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Biomedical subjects

H Silfvenius

Publications and source records attributed to H Silfvenius.

At least 37 records · Page 2Linked to original sources
PubMed1990

Brain perfusion with intracarotid injection of 99mTc-HM-PAO in partial epilepsy during amobarbital testing.

Technetium (99mTc) hexamethyl propylene amine oxime (HM-PAO) was injected into the internal carotid artery in ten epileptic patients after the end of amobarbital speech-memory tests. The cerebral perfusion as visualized from SPET was compared to cerebral angiographies, which showed unilateral filling of intracranial vessels in seven patients. SPET revealed cross-flow between the hemispheres in four of these seven patients. In three patients in whom the angiograms had shown bilateral contrast filling, SPET showed cross-flow in only two. It is concluded that 99mTc-HM-PAO SPET examinations provide valuable information for correct interpretation of amobarbital tests on cognitive hemisphere functions. The SPET technique may help to explain atypical speech and memory responses caused by unusual intracranial vascularization.

Adult↗
PubMed1990

Evaluation of early and late presented tasks in the intracarotid Amytal test for epileptic patients.

The temporal relation between speech and somatomotor effects was analyzed in 24 epileptic patients who underwent bilateral intracarotid Amytal tests. Furthermore, a chronological study of the task presentation was carried out. The memory test included 3 pre- and 12 post-injection items, the latter consisting of 6 words and 6 concrete pictures. Both hemispheres had low free verbal recall capacity. The speech-dominant hemisphere recognized 45% of the words and 58% of the pictures; the non-dominant side 17% and 32%, respectively. An epileptic lesion in the right temporal lobe only reduced the word recognition at a statistically significant level. Despite the early start of task presentation, both hemispheres recognized the early items almost as well as those presented later. This makes it possible for an extensive test battery which in turn helps to quantify memory capacity. If this method is used to test hemisphere memory, the possibility of interhemispheric cooperation is reduced, thereby increasing the validity of the results. The results are discussed in relation to intra- and interhemispheric communication during amobarbital sedation and regression.

Adolescent↗
PubMed1990

Hemisphere memory differences in Sodium Amytal testing of epileptic patients.

Material-specific memory performance was studied by a Sodium Amytal testing procedure in order to diagnose hemispheric memory functions in 27 patients with unilateral temporal or frontal epileptic lesions who were under consideration for surgical therapy. Memory was tested for concrete and abstract words, pictures of common objects, figures, and faces, presented pre- and post-inactivation of the hemisphere contralateral or ipsilateral to the epileptic focus. The results showed that tests involving words and pictures of common objects were conclusive about hemispheric memory functions, in showing cross-over interactions between side of lesion and side of injection. Figures and faces were hemisphere discriminative to a much lesser degree (only a minor preference for the right hemisphere was found) and are presumably more dependent on the functional integrity of both hemispheres. The present findings demonstrate that hemispheric memory functions can be studied in more detail with the Amytal technique than has been shown hitherto in the literature.

Amobarbital↗
PubMed1990

Visual half-field testing for defining cerebral hemisphere speech laterality.

The purpose of this study was to investigate to what extent the noninvasive visual half-field (VHF) test can reliably determine cerebral speech dominance for the individual patient with partial epilepsy considered for surgical treatment. The present VHF test consisted of a list of 36 words presented correctly and mirrored in the lateral visual fields to 13 right-handed and 14 left-handed control subjects and to 14 right-handed and 2 left-handed patients with partial epilepsy. In the controls, it was found that all right-handed and 10 out of 14 left-handed control subjects showed a right VHF (i.e., left hemisphere) advantage. Three of the left-handed control subjects showed the opposite pattern, and one showed no visual field advantage. All of the right-handed patients showed a right VHF advantage, except one who showed no VHF advantage. The two left-handed patients had both a left VHF advantage. Intracarotid amytal speech testing documented left hemisphere speech dominance in all right-handed patients. Of the two left-handed patients, one had right-sided, the other bilateral speech representation. The results suggest that the present VHF test reliably predicts cerebral hemisphere speech in patients with epilepsy.

Adolescent↗
PubMed1989

Barbiturate effects on EEG abnormality in complex partial epilepsy.

Sixteen patients with drug-resistant complex partial epilepsy were, during preoperative investigations for surgical treatment, subjected to intravenous methohexital and amobarbital EEG activation tests. The interictal epileptic spike discharges were visually counted on the seizure-generating side and compared with those found in the contralateral hemisphere. The invasive recordings were made with depth electrodes implanted in the mesial temporal lobes of 5 patients, and with subdural strip electrodes in varying lateral positions over the frontotemporal-parietal lobes of the other 11 patients. The doses of 10% amobarbital, 50-200 mg, were too low to induce any significant activation. In eight patients with unilateral epileptic lesions, 10, 25 and 50 mg 1% methohexital, induced a dose-dependent increase in the interictal spiking, always higher on the side of the seizure-gererating focus. Asymmetric induction of beta activity was noted in five patients. The test gave valuable information when determining the type or location of the epileptic abnormality. Parallels were drawn with earlier studies on spike-activation tests after intracarotid amobarbital injections. Although administered differently, the barbiturates are supposed to act directly on the neurons, and not via integrative wakening mechanisms.

Adult↗
PubMed1989

Pre- and postoperative memory of dichotically presented words in patients with complex partial seizures.

Dichotic listening tests were used to determine cerebral hemisphere memory functions in patients with complex partial seizures before, 10 days after, and 1-3 yr after right (RTE) or left (LTE) temporal-lobe excisions. Control subjects were also tested on two occasions. The tests consisted of presenting a series of 12-word lists and 7-word lists alternately to the two ears while backward speech was presented to the other ear. Measures of immediate free recall, final free recall, final cued recall, and serial recall were employed. The results revealed: (a) that both groups of patients were inferior the control group in tests tapping long-term memory functions rather than short-term memory functions, (b) a right-ear advantage for RTE patients at postoperative testing, (c) that the LTE group was more affected by surgery than the RTE group, and (d) a general improvement in recall performance from early to late postoperative testing. Taken together, these results indicate that the present dichotic test can be used as a non-invasive hemisphere memory test to complement invasive techniques for diagnosis of patients considered for epilepsy surgery.

Adult↗
PubMed1988

The accuracy of the dichotic, the visual half-field, and the intracarotid sodium amytal memory tests in preoperative neuropsychological investigation of epileptic patients.

Three methods for determining the lateralization of memory functions in patients with pharmacologically resistant intractable partial epilepsy were compared and evaluated. The three methods studied were a dichotic memory test, a visual half-field memory test, and an intracarotid Sodium Amytal memory test. A total of 35 epileptic patients considered for surgical therapy and a group of 20 non-epileptic control subjects took part in the study. The results show that the three tests tap different memory functions and that each of the test pick up a memory dysfunction in the hemisphere indicated by EEG recordings. In combination with an extensive neuropsychological test battery, the three methods produce data that concur with the evaluation made of EEG recordings.

Amobarbital↗
PubMed1987

Hemisphere memory of concrete and abstract information determined with the intracarotid Sodium Amytal test.

An extended version of the bilateral intracarotid Sodium Amytal test was administered pre-operatively to 13 patients with intractable complex partial epileptic seizures, to determine cerebral hemisphere speech and memory. There were 6 patients with left temporal lobe lesions and 7 patients with right temporal lobe lesions. Amobarbital (175 mg, 10%), injected on 2 occasions, determined the left hemisphere to be speech dominant in all cases. Memory assessed with recall, cued recall, and recognition of concrete/abstract words and pictures, was studied on 3 occasions: in a baseline test considered to indicate the degree of patient cooperation and the bilateral hemisphere memory; in a right hemisphere Amytal test; and in a left hemisphere Amytal test. The specific data pattern obtained, that abstract pictorial information is most efficiently processed by an intact right hemisphere and that verbal information is processed best by an intact left hemisphere, demonstrates the reliability of the approach taken here to present abstract and concrete to be remembered information.

Adult↗
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↗