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H F Flanigin

Publications and source records attributed to H F Flanigin.

34 records · Page 2Linked to original sources
PubMed1988

Electrical stimulation of the human hippocampus produces verbal intrusions during memory testing.

Verbal memory testing was conducted during electrical stimulation of the human hippocampus in 12 epilepsy surgery candidates with unilateral temporal lobe seizure onset. Performance was assessed during baseline, left hippocampal stimulation and right hippocampal stimulation. Verbal intrusion errors were greater during electrical stimulation of the hippocampus contralateral to the seizure focus. These findings suggest that verbal intrusions are related to memory deficits, and that patients with cerebral disease who intrude words from an earlier portion of a learning test are likely to have bilateral cerebral dysfunction.

Adult↗
PubMed1988

Relationship of limbic evoked potentials to recent memory performance.

The relationship between limbic evoked potentials (LEPs) and memory performance was investigated in eight patients with intractable epilepsy who were candidates for temporal lobectomy. No relationship between the presence or absence of unilateral LEP and memory deficits was present. However, in both patients with bilaterally poorly developed hippocampal LEPs, verbal and visual-spatial memory tasks were impaired. In one patient with well developed LEPs bilaterally, memory function was normal. These data suggest that LEPs may assist in the evaluation of memory function during the preoperative work-up for temporal lobectomy.

Epilepsy↗
PubMed1988

Severe behavioral complications following intracarotid sodium amobarbital injection: implications for hemispheric asymmetry of emotion.

The intracarotid sodium amobarbital (ISA) procedure is effective in determining cerebral language dominance. However, severe emotional and behavioral reactions during ISA evaluation may invalidate the results or necessitate aborting the procedure. In an effort to identify patients at risk for behavioral complications, we reviewed 92 patients undergoing ISA evaluation and found five with severe changes in affect and behavior following amobarbital injection, ranging from prolonged coma to an extended confusional state. Severe behavioral disturbances were more likely to occur in patients with left frontal structural lesions upon injecting amobarbital into the right hemisphere. Analysis of patients with structural lesions of the anterior regions of the right hemisphere showed no evidence of similar behavioral complications. These findings suggest a special role for the left frontal region in the inhibition of affective expression and provide further evidence of the importance of right hemisphere mechanisms in emotion.

Adult↗
PubMed1988

Preserved crossmodal association following bilateral amygdalotomy in man.

The present study investigated the role of the amygdala in crossmodal association in man. Recent experimental evidence indicates amygdalectomized monkeys show deficits when required to identify, through vision, objects that have been previously examined by touch. We employed a delayed nonmatching to sample task pre- and postoperatively in a patient who underwent bilateral stereotaxic amygdalotomy for intractable aggressivity. Bilateral amygdalotomy did not impair our patient's ability to associate an object from one sensory modality to another, following a short delay. The results suggest that sensory association memory does not depend upon the amygdala in humans. Examination of the neuroanatomic structures affected by the differing surgical procedures in the two species revealed entorhinal and perirhinal cortices were damaged in amygdalectomized monkeys but not in the present case. Because entorhinal cortex is an important structure for the formation of new memory traces, it is possible that damage to the entorhinal and surrounding cortical regions, rather than damage to the amygdala itself, is responsible for the crossmodal association deficit in monkeys.

Adult↗
PubMed1988

Cholinergic modulation of human limbic evoked potentials.

Limbic evoked potentials (LEPs) were recorded from the hippocampi of three epilepsy surgery patients with unilateral medial temporal lobe seizure onset. In each patient, stable large amplitude LEPs which displayed polarity inversion across successive levels of hippocampus were present unilaterally, but were absent or rudimentary in the hippocampus corresponding to the electrographically proven seizure onset. After administration of scopolamine, LEPs in the "normal" hippocampi were markedly altered with slowing of the individual components and increased trial to trial variability. In addition, two patients developed reliable, high amplitude, polarity inverting LEPs on the side of seizure onset which had either absent or rudimentary LEPs in the baseline state. The results suggest that LEPs are under cholinergic modulation.

Acetylcholine↗
PubMed1987

Analysis of a four-year experience with depth electrodes and a two-year experience with subdural electrodes in the evaluation of ablative seizure surgery candidates.

Chronically implanted depth and subdural electrodes have both been shown to be satisfactory means of localizing epileptogenic foci. Utilizing bilateral mesial temporal depth electrodes, we have localized mesial temporal foci in a large percentage of patients. Depth electrode investigation of a more limited number of patients with suspected extramesial temporal foci has not been as reliable in giving localizing information. We have more recently used subdural electrodes to investigate this latter category of patients, and preliminary findings suggest that this technique may be of localizing value in several subcategories.

Electrodes, Implanted↗
PubMed1987

The effect of electrical stimulation of medial temporal lobe structures in epileptic patients upon ACTH, prolactin, and growth hormone.

We measured ACTH, cortisol, prolactin, and growth hormone concentrations in patients with temporal lobe epilepsy who were having depth electrode studies. During the collection period, electrical stimuli were applied to amygdala and hippocampus to establish after-discharge thresholds. After-discharges that lasted at least 10 seconds or seizures caused secretion of ACTH and prolactin but not growth hormone. Stimuli that did not produce after-discharges of this duration inhibited ACTH secretion, but had no effect on prolactin or growth hormone secretion.

Adrenocorticotropic Hormone↗
PubMed1987

Limbic evoked potentials predict site of epileptic focus.

Limbic evoked potentials (LEPs) were recorded from intracerebral electrodes in the hippocampi of seven preoperative epilepsy surgery patients. LEPs were evaluated using amplitude, form, and asymmetry by raters blinded as to the side of electrographically proven seizure onset. Raters correctly predicted the side of focus in all four patients with proven unilateral temporal lobe seizure onset. Further, LEP amplitudes in two patients with bilateral independent temporal lobe seizure onset were markedly diminished compared with one patient with a nontemporal lobe seizure onset. LEP recordings may assist in determination of the site of epileptogenic pathology.

Epilepsies, Partial↗
PubMed1986

Temporal lobectomy for partial complex seizures: evaluation, results, and 1-year follow-up.

Twenty-six patients were evaluated for temporal lobectomy. Fourteen underwent initial monitoring with electrodes in the amygdala and hippocampus bilaterally. Twelve had initial monitoring with scalp and sphenoidal electrodes. Four had conclusive localization without depth electrodes. Twenty-three patients underwent lobectomy. At 1-year minimum follow-up, 15 were seizure free. Five had greater than 90% reduction in seizure frequency. Complications of depth electrodes were one hemorrhage and one abscess. One patient developed impaired memory following surgery. Temporal lobectomy is effective in well-selected patients. Depth electrodes localize seizure onset from mesial temporal structures. Scalp and sphenoidal recording may be sufficient in some cases.

Adolescent↗
PubMed1985

Transient global amnesia and meningioma.

A patient with episodes of transient global amnesia and transient partial amnesia was found to have a meningioma impinging on the right medial temporal lobe. Multiple partial complex seizures and EEG abnormalities suggested an epileptogenic disorder.

Amnesia↗
PubMed1984

Pituitary and adrenal function in epileptic patients.

ACTH and cortisol were measured simultaneously in plasma samples obtained every 5 min from subjects at two different diurnal times. In the first study adrenocorticotropic hormone (ACTH) mean concentration and secretory rate were elevated in anticonvulsant drug-treated temporal lobe epileptic patients in comparison to anticonvulsant drug-treated patients with pseudoseizures. Cortisol mean concentrations and secretory rate were similar in these groups of subjects. In the second study, mean ACTH concentration and secretory rate were higher in temporal lobe epileptic patients than in normal controls. Both measures of ACTH secretion were similar in post-temporal lobectomy patients and normal controls. Mean cortisol concentration and secretory rates were highest in the temporal lobe epileptic patients, lowest in normal controls, and intermediate in post-temporal lobectomy patients. We conclude that ACTH and cortisol secretion is abnormal in temporal lobe epileptic patients. Temporal lobectomy restores abnormal ACTH secretion to normal whether or not seizures are controlled. The absence of ACTH changes in the pseudoseizure patients suggests that these changes are not drug induced. Cortisol secretion is similar in temporal lobe epileptic patients and pseudoseizure patients, suggesting a direct effect of the drugs upon the adrenal cortex.

Adolescent↗
PubMed1982

Effect of pressure on cerebrospinal fluid absorption in cats, baboons, and humans: comparison of the linear and logarithmic models.

To circumvent time constraints inherent in indicator clearance measurements of cerebrospinal fluid absorption, investigators have used the relationship between CSF pressure at steady state and the rate of infusion of mock CSF, in both patients and experimental animals, to evaluate the bulk absorption rate of CSF. This latter approach required mathematical model of the effect of CSF pressure on CSF bulk flow. Two such models--a fixed resistance and a variable resistance model of CSF flow through arachnoid villi--have been used in both clinical and laboratory settings. In this study, the relationship between steady state CSF pressure and mock CSF infusion rate was assessed using both mathematical models. We studied two patients, three cats, and seven baboons. Values of CSF outflow resistance calculated according to both models as well as other parameters of CSF bulk flow estimated on the basis of both models were all in the range expected from other studies. The data from these experiments do not provide justification for preferring one model over the other. Depending on the experimental or clinical situation, some of the assumptions behind both models may not be valid. Multiple direct measurements of the rates of CSF absorption and formation over a wide range of CSF pressures in individual subjects will be necessary to validate either the variable or the fixed resistance model or to suggest a more appropriate model. Until such information is available, it is probably reasonable to use both approaches for the analysis of mock CSF infusion data. CSF bulk flow parameters calculated on the basis of either the variable or the fixed resistance model should never be taken as absolute, but should be evaluated critically in the context of the clinical or experimental situation.

Absorption↗
PubMedDate not supplied

Corpus callosotomy for the treatment of intractable epilepsy.

Twenty-five patients underwent anterior corpus callosotomy (ACC) for treatment of uncontrolled seizures. Two patients died, and 6 patients experienced perioperative complications which resolved. A statistically significant reduction of generalized tonic-clonic seizures (17 patients; P less than 0.05) and complex partial seizures (11 patients; P less than 0.05) occurred following ACC. A single patient with atonic seizures became free of atonic seizures. Two patients had a greater than 50% reduction in seizures resulting in falls, a single patient became free of episodes of status epilepticus, and in 2 patients the seizures changed from generalized tonic-clonic seizures to hemiconvulsive seizures. Thus ACC appears to decrease the severity and frequency of disabling seizures in some patients with uncontrolled seizures.

Adolescent↗
PubMedDate not supplied

Spectral analysis of sphenoidal evoked potentials predicts epileptic focus.

Sphenoidal evoked potentials (SpEPs) were recorded in 14 patients with intractable temporal lobe epilepsy. Twelve patients had electrographically proven unilateral seizure onset (five left, seven right). Two patients had partial complex seizures and unilateral mesial temporal lobe lesions shown by magnetic resonance imaging (MRI). Thirteen patients subsequently underwent temporal lobectomy. SpEPs were recorded using the P3 tonal oddball paradigm from sphenoidal electrodes referenced to scalp electrodes (i.e., T3, T4, C3, C4, Cz) and were subjected to spectral analysis for whole band (1-12.6 Hz) power. A significant relationship was found for side of seizure focus and reduced spectral power of the sphenoidal-temporal target SpEPs. In 10 of 14 patients, SpEP spectral power was less from the "epileptogenic" than from the "nonepileptogenic" temporal lobe. Of the remaining 4 patients, 2 had bilaterally equal spectral power, and 2 had lower SpEP power from the nonepileptogenic side. Postoperatively, all 13 patients are seizure-free except for the 2 patients with reduced SpEP power opposite to the ictal onset and 1 patient with fluctuations in SpEP asymmetries. Spectral analysis of SpEPs appears to have utility in the assessment of temporal lobe dysfunction and thus in the preoperative evaluation for epilepsy surgery.

Adolescent↗
PubMedDate not supplied

MR imaging in patients with intractable complex partial epileptic seizures.

Detailed neurologic studies, high-field-strength MR imaging, and CT scanning were performed preoperatively in 53 patients with intractable complex partial seizures who underwent surgical treatment for epilepsy. Macroscopic structural (tumoral or vascular) lesions were found in 28% of patients. The remainder had pathologic findings consistent with mesial temporal gliosis. Tumors were found in 22% of the patients and were benign or of low-grade malignancy in every case. MR was accurate in the preoperative diagnosis of structural lesions, including very small occult tumors and cryptic vascular malformations. In patients with mesial temporal gliosis, there was correlation between the MR observation of a unilaterally dilated anterior temporal horn and the EEG-identified seizure focus and side of temporal lobectomy. However, MR demonstrated T2-weighted signal abnormalities correlating with the epileptogenic focus in only 8% of cases of mesial temporal gliosis. MR provided useful information in 28% of patients who underwent surgery for refractory complex partial epilepsy. MR obviated invasive EEG monitoring in 93% of the patients with structural lesions. MR was useful in only 8% of the patients with pathologic changes of mesial temporal gliosis.

Adolescent↗