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A Valavanis

Publications and source records attributed to A Valavanis.

At least 37 records · Page 2Linked to original sources
PubMed1999

Colour-coded Doppler sonographic study of the haemodynamics in the parent artery of intracranial aneurysms.

We investigated the haemodynamics in the parent artery of 17 small (< 9 mm) and 17 large (L 9.5 mm) saccular aneurysms by transcranial colour-coded Doppler sonography (TCCD) and related the findings to digital subtraction angiography (DSA). We measured flow velocity within the parent artery and, by positioning the Doppler gate within the colour flow image close to the ostium of the aneurysm, obtained a superselective Doppler spectral waveform. The parameters measured included the time-averaged maximal velocity (TAMX), peak systolic, and end-diastolic velocity and pulsatility index (PI). The values were compared to the contralateral side and between small and large aneurysms. DSA was analysed for parent artery stenosis. Mean systolic velocities in the parent arteries of large aneurysms were significantly higher than in the contralateral normal artery (1.08 +/- 0.23 vs 0.80 +/- 0.23 m/s; P = 0.0003) and higher than in the parent artery of small aneurysms (0.89 +/- 0.18 m/s; P = 0.01). Increased systolic velocity accounted for a higher PI in the parent artery of large aneurysms (mean 1.48 +/- 0.42) than on the other side (0.87 +/- 0.12; P = 0.0001) and in the parent artery of small aneurysms (0.85 +/- 0.14; P = 0.0001). PI proximal to seven thrombosed large aneurysms was higher (mean 1.85 +/- 0.38) than close to unthrombosed large aneurysms (1.23 +/- 0.22; P = 0.0005). Increased PI and systolic velocities could not be shown within branches of 5 large aneurysms and were reversible in the parent artery of four patients examined again after occlusion of the aneurysm. Systolic velocities and PI did not differ significantly (P = 0.41 and P = 0.25, respectively) in ruptured and unruptured aneurysms. Stenosis of the parent artery was not shown by DSA in any case.

Adult↗
PubMed1999

Clinical, angiographic, and sonographic findings after structured treatment of cerebral vasospasm and their relation to final outcomes.

OBJECTIVE: To report the early clinical results, quantitative angiographic and sonographic findings, and final outcome in patients with symptomatic vasospasm who had undergone surgical occlusion of the aneurysm and a structured protocol including aggressive intensive care management, endovascular procedures (EP), and barbiturate coma (BC). RESULTS: Thirty consecutive patients (19 women, 11 men, age: 51 +/- 8 years) underwent 38 EP for the treatment of 81 vascular territories (15 balloon dilatations and 66 papaverine infusions). Overall angiographic vasospasm in the intradural ICA improved significantly from 44.7 +/- 19.8% to 16.5 +/- 16%, in the MCA from 44.2 +/- 14.7% to 14.4 +/- 14%, and in the ACA from 38.7 +/- 18.6% to 13.3 +/- 12%. Mean flow velocities (Vm) in the MCA and ACA decreased significantly from 135 +/- 48 cm/sec to 87 +/- 32 cm/sec and from 110 +/- 36 cm/sec to 84 +/- 30 cm/sec, respectively. No significant Vm improvement in the ICA could be demonstrated. Six patients (20%) developed intractable vasospasm after repeated EP and five patients underwent BC. The correlation coefficient between percentage of angiographic vasospasm and Vm increase was -0.19 (p = NS) for the ICA, 0.2 (p < 0.001) for the MCA, and 0.3 (p < 0.05) for the ACA. Correlation coefficient between percentages of angiographic and sonographic improvement was -0.12 (p = NS) for the ICA, 0.42 (p < 0.001), and 0.1 (p < 0.05) for the ACA. Early clinical improvement after EP was observed in 73% of patients and was significantly associated with favourable outcome (GOS 4-5). Sixteen patients (53%) had a GOS 5, six patients (20%) a GOS 4, six patients (20%) a GOS 3, and two patients (6.6%) died as consequence of devastating vasospasm. CONCLUSIONS: Changes in vessel diameter and increases of Vm during vasospasm correlate weakly. In spite of the fact that significant differences in vessel diameter and Vm were demonstrated after treatment, a moderately good correlation between percentages of angiographic and Vm improvement was observed only in the M1 segments. In our experience, a reduction of mortality and disabilities can be achieved with a maximal structured treatment of vasospasm. Early clinical improvement after endovascular treatment is strongly associated with favourable outcome, nevertheless, cost-benefit and controlled trials are necessary to evaluate these techniques.

Adult↗
PubMed1999

Intraoperative validation of functional magnetic resonance imaging and cortical reorganization patterns in patients with brain tumors involving the primary motor cortex.

OBJECT: The purpose of the present study was to compare the results of functional magnetic resonance (fMR) imaging with those of intraoperative cortical stimulation in patients who harbored tumors close to or involving the primary motor area and to assess the usefulness of fMR imaging in the objective evaluation of motor function as part of the surgical strategy in the treatment of these patients. METHODS: A total of 11 consecutive patients, whose tumors were close to or involving the central region, underwent presurgical blood oxygen level-dependent fMR imaging while performing a motor paradigm that required them to clench and spread their hands contra- and ipsilateral to the tumor. Statistical cross-correlation functional maps covering the primary and secondary motor cortical areas were generated and overlaid onto high-resolution anatomical MR images. Intraoperative electrical cortical stimulation was performed to validate the presurgical fMR imaging findings. In nine (82%) of 11 patients, the anatomical fMR imaging localization of motor areas could be verified by intraoperative electrical cortical stimulation. In seven patients two or more activation sites were demonstrated on fMR imaging, which were considered a consequence of reorganization phenomena of the motor cortex: contralateral primary motor area (nine patients), contralateral premotor area (four patients), ipsilateral primary motor area (two patients), and ipsilateral premotor area (four patients). CONCLUSIONS: Functional MR imaging can be used to perform objective evaluation of motor function and surgical planning in patients who harbor lesions near or involving the primary motor cortex. Correlation between fMR imaging findings and the results of direct electrical brain stimulation is high, although not 100%. Based on their study, the authors believe that cortical reorganization patterns of motor areas might explain the differences in motor function and the diversity of postoperative motor function among patients with central tumors.

Adult↗
PubMed1999

Ramsay Hunt syndrome associated with brain stem enhancement.

Postcontrast T1-weighted MR images in a patient with Ramsay Hunt syndrome showed an enhancing lesion in the region of the nucleus of the pontine facial nerve and abnormal enhancement of the intrameatal, labyrinthine, and tympanic facial nerve segments and of the geniculate ganglion, as well as enhancement of the vestibulocochlear nerve and parts of the membranous labyrinth. This enhancement most probably resulted from a primary neuritis of the intrameatal nerve trunks of the seventh and eighth cranial nerves.

Brain Stem↗
PubMed1998

Clinical experience with endovascular treatment of aneurysms using Guglielmi detachable coils.

Guglielmi detachable coils (GDCs) provide an endovascular means for aneurysm treatment; however, their role has yet to be defined. This article reviews the most recent clinical series regarding efficacy, safety, and clinical outcomes in both the acute and nonacute setting. Successful treatment was possible in the majority of cases and included cases of complete aneurysm obliteration and with only a small neck remnant. Patients with a neck remnant often received additional treatments although some patients went on to complete obliteration without further treatment. Successful treatment provided protection from rebleeding in a follow-up period of 2 years. Success depended on operator experience as well as width of the aneurysm ostium. Recurrence and incomplete obliteration were more common with giant or large aneurysms and aneurysms with a wide base. Major procedure-related complications predominantly resulted from intraprocedural rupture and thromboembolic events. These could both be treated via endovascular means at the time of the procedure. Thromboembolic events occurred more frequently with acutely ruptured aneurysms, especially aneurysms with a wide base. Vasospasm rates were not found to vary significantly from those found in surgical series when corrected for Fisher grouping. Morbidity and mortality rates as well as Glasgow outcome scores were at least as good as what would be expected from surgery during both the acute and nonacute setting. The papers reviewed indicate that the GDC provides safe and efficacious treatment for most berry aneurysms in both the acute and nonacute setting relative to surgical results.

Journal Article↗
PubMed1998

A new correlation-based fuzzy logic clustering algorithm for fMRI.

Fuzzy logic clustering algorithms are a new class of processing strategies for functional MRI (fMRI). In this study, the ability of such methods to detect brain activation on application of a stimulus task is demonstrated. An optimization of the selected algorithm with regard to different parameters is proposed. These parameters include (a) those defining the pre-processing procedure of the data set; (b) the definition of the distance between two time courses, considered as p-dimensional vectors, where p is the number of sequential images in the fMRI data set; and (c) the number of clusters to be considered. Based on the assumption that such a clustering algorithm should cluster the pixel time courses according to their similarity and not their proximity (in terms of distance), cross-correlation-based distances are defined. A clear mathematical description of the algorithm is proposed, and its convergence is proven when similarity measures are used instead of conventional Euclidean distance. The differences between the membership function given by the algorithm and the probability are clearly exposed. The algorithm was tested on artificial data sets, as well as on data sets from six volunteers undergoing stimulation of the primary visual cortex. The fMRI maps provided by the fuzzy logic algorithm are compared to those achieved by the well established cross-correlation technique.

Algorithms↗
PubMed1998

The endovascular treatment of brain arteriovenous malformations.

Advances in superselective microcatheterization techniques, which took place in the past decade, established superselective endovascular exploration as an integral and indispensable tool in the pretherapeutic evaluation of brain AVMs. The strict and routine application of superselective angiography furthered our knowledge on the angioarchitecture of brain AVMs, including vascular composition of the nidus, types of feeding arteries and types and patterns of venous drainage. In addition, various types of weak angioarchitectural elements, such as flow-related aneurysms, intranidal vascular cavities and varix formation proximal to high-grade stenosis of draining veins, could be identified as factors predisposing for AVM rupture. A wide spectrum of secondary angiomorphological changes induced by the arteriovenous shunt of the nidus and occurring up- and downstream of the nidus have been identified as manifestations of high-flow angiopathy. These data help to better predict the natural history, understand the widely variable clinical presentation and to define therapeutic targets of brain AVMs. Correlation of the topography of the AVM as demonstrated by MR with the angioarchitecture as demonstrated by superselective angiography provided a system for topographic-vascular classification of brain AVMs, which proved very useful for patient selection and definition of therapeutic goals. This study showed, that 40% of patients with brain AVMs can be cured by embolization alone with a severe morbidity of 1.3% and a mortality of 1.3%. Part of theses patients can, however, be cured equally effective by microsurgery or radiosurgery. Which modality will be chosen for a particular patient will mainly depend on the locally available expertise and experience, but also on the preference of the patient following its comprehensive information about the chances for cure and the risks associated with each of these therapeutic modalities. Embolization has a significant role in the multimodality treatment of brain AVMs, by either enabling or facilitating subsequent microsurgical or radiosurgical treatment. Appropriately targeted embolization in otherwise untreatable AVMs represents a reasonable form of palliative treatment of either ameliorating the clinical condition of the patient or reducing the potential risk of hemorrhage. Regarding the practical aspects of the endovascular treatment the following conclusions could be drawn from the experience obtained with this series of 387 patients with a brain AVM: (1) The goal of endovascular treatment should be defined prior to the procedure. This does not preclude a change in the goal, if additional information obtained during the procedure make this necessary. (2) The result of endovascular treatment of a brain AVM in terms of the degree of obliteration achieved and complication rate depends mainly on the endovascular strategy developed and the technique applied. These depend on the specific angioarchitecture and topography of the individual AVM, on the past history and clinical presentation of the patient and on the predefined goal of embolization. The strategy should include the definition of embolization targets, the selection of the most appropriate approach for endovascular navigation, the determination of the sequence of catheterization of individual feeding arteries, the selection of the type of catheters and microcatheters, the selection of the appropriate embolic materials as well as the site and mode of their delivery. Thereafter, every endovascular move should be, as in a chess game, the result of a logical plan. (3) Atraumatic superselective microcatheterization is a key point in the endovascular treatment of brain AVMs. It requires manual skills, knowledge of anatomy and respect for the vascular wall. (4) All locations of brain AVMs should be regarded as eloquent, and no distinction should be made between eloquent and non-eloquent areas of the brain when deciding on the execution of embolizatio

Adolescent↗
PubMed1998

Selective amobarbital test for the determination of language function in patients with epilepsy with frontal and posterior temporal brain lesions.

PURPOSE: Selective amobarbital tests with selective temporary inactivation of the left frontal operculum and/or the left parietotemporal cortex were performed in 5 patients with left-hemispheric epileptogenic lesions in or adjacent to classical Broca's and/or Wernicke's area. The aim was to assess language functions in these brain regions before surgery, to tailor the surgery according to the individual functional importance of these brain regions, and to predict postoperative outcome. METHODS: Amobarbital was injected by transfemoral selective catheterization of the arteries supplying the target areas. Along with neuropsychological and neurological testing during the amobarbital procedure, EEG recordings were performed in all patients, and [99mTc]HMPAO-single photon emission computed tomography (SPECT) in 2 patients. RESULTS: After the amobarbital injection into the left frontal opercular region, there was no recognizable language dysfunction in 3 patients. In these 3 patients, the lesions in or adjacent to the frontal operculum were completely resected without postoperative language impairment. In the remaining 2 patients, temporary language impairment after the amobarbital injection into the left frontoopercular and Wernicke's region, respectively, suggested language functions in these areas. Surgery was restricted to the left mesiotemporal lobe in 1 patient. In the other patient, the tumor infiltrating the frontal operculum was restrictively resected. Postoperatively, the first patient had no language impairment, but the latter had transient global aphasia, from which she recovered. CONCLUSIONS: Selective temporary amobarbital inactivation of brain regions that may be associated with language has clearly indicated the presence or absence of language functions in these regions. The test contributed substantially to planning of the surgical approach in each patient. The predictive value of the amobarbital test was demonstrated by the postoperative outcome.

Adolescent↗
PubMed1998

Improvement of cerebral oxygenation patterns and metabolic validation of superselective intraarterial infusion of papaverine for the treatment of cerebral vasospasm.

OBJECT: The purpose of the present study was to assess cerebral oxygenation patterns and brain lactate concentration changes before, during, and after intraarterial infusion of papaverine with or without balloon angioplasty in patients with symptomatic vasospasm. METHODS: A total of 23 vascular territories were successfully treated in 10 patients. In three patients balloon angioplasty was performed before the papaverine infusion. Continuous monitoring of jugular bulb vein oxygen saturation with a fiberoptic catheter and blood sampling allowed the assessment of the cerebral arteriovenous oxygen and lactate differences. A significant and rapid improvement in jugular bulb oxygen saturation was observed in all cases, with critical values reflecting an improvement in cerebral oxygenation after endovascular treatment of vasospasm (p = 0.005). Lactate concentration in the jugular bulb normalized within 4 hours in all patients who had evidence of brain lactic acidosis before superselective intraarterial infusion of papaverine. Recurrence of abnormal metabolic and oxygenation patterns were observed in one case in which an optimal hypertension and hypervolemic therapy could not be achieved after the procedure. CONCLUSIONS: Improvement in cerebral oxygenation as well as prevention of cerebral lactic acidosis can be successfully achieved after intraarterial infusion of papaverine. Normalization of the oxygen supply after endovascular treatment has to be supported by optimal and well-monitored hypertension and hypervolemic hemodilution.

Acidosis, Lactic↗
PubMed1998

Functional evaluation using magnetic resonance imaging of the visual cortex in patients with retrochiasmatic lesions.

OBJECT: The goal of this study was to evaluate the clinical potential of combining functional magnetic resonance (fMR) imaging with conventional morphological MR imaging and to assess its usefulness for objective evaluation of visual function as part of treatment planning in patients harboring space-occupying lesions involving the posterior afferent visual system. METHODS: It was hypothesized that regional activation of the visual cortex during visual stimulation would show an asymmetric response consistent with the well-known retinotopical organization of the human visual cortex. To test this hypothesis, the pattern of regional cortical activity detected by fMR imaging during binocular repetitive photic stimulation (10 Hz) was compared with the findings of conventional visual field testing. Functional mapping of the visual cortex was performed using a noninvasive blood oxygen level-dependent MR technique in 10 patients with intraaxial and two with extraaxial lesions. Experiments involving two of the patients were unsuccessful because of motion artifacts. In all the remaining patients functional activity was demonstrated in the primary visual area that corresponded to the anatomical location of the calcarine cortex. In nine patients, the identified patterns of activation in the visual cortex were consistent with the visual field deficits (seven homonymous hemianopsias, one homonymous central scotoma, and one inferior quadrantanopsia) and with the traditional teaching of retinotopical representation. Discordance between fMR imaging and perimetric findings was observed in one case. CONCLUSIONS: These results demonstrate that fMR imaging can be performed routinely and successfully in patients with visual abnormalities as part of a conventional neuroradiological evaluation. The technique provides essential information about the function-structure relationship specific to an individual patient and holds promise not only for diagnosis and therapy planning, but also for understanding the topography and functional specialization of the human visual cortex.

Adult↗
PubMed1998

T2-weighted three-dimensional fast spin-echo MR in inflammatory peripheral facial nerve palsy.

PURPOSE: Our objective was to identify histologically and intraoperatively verified focal nerve thickening of the distal intrameatal segment on three-dimensional fast spin-echo (FSE) T2-weighted MR images as a new diagnostic criterion in patients with inflammatory peripheral facial nerve palsy. METHODS: Twenty-two patients with clinically diagnosed unilateral (n = 20) or bilateral (n = 2) inflammatory peripheral facial nerve palsy were examined on a 1.5-T MR imager using noncontrast and contrast-enhanced T1-weighted SE sequences and 3-D T2-weighted FSE sequences with secondary reformations. Abnormal contrast enhancement and possible focal nerve thickening of the distal intrameatal segment, labyrinthine nerve segment, and geniculate ganglion region were analyzed prospectively. RESULTS: In all patients, the T1-weighted postcontrast SE images showed characteristic smooth, linear, abnormally intense contrast enhancement of the distal intrameatal segment, indicating peripheral inflammatory nerve palsy. In 23 nerves (96%) a focal bulbous nerve thickening of the distal intrameatal segment was observed on 3-D T2-weighted FSE images. In 100% of patients with peripheral inflammatory facial nerve palsy, postcontrast T1-weighted SE images showed a smooth, linear, and abnormally intense contrast enhancement of the distal intrameatal segment; reformatted very thin 3-D T2-weighted FSE images showed a focal bulbous nerve thickening of the distal intrameatal segment in 96% of patients. These findings corresponded to intraoperative and histologic findings. CONCLUSION: Three-dimensional T2-weighted FSE sequences are fast and cheap compared with T1-weighted postcontrast images, but secondary reformations are time-consuming and require exact anatomic knowledge for careful analysis of the different nerve segments.

Adolescent↗
PubMed1998

Tributary venosinus occlusion and septic cavernous sinus thrombosis: CT and MR findings.

PURPOSE: In autopsy reports of patients who died of septic cavernous sinus thrombosis, tributary venosinus occlusion has been a common finding related to intracranial inflammatory complications. The purpose of this article is to illustrate the MR and CT appearance of septic cavernous sinus thrombosis and tributary venous occlusion. METHODS: Over a period of 7 years, eight patients with septic cavernous sinus thrombosis were examined by contrast-enhanced thin-section CT. The CT scans of these eight patients and those of 30 healthy control subjects were assessed independently and subjectively by two blinded readers to ascertain the presence, size, and density of areas of nonopacification within the cavernous sinus and the presence of filling defects and dilation of tributary veins and venous sinuses. In six subjects, MR images supplemented by a contrast-enhanced spoiled gradient-recalled acquisition in the steady state (SPGR) sequence were assessed with respect to the presence of filling defects, expansion, and signal abnormalities within the cavernous sinus and tributary veins and sinuses. The MR and CT findings were compared. RESULTS: The CT studies of the eight patients were consistently differentiated from those of the control subjects by the two readers. Contrast-enhanced CT findings in patients included areas of nonopacification that were present within the cavernous sinus bilaterally in six cases and unilaterally in two. The size of the filling defects exceeded 7 mm in 76% of thrombosed cavernous sinuses compared with 9% of control subjects. The mean density of filling defects in patients differed significantly from those in control subjects. Comparison of the MR and CT findings in six cases showed the contrast-enhanced SPGR sequence to be equivalent to CT with respect to delineation of filling defects. CONCLUSION: Contrast-enhanced high-resolution CT findings indicate that venosinus thrombosis associated with septic cavernous sinus thrombosis is not restricted to the superior ophthalmic vein and is more common than previously assumed. A contrast-enhanced SPGR MR sequence may be used as a reliable alternative to establish the diagnosis of cavernous sinus and tributary venosinus thrombosis.

Adolescent↗
PubMed1998

Transcranial color-coded Doppler sonography of intracranial aneurysms before and after endovascular occlusion with Guglielmi detachable coils.

BACKGROUND AND PURPOSE: Our purpose was to evaluate the ability of transcranial color-coded Doppler sonography (TCCD) to 1) identify Guglielmi detachable coils (GDCs) within intracranial aneurysms, 2) show endovascular aneurysmal occlusion and patency of parent and branch arteries, 3) determine the flow velocities within parent arteries and major branches before and after treatment, and 4) assess persistence of aneurysmal occlusion. METHODS: The sonographic appearance of GDCs was established experimentally by TCCD (2 to 2.5 MHz), which was then performed in 40 patients with 43 aneurysms occluded by GDCs. The patency of parent arteries and major branches was assessed qualitatively and compared with the immediate posttherapeutic angiographic appearance in every patient. Flow velocities were selectively measured and compared before and after treatment in 21 parent arteries and 24 major branches. Follow-up TCCD studies performed in 26 patients were compared with angiographic (16 cases) and MR angiographic (10 cases) findings for signs of recanalization of the treated aneurysms. RESULTS: The GDCs were identified experimentally and in the patients as hyperechoic structures of the size and shape, and in the location of, the treated aneurysm in 41 of 43 cases. TCCD in accordance with angiography showed a lack of flow in 42 aneurysms and the presence of flow signal in one large aneurysm. Patency of the parent artery was shown in 40 aneurysms and in all branches. Follow-up TCCD showed the coils unchanged in 23 of 26 cases. In three large aneurysms, TCCD indicated recanalization and reappearance of a flow signal separate from the parent artery. CONCLUSION: TCCD is a reliable, noninvasive means to assess parent artery and major branch patency and to reveal a lack of hemodynamic compromise in the vicinity of aneurysms after endovascular therapy. On follow-up examinations, TCCD was able to detect signs of aneurysmal recanalization.

Adolescent↗
PubMed1997

[False aneurysm in Behçet's syndrome].

HISTORY AND CLINICAL FINDINGS: A 32-year-old man developed acute right-sided sore throat, a thick voice and epistaxis. 13 years previously he had erythema nodosum, 12 and 10 year ago deep vein thrombosis. On admission he had Horner's syndrome, bulging of the gums and swelling of the paratracheal space. He had been on anticoagulation therapy with phenprocoumon since the leg vein thrombosis. INVESTIGATIONS: Computed tomography demonstrated a false aneurysm of the right internal carotid artery. 9 months later a right radial artery aneurysm occurred, which was treated surgically. An arterial cannula had previously been placed at this site for pressure monitoring. 2 months later a false aneurysm of the right femoral artery was diagnosed: it had previously been used for an intravascular intervention. As embolization to the popliteal artery occurred after sonographically controlled compression had failed and reduction of anticoagulation treatment, this aneurysm, too, was treated surgically. DIAGNOSIS, TREATMENT AND COURSE: Because of the tendency to aneurysm formation after arterial puncture and the history of venous thromboses the diagnosis of Behçet's syndrome was considered, confirmed by subsequently elucidated history of recurrent oral aphthous ulcers and folliculitis. There were no other manifestations of the syndrome. Immunosuppressive treatment was instituted after another two aneurysm recurrences were noted in the right common femoral artery. CONCLUSIONS: This case illustrates that the diagnosis of Behçet's syndrome may be made more difficult if its manifestation is primarily vascular with minimal mucocutaneous involvement. It should be considered in the differential diagnosis of recurrent arterial aneurysms in a young person.

Adult↗
PubMed1997

The anterior and posterior selective temporal lobe amobarbital tests: angiographic, clinical, electroencephalographic, PET, SPECT findings, and memory performance.

The techniques, results, and problems of three types of selective temporal lobe (TL) amobarbital procedures (balloon technique with temporary occlusion of the internal carotid artery distal to the origin of the anterior choroidal artery (acha) [n = 19]; selective anterior catheterization of the acha [n = 20]; and selective catheterization of the peduncular P2-segment of the posterior cerebral artery [n = 5]) are described in a group of 40 patients with medically refractory complex partial seizures of mesial TL origin. Selective amobarbital tests were carried out before surgery to predict the memory deficit after an intended selective amygdalohippocampectomy. The effects of selective anaesthetization of TL were correlated with clinical data, pattern and duration of amobarbital induced EEG changes, and performance on verbal and nonverbal memory tasks measured during the test. In 4 patients the effect of selective amobarbital injection on regional and global metabolism was studied with 18F-FDG-PET, with the PET tracer being injected intravenously immediately after amobarbital. More recently in 2 patients the vascular territory perfused by amobarbital in the acha test was studied with SPECT using 99m Tc ECD injected immediately prior to the amobarbital into the acha. Whereas the PET studies showed a rather widespread and bilateral amobarbital-induced decrease of metabolism, the SPECT studies confirmed the selective distribution of the tracer in the vascular territory of the acha, i.e., in amygdala and hippocampus. The comparison of selective TL amobarbital test performance with postoperative neuropsychological performance showed that the predictive value of this test is rather good for the postoperative verbal memory but underestimates postoperative nonverbal ("figural") memory performance.

Adult↗
PubMed1997

Cerebral metabolic changes (18F-FDG PET) during selective anterior temporal lobe amobarbital test.

Cerebral glucose utilisation using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) was measured in 4 patients with temporal lobe epilepsy during a selective anterior temporal lobe (TL) amobarbital test (ATLAT) and compared with their baseline values. 18F-FDG was injected intravenously immediately after administration of amobarbital into the anterior choroidal artery (acha) in the case of the superselective ATLAT and into the territories of acha, posterior communicating artery, and ophthalmic artery in the case of the ATLAT using the temporary balloon occlusion technique. A decrease in glucose uptake as a result of amobarbital application was observed in ipsilateral temporolateral (4 patients), ipsilateral temporomesial (2 patients) and bilateral frontolateral (1 patient) cortices. All patients showed decreased glucose uptake in contralateral temporolateral regions. Cerebellar diaschisis was observed in 2 patients. In conclusion, although aimed at selective inactivation of the mesiobasal TL structures, the ATLAT does not result in exclusive selective glucose hypometabolism of these structures. Relatively widespread ipsilateral and contralateral effects were observed suggesting local and remote metabolic deafferentation. No association was observed between the glucose uptake, clinical or memory performance.

Adolescent↗
PubMed1997

MR differentiation of adamantinous and squamous-papillary craniopharyngiomas.

PURPOSE: To determine MR criteria for differentiating adamantinous from squamous-papillary craniopharyngiomas. METHODS: The MR imaging features of 42 histologically proved craniopharyngiomas (25 adamantinous, 15 squamous-papillary, and two mixed subtypes) were examined with multiplanar T2-weighted and noncontrast and contrast-enhanced T1-weighted imaging. Differences in the mR features of both subtypes were evaluated retrospectively. RESULTS: The adamantinous craniopharyngioma is a mixed solid-cystic or mainly cystic lobulated suprasellar or intrasellar/suprasellar tumor occurring in children and adults, typically with large nonenhancing hyperintense cysts on T1-weighted images. The squamous-papillary craniopharyngioma is a predominantly solid or mixed solid-cystic suprasellar tumor occurring in adults, appearing as a hypointense cyst on noncontrast T1-weighted images. Calcifications and recurrent tumors are more often observed in adamantinous tumors but can be seen in squamous-papillary tumors as well. Statistically significant parameters useful for differentiating the two tumor subtypes are the encasement of vessels, the lobulated shape, and the presence of hyperintense cysts in adamantinous tumors, and the round shape, the presence of hypointense cysts, and the predominantly solid appearance in squamous-papillary tumors. CONCLUSION: Craniopharyngiomas can be divided into two clinically, histologically different subtypes, which suggests a different pathogenesis of these two types of tumor.

Adolescent↗