Regional relationships between focal hypofixation images in 123I-IMP single photon emission computed tomography and epileptic EEG foci in interictal periods in patients with partial epilepsy.

Single photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123)-p-iodoamphetamine were performed in interictal periods in 40 patients with partial epilepsies and normal X-ray CT findings, and the regional relationships between the SPECT abnormalities and interictal epileptic EEG foci were studied. Twenty-six patients (65%) had abnormal SPECT images consisting of one or more focal hypofixation images, i.e., zones of decreased regional cerebral blood flow, while the remaining 14 patients showed normal images. Nineteen (73%) of the 26 patients showed complete or partial regional agreement between the abnormal SPECT findings and the interictal epileptic EEG foci determined from EEGs recorded repeatedly during their clinical course, while the regional relationships with the EEG foci determined from the single EEG recorded just after the SPECT scans or a short interval after the scans showed a lower rate of agreement (13 of 21 patients, 61.9%). These results confirm the utility of SPECT scans in the regional diagnosis of epileptic foci.     

Reexamination of 123 I-IMP-SPECT at Interictal Stages in Adult Partial Epilepsy

¹²³I-ZMP-SPECT scans at the interictal stages in 13 epileptic patients with normal X-ray CT findings were reexamined at intervals of 1.9 ± 0.8 years. Interictal scalp EEGs were recorded a few hours after each SPECT scan. All of the SPECT abnormalities indicated focal hypo fixation images of ¹²³I-IMP, i.e. zones of a decreased rCBF reflecting a functional inactivation. Among 11 patients with the SPECT abnormalities in the first SPECTs, eight cases had the complete or partial regional reproduction of the abnormalities in the second SPECTs. As changes in the SPECT findings, an alteration from the abnormal SPECT images to     

High reproducibility of regional abnormalities on interictal123I-IMP SPECT brain scans in adults with partial epilepsy

Summary The reproducibility of twoN-isopropyl-(iodine 123)p-iodoamphetamine (¹²³I-IMP single photon emission computed tomography (SPECT) scans both taken during interictal periods was studied in 13 adult patients with partial epilepsy who had normal CT scans. The frequency of the seizures and the nature of the ictal symptoms were virtually unchanged during the interval between the two SPECT scans performed in each case. In 8 (72.7%) of 11 patients who had abnormal images consisting of focal hypofixation images of¹²³I-IMP, i.e. zones of decreased regional cerebral blood flow on the first scans, complete or partial regional reproduction of the SPECT abnormalities was observed. This high reproducbility supports the usefulness of SPECT scans in the regional diagnosis of epileptic foci.     

Paradoxical enhancement of hypoperfusion single photon emission CT images in epileptic focus with bemegride activation. Observation from subtraction of 99mTc hexamethyl-propyleneamine oxime brain single photon emission CT images.

Changes of brain images in single photon emission CTs (SPECTs) before and after intravenous injection of bemegride were examined with simultaneous EEG recording in a patient with occipital lobe epilepsy and in a hysteric patient, using a new method, i.e. subtraction of the SPECT images with 99mTc hexamethyl-propyleneamine oxime. The bemegride injection in the epileptic patient paradoxically intensified the hypoperfusion images as epileptic foci in SPECTs, associated with enhanced interictal epileptic discharges, whereas the hysteric showed no such effects. These findings suggest that the hypoperfusion images closely correlate to the severity of epileptic activity, reflecting a functional rather than a morphological deficit.     

The role of quantitative ictal SPECT analysis in the evaluation of nonepileptic seizures.

Nonepileptic seizures may represent difficult diagnostic problems. Identifying their presence and frequency is critical for determining appropriate treatment. The authors investigated the value of quantitative perfusion changes as measured by ictal single-photon emission tomography (SPECT) difference images in differentiating nonepileptic from epileptic seizures. Eleven patients with a clinical suspicion of nonepileptic events had ictal and interictal technetium-99m hexamethylpropylene amine SPECT scans during continuous audiovisual surface electroencephalogram (EEG) monitoring. The authors analyzed perfusion difference images based on registration, normalization, and subtraction of ictal and interictal SPECT images. The difference images were registered to each patient's magnetic resonance imaging scan to anatomically localize ictal perfusion changes. Three of 11 patients also carried the diagnosis of epilepsy and were taking antiepileptic medication. Five patients were taking antiepileptic drugs, but the diagnosis of epilepsy was not confirmed. In all patients, continuous video EEG monitoring revealed no ictal EEG findings. In nine of these patients, visual interpretation of ictal SPECT was suggestive of localized increased (n = 6) or decreased perfusion (n = 3). In all patients, however, no blood flow changes were noted on quantitative SPECT analysis with injections performed during the seizure-like event, suggesting the diagnosis of pseudoseizures. The authors' results suggest that quantitative ictal SPECT analysis is a useful tool in the diagnosis of nonepileptic seizures.     

Regional cerebral blood flow in relation to MRI and EEG findings in tuberous sclerosis.

To identify the focus of paroxysmal neuronal activity causing epilepsy in tuberous sclerosis (TS), the regional cerebral blood flow (r-CBF) in 19 patients with TS was assessed using single-photon emission computed tomography (SPECT) with I-123 iodoamphetamine (IMP), in correlation with serial interictal EEGs and organic changes observed on magnetic resonance imaging (MRI). There was a general irregularity of cortical IMP uptake and retention in TS, and two-thirds of the cerebral regions exhibiting high intensity in T2-weighted MRI images (cortical tubers) showed a decrease in r-CBF. In addition to in tubers, decreased r-CBF was observed in regions in which MRI was considered to indicate destruction of the normal cortex, atrophy or vascular abnormalities, although these areas did not consistently show epileptic changes in serial EEGs. Among the cortical regions which consistently showed epileptic foci in serial EEGs, none showed abnormal r-CBF without lesions on MRI. We conclude that IMP-SPECT is useful for visualizing the epileptogenic laterality in cases with bilateral MRI lesions and EEG epileptic changes, and to differentiate epileptogenic foci from electrophysiological propagated areas. However, regarding the severity of epilepsy, the MRI findings showed a better correlation than the IMP-SPECT findings did.     

Brain SPECT, CT and EEG in 45 cases of epilepsy during the intermission

The regional cerebral blood flows (rCBF) in 45 cases of epilepsy during the interictal period were determined with brain SPECT. The results were compared those obtained with CT scans and EEG. 48.89% of the SPECT were found to be abnormal while 8.98% were suspected to be abnormal; the 35.71% of the CT scans were found to be abnormal; 16 cases (39.02%) were found to show focal abnormalities in the EEG while 9 cases (21.95%) had epileptic form discharge. SPECT seemed to show more significance in discovering the abnormalities in the epileptics during the interictal period than CT or EEG. However, the combined use of these three methods of examinations would be of greater help for identifying the focal abnormalities in epilepsy. Two of the 22 cases with abnormal SPECT had increased rCBF, whereas the other 20 cases had decreased rCBF. Among the 22 cases of abnormal SPECT and 4 cases of suspected abnormalities, the locations of the lesions as indicated with SPECT in 3 cases were not consistent with those as with CT. There were 5 cases in which the SPECT findings were not consistent with those in EEG.     

Periictal SPECT localization verified by simultaneous intracranial EEG

PURPOSE: We investigated whether blood-flow changes measured by ictal or immediate postictal single photon emission computed tomography (SPECT) reflect with accuracy the actual location of ictal discharge as measured by simultaneous intracranial EEG. In addition, we evaluated the reliability of ictal SPECT obtained with implanted electrodes by comparing results with those of ictal SPECT performed during scalp EEG monitoring in selected patients. METHODS: Eleven patients with intractable partial epilepsy who had both ictal and interictal SPECT scans during invasive EEG monitoring were studied. We analyzed perfusion differences based on registration, normalization, and subtraction of periictal and interictal SPECT images. SPECT results were interpreted in relation to location and evolution of ictal EEG change, as reflected by simultaneous intracranial EEG. In five patients, we also compared ictal SPECT results that were obtained during both scalp and intracranial EEG monitoring. RESULTS: In 10 of 11 patients, localized increases or decreases in blood flow or both were identified in regions of ongoing or prior seizure discharge, respectively, at the time of SPECT brain perfusion. In one patient, SPECT localization could not be verified by the available electrode array. CONCLUSIONS: Localization of ictal discharge during or before SPECT injection accurately determines increase or decrease in perfusion, respectively, and both are of equal validity in reflecting the region of epileptic discharge. SPECT perfusion changes can be reliably obtained during intracranial monitoring.     

Interictal brain SPECT in patients with medically refractory temporal lobe epilepsy

The objective of this study was to evaluate the utility of interictal brain SPECT in localizing the epileptogenic focus in a population of patients of Epilepsy Clinic of Hospital Universitário Clementino Fraga Filho (HUCFF/UFRJ), with medically refractory temporal lobe epilepsy (TLE) and normal computed tomography (CT) scans, studying the correlation between SPECT, electroencephalogram (EEG) and, in 11 cases, brain magnetic resonance imaging (MRI), and to compare the results to the other six literature series. Twelve (52.2%) patients presented abnormal SPECT. Among these, five (41.6% of abnormal SPECTs) presented unilateral SPECT changes at the same side of EEG (hypoperfusion in four and hyperperfusion in one), three (25% of abnormal SPECTs) presented bilateral hypoperfusion and bilateral EEG changes too, and four (33.3%) presented unilateral hypoperfusion and bilateral EEG changes. The statistical analysis was based on fuzzy logic. The correlation index among SPECT X EEG, SPECT X MRI and SPECT X EEG X MRI were highly significant, with significance levels at 0.01, p < 0.0005 and trust interval at 99% in all correlations. The correlation studies between the series presented similar results.     

Time-course changes of regional cerebral blood flow by SPECT with N-isopropyl-p-[123I]-iodoamphetamine in childhood partial seizures]

Single photon emission computed tomography (SPECT) with N-isopropyl-p-[123I]-iodoamphetamine was performed twice at different times in 18 children suffering from partial seizures to evaluate the time-course changes of the hemodynamics in the focal region. Comparison of the 2 SPECT images revealed that a decreased regional cerebral blood flow (CBF) in the first was normalized in 4 cases (22.2%) and contracted in 7 cases (38.9%). The region of decreased blood flow in the second was contralateral to that in the first in 1 case (5.6%) and unchanged in 6 cases (33.3%). Most of the normalized and contracted cases were those in which clinical seizures disappeared and the EEG findings were normalized. In these cases which responded to treatment, the decreased regional CBF was also found to be improved. Repeated SPECT appears to be useful for evaluating the therapeutic efficacy. On the other hand, most of the unchanged cases were those in which clinical seizures were frequent or uncontrolled, or which persistently showed the abnormalities in their EEG. SPECT was considered to reflect well the conditions of the epileptic foci. These results indicate that repeated SPECT for observing the time-course changes of the regional CBF represents a useful technique with can be applied in evaluating the therapeutic efficacy or deciding the time to discontinue treatment and for pathogenetic elucidation of the epileptic foci.     

Ictal and interictal 99mTc-HMPAO-SPECT studies in temporal lobe epilepsy with unilateral EEG focus]

Ictal and interictal SPECT measurements using 99mTc-HMPAO are helpful in localising an epileptic focus. 24 patients (12 women and 12 men; mean age 30 years) suffering from temporal lobe epilepsies with unilateral EEG foci were examined. In all patients a presurgical evaluation including sphenoidal and foramen oval electrodes was carried out. The analysis of SPECT measurement was done visually and semi-quantitatively, comparing the data with findings in healthy persons (10 women and 10 men; mean age 24 years). The etiology of the epilepsy was confirmed by histological investigation in 16 cases, and by CT and MRI in 8 cases. The findings were gliosis in 6 cases, astrocytoma in 3 cases, cysts in 4 cases, and angioma in 3 cases. In 8 cases no pathological findings could be detected. In 46% of cases interictal SPECTs exhibited a focal hypoperfusion corresponding with the EEG-focus. In ictal SPECTs this could be found in 75% of cases. In all 10 patients without morphological findings or with gliosis (proved by histological investigations) a hyperperfusion coincident with the EEG-focus appeared in ictal SPECTs.     

Comparison of SPECT, EEG, CT, MRI, and pathology in partial epilepsy.

Twenty children with partial epilepsy who had surgery between the ages of 4 1/2 months and 18 years were studied preoperatively with electroencephalography (EEG), computed tomography (CT), and technetium-99m hexamethylpropyleneamineoxime 99mTc-HmPAO single photon emission computed tomography (SPECT; 20 interictal, 4 postictal). Fourteen had magnetic resonance imaging (MRI). All had an epileptiform focus (12 unilateral, 8 predominantly unilateral) on EEG. The combination of interictal and postictal regional cerebral blood flow (rCBF) abnormalities alone correlated with EEG foci in 16 of 20 patients. Interictal rCBF abnormalities correlated with EEG foci in 14 of 20. CT findings correlated with EEG foci in 14 of 20. MRI findings correlated with EEG foci in 13 of 14. Pathology demonstrated tumor in 6, cortical dysplasia in 4, mesial temporal sclerosis in 3, Sturge-Weber in 2, cavernous hemangioma in 1, Rasmussen encephalitis in 1, porencephalic cyst and gliosis in 1, and cysts found at surgery (but normal histology) in 2. Interictal and postictal SPECT, EEG foci, and CT findings each correlated with the pathology site in 17, 19, and 15 patients, respectively. MRI correlated with pathology site in 13 of 14 patients. Postictal and interictal abnormalities of rCBF correlated with EEG and pathology as frequently as CT. In 5 patients with normal CT scans and in 1 with a normal MRI, postictal and interictal rCBF correlated with EEG and pathology results; however, these 6 patients all had abnormalities on CT or MRI. SPECT, therefore, may be considered a valuable additional diagnostic procedure in the evaluation of epilepsy surgery candidates in that it adds to the evidence of abnormality at the involved site.(ABSTRACT TRUNCATED AT 250 WORDS)     

Imaging of propagated sites of epileptic discharges in repeated 123I-IMP SPECT scans

Single-photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123-p-iodoamphetamine (123I-IMP) were performed twice at an interval of about 2.5 years in the interictal period in an adult patient with occipital-lobe epilepsy. The first SPECT scan showed an abnormal image of decreased 123I-IMP uptake in the right occipital lobe. This abnormal image was regarded as the primary focus of his epilepsy on the basis of its regional agreement with right-occipital spikes consistently seen in interictal electroencephalographic recordings throughout his clinical history. In the second scan, he showed multiple abnormal images of decreased uptake in the right frontotemporal lobes and left occipital lobe together with the right occipital lobe. These additional abnormal images were considered to be propagated sites of epileptic discharges.     

Postictal SPECT in Epileptic Versus Nonepileptic Seizures

Despite advances in video-electroencephalogram (EEG) technology, in many patients distinguishing epileptic seizures from nonepileptic seizures (NES) remains a challenge. Reliable methods to make this distinction are needed. In a pilot study, we performed postictal and interictal single photon emission computed tomography (SPECT) in 22 patients undergoing video-EEG monitoring who had altered responsiveness during an episode. Eleven had seizures, defined as episodes associated with EEG seizure patterns or postictal prolactin (PRL) elevations greater than 1.5 times the highest interictal baseline PRL; 11 had NES. Among the 11 seizures, postictal SPECT was abnormal in seven (regions of hypoperfusion in six and hyperperfusion in one) and normal in four. In six cases (55%), the interictal and postictal SPECT changed. Among the 11 NES cases, postictal SPECT was abnormal in three cases (all hypoperfusion abnormalities) and normal in eight cases. In no case did the interictal and postictal SPECT change. This small sample revealed a trend toward greater hypometabolism (postictal versus interictal) on SPECT for epileptic seizures compared to NES (p < 0.12). There were postictal SPECT changes in two of five seizures unassociated with postictal PRL elevation. Prolactin was elevated in two cases unassociated with change on SPECT. Comparision of postictal to interictal SPECT may help distinguish epileptic seizures from NES. Results from SPECT may also help identify epileptic seizures unassociated with PRL elevation.     

Functional and morphological abnormalities in temporal lobe epilepsy: a comparison of interictal and ictal EEG,CT, MRI,SPECT and PET

Summary Ten patients suffering from drug-resistant complex partial seizures, with EEG abnormalities in the temporal region, were studied by means of non-invasive electrophysiological techniques (video-monitored, 16-channel, prolonged surface and sphenoidal EEG) as well as by imaging techniques (CT, MRI, SPECT and PET). Analysis of interictal and ictal EEG indicated the localization of epileptic activity in one side in eight cases. CT demonstrated focal abnormalities in three, SPECT in five unequivocally (in another four questionably, with the same lateralization as indicated by PET), MRI in eight, and PET in all cases. While only EEG provided specific diagnostic information, the focus definition was consistently good on PET images, poor on CT scans, and generally good but less consistent on MRI.     

Comparative utility of technetium-99m hexamethylpropylenamine oxime single photon emission computed tomography (SPECT) with anatomic neuroimaging and electroencephalography (EEG) in childhood intractable epilepsy

Intractable epilepsies pose a therapeutic challenge. Precise localization of the epileptic focus is imperative before planning surgical intervention. Functional imaging is an important component of presurgical work-up. Positron emission tomography is unavailable in developing countries; hence, the need to evaluate the available imaging modality, single photon emission computed tomography (SPECT), was felt. We investigated 61 children with intractable epilepsy, identified by predefined criteria, by performing electroencephalography (EEG), magnetic resonance imaging (MRI), computed tomography (CT), and ictal and interictal SPECT. The localizing value of ictal and interictal SPECT imaging for epileptic foci was correlated with clinical, electrophysiologic, and anatomic neuroimaging data. An ictal SPECT was obtained in 9, and interictal SPECT was performed in all (61). Ictal SPECT was localizing in 8 of 9 (88.8%). Interictal SPECT was localizing in a significantly higher proportion of patients (47.54%) than either the scalp EEG (16.39%) (P = .0003) or CT scan (21.56%) (P = .0046). Our data demonstrated that interictal and ictal SPECT identified more focal changes in children with intractable epilepsy than interictal EEG, CT, and probably MRI. The definitive proof of the SPECT-based findings being epileptogenic foci awaits correlation with intraoperative monitoring and postoperative follow-up.     

Correlation of abnormalities of interictal n-isopropyl-p-iodoamphetamine single-photon emission tomography with focus of seizure onset in complex partial seizure disorders

Single-photon emission tomography (SPECT) scanning with n-isopropyl-p-iodoamphetamine (IMP) was performed on 23 patients with complex partial seizures undergoing long-term video electroencephalographic (EEG) seizure monitoring. Twenty-one of the 23 patients had abnormalities on SPECT scanning consisting of areas of decreased activity reflecting diminished cerebral blood flow. In 15 of these 21 patients, there was good correlation between the site of the abnormality on SPECT scan and the site of origin of seizures monitored by EEG. Of the six remaining patients, four had multifocal SPECT abnormalities, with one of the abnormal areas corresponding with an ictal site. The two remaining patients had SPECT abnormalities and major ictal EEG foci in entirely different areas. In contrast to the high proportion of abnormal SPECT scans, only 10 of 23 focal abnormalities were discovered on magnetic resonance imaging (MRI) scans. Three patients who had seizures within 2 h of an initial scan were rescanned 4-5 h after injection. Focal areas of increased blood flow were noted on all three scans, although not always at the ictal site. The SPECT scan appears to be useful in interictal localization of seizure foci. Postictal scans may also be useful, although our numbers are too small to draw conclusions.     

Short-term plasticity of central benzodiazepine receptors in status epilepticus: case report

¹²³I-iomazenil SPECT is of value in determining an epileptogenic focus, however, transient uptake change has been rarely reported in epileptic disorders. A 78-year-old woman diagnosed as status epilepticus (SE) showed transient reduction in ¹²³I-iomazenil uptake within the epileptic foci on SPECT images during a couple of weeks. It suggests a seizure-related 'short-term' plasticity in the central benzodiazepine receptors and dynamic change in the regulatory mechanisms of inhibitory neurotransmitter system within the epileptic foci in patients with SE.     

Ictal and Interictal Single Photon Emission Computed Tomography in a Patient With Benign Familial Infantile Convulsions

Ictal and interictal single photon emission computed tomography (SPECT) and ictal electroencephalography (EEG) were studied in a 3-month-old girl with benign familial infantile convulsions (BFIC) to reveal the epileptic focus. There was bilateral diffuse propagation from a left frontal lobe focus on the ictal EEG. Perfusion in the left frontal region was increased on ictal SPECT and decreased on interictal SPECT. Epileptic foci of BFIC showed the same characteristics as foci of symptomatic partial epilepsy.     

Fluctuations of interictal brain imaging in repeated 123I-IMP SPECT scans in an epileptic patient

Summary Single photon emission computed tomography (SPECT) brain scans with N-isopropyl-(iodine 123) p-iodoamphetamine (¹²³I-IMP) were performed three times in interictal periods in a 35-year-old man with intractable frontal lobe epilepsy and normal X-ray CT findings. The first scan showed decreased ¹²³I-IMP uptake in the right frontal lobe. This abnormal image was regarded as the primary focus of his epilepsy on the basis of its regional agreement with focal epileptic discharges on EEGs. In the second scan, he showed normal imaging, while the third scan showed the same abnormal image as before, in the right frontal lobe. The frequency of his clinical seizures was almost unchanged during the intervals between scans and further EEGs recorded soon after each scan showed almost no changes in the basic activities and frequency of the epileptic discharges. Such fluctuations in SPECT brain imaging suggest that the severity of functional inactivation underlying the focal hypoperfusion image as an epileptic focus may fluctuate considerably in the interictal state with no relation to the clinical features of epilepsy.