven by electrical stimulation of the medial septal area at frequencies within the theta range. The threshold for septal driving is lowest at that frequency which the rat displays in response to frustrative nonreward; the driving threshold is selectively raised at this frequency by sodium amobarbital. It is suggested that the behavioral effects of amobarbital are due to a disruption of the theta frequency normally displayed in response to nonreward.

Amobarbital↗
PubMed1980

Species differences of amobarbital metabolism: dihydroxyamobarbital formation.

Amobarbital is almost completely metabolized in animals and man. The major metabolite is 3'-hydroxyamobarbital. The second major metabolite in dog, mice, hamsters, guinea pigs, and rats could be identified as 3',4'-dihydroxyamobarbital. A striking contrast between man and animals is the virtual absence of the diol in man and absence of amobarbital-N-glucoside in animals.

Amobarbital↗