Ictal cerebral perfusion related to EEG in drug resistant focal epilepsy of childhood.

OBJECTIVES: To evaluate the EEG changes during seizures in children with drug resistant focal epilepsy who demonstrate hypoperfusion at the "seizure focus" interictally, but no perfusion change during the seizure. METHODS: Ictal EEG findings of six children with focal epilepsy who demonstrated hypoperfusion on rCBF SPECT after an interictal injection of (99)Tc(m) HMPAO concordant with the seizure focus, but who did not demonstrate rCBF change after an ictal injection (group 1) were reviewed. These were contrasted with the EEG data of six children matched as closely as possible for age, type of epilepsy, and pathology who did show hyperperfusion at the seizure focus on ictal scan when compared with the interictal study (group 2). RESULTS: The children in group 1 showed slowing of the EEG at the time of the (99)Tc(m) HMPAO injection relative to that seen at the onset of the seizure. Those in group 2 showed rhythmic activity, or sharp waves, or both on EEG at the time of injection. This last change was also seen consistently when the EEG data of a further 13 children who also showed ictal hyperperfusion at the seizure focus were reviewed. CONCLUSION: Ictal rCBF does not invariably increase at the seizure focus in patients with drug resistant focal epilepsy.     

Correlation between inter-ictal regional cerebral blood flow and sphenoidal electrodes--recorded inter-ictal spikes in mesial temporal lobe epilepsy

The objective of this study was to assess the reliability of the diagnosis of mesial temporal lobe epilepsy using EEG and sphenoidal electrodes. Inter-ictal 99 m Tc-HMPAO SPECT scans were registered in 21 patients with confirmed mesial temporal lobe epilepsy identified by scalp EEG and sphenoidal electrodes. Visual and quantitative SPECT analysis was performed blind to EEG data. An asymmetry index (AI) was measured from the ratio of two symmetrical regions of interest. A temporal lobe hypoperfusion was defined as an uptake reduced by 5% with respect to the contralateral region. Inter-ictal SPECT abnormalities were observed in 12 out of 21 patients (57%) from both visual and quantitative analysis (focal hypoperfusion in 11 cases, focal hyperperfusion in one case). In seven patients (33%) both visual and quantitative scintigraphy were normal. Abnormal AI was found in 11/15 patients with a high frequency of seizures and in 1/6 patients with a low frequency of seizures. The major data is that the probability to have an abnormal SPECT is statistically correlated to the frequency of the epileptic fits. The couple EEG recordings with sphenoidal electrodes and SPECT is sensitive and reliable in the diagnosis of mesial temporal lobe epilepsy.     

Postictal SPECT in Epileptic Versus Nonepileptic Seizures

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

Correlation between inter-ictal regional cerebral blood flow and sphenoidal electrodes - recorded inter-ictal spikes in mesial temporal lobe epilepsy

Abstract

The objective of this study was to assess the reliability of the diagnosis of mesial temporal lobe epilepsy using EEG and sphenoidal electrodes. Inter-ictal 99 m Tc-HMPAO SPECT scans were registered in 21 patients with confirmed mesial temporal lobe epilepsy identified by scalp EEG and sphenoidal electrodes. Visual and quantitative SPECT analysis was performed blind to EEG data. An asymmetry index (Al) was measured from the ratio of two symmetrical regions of interest. A temporal lobe hypoperfusion was defined as an uptake reduced by 5% with respect to the contralateral region. Inter-ictal SPECT abnormalities were observed in 12 out of 21 patients (57%) from both visual and quantitative analysis (focal hypoperfusion in 11 cases, focal hyperperfusion in one case). In seven patients (33%) both visual and quantitative scintigraphy were normal. Abnormal Al was found in 11/15 patients with a high frequency of seizures and in 1/6 patients with a low frequency of seizures. The major data is that the probability to have an abnormal SPECT is statistically correlated to the frequency of the epileptic fits. The couple EEG recordings with sphenoidal electrodes and SPECT is sensitive and reliable in the diagnosis of mesial temporal lobe epilepsy. [Neurol Res 2000; 22: 674-678]     

Tc99m HM-PAO single photon emission computed tomography in temporal lobe epilepsy

We present the results of single photon emission computed tomography (SPECT) in 40 patients with temporal lobe epilepsy and normal computed transmission tomography (CT). Abnormalities of regional cerebral blood flow were found in 26 patients. There was focal hypoperfusion alone in 14, focal hyperperfusion alone in 6, and both types of abnormality in 6. In 4 patients there were bilateral abnormalities. Repeat SPECT showed persistence of interictal hyperperfusion in 5/12 patients. There were no significant correlations between SPECT findings and clinical parameters, and no relation between the persistence of interictal hyperperfusion and time since last seizure or seizure frequency. Where SPECT and multiple surface EEG recordings were both lateralising, agreement between them was good. The results of this study support the usefulness of HMPAO SPECT in detecting lateralising abnormalities in temporal lobe epilepsy. Interictal hyperperfusion may be commoner than previous publications suggest, and may be persistent in some cases.     

Postictal symptoms help distinguish patients with epileptic seizures from those with non-epileptic seizures.

The aim of the study was to assess whether post-ictal symptoms can help distinguish patients who have epileptic seizures from those with non-epileptic seizures (NES). We reviewed the spontaneous responses to the question 'What symptoms do you have after a seizure?' in 16 patients with epileptic seizures (predominantly focal with secondary generalization or generalized tonic-clonic) and 23 NES patients. Six of the 16 patients (38%) vs. only one of 23 NES patients (4.3%) noted post-ictal headache (P = 0.008). Nine epilepsy patients (56%) vs. three NES patients (13%) reported post-ictal fatigue (P = 0.004). Confusion or other symptoms did not distinguish epilepsy patients from those with NES. All epilepsy patients had at least one post-ictal symptom while 12 NES patients (52%) had none (P = 0.001). Therefore, patients evaluated for epileptic vs. non-epileptic seizures who have post-ictal fatigue or headache, are more likely to have epileptic seizures. Patients with a diagnosis of NES who note post-ictal fatigue or headache should be investigated further.     

Interictal Temporal Hypoperfusion Is Related to Early-Onset Temporal Lobe Epilepsy

Previous studies of interictal regional cerebral blood flow (rCBF) in temporal lobe epilepsy have shown variable correlations with clinical measures. We used high spatial resolution hexamethyl propyleneamine oxime single photon emission computed tomography (HMPAO SPECT) in 80 consecutive patients with complex partial seizures (CPS), comparing results with those from a large series of normal subjects. Visual image analysis detected abnormalities of rCBF in 41 of 80 (51%; numeric analysis detected abnormalities in 38 of 80). Age at epilepsy onset was significantly younger in patients with temporal hypoperfusion (p = 0.002), and the frequency distribution of hypoperfusion versus age at epilepsy onset was reverse exponential. The results of numerical image analysis showed that degree of hypoperfusion did not vary with age at epilepsy onset. These data suggest a single insult operating early in life as a cause of temporal hypoperfusion, as has been shown for mesial temporal sclerosis (MTS). We could not demonstrate relationships with other clinical variables, including time since last seizure.     

Cryptogenic temporal lobe epilepsy. Semi-quantitative interictal 99mTc HMPAO SPECT: statistical correlation with clinical data and EEG

The aim of our work was to identify clinical and electroencephalographic factors that are statistically correlated to 99mTc HMPAO hypofixation in cryptogenic temporal lobe epilepsy. We selected a homogeneous group of patients (28 males and 17 females) affected by temporal lobe epilepsy and having normal results on computed tomography and magnetic resonance imaging. Patients were classified according to semeiological characteristics of the seizures, presence or absence of spikes on electroencephalography (EEG), age at onset, illness duration, and drug resistance.The presence of focal interictal spikes on EEG was statistically correlated to 99mTc HMPAO temporal hypofixation (p = 0.04). The other electroclinical factors considered in this series did not play an important role in modifying radiopharmaceutical fixation in focal epilepsy in interictal phase. We speculate that a possible explanation for focal radiopharmaceutical hypofixation, in addition to hypoperfusion, is an increased permeability of the blood-brain barrier (due to perivascular inflammation or other causes) which can be responsible for 99mTc HMPAO escape with a resultant hypofixation.     

Abnormalities of cerebral blood flow in the acute phase of bacterial meningitis in adults

Summary The frequency, course and clinical significance of changes in regional cerebral blood flow (rCBF) during bacterial meningitis were investigated in 14 adult patients. The results of^99mTc-hexamethylpropylene amine oxime (HMPAO) single photon emission computed tomography (SPECT) were compared with the clinical signs and findings using cerebral angiography and conventional CT. HMPAO SPECT was performed 2–15 days (median 4.5 days) after the onset of neurological disease. Decreased HMPAO accumulation was detected in 13 patients. SPECT studies revealed focal hypoperfusion cor responding to the clinical symptoms in 6 patients suffering from hemiparesis or hemiataxia. Conventional cranial CT disclosed brain infarction in only 1 patient. Focal hypoperfusion was also found in 7 of 8 patients without clinical evidence of focal neurological deficits. In 6 patients, HMPAO SPECT findings were abnormal although cerebral angiography was normal. At follow-up examinations 3–45 weeks after the acute disease, abnormalities revealed by HMPAO SPECT had improved or had even disappeared in all patients studied. Our results indicate that reduced rCBF is a frequent finding in bacterial meningitis in the adult. In most patients it probably represents a functional and reversible disorder without structural lesion detectable on CT.     

Infantile Spasms: Localized Cerebral Lesions on SPECT

Summary: Ten infantile spasms (IS) patients had single photon emission computed tomography (SPECT) with [^99mTc]HMPAO, EEG, and magnetic resonance imaging (MRI) studies. SPECT showed localized cerebral hypo-perfusion in 7 infants (4 unifocal; 3 multifocal) always involving the temporal regions either unilaterally or bilaterally. EEGs obtained in near time of the SPECT studies showed focal abnormalities in all 7 infants with hypoper-fusion on SPECT, with complete correspondence of the abnormalities in 5. MRI showed localized cerebral lesionsin only 3 of the 10 infants, all of whom had corresponding areas of hypoperfusion on SPECT. Our study indicates that localized cerebral abnormalities (especially of the temporal lobes) may often be associated with IS and that such patients may have localized cerebral hypoperfusion on SPECT even when the MRI is normal.     

Interictal brain 99mTc-HM-PAO SPECT hypoperfusion in patients with unstable partial epilepsy and normal CT

Brain perfusion was studied interictally with 99mTc-HM-PAO SPECT in 47 adult patients with partial epilepsy and normal brain CT. Epilepsy was classified as secondarily generalized in 24 patients, as complex partial in 17 patients and as simple partial in 6 patients. In 24 patients good seizure control was not achieved as these patients had a median number of 78 seizures during the preceding month, while in the rest of the patients seizure control was relatively good (less than 6 seizures during preceding month). Local brain hypoperfusion was observed in 41 or 87% of the patients. Hypoperfusion was located close to the EEG foci in 76% and equally often with temporal and frontal foci. Hypoperfusion and the EEG focus were located on the same side in 83%. Hypoperfusion was more frequent in secondarily generalized epilepsy and simple partial epilepsy than in complex partial epilepsy. Left-sided hypoperfusion was especially associated with complex partial epilepsy. It is likely that the significant epileptogenic brain area was revealed in patients with SPECT focus and EEG focus in the same brain area. In one of our patients MRI showed a small temporal lesion which on successful removal was identified as a low-grade oligodendroglioma. Abnormalities of regional brain uptake of HM-PAO demonstrated by SPECT in patients with partial epilepsy and normal brain CT give further information about pathophysiology in partial epilepsy; this may be of use both for selecting appropriate therapy and in presurgical localization of foci.     

Single Photon Emission Computed Tomography (SPECT) in a Patient with Bilateral Temporal Seizures: Correlation Between Ictal EEG and Postictal/Ictal SPECT

Summary: We report a patient with bilateral independent temporal lobe seizures in whom two [^99mTc]HMPAO single photon emission computed tomograph (SPECT) scans were performed during two different seizures. In the first perüctal SPECT, [^99mTc]HMPAO was injected in the interval between two closely spaced seizures (one localized in the left temporal lobe and the other in the right temporal lobe). SPECT images showed hypoperfusion in the left lateral temporal lobe, hyper-perfusion of the left mesial temporal region, and pronounced hyperperfusion in the right anterior temporal lobe. These results suggest both a postictal left temporal SPECT pattern and an ictal right temporal pattern. In the second periictal SPECT, [^99mTc]HMPA was injected immediately after a right temporal lobe seizure and showed right lateral temporal lobe hypoperfusion and right mesial hyperperfusion, suggesting a postictal right temporal SPECT pattern. Interpretation of the periictal SPECT should take into account EEG changes at the time or in the minutes immediately after injection of [^99mTc] HMPAO.     

Ictal single photon emission computed tomography in absence seizures: apparent implication of different neuronal mechanisms

Absence seizures represent a complex group of epilepsy, characterized by lapse of consciousness with staring. Bilateral, synchronous, and symmetric bursts of 3-Hz spike-and-wave discharges are observed on the electroencephalogram, whereas interictal background activity is normal. This kind of epilepsy has to be differentiated from other generalized epilepsies such as juvenile absence epilepsy and juvenile myoclonic epilepsy. Moreover, absence seizures, together with generalized spike-and-wave discharges, may coexist with other types of epilepsy such as frontal lobe epilepsy, temporal lobe epilepsy, benign epilepsy with centrotemporal spikes, and childhood epilepsy with occipital paroxysms. We have carried out ictal single photon emission computed tomography (SPECT) in 10 patients with clinical evidence of absence seizures with the aim to better understand and to distinguish this kind of seizure as primarily or secondarily generalized to a specific area and to obtain more information on the neuronal mechanisms involved in the different types of seizures, usually not identifiable at the first appearance. During the long follow-up period (9 months to 14 years), 7 of the 10 examined patients underwent interictal SPECT when they became seizure free. Our data permitted, in two patients, the diagnosis of childhood absence seizures; in three patients, they suggested the possibility of later appearance of other seizure types, on the basis of focal hyperperfusion indicating a possible focal firing. In three of the examined patients, the diagnosis of idiopathic localization-related epilepsies mimicking childhood absence seizures could be performed. In the last two patients, the hypothesis of a coexistence of absences with partial and generalized seizures was considered. From our results, it can be presumed that ictal SPECT findings may contribute to the physiopathologic classification of the different types of epilepsies. Moreover, anticonvulsant treatment more appropriate to the different forms of seizures can be used.     

Ictal HMPAO-Single Photon Emission Computed Tomography Findings in Reading Epilepsy in a Japanese Boy

Summary: Reading epilepsy is rare. We report a 14-year-old right-handed Japanese boy who had had jaw jerking only while reading since age 12 years. The episodes occurred every time he read an English textbook and some-times during prolonged reading of a Japanese textbook. The jaw jerking evolved to generalized tonic-clonic seizures (GTCS) on only two occasions during prolonged reading aloud. Routine EEGs showed no abnormality. After a few minutes of reading, however, the EEG showed bilateral 2-Hz, 150-μ V spike-wave complexes with left frontotemporal accentuation, accompanied by jaw jerking. Ictal single photon emission computed tomography (SPECT) with [^99mTc]hexamethylpropylene amine oxime (HMPAO) showed focal hyperperfusion of the frontal lobes bilaterally and of the left temporal area. Interictal SPECT and magnetic resonance imaging (MRI) were normal. The combination of valproate (VPA) and clonazepam (CZP) almost eliminated his symptoms. Ictal SPECT is a useful technique for seizure localization in reading epilepsy.     

Correlation of SPECT, EEG and CT in patients with epilepsy. A preliminary report

Single photon emission computed tomography (SPECT) were performed in 14 patients with epilepsy. Among 6 patients with GTC, five had no focal abnormalities in EEG and CT scan, SPECT also showed no changes of regional cerebral perfusion. In another one patient EEG was normal, CT scan showed hypodensity in right frontal area, SPECT showed decreased regional cerebral perfusion in right frontotemporal area. AVM in frontal lobe was found at operation. In 3 patients with complex partial seizures and 5 patients with complex partial seizures and GTC, SPECT showed regional cerebral perfusion coincided with the area of focal epileptic form discharges in EEG. In one patient with complex partial seizures and GTC EEG showed right antero-temporal focal sharp wave discharges, discrete calcification in superior suprasella cisterna on CT, SPECT showed decreased regional perfusion in right temporal area, pathological examination revealed hematoma in right temporal lobe. SPECT is useful for localizing epileptogenic foci in epileptics.     

Cerebral blood flow distribution and reactivity during the symptom-free stages of transient ischemic attacks--a 99mTc-HMPAO SPECT study]

Even during the symptom-free stages, patients with transient ischemic attacks (TIA) often show cerebral blood flow (CBF) disturbances. For evaluating the factors which cause these abnormalities, we studied CBF and CBF reactivity to acetazolamide (Diamox) using a 99mTc-hexamethylpropyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT). The results from CBF-SPECT were compared with X-ray computed tomography (CT), cerebral arteriogram, clinical characteristics of TIA and cerebrovascular risk factors. The overall sensitivity rates in detecting the lesion were 68% in CBF-SPECT and 9% in CT. The size of the hypoperfused area tended to be wide in patients who had intracranial, severe stenotic or multiple arterial lesions on the ipsilateral side. No such relations were found between CBF and other examinations. Brain hypoperfusion was located in the subcortical region in eight patients; two patients showed a small hypodense lesion on CT which corresponded to the hypoperfusion on SPECT, and three patients showed no arteriographic abnormality. Hypoperfusion in the cortex was seen in seven patients; all patients showed arteriographic abnormality, but no CT abnormality. The severity rating of the vascular stenosis and hypoperfusion, and the incidence of the intracranial lesions were higher in this group than the group with subcotical hypoperfusion. Seven patients showed fixed normoperfusion before and after diamox injection. Two patients with a subcortical small infarction showed fixed hypoperfusion even after diamox injection. Twelve patients showed focal hypoperfusion before diamox with a new filling-in after diamox. Only one patient showed resting hypoperfusion and decreased CBF reactivity to diamox.(ABSTRACT TRUNCATED AT 250 WORDS)     

De Novo Psychogenic Nonepileptic Seizures After Epilepsy Surgery

Summary: Purpose: The occurrence of de novo nonepileptic seizures (NES) after epilepsy surgery have been reported only twice in the literature (one article and one abstract).
Methods: We report three patients whose de novo NES were documented by video-EEG telemetry after epilepsy surgery. These patients were drawn from a sample of 166 consecutive patients who underwent epilepsy surgery at our center between 1989 and 1996.
Results: Two patients became seizure free after surgery, and one had significant improvement of her seizures. The interval between the date of surgery and the development of the symptoms was variable (8, 10, and 47 months, respectively). The clinical phenomena of NES differed from those of the epileptic seizures preceding surgery. Their diagnosis had not been suspected in two patients before the diagnostic video-EEG monitoring study. After the diagnosis of NES, spells stopped in two patients and recurred rarely in one.
Conclusions: We conclude that de novo NES appears to occur rarely after epilepsy surgery. Given that the possibility of NES was suspected in only one patient, its incidence after surgery may be higher than so far reported. Physicians should therefore consider NES in the differential diagnosis of recurrent seizures after a seizure-free period after epilepsy surgery.     

Usefulness of Ictal and Interictal 99mTC Ethyl Cysteinate Dimer Single Photon Emission Computed Tomography in Patients with Refractory Partial Epilepsy

Summary: Purpose: Ictal perfusion single photon emission computed tomography (SPECT), using HMPAO, has been shown to localize epileptic foci in ～90% of studies. Unfortunately, HMPAO decomposes rapidly, precluding the performance of ictal studies. Ethyl cysteinate dimer (ECD) is a SPECT perfusion agent recently approved by the Food and Drug Administration. After preparation, this compound is stable for ～6 h. facilitating the performance of ictal studies. Methods: In a prospective, open-label, uncontrolled, non randomized study, we evaluated the potential benefits of the use of ^99mTc-ECD SPECT for lateralization of the epileptic focus. Ten consecutive adult epilepsy surgery candidates were studied with ictal and interictal ^99mTc-ECD SPECT. Results: The mean delay between seizure onset and ictal SPECT injection was 23.2 s. The mean seizure duration was 84.1 s. Ictal studies agreement between the epilepsy focus and area of hyperperfusion was evident in 8 of 10 cases. In one case, SPECT was lateralized in a patient with bilateral temporal lobe epilepsy (TLE); however, hyperperfusion was observed on the same side of that particular seizure. In another case, there was location disagreement. Interictal SPECT showed focal hypoperfusion in three cases. Conclusions: ^99mTc-ECD proved to be an optimal tracer for ictal studies. Although this is a small series, the results of ictal and interictal findings using 99mTc-ECD are similar to those reported with ^99mTc-HMPA0. Because ^99mTc-ECD has a longer decomposition time, true ictal studies are easier to obtain. This new tracer will probably allow the use of ictal SPECT to become widely accepted in most epilepsy centers.     

Role of I-123-Iomazenil SPECT imaging in drug resistant epilepsy with complex partial seizures

Fifteen patients with therapy resistant partial complex seizures with no structural lesions were examined interictally with 123-I-IOMAZENIL SPECT for measurement of benzodiazepine receptor distribution and with 99m-Tc-HMPAO SPECT for measurement of cerebral blood flow distribution. Regional abnormalities were correlated with the seizure onset patterns in EEG later recorded with implanted subdural strips. SPECT scans were made immediately after and at 1 and 2 h after intravenous injection of 123-I-Iomazenil. During that time there was a continuous change from an immediate flow-related distribution toward a more specific receptor distribution. The decay of radioactivity of I-123 in the brain was linear over time. Two patients on benzodiazepine treatment showed much faster elimination and showed no focal abnormalities. Eight patients with clear-cut unifocal seizure onset showed concordant focal benzodiazepine defects. These patients showed a progressive focus/homotopic non-focus enhancement over time much larger than the HMPAO scans in the same patients. Also the estimated focal area of abnormality was more restricted in the Iomazenil scans than in HMPAO scans. Five patients had more complex seizure onset patterns. In these patients a mismatch between the locations of abnormalities in Iomazenil and HMPAO scans were often found but benzodiazepine receptor abnormalities were more circumscribed also in these patients. The results suggest that 123-I-Iomazenil SPECT is more useful than 99m-Tc-HMPAO SPECT when applied interictally in patients with partial complex epilepsy, since in addition to demonstrate the hemispheric laterality of the epileptogenic zone, 123-I-Iomazenil appears to indicate its anatomical location with higher confidence, which could be of practical value for positioning of intracranial EEG electrodes.