technetium-tc-99m-exametazime and Seizures

Generalized seizures are commonly thought to involve the entire brain homogeneously. However, recent evidence suggests that selective cortical-subcortical networks may be crucial for the initiation, propagation, and behavioral manifestations of generalized seizures, while other brain regions are relatively spared. Here we review previous studies, and describe a new human model system for the investigation of generalized seizures: single-photon emission computed tomography, ictal-interictal difference imaging of generalized tonic-clonic seizures induced by electroconvulsive therapy (ECT). Bitemporal ECT activates focal bilateral frontotemporal and parietal association cortex, sparing other regions; bifrontal ECT activates mainly prefrontal cortex; while in right unilateral ECT the left frontotemporal region is relatively spared. Associated midline subcortical networks are also involved. Focal verbal memory deficits parallel the focal regions involved in these neuroimaging studies. Further studies of this kind may elucidate specific networks in generalized tonic-clonic seizures, providing targets for new therapeutic interventions in epilepsy.

Topics: Brain Mapping; Cerebral Cortex; Electroconvulsive Therapy; Electroencephalography; Functional Laterality; Humans; Nerve Net; Regional Blood Flow; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed; Tomography, Emission-Computed, Single-Photon

A case of transethmoidal meningocele presenting seizure attack is reported. A 59-year-old man was admitted to our hospital because of seizure attack. On admission, he was neurologically free without right olfactory dysfunction. T2-weighted image of MRI showed high intensity signal area in right frontal base, and this signal increase herniated into the ethmoidal sinus. Then 3 DCT image clearly showed right frontal base bony defect. After admission, we compared brain activity in this patient during a seizure attack and resting state using SPECT. And we found increased activity in right frontal base using 99mTc HM-PAO. So it was suspected that indicated the focus of the seizure. During the operation a unilateral bony defect and hypoplastic olfactory nerve were observed, but there was no herniated brain tissue. The association of seizure with frontobasal meningoencephalocele is reported only two cases. In one of two cases, it is presumed that reactive gliosis was epileptogenesis. On the other hand, the relationship of the temporal meningoencephalocele to the genesis of temporal lobe seizure is suggested by the extension of gliosis to the amygdalohippocampal lesion. In our case, it is possible that reactive gliosis or scar of the cyst wall may be the focus of seizure. In terms of diagnosis, 3 DCT is useful to identify the bony defect. It makes easy to diagnose the front-basal encephaloceles.

Topics: Ethmoid Sinus; Humans; Male; Meningocele; Middle Aged; Radiopharmaceuticals; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

We studied clinical and ictal single-photon emission computed tomography (SPECT) features in 14 patients with parietal lobe epilepsy, nine of whom had structural parietal lobe lesions. Thirteen patients had simple partial seizures of somatosensory (eight), psychic (four), and motor (nine) types. Complex partial seizures (CPS) occurred in seven patients; six were psychoparetic (prominent staring, relative immobility) and one had hyperkinetic activity. Seizures lasted 7 to 110 seconds; 99mTc-HMPAO (hexamethylpropylene amine oxime) was injected ictally, 7 to 89 seconds from seizure onset and 0 to 74 seconds (mean, 21.0 +/- 24.4 seconds) before seizure termination. Ictal SPECT demonstrated focal areas of parietal hyperperfusion in all 14 cases and corresponded with sites of the structural lesions. Parietal hyperperfusion was anterior in eight, posterior in four, and diffuse in two. Quantitative analysis revealed increases in parietal side-to-side perfusion ratios on ictal compared with interictal scans of 11 to 51% (mean, 25.5 +/- 14.4%). Ictal SPECT localization correlated with two main clinical seizure patterns: an anterior syndrome characterized by sensorimotor manifestations and a posterior syndrome characterized by CPS of the psychoparetic type. Ictal SPECT is helpful for localization of parietal seizures. Parietal hyperperfusion is discrete and short-lived, demanding true ictal injections for diagnostic studies.

Topics: Adolescent; Adult; Brain Mapping; Epilepsies, Partial; Female; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Parietal Lobe; Posture; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

This retrospective study investigates the predictive value of ictal subtraction single-photon emission computed tomography (SPECT) co-registered to magnetic resonance imaging (MRI) (SISCOM) for successful epilepsy surgery.. 57 patients examined with SISCOM as a part of epilepsy surgery evaluation were divided into two groups based on seizure duration after tracer injection (group 1: Seizure duration above or equal to 30 s, group 2: Seizure duration under 30 s). SISCOM was compared to the surgical site and categorized as good or poor concordance. Subsequently, Odds ratios (ORs) and positive predictive values (PPVs) were calculated for each group for good surgical outcome, freedom from disabling seizures.. The PPVs and ORs for good surgical outcome was 74.1% and 5.71 for group 1 and 40% and 0.22 for group 2. SISCOM had a similar positive predictive value regardless of whether the focus was in the same or neighboring lobe, but same hemisphere as the resection.. In conclusion, the implementation of a precise definition for a well-executed ictal SPECT scan with respect to seizure duration after injection enhances the positive predictive value (PPV) and odds ratio (OR) for successful surgical outcome, surpassing previous findings, whether the focus in resected lobe or the neighboring.

Topics: Epilepsy; Humans; Retrospective Studies; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Single-photon emission computed tomography (SPECT) with the tracer. Fifty-six patients operated for epilepsy who had been investigated with SISCOM were included in the analysis. The patients were divided into two groups based on seizure duration after tracer injection, above or below 30 s. The preoperative SISCOM description was compared to the area of resection and given a concordance score. The 56 SISCOM were recalculated visualizing also areas of hypoperfusion and again compared to the site of resection using the same scale of concordance. The reversed SISCOM were categorized into three subgroups: "Altered Conclusion," "Confirmed Conclusion," and "Adds Nothing." If an area of hyperperfusion had an area of hypoperfusion in close proximity, it was re-interpreted as noise, thus possibly altering the conclusion. If the areas of hypoperfusion were in the opposite hemisphere it was interpreted as confirming factor. Further the concordance scores from conventional SISCOM and reversed SISCOM was compared to surgical outcome to explore the difference in sensitivity, positive predictive value (PPV), and odds ratio.. In approximately half of the cases reversed SISCOM added additional value, meaning either altered the conclusion or confirmed the conclusion. The sensitivity, PPV, and odds ratio was also better in the subgroup of long, >30 s seizure duration after injection, and got worse in the group with short, <30 s seizure duration after injection.. Adding reversed SISCOM performed better than conventional SISCOM at predicting good surgical outcome.

Topics: Epilepsy; Humans; Retrospective Studies; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Ictal brain perfusion SPECT with the tracer 99mTc-HMPAO or 99mTc-ECD is widely used for identification of the epileptic seizure onset zone (SOZ) in presurgical evaluation if standard pointers are uncertain or inconsistent. For both tracers, there are theoretical arguments to favor it over the other for this task. The aim of this study was to compare the performance of ictal brain perfusion SPECT between 99mTc-HMPAO and 99mTc-ECD in a rather large patient sample.. The study retrospectively included 196 patients from clinical routine in whom ictal perfusion SPECT had been performed with stabilized 99mTc-HMPAO (n = 110) or 99mTc-ECD (n = 86). Lateralization and localization of the SOZ were obtained by the consensus of 2 independent readers based on visual inspection of the SPECT images.. The 99mTc-HMPAO group and the 99mTc-ECD group were well matched with respect to age, sex, age at first seizure, duration of disease, seizure frequency, history of previous brain surgery, and findings of presurgical MRI. The proportion of lateralizing ictal SPECT did not differ significantly between 99mTc-HMPAO and 99mTc-ECD (65.5% vs 72.1%, P = 0.36). Sensitivity of ictal perfusion SPECT (independent of the tracer) for correct localization of the SOZ in 62 patients with temporal lobe epilepsy and at least worthwhile improvement (Engel scale ≤ III) 12 months after temporal epilepsy surgery was 63%.. This study does not provide evidence to favor 99mTc-HMPAO or 99mTc-ECD for identification of the SOZ by ictal perfusion SPECT.

Topics: Brain; Cysteine; Electroencephalography; Humans; Organotechnetium Compounds; Perfusion; Retrospective Studies; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Medial temporal lobe epilepsy (MTLE) is associated with limbic atrophy involving the hippocampus, peri-hippocampal and extra-temporal structures. While MTLE is related to static structural limbic compromise, it is unknown whether the limbic system undergoes dynamic regional perfusion network alterations during seizures. In this study, we aimed to investigate state specific (i.e. ictal versus interictal) perfusional limbic networks in patients with MTLE.. We studied clinical information and single photon emission computed tomography (SPECT) images obtained with intravenous infusion of the radioactive tracer Technetium- Tc 99 m Hexamethylpropyleneamine Oxime (Tc-99 m HMPAO) during ictal and interictal state confirmed by video-electroencephalography (VEEG) in 20 patients with unilateral MTLE (12 left and 8 right MTLE). Pair-wise voxel-based analyses were used to define global changes in tracer between states. Regional tracer uptake was calculated and state specific adjacency matrices were constructed based on regional correlation of uptake across subjects. Graph theoretical measures were applied to investigate global and regional state specific network reconfigurations.. A significant increase in tracer uptake was observed during the ictal state in the medial temporal region, cerebellum, thalamus, insula and putamen. From network analyses, we observed a relative decreased correlation between the epileptogenic temporal region and remaining cortex during the interictal state, followed by a surge of cross-correlated perfusion in epileptogenic temporal-limbic structures during a seizure, corresponding to local network integration.. These results suggest that MTLE is associated with a state specific perfusion and possibly functional organization consisting of a surge of limbic cross-correlated tracer uptake during a seizure, with a relative disconnection of the epileptogenic temporal lobe in the interictal period. This pattern of state specific shift in metabolic networks in MTLE may improve the understanding of epileptogenesis and neuropsychological impairments associated with MTLE.

Topics: Adult; Child; Child, Preschool; Demography; Epilepsy, Temporal Lobe; Humans; Infant; Middle Aged; Nerve Net; Perfusion; Radionuclide Imaging; Seizures; Technetium Tc 99m Exametazime; Young Adult

Patients who have seizure onset from different brain regions can produce seizures that appear clinically indistinguishable from one another. These clinically stereotypic manifestations reflect epileptic activation of specific networks. Several studies have shown that ictal perfusion single photon emission computed tomography (SPECT) can reveal propagated ictal activity. We hypothesize that the pattern of hyperperfusion may reflect neuronal networks that generated specific ictal symptomatology.. All patients were identified who were injected with (99m)Tc-hexamethyl-propylene-amine-oxime (HMPAO) during versive seizures (n = 5), bilateral asymmetric tonic seizures (BATS; n = 5), and hypermotor seizures (n = 7) in the presurgical epilepsy evaluation between 2001 and 2005. The SPECT ictal–interictal difference image pairs of each subgroup were compared with image pairs of 14 controls using statistical parametric mapping (SPM 2) to identify regions of significant hyperperfusion. Hyperperfused regions with corrected cluster-level significance p < 0.05 were considered significant.. We have identified a distinct ictal perfusion pattern in each subgroup. In versive seizure subgroup, prominent hyperperfusion was present in the frontal eye field opposite to the direction of head version. In addition, there was associated caudate and crossed cerebellar hyperperfusion. The BATS subgroup showed pronounced hyperperfusion supplementary sensorimotor area ipsilateral to the epileptogenic region, bilateral basal ganglia, and contralateral cerebellar hemisphere. The hypermotor seizure subgroup demonstrated two clusters of significant hyperperfusion: one involving bilateral frontomesial regions, cingulate gyri, and caudate nuclei, and another involving ipsilateral anteromesial temporal structures, frontoorbital region, insula, and basal ganglia.. We have identified distinct hyperperfusion patterns for specific ictal symptomatology. Our findings provide further insight into understanding the anatomic basis of seizure semiology.

Topics: Adolescent; Adult; Brain; Brain Mapping; Cerebral Cortex; Child; Electroencephalography; Epilepsy, Partial, Motor; Female; Functional Laterality; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Male; Neurosurgical Procedures; Regional Blood Flow; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Aged; Aged, 80 and over; Benzodiazepines; Brain; Cerebrovascular Circulation; Female; Humans; Radiopharmaceuticals; Seizures; Substance Withdrawal Syndrome; Suicide, Attempted; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

The uncoupling between brain perfusion and metabolism was evaluated as a potential tool for seizure localization by creating an interictal SPET divided by interictal PET functional ratio-image and by evaluating its sensitivity and specificity to areas subsequently surgically resected. The uncoupling between brain perfusion and metabolism was evaluated through the creation of a functional SPET/PET ratio-image relying on interictal single-photon emission computed tomography (SPET) and positron emission tomography (PET) scans in epilepsy patients. The uncoupling of these two physiological brain functions has been demonstrated to be a characteristic of epileptogenic tissue in temporal lobe epilepsy and could potentially serve as a diagnostic measure for localization of seizure onset areas in the brain. The accuracy of hemispheric localization, sensitivity, and specificity of perfusion to metabolism ratio-images were evaluated as compared to standard methods of PET reading.. Interictal HMPAO-SPET and FDG-PET scans were obtained from 21 patients who then went on to remain seizure free for a minimum of 1 year post surgical resection. Using Statistical Parametric Mapping (SPM2), the SPET and PET scans were spatially registered and spatially normalized to a standard template (geometric warping). A functional image was created by calculating the ratio of perfusion to metabolism. Discrete areas of uncoupling in the ratio-images were selected, quantified, and compared to visually interpreted PET readings as well as the actual site of subsequent surgical resection. Localization was determined by comparing the hemispheric location of these areas to sites of surgical resection. Sensitivity and specificity of ratio-images and PET readings were calculated by dividing the brains into four sections per hemisphere.. When compared to known sites of successful surgical resection, the pre-surgical visually interpreted PET readings had a correct hemispheric localization in 69.6% of cases, while the regions of uncoupling selected in the pre-surgical ratio-images had a correct hemispheric localization of 82.6%. In addition, the regional sensitivity of visually interpreted PET readings was 63.0% with a specificity of 95.7%, while the sensitivity of the ratio-images was 68.0% with a specificity of 96.0%.. Compared to the PET readings, the ratio-images yielded similar sensitivity and specificity measures, but had an improved hemispheric localization. Hence, ratio-images may be a valuable diagnostic tool in the hemispheric localization, which could enhance the use of PET readings alone.

Topics: Brain; Female; Fluorodeoxyglucose F18; Humans; Male; Positron-Emission Tomography; Radiopharmaceuticals; Reproducibility of Results; Seizures; Sensitivity and Specificity; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Nocturnal hypermotor seizures (NHSs) suggest seizure onset in the frontal lobe. We present a patient with NHSs and insular seizure onset who underwent successful surgical treatment. A 29-year-old right-handed man suffered from intractable NHSs since the age of 12 years. High-resolution MRI, [(18)F]FDG-PET, and neuropsychological examination gave normal results, ictal EEG was obscured by artifacts. Ictal [(99m)Tc]HMPAO-SPECT revealed hyperperfusion in the right anterior part of the insula and right frontal operculum. The seizure onset zone was localized in the right anterior insula based on invasive recordings. Electrical stimulation in that area elicited habitual seizures. A limited resection of the anterior part of the right insula and the right frontal operculum was performed rendering the patient seizure-free (follow-up 1 year). To our knowledge, this is the first reported nonlesional patient with an insular seizure onset and NHSs who underwent successful epilepsy surgery.

Topics: Adult; Cerebral Cortex; Disease-Free Survival; Electrodes, Implanted; Electroencephalography; Epilepsy, Frontal Lobe; Follow-Up Studies; Frontal Lobe; Functional Laterality; Humans; Magnetic Resonance Imaging; Male; Neurosurgical Procedures; Seizures; Sleep Wake Disorders; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

Landau-Kleffner syndrome (LKS) is a childhood disorder of unknown etiology characterized by an acquired aphasia and epilepsy. We have performed comprehensive neurofunctional studies on an 8-year-old girl with typical LKS, with the aim of identifying lesions that may be responsible for her condition. 18F-fluoro-D-glucose (FDG) positron emission computed tomography (PET), 11C-Flumazenil (FMZ) PET, 99mTc-hexamethylpropyleneamine oxime single photon emission computed tomography (SPECT) and magnetoencephalography were performed before and after changes to the patient's medication led to a clinical improvement. Interictal SPECT showed hypoperfusion in the left frontal, left temporal, and left occipital lobes. 18F-FDG PET demonstrated a decrease in glucose metabolism medially in both temporal lobes and superiorly in the left temporal lobe. 11C-FMZ PET revealed a deficit in benzodiazepine receptor binding at the tip of the left temporal lobe. Magnetoencephalography demonstrated equivalent current dipoles located superiorly in the left temporal lobe. Our results suggest that the tip of the left temporal lobe plays an important role in the pathogenesis of LKS in our patient.

Topics: Anticonvulsants; Child; Electroencephalography; Female; Humans; Landau-Kleffner Syndrome; Magnetic Resonance Imaging; Magnetoencephalography; Positron-Emission Tomography; Seizures; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed, Single-Photon

Functional neuroimaging can address some challenges of seizure localization, and sometimes preclude the need for EEG recording using intracranial electrodes. Ictal Single Photon Emission Computed Tomography (SPECT) has developed into an important tool in the presurgical evaluation of patients with medically-intractable localization-related epilepsy. The purpose of the study was to determine whether the development of a programme using trained nurses to perform ictal injections enabled a more efficient delivery of radiopharmaceuticals and therefore a greater sensitivity and specificity of outcome.. In our epilepsy unit, nursing staff inject 99mTc-HMPAO at bedside, during or at seizure onset. Brain SPECT is performed later on a gamma camera.. Since the implementation of the new protocol (February 2005), 57 scans have been performed: 22 ictal and 35 interictal. Latency of ictal injection was found to be 5-40 seconds (mean 19.7 sec, standard deviation (SD) 10.4). Only 20% of reconstituted radiopharmaceutical vials were not used. Contamination rate was nil. Sixty three percent of SPECT studies were concordant with standard presurgical evaluation.. The latency of injections and the percentage of unused vials indicated an efficient and effective protocol compared to the literature. Our results show that ictal SPECT can be a safe, noninvasive procedure performed on a routine basis in the epilepsy unit when appropriately trained support staff are incorporated into a structured multidisciplinary programme.

Topics: Brain; Brain Mapping; Canada; Epilepsy; Humans; Nursing Staff, Hospital; Radiopharmaceuticals; Seizures; Staff Development; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

We analyzed preoperative ictal SPECT results from 18 frontal lobe epilepsy patients who underwent epilepsy surgery (mean age 22.9 years). Seizure onset at implanted subdural electrodes was defined as the epileptic focus in 16 of 18 patients. In two additional patients, the resected area on postoperative magnetic resonance images was defined as the epileptic focus. The radioisotope 99mTc-ECD was injected in all patients within 5 s after seizure onset. SPECT images were analyzed by three-dimensional stereotactic surface projection (3-D SSP). Areas of hyperperfusion identified by ictal SPECT were concordant with the site of epileptic focus in 11 patients (61.1%, concordant group) and were non-concordant in 7 patients (38.9%, non-concordant group). The non-concordant group had a higher number of patients with a history of acquired brain damages, such as encephalitis or brain surgery (p < 0.05). Only 3 of 11 patients in the concordant group showed areas of localized hyperperfusion within epileptic foci, whereas 8 patients showed areas of hyperperfusion extending to other regions. Ictal SPECT analyzed by 3-D SSP is useful as a mode of presurgical evaluation in frontal lobe epilepsy patients without a history of encephalitis or surgical treatment. We caution that rapid seizure spread may result occasionally in areas of hyperperfusion extending to adjacent or remote regions.

Topics: Adolescent; Adult; Cerebrovascular Circulation; Child; Epilepsy, Frontal Lobe; Female; Frontal Lobe; Humans; Image Processing, Computer-Assisted; Imaging, Three-Dimensional; Magnetic Resonance Imaging; Male; Middle Aged; Preoperative Care; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Treatment Outcome

A 29-y-old man had taken small daily doses of barbiturates as hypnotics (50 mg pentobarbital, 30 mg phenobarbital) for 4y with no evident intoxication. When he attempted suicide by ingestion of 15 g amobarbital, treatment with charcoal hemoperfusion resulted in rapid disappearance of drug from the blood. Generalized convulsions and delirium ensued; these were responsive to phenobarbital. An electroencephalogram (EEG) showed diffuse 5-Hz theta activity. Tc-99m hexamethylpropyleneamineoxime (HMPAO) single photon emission computed tomographic (SPECT) imaging of the brain demonstrated a diffuse bilateral decrease in blood flow to the cerebral cortex. These investigations were performed interictally on day4 without sedative drugs, prior to initiation of anticonvulsants, and at a time when barbiturates were no longer detected in the serum. An EEG on day 15 no longer showed abnormal slowing. On the other hand, Tc-99m HMPAO SPECT of the brain demonstrated residual cerebral hypoperfusion on day 20, with nearly full recovery of cerebral perfusion on day 51. Barbiturate withdrawal syndrome is presumed to require a history of abuse; however in patients with a history of treatment with barbiturates physicians treating acute barbiturate poisoning should be alert for the possibility of barbiturate withdrawal syndrome even in the absence of barbiturate abuse.

Topics: Adult; Barbiturates; Brain; Humans; Male; Seizures; Substance Withdrawal Syndrome; Suicide, Attempted; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Cerebral perfusion single photon emission computed tomography (SPECT) has been used to confirm the localization of the epileptic focus and the evaluation of seizure. Recently, diffusion-weighted MR imaging (DWI) has been recognized for evaluation of seizure activity. We describe a case of transient seizure activity demonstrated by Tc-99m HMPAO SPECT and DWI. This patient was a 61-year-old woman with a 10-month history of right middle cerebral artery (MCA) infarction who had a generalized seizure during MRI. DWI immediately after seizure showed transient hyperintensity in the right frontal gray matter and the white matter, and these apparent diffusion coefficients (ADC) were transiently decreased. This transient hyperintensity on DWI corresponded to transient hyperperfusion identifying the epileptic focus on interictal Tc-99m HMPAO SPECT. Transient sustained seizure activity might cause these changes on DWI and SPECT. It was considered that interictal Tc-99m HMPAO SPECT showed the delayed hyperperfusion caused by excitatory neuronal overaction and DWI showed cytotoxic edema seizure-induced by energy failure of the membrane-bound Na/K-ATPase pump.

Topics: Cerebral Infarction; Female; Humans; Magnetic Resonance Imaging; Middle Aged; Paresis; Radiopharmaceuticals; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Left hemiconvulsions occurred in a 13-month-old girl with Hemophilus influenzae (H. influenzae) central nervous system (CNS) infection. Tc-99m HMPAO brain SPECT showed a focal hyperperfusion area in the right frontal lobe. The patient recovered without complications, and follow-up SPECT revealed markedly improved findings. Tc-99m HMPAO brain SPECT is useful for evaluating focal convulsions associated with H. influenzae CNS infection.

Topics: Brain; Central Nervous System Infections; Female; Haemophilus Infections; Haemophilus influenzae; Humans; Infant; Organotechnetium Compounds; Oximes; Radiopharmaceuticals; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

We describe a patient with seizures following a stroke in whom on ictal 99mTc-HMPAO single-photon emission computed tomography demonstrated cerebral blood flow "schistotaxis", i.e., focal hyperaemia corresponding to an epileptogenic focus together with an extensive hypoperfused area in the same hemisphere. This phenomenon may have been caused by haemodynamic alternation and a remote transneural effect during the seizures.

Topics: Aged; Cerebrovascular Circulation; Female; Humans; Radiopharmaceuticals; Regional Blood Flow; Seizures; Stroke; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Although the intracarotid amobarbital procedure (IAP) or Wada test is useful in lateralizing seizure focus in patients with temporal lobe epilepsy (TLE), the results of the IAP memory test are frequently nonlateralizing. An insufficient suppression of the medial temporal region contralateral to the seizure focus may contribute to the failure of lateralization. We tried to correlate IAP memory results with the functional changes in the contralateral medial temporal region as measured by single photon emission computed tomography (SPECT) during IAP.. We performed a (99m)technetium-(Tc) hexamethylene-propylene-amine-oxime (HMPAO) brain SPECT in 19 medial TLE patients during a contralateral IAP (sodium amobarbital injected contralateral to the seizure focus). Regional cerebral blood flow (rCBF) was measured in the contralateral medial temporal region. The amount of decrease in the rCBF was calculated by subtracting the previous measurement from the one obtained with the interictal SPECT.. Ten (53%) patients passed and nine (47%) failed the contralateral IAP. The mean percentage decrease in rCBF was 5.3+/-5.3%. There was a significant negative correlation between a decrease in the rCBF and the IAP memory-retention score by Spearman correlation (p = -0.53: p<0.021). Patients with smaller decreases in rCBF (<5%) more frequently passed the contralateral IAP memory test than did those with larger decreases (80 vs. 22%; p<0.023).. We suggest that an insufficient suppression of the contralateral medial temporal function is partly responsible for nonlateralizing IAP memory tests. An IAP-SPECT may be useful in interpreting IAP memory tests for the lateralization of seizure focus in TLE patients.

Topics: Adult; Dominance, Cerebral; Female; Humans; Male; Memory; Neuropsychological Tests; Radiopharmaceuticals; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Increased regional cerebral blood flow (rCBF) at the epileptogenic site has been consistently reported for single photon emission computed tomography (SPECT) injections made during seizure activity, and the increased rCBF has been shown to remain elevated at the epileptogenic site in some cases, even when SPECT injections are made after seizure termination (postictal). A sustained increase in rCBF after seizure cessation was recently confirmed, but for no more than 100 s from seizure onset [Avery, R.A., Spencer, S.S., Spanaki, M.V., Corsi, M., Seibyl, J.P., Zubal, I.G., 1999. Effect of injection time on postictal SPET perfusion changes in medically refractory epilepsy. Eur. J. Nucl. Med. 26, 830-836]. In the current study, it is examined whether ictal SPECT injections demonstrate a similar change in rCBF around 100 s from seizure onset. Twenty-one patients with medically refractory epilepsy and a known area of seizure onset receiving ictal and interictal 99mTc-Hexamethyl-propyleneamineoxime (HMPAO) SPECT scans were studied. The results of SPECT subtraction analysis which visualize increased and decreased rCBF were compared to seizure duration and HMPAO injection time. Five patients received ictal SPECT injections (during ongoing seizure activity) more than 90 s after seizure onset and demonstrated decreased rCBF. Two of these patients also demonstrated areas of increased rCBF. Decreased rCBF was localized to the epileptogenic lobe in four of the five patients. By examining ictal SPECT injections made 90 s after seizure onset, evidence was found that reduced rCBF may exist during ictus. The change in rCBF around 90 s is also observed in postictal injections, suggesting a common metabolic mechanism may be responsible.

Topics: Adolescent; Adult; Cerebrovascular Circulation; Child; Epilepsy; Female; Humans; Middle Aged; Radiopharmaceuticals; Seizures; Technetium Tc 99m Exametazime; Time Factors; Tomography, Emission-Computed, Single-Photon

Systemic injections of 4-aminopyridine precipitate epileptiform generalized seizures characterized mainly by shivering of the body, tail movements and tonic-clonic convulsions in rats and mice. However, only few details are known as concerns which brain regions are possibly affected and stimulated by the compound. The aim of the present study was to investigate the changes in regional cerebral blood flow in mice by using the lipophilic compound technetium-99m-hexamethyl-propyleneamineoxime (99mTc-HMPAO). Whilst the uptake of 99mTc-HMPAO was increased significantly in the neocortex and thalamus following the induction of acute 4-aminopyridine seizures, no such changes were observed in the allocortex of the mice. The increases in uptake in the neocortex and thalamus were completely prevented by carbamazepine (which abolished the symptoms of the seizure, too). The primary involvement of the neocortex and thalamus points to the importance of thalamocortical circuits in the precipitation and maintenance of experimental 4-aminopyridine convulsions.

Topics: 4-Aminopyridine; Animals; Anticonvulsants; Autoradiography; Carbamazepine; Cerebrovascular Circulation; Male; Mice; Neocortex; Radionuclide Imaging; Radiopharmaceuticals; Rats; Regional Blood Flow; Seizures; Technetium Tc 99m Exametazime; Thalamus

The aim of this study was to examine the haemodynamic response to seizures in three infants with Sturge-Weber syndrome by measuring regional cerebral blood flow using transcranial Doppler sonography and 99mTc HMPAO SPECT. Time-locked video/digital EEG recording was carried out for ictal studies. MRI was performed in all subjects. SPECT showed hemispheric hypoperfusion interictally in all three patients and also ictally in one of the three; a small region of hyperperfusion was seen on the same ictal scan in the latter, ie. the patient with interictal and ictal hypoperfusion. In the two older children middle cerebral artery velocity (MCAV) was reduced by between 29 and 62% in the middle cerebral artery of the predominantly affected hemisphere compared with the contralateral side. During seizures, increases of 6 to 30% in MCAV were recorded for the clinically seizing hemisphere compared with 24 to 170% for the contralateral side in four of the seizures recorded. In one infant, MCAV fell bilaterally during a seizure that generalized (-18 and -43% in the predominantly affected and contralateral side respectively). Sequential recordings in one infant suggested that, with time, the haemodynamic response to seizures of the unaffected hemisphere may decrease. These findings suggest that the venous malformation in SWS is associated with an impairment of the cerebral haemodynamic response to seizure activity.

Topics: Cerebral Cortex; Cerebrovascular Circulation; Electroencephalography; Female; Humans; Infant; Infant, Newborn; Intracranial Arteriovenous Malformations; Male; Radionuclide Imaging; Radiopharmaceuticals; Seizures; Sturge-Weber Syndrome; Technetium Tc 99m Exametazime

The authors report 2 clinical cases that illustrate the difficulties with video-monitored EEG and the advantages of brain SPECT in differential diagnosis of true epileptic seizures and nonepileptic seizures. Injection of [99mTc]HMPAO at the time of the ictal event provides a means to obtain a SPECT image postictally for comparison with interictal examinations so that an epileptic or nonepileptic focus may be localized.

Topics: Adult; Cerebrovascular Circulation; Diagnosis, Differential; Electroencephalography; Epilepsy; Humans; Male; Organotechnetium Compounds; Oximes; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Seizures with ictal laughter (also termed gelastic seizures) have been associated with hypothalamic hamartomas and precocious puberty. It is not known, however, where in the brain such seizures originate. We describe a child with gelastic seizures and a hypothalamic lesion (probably a hamartoma) in whom two dysfunctional phenomena were observed.. First, there was a hyperperfusion in the hypothalamopituitary areas shown by ictal [99m]Tc hexamethyl-propyleneamine oxime (HM-PAO) single photon-emission computed tomography (SPECT). Second, there was an ictal pulse of gonadotropins, 17 beta-estradiol, and growth hormone well above the normal limits in one of the seizures.. These findings suggest that gelastic seizures associated with hypothalamic hamartomas are generated in the hypothalamus or in its neighboring regions and that these seizures may cause paroxysmal dysfunction of the hypothalamopituitary axis.

Topics: Adolescent; Epilepsy; Female; Hamartoma; Humans; Hypothalamic Diseases; Hypothalamo-Hypophyseal System; Laughter; Organotechnetium Compounds; Oximes; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Patients with epileptic and nonepileptic seizures are commonly encountered in clinical practice, and they can pose a difficult diagnostic problem. We present two cases that show the difficult task of differentiating between true epileptic and nonepileptic or psychogenic seizures in some patients. The clinical presentations were complex and the use of video-monitored EEG alone was insufficient to make definitive diagnoses. Ictal and interictal Tc-99m HMPAO brain perfusion SPECT imaging examinations were used to help establish the correct diagnoses. This report describes the advantage of using the brain perfusion SPECT imaging examination. The injection of stabilized Tc-99m HMPAO during an ictal event followed by appropriate medical therapy provides a method of obtaining a reasonable image of relative perfusion (activity) during the seizure. These images can then be compared with interictal examinations and an epileptic or nonepileptic focus may be localized. The Tc-99m HMPAO brain perfusion SPECT imaging study was helpful in establishing the correct diagnosis in both cases.

Topics: Adult; Anticonvulsants; Brain; Cerebrovascular Circulation; Delta Rhythm; Depression; Diagnosis, Differential; Diazepam; Electroencephalography; Epilepsy; Epilepsy, Complex Partial; Female; Frontal Lobe; Humans; Image Enhancement; Organotechnetium Compounds; Oximes; Psychophysiologic Disorders; Radiopharmaceuticals; Seizures; Subtraction Technique; Technetium Tc 99m Exametazime; Temporal Lobe; Tomography, Emission-Computed, Single-Photon; Video Recording

A 60-yr-old woman experienced several episodes of generalized seizures following 2 wk of immunosuppressive therapy with cyclosporine for orthotopic liver transplantation. CT showed low density in the white matter of the parieto-occipital lobes. A 99mTc-HMPAO brain SPECT showed diminished perfusion in the parieto-occipital cortex bilaterally. Although the cyclosporine was discontinued, the patient's neurologic status initially worsened and then improved over the next several days. Repeat perfusion brain SPECT showed resolution of most of the perfusion abnormalities, while repeat CT showed persistent white matter changes in the parieto-occipital lobes. We report the presence of reversible cortical perfusion abnormalities in conjunction with cyclosporine therapy. The findings suggest that perfusion brain SPECT may be a sensitive monitor of cyclosporine-induced neurotoxicity.

Topics: Brain; Brain Ischemia; Cerebrovascular Circulation; Cyclosporine; Female; Humans; Immunosuppression Therapy; Liver Transplantation; Middle Aged; Occipital Lobe; Organotechnetium Compounds; Oximes; Parietal Lobe; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Topics: Brain Neoplasms; Humans; Male; Middle Aged; Organotechnetium Compounds; Oximes; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Twenty-one children with various seizure disorders were studied using Tc-99m HMPAO brain SPECT, cranial CT, and electroencephalography (EEG). The rates of pathologic findings on SPECT, CT, and EEG were 67%, 38%, and 52%, respectively. SPECT showed congruent, or more extensive, lesions in all eight patient with CT lesions. Six of the 13 children who had normal CT results, had abnormal SPECT study results. In this postictal series, 4 of the 14 abnormalities detected in the first SPECT study that was applied within 24 hours of a seizure, were in the form of hyperperfused areas. Eight of the 14 abnormal first SPECT studies had become normal by the second SPECT. We conclude that, with respect to the depiction of some kind of abnormality, HMPAO brain SPECT is superior to CT and EEG, and considerable changes in brain perfusion are likely to occur over a period of a few weeks.

Topics: Brain; Cerebrovascular Circulation; Electroencephalography; Female; Humans; Infant; Male; Organotechnetium Compounds; Oximes; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon; Tomography, X-Ray Computed

Topics: Aged; Amphetamines; Brain; Cerebellar Diseases; Cerebral Hemorrhage; Cerebrovascular Circulation; Humans; Iodine Radioisotopes; Iofetamine; Male; Organotechnetium Compounds; Oximes; Putamen; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Topics: Brain; Child; Humans; Magnetic Resonance Imaging; Male; Organotechnetium Compounds; Oximes; Seizures; Skull; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

Neonatal seizures can be difficult to classify according to partial versus generalized onset on the basis of clinical appearance or electroencephalography (EEG). Single-photon emission computed tomography has proven to be useful in adults when adjunctive tests are needed to identify the nature of seizure onset. Although its use has been extended recently to children, the lower age limit at which this technique is useful remains to be established. A case is reported in which ictal Tc-99m HMPAO SPECT of a 16-day-old infant revealed an area of focal hypermetabolism in the right temporal lobe corresponding to an area of focal atrophy revealed by MRI. The EEG of this infant demonstrated multifocal interictal epileptiform abnormalities and an ictal pattern with a generalized onset. This case indicates that ictal SPECT is a useful tool in the evaluation of even the youngest patients with seizures.

Topics: Electroencephalography; Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Magnetic Resonance Imaging; Organotechnetium Compounds; Oximes; Seizures; Technetium Tc 99m Exametazime; Tomography, Emission-Computed, Single-Photon

This study was designed to rate the clinical value of [123I]iodoamphetamine (IMP) or [99mTc] hexamethyl propylene amine oxyme (HM-PAO) brain single photon emission computed tomography (SPECT) in neonates, especially in those likely to develop cerebral palsy. The results showed that SPECT abnormalities were congruent in most cases with structural lesions demonstrated by ultrasonography. However, mild bilateral ventricular dilatation and bilateral subependymal porencephalic cysts diagnosed by ultrasound were not associated with an abnormal SPECT finding. In contrast, some cortical periventricular and sylvian lesions and all the parasagittal lesions well visualized in SPECT studies were not diagnosed by ultrasound scans. In neonates with subependymal and/or intraventricular hemorrhage the existence of a parenchymal abnormality was only diagnosed by SPECT. These results indicate that [123I]IMP or [99mTc]HM-PAO brain SPECT shows a potential clinical value as the neurodevelopmental outcome is clearly related to the site, the extent, and the number of cerebral lesions. Long-term clinical follow-up is, however, mandatory in order to define which SPECT abnormality is associated with neurologic deficit.

Topics: Amphetamines; Asphyxia Neonatorum; Brain; Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Iodine Radioisotopes; Male; Muscle Hypertonia; Muscle Hypotonia; Organometallic Compounds; Oximes; Seizures; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed

In nine patients with suspected psychogenic seizures and in three patients with proven epileptic seizures HMPAO-SPECT was performed prior to and during seizure. In the patients with later on-proven psychogenic seizures no, or only slight, changes of regional cerebral blood flow were found. Patients with proven epilepsy revealed partly normal findings interictally but during seizure a markedly increased circumscript blood flow was found in all patients. Even though PET is superior to SPECT with respect to spatial resolution, in the diagnosis of seizures HMPAO-SPECT has the advantage of enabling injection of the tracer during the seizure and the performance of the SPECT study subsequently.

Topics: Epilepsy; Humans; Organometallic Compounds; Oximes; Seizures; Technetium; Technetium Tc 99m Exametazime; Tomography, Emission-Computed