Ictal SPECT in Nonlesional Extratemporal Epilepsy

Summary:  Purpose: Ictal single-photon emission computed tomography (SPECT) may be a reliable indicator of the ictal onset zone in patients with intractable partial epilepsy who are being considered for epilepsy surgery. The rationale for the illustrated case report is to evaluate the use of an innovation in SPECT imaging in a patient with nonlesional extratemporal epilepsy.
Methods: We investigated the presurgical evaluation and operative outcome in a patient with intractable partial epilepsy. The ictal semiology indicated a "hypermotor" seizure with bipedal automatism. The electroclinical correlation and magnetic resonance imaging (MRI) did not suggest the appropriate localization of the epileptogenic zone. A subtraction periictal SPECT coregistered to MRI (SISCOM) was peformed.
Results: SISCOM revealed a region of localized hyperperfusion in the right supplementary sensorimotor area. Chronic intracranial EEG monitoring confirmed the relationship between the localized SISCOM alteration and the ictal onset zone. The patient was rendered seizure free after surgical treatment.
Conclusions: SISCOM may be used to identify potential candidates for surgical treatment of nonlesional extratemporal epilepsy. Periictal imaging may also alter the strategy for intracranial EEG recordings and focal cortical resection.     

The Relative Contributions of MRI, SPECT, and PET Imaging in Epilepsy

Summary: Functional and structural neuroimaging techniques are increasingly indispensable in the evaluation of epileptic patients for localization of the epileptic area as well as for understanding pathophysiology, propagation, and neurochemical correlates of chronic epilepsy. Although interictal single photon emission computed tomography (SPECT) imaging of cerebral blood flow is only moderately sensitive, ictal SPECT markedly improves yield. Positron emission tomography (PET) imaging of interictal cerebral metabolism is more sensitive than measurement of blood flow in temporal lobe epilepsy. Furthermore, PET has greater spatial resolution and versatility in that multiple tracers can image various aspects of cerebral function. Interpretation of all types of functional imaging studies is difficult and requires knowledge of time of most recent seizure activity and structural correlates. Only magnetic resonance imaging (MRI) can image the structural changes associated with the underlying epileptic process, and quantitative evidence of hippocampal volume loss has been highly correlated with seizure onset in medial temporal structures. Improved resolution and interpretation have made quantitative MRI more sensitive in temporal lobe epilepsy, as judged by pathology. When judged by electroencephalography (EEG), ictal SPECT and interictal PET have the highest sensitivity and specificity for temporal lobe epilepsy; these neuroimaging techniques have lower sensitivity and higher specificity for extratemporal EEG abnormalities. Regardless of the presence of structural abnormalities, functional imaging by PET or SPECT provides complementary information. Ideally these techniques should be used and interpreted together to improve the localization and understanding of epileptic brain.     

Epilepsy-associated stigma in Bolivia: A community-based study among the Guarani population: An International League Against Epilepsy/International Bureau for Epilepsy/World Health Organization Global Campaign Against Epilepsy Regional Project

Epilepsy is associated with a significant burden of social stigma that appears to be influenced by psychosocial and cultural factors. Stigma has a negative effect on the management of people with epilepsy (PWE), representing one of the major factors that contribute to the burden of epilepsy. To assess stigma perception among the Guarani population, one hundred thirty-two people living in Guaraní communities in Bolivia were invited to complete the Stigma Scale of Epilepsy questionnaire. The main determinants of stigma identified were: the fear linked to loss of control, the feelings of sadness and pity toward PWE, the difficulties faced by PWE in the professional and relationship fields, the level of education and type of seizure. Our study pointed out that, in this population, PWE face difficulties in everyday life because of epilepsy-associated stigma and the results attest to the importance of promoting community-based educational programs aimed at reducing the stigmatization process.     

Regional Distribution of Interictal 31P Metabolic Changes in Patients with Temporal Lobe Epilepsy

Summary: Purpose: We compared the ³¹P metabolites in different brain regions of patients with temporal lobe epilepsy (TLE) with those from controls.
Methods: Ten control subjects and 11 patients with TLE were investigated with magnetic resonance imaging (MRI) and [³¹P]MR spectroscopic imaging (MRSI). [³¹P]MR spectra were selected from a variety of brain regions inside and outside the temporal lobe.
Results: There were no asymmetries of inorganic phosphate (Pi), pH, or phosphomonoesters (PME) between regions in the left and right hemispheres of controls. In patients with TLE, Pi and pH were higher and PME was lower throughout the entire ipsilateral temporal lobe as compared with the contralateral side and there were no significant asymmetries outside the temporal lobe. The degree of ipsilateral/contralateral asymmetry for all three metabolites was substantially greater for the temporal lobe than for the frontal, occipital, and parietal lobes, and these asymmetries provided additional data for seizure localization. As compared with levels in controls, Pi and pH were increased and PME were decreased on the ipsilateral side in patients with TLE. There were changes in Pi, pH, and PME on the contralateral side in persons with epilepsy as compared with controls, contrary to changes on the ipsilateral side.
Conclusions: Our findings provide some insight into the metabolic changes that occur in TLE and may prove useful adjuncts for seizure focus lateralization or localization.     

Time-Course of Changes of SPECT, EEG, and Seizures in Temporal Lobe Epilepsy

Purpose : Rccent reports havc shown that diagnostic imaging by SPECT is uscfiil in the assessment of cpilcptogcnic foci in the brain. We investigated the relationship betwcen the time-course of SPECT, EEG, and seizure changes over 3- to 6-year periods. Changes wcre correlatcd with therapeutic effect assessments and predicted prognoses. In our study, SPECT and EEG data werc recorded on the same day.
Subjects: Subjects comprised 27 outpaticnts with temporal lobe epiIcpsy, mean age and duration of disease of 39.2 years and 23.2 years, respectively. Seizure frequencies were weekly in 4 subjects, monthly in 7, yearly in 6, no seizure for I to 4 years in 6, and no seizure for 2 3 years in 4.
Methods : The early phase SPECT images were taken 30 minutes after intravcnous administretion of 1231-IMP. Resting EEG was sub-scqucntly recorded. SPECT scanning was performed on horizontal and coronary sections. Regional cerebral blood flow findings were coin-parcd by visual inspection.
Results : In 9 of the 14 subjects whose seizure severity improved over time, focal spikes wcrc tiot observed i n either examination, or disappeared by second examination. I n contrast, only 5 of the 14 subjects had normal basic EEG activity by the second examination. SPECT usually did not improve. Only I ol the 14 subjects whose seizure scvcrity improved over time showed normalized SPECT findings. No subjects with scizure severity rating "unchanged" or "worsened" showed normalized SPECT findings. SPECT normalized i n only I of the 16 subjects i n whoin focal spikes wcrc not observed in either cxamination, or disappeared by second examination.
Conclusions : In our present study, improvement of seizures with treatment or over tiinc wits likely to be correlated with improvement in focal spikes but not with SPECT findings. This agrees with the report of Michihiro et al. in that focal spike disappearance preceded SPECT finding normalization during treatment.     

Interictal 99Tcm HMPAO SPECT and 1H MRS in Children with Temporal Lobe Epilepsy

Summary: Purpose: To understand the pathological basis of focal hypoperfusion seen on interictal ⁹⁹Tc^m hexamethylpropyleneamine oxime (HMPAO) single-photon-emission computed tomography (SPECT) in intractable temporal lobe epilepsy, and to determine why the technique may be misleading in the localization and lateralization of the seizure focus in some cases.
Methods: Interictal ⁹⁹Tc^m HMPAO SPECT and proton magnetic resonance spectroscopy (¹H MRS) of the mesial temporal regions were performed in 14 children with intractable temporal lobe epilepsy not caused by a foreign tissue lesion.
Results: Hypoperfusion of one temporal lobe ipsilateral to the seizure focus was demonstrated in 10 (71%) of the children; ¹H MRS correctly lateralised in eight of these 10. No asymmetry of perfusion of the anterior temporal regions was seen in the remaining four children; on ¹H MRS, three of these were bilaterally abnormal but nonlateralising. Repeated SPECT and ¹H MRS in three children demonstrated changes over time, the findings from the two techniques being consistent with each other on both the initial and the repeated scans.
Conclusions: Abnormalities demonstrated by ¹H MRS correlate well with those seen on interictal SPECT and can help to understand the pathologic basis of these SPECT abnormalities. Furthermore, the presence of bilateral damage can result in an absence of perfusion asymmetry on interictal SPECT.     

Regional cerebral blood flow measured by99mTc-HMPAO SPECT differs in subgroups of Alzheimer's disease

Summary Alzheimer's disease (AD) is a heterogeneous entity. Identifying AD subtypes might have impact in patients' response to different treatment strategies. We designed a study to examine regional cerebral blood flow (rCBF) in AD subtypes. To identify AD subtypes, we performed a cluster analysis including performance on memory, language, visuospatial, praxis, and executive functions. The rCBF measured by^99mTc-HMPAO SPECT was referred to the cerebellum. We examined 35 patients fulfilling the NINCDS-ADRDA criteria of probable AD and 13 age and sex-matched healthy cognitively intact controls. AD patients were at the early stage of the disease, their mean Mini-Mental Status (MMS) score (S.D.) was 22.5 (3.6). The cluster analysis revealed two AD subgroups: AD1 (N=12) and AD2 (N=23). The subgroups did not differ in age, sex, or global clinical severity as assessed by MMS and Brief Cognitive Rating Scale (BCRS). Both subgroups had equally impaired memory. The AD2 group was inferior to the AD1 group on verbal, visuospatial, praxic, and executive functions. The AD1 group showed reduced rCBF ratios in the temporal and parietal cortices and the amygdala compared to controls. The AD2 group differed from controls in the rCBF ratios of frontal, temporal, parietal, occipital, basal ganglia, and amygdaloid regions bilateral and from AD1 in the rCBF ratios of frontal and temporal cortices. In AD patients, the rCBF ratios did not correlate with MMS or BCRS scores. In contrast, several significant correlations were found between decreases rCBF ratios and impairment of memory and other cognitive functions. In conclusion, a cluster analysis on neuropsychological test performance identified two AD subgroups that differed on the neuropsychological profile and on the rCBF in spite of similar global clinical severity.     

Temporal Lobe Epilepsy Subtypes: Differential Patterns of Cerebral Perfusion on Ictal SPECT

Summary: Purpose : We studied cerebral perfusion patterns in the various subtypes of TLE, as determined by pathology and good outcome after temporal lobectomy (as confirmation of temporal origin).
Methods : We studied clinical features and ictal technetium ^99m hexamethyl-propyleneamineoxime (99mTc-HM-PAO) single-photon emission-computed tomography (SPECT) in four subgroups of patients with intractable temporal lobe epilepsy (TLE) treated with surgery: hippocampal sclerosis (group 1, n = 10), foreign-tissue lesion in mesial temporal lobe (group 2, n = 8), foreign-tissue lesion in lateral temporal lobe (group 3, n = 7), and normal temporal lobe tissue with good surgical outcome (group 4, n = 5).
Results : No major clinical differences in auras, complex partial seizures or postictal states were identified among the groups. Ictal SPECT showed distinct patterns of cerebral perfusion in these subtypes of TLE. In groups 1 and 2, hyperperfusion was seen in the ipsilateral mesial and lateral temporal regions. In group 3, hyperperfusion was seen bilaterally in the temporal lobes with predominant changes in the region of the lesion. Hyperperfusion was restricted to the ipsilateral anteromesial temporal region in group 4. Ipsilateral temporal hyperperfusion in mesial onset seizures can be explained by known anatomic projections between mesial structures and ipsilateral temporal neocortex. Bilateral temporal hyperperfusion in lateral onset seizures can be explained by the presence of anterior commissural connections between lateral temporal neocortex and the contralateral amygdala.
Conclusions : We conclude that the perfusion patterns seen on ictal SPECT are helpful for subclassification of temporal lobe seizures, whereas clinical features are relatively unhelpful. These perfusion patterns provide an insight into preferential pathways of seizure propagation in the subtypes of TLE.     

Regional cerebral blood flow in childhood autism: a SPECT study.

OBJECTIVE: The authors investigated a possible cortical brain dysfunction associated with infantile autism. METHOD: They measured regional cerebral blood flow with single photon emission computed tomography (SPECT) and xenon-133 in 21 children with primary autism (according to DSM-III-R criteria). Five cortical brain areas including frontal, temporal, and sensory association cortices were examined in order to test the recent hypothesis of cerebral dysfunction in primary autism. Anatomical references for each subject were obtained with computerized tomography or magnetic resonance imaging and were used to delimit the regions of interest for SPECT analysis. RESULTS: When the results from the group with primary autism were compared with an age-matched group of nonautistic children with slight to moderate language disorders (N = 14), no cortical regional abnormalities were found. CONCLUSIONS: It appears that there is no regional cortical dysfunction in primary autism; however, in light of methodological limitations, one cannot exclude the possibility of more localized or subcortical brain dysfunctions in autism.     

Integration of EEG, MRI, and SPECT in Localizing the Seizure Focus for Epilepsy Surgery

Summary: Several modalities are now available for detecting the structural and the functional abnormalities of a seizure focus. This article discusses the principles and techniques that can be used to integrate the data derived from different test modalities in delineating the seizure focus in epilepsy surgery candidates. An approach in integrating EEG, MRI, and SPECT abnormalities is described to demonstrate how the spatial relationships among them can be precisely determined by co-registering images of the abnormalities on the MRI. The recently developed technique of subtraction ictal SPECT co-registered to MRI (SISCOM) can reveal a discrete hyperperfusion focus with its relationship to the cerebral anatomy. The SISCOM focus can also serve as a target for intracranial electrode implantation and for subsequent surgical resection. This can be achieved by using a computer-based system of relating the image space to the surgical field. The limitations of each test in localizing the surgical seizure focus must be recognized when the value of each test is interpreted relative to those of other tests. In many patients, not all tests will show localizing abnormalities, and the foci determined by different tests may be incongruent. When the location of the focus is not compatible with the possible origin of the patient's habitual seizures, further evaluation with other tests, including intracranial EEG recordings, is necessary. The decision in determining which tests and how many to employ for localizing the surgical focus must be individualized for each patient.     

Regional cerebral hyperperfusion with ictal dystonic posturing: ictal-interictal SPECT subtraction

PURPOSE: Ictal-interictal single-photon emission computed tomography (SPECT) subtraction was performed to find brain structures related to ictal dystonic posturing (DP) in patients with temporal lobe epilepsy (TLE). METHODS: Thirty-two patients with mesial TLE who had ictal and interictal SPECTs were included. They were divided into two groups; DP group with ictal dystonia during ictal SPECT (n = 15) and Non-DP group without ictal DP (n = 17). Ictal-interictal SPECT subtraction was performed, and then subtracted SPECT was coregistered with brain spoiled gradient recalled (SPGR) magnetic resonance imaging (MRI). The ictal hyperperfusion on subtracted SPECT was analyzed in basal ganglia, frontal cortex, thalamus, temporal lobe, and insular cortex. RESULTS: The incidences of ictal hyperperfusion on brain regions in DP versus Non-DP groups were 80.0% (12 of 15 patients) versus none (0 of 17), p = 0.001, chi2, in caudate nucleus; 93.3% (14 of 15) versus 47.0% (eight of 17), p = 0.005, in putamen; and 80.0% (12 of 15) versus 41.2% (seven of 17), p = 0.026, in thalamus. No significant difference of ictal hyperperfusion was found in globus pallidus, temporal lobes, insular and frontal cortices between DP and Non-DP groups. DP patients showed an earlier age at seizure onset [8.6 years (DP) vs. 15.7 years (Non-DP) (p = 0.015)] and a longer duration of seizure history [19.0 years (DP) vs. 11.9 years (Non-DP) (p = 0.015)]. CONCLUSIONS: Caudate nucleus, putamen, and thalamus were significantly related to the ictal DP during TLE seizures. Our study showed first an active involvement of the caudate nucleus in the generation of ictal DP.