Ictal SPECT and interictal PET in the localization of occipital lobe epilepsy

PURPOSE: To compare the localizing value of ictal single photon emission computed tomography (SPECT) and interictal fluorodeoxyglucose-positron emission tomography (FDG-PET) in refractory occipital lobe epilepsy. METHODS: Six patients who underwent surgery for refractory epilepsy associated with pathology in the occipital lobe were retrospectively selected from records of the Austin & Repatriation Centre Comprehensive Epilepsy Programme. Interictal SPECT and PET and ictal SPECT were obtained by standard methods. All studies were read by a nuclear medicine expert blinded to clinical data except the diagnosis of epilepsy. RESULTS: Ictal SPECT showed unilateral occipital hyperperfusion in five of six cases often accompanied by temporal lobe hyperperfusion. These patterns were seen in cases with or without magnetic resonance imaging (MRI) abnormality. Interictal SPECT was not localizing in any case, in contrast to PET, which showed occipital hypometabolism in three of five studies. CONCLUSIONS: Ictal SPECT can provide novel localizing data in MRI-negative occipital lobe epilepsy. Interictal PET can provide useful localizing information, but its role in providing novel information was not demonstrated. Interictal SPECT is useful only as a baseline to aid in interpretation of ictal studies.     

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.     

Ictal brain imaging in presurgical evaluation of patients with medically intractable complex partial seizures

At the Indiana University Medical Center, 99 patients with medically intractable complex partial seizures (MI-CPS) had presurgical evaluation with subsequent anterior temporal lobectomy. The majority of the patients had single photon emission tomography (SPECT) performed interictally as well as during an actual epileptic seizure (ictal scan). Decreased regional cerebral perfusion (rCP) was seen in 54/94 (57%) of the interictal scans corresponding to the eventual site of the surgery. However, ictal scans provided a higher yield; increased rCP in the temporal lobe during an actual seizure was observed in 60/82 (73%) concordant to the side of surgery. SPECT is a useful, noninvasive method of localizing the epilepti-form focus in patients with MI-CPS considered for resective surgery. Both interictal and ictal SPECT need to be performed; combined interictal hypo-perfusion and ictal hyperperfusion in the same focal area are unique to epileptogenic lesions. Ictal SPECT studies can be performed in the majority of patients during the period of continuous video/EEG monitoring with only a little additional effort. Combining the results of functional brain imaging (interictal and ictal SPECT, PET) with clinical semiology of seizures, surface and sphenoidal EEG, magnetic resonance imaging and other non-invasive tests, anterior temporal lobectomy can be recommended in approximately two-thirds of the patients without resorting to potentially dangerous intracranial EEG monitoring.     

Multimodality imaging for focus localization in pediatric pharmacoresistant epilepsy.

Multiple structural and functional imaging modalities are available to localize the epileptogenic focus. In pre-surgical evaluation of children with pharmacoresistant epilepsy, investigations with the maximum yield should be considered in order to reduce the complexity of the workup. OBJECTIVE: To determine the extent to which PET, ictal/interictal SPECT and its co-registration with the patient's MRI contributes to correct localization of the epileptogenic focus, surgical intervention and to the post surgical outcome in paediatric patients. METHODS: The study population included children and adolescents with pharmacoresistant epilepsy (n = 50) who underwent preoperative evaluation, surgery and had postoperative follow-up for at least 12 months. Outcome was measured by postoperative seizure frequency using Engel's classification. RESULTS: Thirty-nine patients (78%) became completely seizure free after surgical intervention. The likelihood to benefit from surgical treatment was significantly higher if localization with more imaging modalities (MRI, PET, SPECT) were concordant with respect to the resected brain area (p < 0.01). Preoperative PET examination provided better localizing information in patients with extratemporal epilepsy and/or dysplastic lesions, whereas SPECT was found to be superior to PET in patients with temporal lobe epilepsy and/or tumors (p < 0.05). No significant difference was noted in the surgical outcome in younger or older age group, in children with or without special education needs. CONCLUSION: In paediatric epilepsy pre-surgical evaluation, the combined use of multiple functional imaging modalities for a precise localisation of the epileptogenic focus is worthwhile for both extratemporal and temporal lobe epilepsy, also when EEG and MRI alone are non-contributive, given the potential benefit of complete postoperative seizure control.     

Comparative study of interictal PET and ictal SPECT in complex partial seizures

Objective – To compare the sensitivity of ictal ^99mTc-HMPAO single photon emission computed tomography (SPECT) with interictal ¹⁸F-fluorodeoxyglucose positron emission tomography (PET) in localization of the epileptogenic focus in patients with medically intractable complex partial seizures (MI-CPS). Material and methods – Retrospective analysis was performed on patients with MI-CPS who underwent anterior temporal lobectomy from January 1993 onwards when PET became available to us for clinical studies at the Indiana University Medical Center. There were 38 female and 29 male patients (total=67) with MI-CPS, 10 to 55.5 years of age (mean 31) and duration of their epilepsy from 1-46 years (mean 21). Interictal PET was evaluated for evidence of focal hypometabolism and ictal SPECT for focal perfusion abnormality (hyperperfusion or hypoperfusion) by visual analysis. Results – Both Ictal SPECT and interictal FDG-PET studies were obtained in 36 patients with MI-CPS. PET showed definite hypometabolism in 30 and questionable hypometabolism in an additional two patients. Ictal SPECT correctly localized the seizure focus in 27 patients by demonstrating ictal hyperperfusion whereas in one the hyperperfusion was falsely localized. In an additional seven patients the ictal SPECT provided probable localization by demonstrating ictal hypoperfusion in the appropriate temporal lobe. The sensitivity of ictal SPECT and interictal PET was 34/36 and 32/36, respectively, the difference was not statistically significant (χ²_y=0.18, DF=1, P=0.67). In six of the 36 patients the two tests were complementary to each other in providing localizing information. Conclusion – Ictal SPECT and interictal PET are equally sensitive and reliable techniques in localizing the epileptogenic focus in patients with MI-CPS. They play a critical role in providing localization in MRI negative patients allowing surgical resection to be undertaken in many without additional invasive electrographic monitoring.     

Correlation of single photon emission computed tomography with pathology and seizure outcome in children undergoing epilepsy surgery

Introduction:  Single photon emission computed tomography (SPECT) imaging regional cerebral blood flow (rCBF) can help localize the seizure focus in partial epilepsies during presurgical evaluation. Few studies have explored the possible relationship between preoperative SPECT and underlying pathology, or any relationship to postsurgical outcome.
Study group:  Thirty-five children with medically intractable epilepsy undergoing resective surgery between the ages of 11 months and 18 years had presurgical ictal and interictal rCBF and post surgery follow up of 3–6 years.
Results:  Pathological examination revealed 13 to have hippocampal sclerosis (HS): of these 11 had relatively low interictal rCBF perfusion on the side of seizure onset, and eight had hyperfusion ictally. Eight children had morphological evidence of cortical dysplasia: all had a localizing ictal rCBF concordant with the area resected whereas only six demonstrated localized reduction in perfusion on interictal rCBF. All three patients with Rasmussens encephalitis had informative rCBF scans, concordant with the seizure focus. However, infarct, tumours and nonspecific pathology demonstrated poor localization of the seizure focus. No SPECT parameter correlated independently with outcome, although overall the HS group had the best outcome, particularly those with localizing ictal SPECT.
Comment:  Ictal SPECT appears predictive of underlying cortical dysplasia. Although in this small group of HS in children, ictal SPECT added little to interictal SPECT for seizure localization, it may be useful in the prediction of outcome. SPECT adds little to the evaluation of children being considered for hemispherectomy over and above the abnormalities detectable on MRI scan.     

Nichtinvasives Protokoll für die epilepsiechirurgische Behandlung fokaler Epilepsien

We present a non-invasive epilepsy surgery protocol, which includes EEG-video-monitoring, magnetic resonance imaging (MRI), interictal positron emission tomography (PET) and ictal single photon emission computerized tomography (SPECT). According to this non-invasive protocol 50 of 173 patients with medically intractable focal epilepsy underwent resective surgery. The localization of the epileptogenic zone was based on the congruence of the localizing results of EEG-video-monitoring, MRI, interictal PET and ictal SPECT. 46 (92%) of the patients had temporal and 4 (8%) had extratemporal epilepsies. 78% (n = 39) of all patients operated according to our non-invasive protocol were postoperatively completely or almost seizure free. Extramesiotemporal resections could be carried out without invasive EEG-recording if the epileptogenic zone was not adjacent to the eloquent cortex. We conclude from our results that in a considerable number of patients with medically intractable particularly temporal focal epilepsies, resective epilepsy surgery can be based on non-invasive EEG-evaluations and the risk of invasive recordings can be avoided.     

Utility of Ictal SPECT in the presurgical evaluation of Rasmussen's encephalitis

BACKGROUND: Rasmussen's encephalitis is a progressive disease characterized by severe progressive neurological and cognitive deficits. It is a difficult condition to treat with conventional medical treatment and requires, in most of the cases, surgical intervention. METHODS: We present the case of a patient with Rasmussen's encephalitis who presented with epilepsia partialis continua, who did not respond to antiepileptic treatment and was evaluated for possible surgical intervention. RESULTS: The electroencephalographic studies revealed bihemispheric involvement during seizures, although magnetic resonance imaging (MRI) showed a marked right hemispheric atrophy. Hyperperfusion over the right hemisphere was seen with the performance of ictal single photon emission computed tomography (SPECT), which finally guided a right functional hemispherectomy and subsequent seizure control. CONCLUSION: Ictal SPECT could be a useful tool in the armamentarium of tools used for the localization of the epileptogenic focus in patients with Rasmussen's encephalitis and other localization-related epilepsies.     

Utility of interictal SPECT of rCBF for focal diagnosis of the epileptogenic zone(s)

With Single Photon Emission Computed Tomography (SPECT) of regional cerebral bloodflow (rCBF) ictally and interictally, regional changes of rCBF can be detected in many cases with medically intractable complex partial seizures. Interictal SPECT shows abnormal rCBF in the epileptogenic temporal lobe in 40% to 85% of the patients. A critical survey of the methodological problems considering isotopes, scanners, data analysis and patient population is presented here as well as a few semi-quantitative studies including our own. It is concluded, that SPECT of rCBF is a useful, non-invasive method of localizing the epileptogenic zone in patients with severe partial focal epilepsy. Ictal SPECT of rCBF has a higher predictive value and is more sensitive than interictal studies for localization of the seizure focus. Interictal SPECT using a high-resolution system obtains an almost as high frequency of localization of the focus. With low resolution scanners, a minor frequency is observed. Both interictal and ictal SPECT recordings should be obtained for localization of the epileptogenic focus in presurgical cases as interictal hypoperfusion and ictal hyperperfusion demonstrated in the same focal area are highly characteristic of a seizure focus.     

Thursday July 6, 2006Thursday July 6, 20067:30–9:00Hall 5ATeaching SessionEpilepsy surgery in infancy and childhood

¹ I. Tuxhorn (   ¹ Epilepsy Center Bethel, Germany )
Epilepsy surgery is no longer a treatment of last resort for children with drug resistant focal epilepsy. It should be considered early to reduce the negative impact of epilepsy on developmental and social outcome.
The spectrum of surgically remediable epilepsy syndromes of childhood has expanded in recent years to include 1) patients with tuberous sclerosis who have a leading resectable focus, 2) infantile spasms or Lennox-Gastaut syndrome (or other age specific epileptic encephalopathies) secondary to a resectable epileptogenic zone and 3) formerly "cryptogenic" cases with very subtle cortical dysplasias.
The goal of the presurgical evaluation is to identify patients who have surgically treatable epilepsy by assessing the risk benefit scenario of surgical intervention.
The accepted standards of evaluation include seizure analysis with video monitoring and scalp recording of the interictal and ictal EEG, high resolution MRI, neuropsychology, WADA test for assessing laterality of mnestic and language functions. Functional imaging including PET, ictal SPECT, postprocessing MRI techniques and fMRI are important techniques to evaluate difficult extratemporal cases.
The role of invasive neurophysiology with subdural, epidural and intracerebral recordings is changing since the advent of functional imaging of the epileptogenic region e.g., EEG triggered MRI and methods outlined above.
Patients with a focal electroclinical syndrome and a congruent MRI lesion are excellent candidates for selection and the seizure outcome prognosis may be considered high if the epileptogenic zone is completely resectable.
In pediatric epilepsy early patient referral for presurgical evaluation should be considered in specific syndromes—catastrophic focal epilepsy, hemispheric syndromes, Sturge Weber syndrome, and well localized symptomatic epilepsies.     

Electroencephalography/functional MRI in human epilepsy: what it currently can and cannot do

PURPOSE OF REVIEW: Simultaneous recording of electroencephalogram and functional MRI is being increasingly applied to the investigation of normal cerebral processes and disorders, particularly epilepsies. We will summarize recent epilepsy-related studies and appraise the clinical and scientific value of EEG/fMRI. RECENT FINDINGS: Interictal and ictal EEG/fMRI can provide helpful information in the presurgical evaluation of epilepsy. At present, EEG/fMRI cannot supercede any of the current methods because validation studies are lacking, informative results are only obtained in some patients, and haemodynamic activation and deactivation patterns are not always of localizing value. EEG/fMRI data often identify distributed brain areas and can help to generate concepts of epileptogenic networks both in individual patients and groups with particular epilepsy syndromes. SUMMARY: Clinically, EEG/fMRI studies may influence further investigations such as more detailed structural imaging or the planning of intracranial electrophysiological studies by generating hypotheses about the location of epileptic foci. Validation studies are underway to determine whether such clinical applications are appropriate. EEG/fMRI can also assess epileptogenic networks and changes in brain state, leading to a new dimension of understanding of dynamic cerebral processes in health and disease.     

Neuroimaging and presurgical evaluation of symptomatic epilepsies

The goal of presurgical evaluation of intractable epilepsy is to identify epileptogenic regions in the brain. From our experience of 38 cases of resective epilepsy surgery from the last 3 years, ictal SPECT was considered the most sensitive at detecting focal changes relating to seizures compared to other neuroimaging modalities, such as MRI, FDG-PET, SPECT and MEG. At interictal state, on the other hand, FDG-PET was most sensitive, especially in cases with focal cortical dysplasia, which is often MRI-invisible. In dysplastic tumors, MRI showed the highest concordance rate to clinically verified epileptogenic regions. Activation studies using functional neuroimaging such as PET and fMRI is useful to evaluate brain functions at epileptogenic regions presurgically. The role of functional brain imaging in epilepsy surgery is considered to be: (i). case selection for resective surgery, (ii). case selection for invasive EEG monitoring, and (iii). navigation of electrode placement and cortical resection.     

Evaluation of SPECT in the assessment and treatment of intractable childhood epilepsy

The authors retrospectively examined the role of SPECT in 65 children undergoing video-EEG telemetry. SPECT was concordant in most children whose lesions were already localized by MRI and epilepsy syndrome and provided localizing data in more than half not localized by these modalities. Ictal SPECT provided no additional prognostic benefit in patients undergoing epilepsy surgery (n = 23) who have a localized MRI lesion. In patients without lesions, however, ictal SPECT provides useful additional localization that may be used as a guide to intracranial implantation.     

Ictal SPECT in the epileptic child. Contribution of subtraction interictal images and superposition of with MRI]

Ictal SPECT is a highly sensitive method to localize the epileptogenic focus in refractory temporal lobe epilepsy in adults. In extratemporal epilepsy, sensitivity can be improved by subtracting interictal from ictal images and superimposing subtraction images on MRI. In children, such a procedure is potentially interesting because most epilepsies are extratemporal and ictal SPECT not yet routinely developed. The aim of this study was to test the feasibility of ictal SPECT with subtraction image processing in a pediatric population. Twenty-six children with refractory partial epilepsy and aged from 3 months to 18 years underwent ictal ECD-SPECT (20 mCi/1.73 m2) combined with video-EEG and interictal ECD-SPECT plus 3D-MRI two days later. Ictal-interictal subtraction images were computed by registering and normalizing the ictal to the interictal SPECT scans for each child. The ictal, interictal SPECT and subtraction images were registered to the children's MRI. Difference images were then superimposed to MRI for anatomical localization of the perfusion changes (overlay images). Looking for perfusion changes, overlay images allowed to detect at least one hyperperfused focus in 92 p. 100 of the 26 children compared to 73 p. 100 visually comparing ictal and interictal scans separately. Seizure onset was suspected on clinical and/or EEG and/or MRI in 19 children. Positive overlay images were concordant (n = 11) or larger (n = 7) than the suspected focus in 17/19 (90 p. 100), whereas they failed to show any abnormality in 1 child and were discordant with MRI in another one. In the 7 remaining patients, images showed cortical localization in 6 cases. Ictal SPECT is therefore faisable in very young children. Ictal-interictal subtraction SPECT images co-registered to MRI improves sensitivity compared to classical visual analysis. It seems therefore to be a helpful technique to localize the onset of seizure and to guide the intracranial recording in childhood epilepsy.     

Localization of the epileptogenic zone by ictal and interictal SPECT with 99mTc-ethyl cysteinate dimer in patients with medically refractory epilepsy.

PURPOSE: To evaluate the accuracy, feasibility and clinical value of both ictal and interictal 99mTc-ethyl cysteinate dimer (ECD) single photon emission computed tomography (SPECT) in patients with medically refractory epilepsy. METHODS: The study included 75 consecutive patients, 48 with temporal lobe epilepsy (TLE group), and 27 with extratemporal epilepsy (ExT group). The accuracy of SPECT was analyzed considering the final diagnosis reached by convergence of clinical, electrophysiologic, structural, pathologic and outcome data. RESULTS: Ictal SPECT correctly identified the epileptogenic zone in 21 (91.3%) of 23 patients, whereas interictal SPECTs could correctly identify the epileptogenic zone in only 41 (62.1%) of 66 patients (chi2 = 5.56, df = 1, p < 0.05). Results were similar when the two study groups were analyzed separately. Moreover, ictal studies had significantly higher specificity (91.3 vs. 60.6%) and positive predictive value (91.3 vs. 66.2%) than interictal studies for the whole series of patients. Considering all tools used in the preoperative workup of these patients, ictal SPECT significantly contributed to the final topographic diagnosis in seven of 14 patients from TLE group and in six of nine patients from the ExT group. In these patients, ictal SPECT either obviated the need for invasive EEG or helped to define where to concentrate the efforts of invasive investigation. CONCLUSIONS: These data demonstrate that ictal SPECT can be easily achieved by using 99mTc-ECD and can accurately localize the epileptogenic zone in both temporal and extratemporal epilepsies. Ictal ECD SPECT proved to be significantly more sensitive and specific than interictal ECD SPECT, and clinically useful in the definition of the epileptogenic zone.     

功能磁共振成像对顽固性癫痫手术前的功能区定位的初步研究

目的 利用功能磁共振成像技术显示顽固性癫痫患者脑内致痫灶周围重要功能脑区的位置，避免手术损伤及术后功能障碍。方法 对4例顽固性癫痫患者于手术前分别进行了运动、语言及视觉的磁共振脑功能成像扫描。结果 4例患者经不同刺激任务的功能成像扫描及数据处理后，均成功地显示了各自相应的运动、语言、视觉功能活动区的范围及程度，为致痫灶与其周围不同脑功能区的关系提供了直观、准确的信息。结论 功能磁共振成像的临床应用是一项极具前景的工作，它对神经外科完整切除脑内病灶，同时减少因手术而导致的脑功能障碍提供了极大的帮助。     

Planned ictal FDG PET imaging for localization of extratemporal epileptic foci

PURPOSE: This work demonstrates the feasibility of planned ictal positron emission tomography (PET) with [18F]fluoro-2-deoxy-glucose (FDG) for localization of epileptic activity in patients with frequent partial seizures of extratemporal origin. METHODS: Ictal PET imaging was performed in four patients (two men and two women, ages 28-61) with continuous or very frequent (every 3-15 min) partial seizures. All patients had abnormalities apparent on magnetic resonance (MR) or computed tomographic (CT) imaging, two with extensive brain lesions that precluded precise localization of the seizure focus with interictal PET or single-photon emission tomography (SPECT) imaging. RESULTS: Ictal PET imaging demonstrated a restricted area of focal hypermetabolism concordant with surface electroencephalographic (EEG) recording in all cases. The PET images were registered to MR imaging data for further anatomic localization of hypermetabolic regions in three cases. The ictal PET data were used to guide neurosurgical intervention in one case. CONCLUSIONS: We conclude that planned ictal PET imaging may be a useful and potentially superior approach to ictal SPECT for identifying the epileptic focus in a selected group of patients with continuous or frequent simple partial seizures.     

Magnetic source imaging and ictal SPECT in MRI‐negative neocortical epilepsies: Additional value and comparison with intracranial EEG

Purpose: To investigate the utility of magnetic source imaging (MSI) and ictal single photon emission computed tomography (SPECT), each compared with intracranial electroencephalography (EEG) (ICEEG), to localize the epileptogenic zone (EZ) and predict epilepsy surgery outcome in patients with nonlesional neocortical focal epilepsy. Methods: Studied were 14 consecutive patients with nonlesional neocortical epilepsy who underwent presurgical evaluation including ICEEG, positive MSI, and localizing subtraction Ictal SPECT coregistered to MRI (SISCOM) analysis. Follow‐up after epilepsy surgery was ≥24 months. ICEEG, MSI, and SPECT results were classified using a sublobar classification. Key Findings: Of 14 patients, 6 (42.9%) became seizure‐free after surgery. Sublobar ICEEG focus was completely resected in 11 patients; 5 (45.5%) of them became seizure‐ free. Concordance of ICEEG and MSI and complete focus resection was found in 5 (35.7%) patients; 80% of them became seizure‐free. Sublobar ICEEG‐MSI concordance and complete focus resection significantly increased the chance of seizure freedom after epilepsy surgery (p = 0.038). In contrast, of the 6 patients (42.9%) with concordant ICEEG and SISCOM and complete focus resection, only 66.7% became seizure‐free (p = 0.138). Assuming concordant results, the additive value to ICEEG alone for localizing the EZ is higher with ICEEG‐MSI (odds ratio 14) compared to ICEEG‐SISCOM (odds ratio 6). Significance: This study shows that combination of MSI and/or SISCOM with ICEEG is useful in the presurgical evaluation of patients with nonlesional neocortical epilepsy. Concordant test results of either MSI or SISCOM with ICEEG provide useful additive information for that provided by ICEEG alone to localize the EZ in this most challenging group of patients. When sublobar concordance with ICEEG is observed, MSI is more advantageous compared to SISCOM in predicting seizure‐free epilepsy surgery outcome.     

The EEG evaluation of single photon emission computed tomography abnormalities in epilepsy.

Single photon emission computed tomography (SPECT) has increasingly been used as a diagnostic procedure for localizing epileptic seizure foci and as a research tool for investigating the physiologic mechanisms underlying seizure activity. With increasing use of SPECT in localizing the seizure focus for epilepsy surgery, there arises a need to critically assess its current role in the evaluation of patients for epilepsy surgery, especially as it relates to other clinical and laboratory data used in presurgical evaluation. Ictal EEG discharge has traditionally been used as the "gold standard" against which SPECT studies are compared in assessing the latter's localizing value. However, this practice presents a major challenge because SPECT studies are often reserved for patients with nonlocalizing EEG or magnetic resonance imaging findings. Nonetheless, SPECT studies in evaluation for epilepsy surgery should always be performed with the knowledge of the patient's EEG activity preceding, during, and after the injection of the radiotracer. The advent of techniques such as subtraction SPECT with co-registration on magnetic resonance imaging (SISCOM) and computer image-guided surgery has great potential in enhancing the clinical electrophysiologic evaluation of SPECT-detected abnormalities in epilepsy. These techniques permit accurate spatial correlation between intracranial EEG activity and SPECT perfusion patterns. The techniques can also be used to evaluate the effect of the extent of EEG focus resection compared with that of SISCOM focus resection to determine which has more prognostic importance in postsurgical control of seizures. Both animal and human studies are warranted to advance our knowledge of the electrophysiology associated with the various SPECT perfusion patterns.     

Localizing and prognosis value of 99Tcm-ECD spect in patients with refractory temporal lobe epilepsies]

Interictal and ictal 99Tcm ECD-SPECT were retrospectively studied in 46 patients with refractory temporal lobe epilepsy. Forty two of these patients underwent an anterior temporal lobectomy with amygdalo-hippocampectomy or a cortical resection. SPECT findings as indicator of localization for the epileptogenic zone (EZ) and surgical prognosis were validated by comparison with other investigations including video-EEG monitoring with surface electrodes in all the patients, intracranial electrodes in 18 patients and the results of post-surgery outcome. Reliability of SPECT for localizing the epileptogenic zone (EZ) was found for mesial temporal epilepsy (28 patients) and the presumed bilateral temporal epilepsies (7 patients). In these latter cases, ECD-SPECT findings may serve to replace invasive methods with use of intracranial electrodes. SPECTs were unreliable when EZ was undetermined whether mesial or lateral by other non invasive investigations. Unilateral mesial temporal hyperperfusion associated with hypoperfusion of contralateral mesial structures evidenced by ictal SPECTs appear to be preoperative criteria for a successful outcome after surgery.