Temporal Lobe Complex Partial Seizures Research Articles

6. The involvement of subcortical inhibitory structures in complex partial seizures

The network mechanisms underlying loss of consciousness during temporal lobe complex partial seizures (CPS) are not well understood. The Blumenfeld hypothesis states that unconsciousness results not from epileptic hyper-excitation of the neocortex — which was the traditional view — but from secondary inhibition of the cortex due to the suppression of subcortical arousal systems. To investigate this hypothesis – and more specifically, to characterize the major inhibitory structures involved – we have performed local stimulation experiments and hippocampal kindling studies in rats. We have found that 10 Hz stimulation of the lateral septal nuclei and the nucleus accumbens shell causes behavioural arrest and slow waves in the cortex. Preliminary hippocampal kindling studies have also revealed that the occurrence of propagated discharge in the lateral septum and the nucleus accumbens shell is highly correlated with the presence of neocortical slow waves but not the onset of behavioural arrest. These findings identify the lateral septum and nucleus accumbens shell as key subcortical structures underlying seizure-related neocortical deactivation. Future studies will be needed to determine the role of other possible candidates.

Interictal epileptiform discharges in new‐onset epilepsy among older adults

AbstractBackgroundThe incidence of epilepsy is highest in older adults and exceeds that observed in children. Seizure disorders are also more common among older adults. However, there are few reports of interictal epileptiform discharges in new‐onset epilepsy among older adults.AimTo investigate the rate of interictal epileptiform discharges in elderly patients with new‐onset epilepsy.MethodsWe defined elderly patients with new‐onset epilepsy as those who developed epilepsy after the age of 65 years. We reviewed the interictal electroencephalographic characteristics of patients with new‐onset epilepsy treated between April 2005 and December 2011 at a tertiary referral center. Both outpatients and inpatients were included in this study. Epilepsy was diagnosed on the basis of clinical history, scalp‐recorded electroencephalography, physical findings, brain 3.0‐T magnetic resonance imaging/computed tomography, single‐photon emission tomography and neuropsychological evaluation. Epilepsy and seizure classifications, and age of onset were also reviewed.ResultsWe included 112 patients (58 men and 54 women) in this study. The mean age of seizure onset was 73.5 ± 6.7 years. Interictal epileptiform discharges were detected in 82 patients (73.2%). Temporal lobe epilepsy (odds ratio 6.3, P = 0.004) and complex partial seizures (odds ratio 8.0, P = 0.033) were associated with interictal epileptiform discharges.ConclusionInterictal epileptiform discharges were present in 73.2% of the elderly patients with new‐onset epilepsy in our cohort, which was higher than the previously reported rate. Temporal lobe epilepsy was the most frequent epilepsy diagnosis among the interictal epileptiform discharge‐positive patients.

Theories of impaired consciousness in epilepsy.

Although the precise mechanisms for control of consciousness are not fully understood, emerging data show that conscious information processing depends on the activation of certain networks in the brain and that the impairment of consciousness is related to abnormal activity in these systems. Epilepsy can lead to transient impairment of consciousness, providing a window into the mechanisms necessary for normal consciousness. Thus, despite differences in behavioral manifestations, cause, and electrophysiology, generalized tonic-clonic, absence, and partial seizures engage similar anatomical structures and pathways. We review prior concepts of impaired consciousness in epilepsy, focusing especially on temporal lobe complex partial seizures, which are a common and debilitating form of epileptic unconsciousness. We discuss a "network inhibition hypothesis" in which focal temporal lobe seizure activity disrupts normal cortical-subcortical interactions, leading to depressed neocortical function and impaired consciousness. This review of the major prior theories of impaired consciousness in epilepsy allows us to put more recent data into context and to reach a better understanding of the mechanisms important for normal consciousness.

A Neurofunctional Evaluation Strategy for Presurgical Selection of Temporal Lobe Epilepsy Patients

Introduction Temporal lobe epilepsy (TLE) is the prototype of a surgically correctable syndrome. Successful surgical outcomes depend on a thorough presurgical evaluation aimed primarily at identifying the epileptogenic zone. Objective Describe the noninvasive presurgical selection and evaluation strategy for TLE patients introduced at the International Neurological Restoration Center (CIREN) in Havana, Cuba, and evaluated between 2001 and 2006 for its accuracy in identifying candidates for non-lesional resection surgery. Methods Ictal onset electrographic patterns of 1,679 seizures in 72 patients with drug-resistant partial epilepsy, obtained through longterm scalp Video EEG (V-EEG) monitoring, were evaluated. The correlation between the V-EEG-defined epileptogenic zone and the dysfunction shown by single photon emission computed tomography (ictal and interictal brain SPECT) and nuclear magnetic resonance spectroscopy (MRS) was established. Results V-EEG monitoring determined that 44.4% of evaluated patients had complex partial temporal lobe seizures. Identification of patients with medial temporal epilepsy (MTE) increased as a result of lateralization and localization of the dominant mean ictal pattern frequency (5.56 ± 1.31 Hz) during the period of maximum spectral power VARETA localization of an ictal epileptiform activity source coincided with the epileptogenic zone in all TLE patients who subsequently underwent a successful temporal lobectomy. Semiquantitative analysis of ictal and interictal brain SPECT images, as well as metabolic ratios measured by MRS, combined with V-EEG findings, enabled localization/lateralization of the epileptogenic zone in TLE patients whose MRIs were normal or showed bilateral structural abnormalities. Conclusions Confirmation of correct localization/lateralization of the epileptogenic zone following successful surgical outcomes in selected TLE patients led CIREN to develop a surgical treatment strategy for patients in Cuba with drug-resistant temporal lobe epilepsy. This strategy offers an appropriate, cost-effective treatment alternative for developing countries like Cuba, with the benefit of significantly improving TLE patients' quality of life.

Heart rate analysis differentiates dialeptic complex partial temporal lobe seizures from auras and non-epileptic seizures

The distinction of non-epileptic from epileptic events is difficult even for experienced neurologists. We retrospectively evaluated 59 dialeptic events from 27 patients admitted for video EEG monitoring to check whether heart rate (HR) analysis could help in differentiating dialeptic complex partial temporal lobe seizures (TLS) from dialeptic simple partial TLS, and non-epileptic dialeptic events. Baseline HR was increased in the simple partial TLS in comparison to complex partial TLS and non-epileptic groups (p<0.05). HR increase accompanied each individual dialeptic complex partial TLS (100% of the events, p<0.05) bur HR returned to baseline in the post-ictal phase. Ictal HR was not altered in the non-epileptic or simple partial TLS groups. Our findings suggest that ictal centrally mediated tachycardia is characteristic of dialeptic TLS (both tachycardia and bradycardia have been reported during TLS). This finding may be used as a criterion to distinguish dialeptic complex partial TLS from simple partial and non-epileptic dialeptic events.

Interictal and Postictal Language Testing Accurately Lateralizes Language Dominant Temporal Lobe Complex Partial Seizures

Noninvasive tests that accurately localize seizure onset provide great value in the presurgical evaluation of patients with intractable epilepsy. This study examined the diagnostic utility of three expressive language disturbances in lateralizing language-dominant (DOM) temporal lobe complex partial seizures: (1) the postictal language delay (PILD; time taken to correctly read a test phrase out loud immediately following seizures); (2) the production of postictal phonemic paraphasic errors (PostPE); and (3) interictal phonemic paraphasic errors (InterPE). All 60 subjects underwent inpatient video/EEG monitoring and had surgically confirmed temporal lobe epilepsy (TLE). We determined the presence and number of PostPE and, PILD times (in s) for 212 seizures, and InterPE on the Boston Naming Test (BNT). Each technique's diagnostic usefulness was evaluated via logistic regression and ROC curve analysis. Sensitivity, specificity, positive predictive value and negative predictive values were computed. PILD, PostPE and InterPE production were equally effective and accurate in lateralizing DOM seizure onset. Patients with DOM TLE had a longer PILD and committed more PostPE and InterPE than those with nondominant (NDOM) TLE. Respective sensitivity and specificity values were as follows: PILD (84%, 86%), PostPE (94%, 64%), and InterPE (97%, 86%). No single predictor was significantly better but a combination model yielded enough incremental utility to collectively outperform each separate predictor model. Interictal language testing is as accurate as postictal language testing in predicting DOM lateralization of TLE. Clinicians should also attend to the quality of errors produced during interictal and postictal language testing.

Autoimmune Encephalopathies

Evaluation of patients with recent onset of progressive cognitive and behavioral problems can be challenging. Psychiatric disorders, metabolic derangements, toxins and infections are generally considered in the differential diagnosis along with prion disorders (Creutzfeldt-Jakob disease) and rapidly progressive degenerative dementias. Some subacute encephalopathies are caused by autoimmune or inflammatory mechanisms, recognized by the association with autoantibody markers and/or clear response to immunomodulatory treatment. This review describes the clinical features of these potentially reversible autoimmune encephalopathies. Morvan syndrome, paraneoplastic limbic encephalitis (PLE), and nonparaneoplastic autoimmune limbic encephalitis have characteristic clinical and serological features. Limbic encephalitis is characterized by short-term memory impairment, complex partial temporal lobe seizures and psychiatric symptoms. Signal abnormalities in the mesial temporal lobes without contrast enhancement are the typical MRI findings. Morvan syndrome presents with behavioral changes, hallucinations, severe insomnia, autonomic hyperactivity and neuromyotonia (spontaneous muscle activity). Corticosteroid-responsive encephalopathy associated with evidence of thyroid autoimmunity (sometimes called Hashimoto encephalopathy) has a broad range of clinical presentation. Cognitive impairment with tremor, seizures, stroke-like events (including transient aphasia) and normal thyroid hormone levels is a common scenario. In the absence of diagnostic serological findings, clinical improvement with corticosteroids may be the only evidence of autoimmune encephalopathy. Autoimmune encephalopathies are an important cause of rapidly progressive cognitive and behavioral decline that probably remain under recognized. Electroencephalography, brain MRI, cerebrospinal fluid examination and serological tests are useful diagnostic tools. With increased clinical suspicion, these diseases may be diagnosed and treated successfully.

Suicidality and Antiepileptic Drugs

The main purpose of the present article is to review the possible risk factors for suicidal behaviour in epilepsy with a special emphasis on the different antiepileptic drugs (AEDs). Epidemiological data show that, in general, the suicide rate among patients with epilepsy is 5-fold higher than that in the general population, while in temporal lobe epilepsy and complex partial seizures it is approximately 25-fold higher. A certain psychiatric comorbidity may provoke suicidality in patients with epilepsy, and depression and cognitive impairment seem to be the main risk factors for suicidality in epilepsy. In addition, depression and cognitive deterioration in epilepsy may share common neuropsychological mechanisms in terms of hypofrontality. This may cause similar psychopathological signs in both diagnostic categories, including suicidality. Analysis of the literature has shown that serotonin metabolism disturbances are involved in the pathogenesis of suicidal behaviour irrespective of primary diagnosis. Serotonin disturbances also seem to be a common link between depression, suicidality and even epilepsy itself. The various AEDs differ not only in their mechanisms of action, but also in influences on cognition and mood in epileptic patients and suicidality, respectively. Until now, only Ketter's hypothesis has been proposed to explain the psychotropic effects of different AEDs, although it does not explain the positive psychotropic effects of some AEDs, such as carbamazepine and oxcarbazepine. According to this model, all psychotropic effects of AEDs may be the result of effects on the function of two types of receptor functions: gamma-aminobutyric acid (GABA) ergic and antiglutamatergic; other possible mechanisms have not been incorporated. Presumably, other neurochemical mechanisms, and a serotonergic mechanism in particular, should also be taken into account when explaining the psychotropic effects of different AEDs. Based on these data, it has been suggested that AEDs with certain serotonergic properties should reduce the suicidality risk because they exert effects similar to antidepressants (i.e. selective serotonin reuptake inhibitors), whereas AEDs that lack serotonergic mechanisms would not be effective in suicidality prevention. In line with this paradigm, phenobarbital and phenytoin seem to be the only drugs with proven suicidality risk. On the other hand, carbamazepine, oxcarbazepine, valproate and lamotrigine could be regarded as drugs with antisuicidal properties because they all improve cognitive functions and mood in epileptic patients, and possess serotonergic mechanisms of action. The other AEDs, including topiramate, tiagabine, vigabatrin, levetiracetam and zonisamide, all exert negative effects on mood and cognition, although their influence on suicidality has not been proven in evidence-based studies yet. Although zonizamide has serotonergic properties, it exerts negative psychotropic effects, whereas gabapentin is devoid of serotonergic properties but has positive psychotropic effects on mood and cognition. To more fully explain the positive and negative psychotropic effects and influence on suicidality of AEDs, Ketter's paradigm should be supplemented by an understanding of the serotonergic mechanisms of different AEDs. Further trials are required to prove or refute this model.

Distribution of partial seizures during the sleep--wake cycle: differences by seizure onset site.

To evaluate the effects of sleep on partial seizures arising from various brain regions. The authors prospectively studied 133 patients with localization-related epilepsy undergoing video-EEG monitoring over a 2-year period. Seizure type, site of onset, sleep/wake state at onset, duration, and epilepsy syndrome diagnosis were recorded. Periorbital, chin EMG, and scalp/sphenoidal electrodes were used. A subset of 34 patients underwent all-night polysomnography with scoring of sleep stages. The authors analyzed 613 seizures in 133 patients. Forty-three percent (264 of 613) of all partial seizures began during sleep. Sleep seizures began during stages 1 (23%) and 2 (68%) but were rare in slow-wave sleep; no seizures occurred during REM sleep. Temporal lobe complex partial seizures were more likely to secondarily generalize during sleep (31%) than during wakefulness (15%), but frontal lobe seizures were less likely to secondarily generalize during sleep (10% versus 26%; p < 0.005). Partial-onset seizures occur frequently during NREM sleep, especially stage 2 sleep. Frontal lobe seizures are most likely to occur during sleep. Patients with temporal lobe seizures have intermediate sleep seizure rates, and patients with seizures arising from the occipital or parietal lobes have rare sleep-onset seizures. Sleep, particularly stage 2 sleep, promotes secondary generalization of temporal and occipitoparietal, but not frontal, seizures. These findings suggest that the hypersynchrony of sleep facilitates both initiation and propagation of partial seizures, and that effects of sleep depend in part on the location of the epileptic focus.

Reduction of rapid eye movement sleep by diurnal and nocturnal seizures in temporal lobe epilepsy.

Patients with brief, complex partial seizures frequently suffer from tiredness and decreased productivity that continue well beyond the postictal period. A possible explanation is that seizures, even when occurring during the day, disrupt sleep the following night. To determine the effect of temporal lobe complex partial seizures on sleep structure and daytime drowsiness. Patients with temporal lobe epilepsy were admitted for video-electroencephalography monitoring. All-night polysomnography was recorded under the following 3 conditions: seizure free, seizure during the day before the recording, and seizure during the recording. Percentage of time in each sleep stage, sleep efficiency, and time to first and second rapid eye movement (REM) period were compared for seizure vs control conditions. Daytime drowsiness was also measured, using a modified maintenance of wakefulness test and 2 subjective drowsiness tests. Daytime seizures reduced REM from 18%+/-1% to 12%+/-2% (P = .003). Night seizures reduced REM from 16%+/-1% to 6.8%+/-2% (P<.001). Night seizures also significantly reduced stages 2 and 4 while increasing stage 1 sleep. Night seizures, but not day seizures, significantly reduced sleep efficiency, increased time to first REM period, and increased drowsiness as measured by the maintenance of wakefulness test. Temporal lobe complex partial seizures decrease REM sleep, particularly when occurring during sleep but also when occurring on the previous day. This may, in part, be responsible for the prolonged impairment of functioning that some patients report following seizures.

Time-frequency mapping of R–R interval during complex partial seizures of temporal lobe origin

Background: Activation of autonomic nervous system is common with seizures. No reliable biological markers of impending seizures have been found. Evaluation of autonomic changes might help elucidate the transition from interictal to ictal states. Methods: We studied twelve patients (eight females, four males), from 19 to 62 years old with temporal lobe complex partial seizures (CPS). Dynamics of autonomic functions from oscillations in R–R interval (RRI) using time-frequency mapping based upon a Wigner distribution during pre-ictal, ictal and post-ictal periods. Oscillations in RRI at respiratory frequencies (RF) (>0.1 Hz) are parasympathetically mediated and at nonrespiratory frequencies (NONRF) (0.01–0.09 Hz) are under combined sympathetic and parasympathetic influence. Results: CPS evoked marked autonomic imbalance and tachycardia. Spectral powers at both RF_RRI and NONRF_RRI increased over the pre-ictal period. RF_RRI power then fell rapidly over the 30 s before seizure onset and remained markedly reduced during seizure ( P<0.004). NONRF_RRI power reached a maximum at seizure onset and declined to a minimum before the seizure cessation ( P<0.05). Conclusion: Time-frequency analysis revealed that autonomic activation hallmarks clinical seizure onset for several minutes. After combined parasympathetic and sympathetic activation, rapid parasympathetic withdrawal occurred ∼30 s before the seizure, and sympathetic activation peaks at seizure onset. Therefore, the transition from interictal to ictal states is relatively long and associated with subclinical autonomic changes.

Common dynamics in temporal lobe seizures and absence seizures

Similarities among the clinical features of complex partial temporal lobe seizures and absence (petit mal) seizures suggest shared underlying mechanisms, but dissimilar electrographic features of the two seizure types have cast doubt on common neuronal substrates. However, visual inspection and traditional approaches to quantitative analysis of the electroencephalogram and electrocorticogram, such as Fourier analysis, may not be appropriate to identify and characterize the highly non-linear mechanisms likely to underlie ictal events. We previously introduced a technique, non-linear autoregressive analysis, that is designed to identify non-linear dynamics in the electroencephalogram [Schiff N. D. et al. (1991) Society of Neuroscience 21st Annual Meeting, 638.6; Schiff N. D. et al. (1995) Biol. Cybern. 72, 519–526, 527–533]. The non-linear autoregressive analysis technique is aimed at describing seizure discharges as a disturbance of synchrony at the level of neuronal circuits. In absence seizures, we showed that non-linear autoregressive analysis revealed a consistent “fingerprint” of these non-linearities in 3/s discharges within and across patients. Here, we investigate the possibility that non-linear autoregressive modeling of seizure records from patients with temporal lobe epilepsy might reveal common circuit mechanisms when compared with the non-linear autoregressive analysis fingerprint of absence seizures. Electrocorticographic records of seizure activity were obtained in four patients who had received subdural grids or strips implanted in preparation for epilepsy surgery. Decomposition of the multichannel data recorded from these patients by principal component analysis revealed that at least three to five independent “generators” were required to model the data from each patient. Non-linear autoregressive analysis of these extracted generators revealed non-linear dynamics in two patients. In both patients, the temporal aspects of these non-linearities were similar to the characteristic non-linearities identified in the non-linear autoregressive analysis fingerprint of absence seizures. In particular, both patients showed a non-linear interaction of signals 90 ms in the past with signals 150 ms in the past. This was the most prominent interaction seen in all patients with absence seizures (typical and atypical). These results suggest that seizures from some patients with temporal lobe epilepsy may share common underlying circuit mechanisms with those of absence seizures. Physiological interpretations of these results are considered and proposed mechanisms are placed into the context of the alterations of consciousness seen in both epilepsies.

Postictal nose wiping: A lateralizing sign in temporal lobe complex partial seizures

Postictal nose wiping: A lateralizing sign in temporal lobe complex partial seizures

Postictal nose wiping: a lateralizing sign in temporal lobe complex partial seizures.

We report postictal nose wiping as a postictal symptom of localizing and lateralizing significance in focal epilepsy. We reviewed videotapes of 444 focal seizures in 101 patients who underwent prolonged video and EEG monitoring during presurgical epilepsy evaluation, and observed postictal nose wiping in 51.3% of 76 patients with temporal lobe epilepsy. The hand used to perform postictal nose wiping was ipsilateral to the side of seizure origin in 86.5% of all seizures and in 97.3% of all patients. We conclude that postictal nose wiping is a common, easily assessed symptom after focal seizures of temporal lobe origin that provides reliable lateralizing information on the side of seizure onset.

Nocturnal temporal lobe epilepsy.

To analyze clinical, electrophysiologic, and neuroradiologic characteristics and prognostic factors in a group of patients with temporal lobe epilepsy (TLE) and complex partial seizures (CPS) occurring exclusively or predominantly after they fall asleep or before they awaken. CPS arising during sleep are classically identified with frontal lobe epilepsy. TLE associated with seizures occurring only or predominantly during sleep (nocturnal TLE) is less common. From a series of patients with refractory TLE studied between 1980 and 1996, the authors identified 26 patients (15 men) with nonlesional nocturnal TLE (mean age, 40 years). Clinical and laboratory characteristics of these individuals were studied and compared with a group of 72 age-matched, randomly selected patients with nonlesional TLE and predominantly diurnal seizures (diurnal TLE). Mean age at seizure onset was similar for both groups (16.3 versus 18.7 years). In the nocturnal TLE group, 2 of 26 patients had a positive family history of epilepsy, 18 reported an aura, 4 presented with CPS in clusters, 11 had unilateral and 15 bilateral temporal EEG abnormalities, and 14 of 21 studied had unilateral mesial temporal atrophy. None of these factors differed significantly in the two groups except for higher frequency of the following in the diurnal TLE group compared with the nocturnal TLE group: positive family history for epilepsy (33% versus 8%, p=0.01), estimated frequency of seizures (median, 14 versus 2 per month; p < 0.01), and presence of antecedent febrile convulsions (33% versus 11%, p=0.04). In the nocturnal TLE group, eight patients underwent surgical therapy and became seizure free (follow-up, > 12 months). Only two were seizure free on medication. Infrequent and nonclustered seizures, rare family history of epilepsy, and low prevalence of childhood febrile convulsions characterize nocturnal TLE. Within the TLEs, the nocturnal TLE form seems to have a better surgical prognosis.

Outcome after temporal lobectomy in bilateral temporal lobe epilepsy.

We determined how noninvasive presurgical data relate to prognosis after temporal lobectomy in patients with independent bilateral temporal lobe (IBTL) complex partial seizures on the intracranial electroencephalogram (EEG). Between 1986 and 1994, 28 patients had IBTL seizures on intracranial EEG. Fifteen of these 28 patients underwent temporal lobectomy and 13 were not offered surgery. Of the 15 patients who had surgery, 10 patients became seizure-free. Magnetic resonance imaging (MRI) and the Wada test were the only variables associated with a seizure-free outcome. Seven of 10 seizure-free patients had a lateralized Wada result or the presence of unilateral hippocampal sclerosis, whereas none of the patients with persistent seizures had either of these findings. Variables not found to be predictive of a seizure-free outcome included location of scalp interictal spikes, degree of seizure-onset laterality, presence of early epilepsy risk factor, duration of epilepsy, and full-scale intelligence quotient. We conclude that MRI and the Wada test provide information of prognostic value in patients with bilateral temporal seizures independent of intracranial EEG data.

The significance of ictal depth EEG patterns in patients with temporal lobe epilepsy

We reviewed 187 depth recorded seizures in 33 patients with non-lesional temporal lobe complex partial seizures. All patients had a minimum of 1 year follow-up following temporal lobectomy. We classified seizure onset pattern as rhythmic activity, attenuation, or repetitive spikes or spike wave complexes. The most common pattern of seizure onset was rhythmic activity and the next most common pattern was repetitive spikes. Seventy-five seizures (49%) had only one seizure onset pattern, and 79 seizures (51%) had a combination of seizure onset patterns. The degree of hippocampal gliosis strongly predicted the type of seizure onset pattern (Chi square = 24.07, 2 d.f., P < 0.01). The rhythmic activity pattern was associated with mild gliosis, and the repetitive spike pattern was associated with severe gliosis. We classified seizure onset as focal or regional based on the number of electrode contacts that were involved by the ictal EEG. A focal seizure onset was associated with an excellent outcome following temporal lobectomy.

Postictal language dysfunction in patients with right or bilateral hemispheric language localization.

As shown previously, when temporal lobe complex partial seizures (TLCPS) originate from the language dominant hemisphere, patients cannot read a test phrase correctly within 60 s of the end of the ictal discharge. We wished to assess whether postictal language testing results discordant with this pattern identified patients with non-left (right hemisphere or mixed) language dominance. Since 1988, all patients undergoing video/EEG monitoring at our institution have been given a test phrase to read aloud as soon as a seizure is detected. Inclusion criteria for this study were (a) postictal language testing within 60 s of seizure end for at least one TLCPS, (b) > 90% seizure reduction after anterior temporal lobectomy with 2-year minimum follow-up, and (c) language localization by either intracarotid amobarbital test (IAT) or direct electrical stimulation of left hemisphere cortex. Two hundred twenty-four seizures in 64 patients were analyzed. Discordant postictal language patterns were noted in 10 of 11 patients with IAT documented non-left language dominance and in 15 of 53 with left dominance (p = 0.006; sensitivity 90.9%, specificity 71.7%). Postictal language testing accurately identifies patients with non-left language dominance and may be useful in selecting appropriate patients for IAT.

Does technetium-99m bicisate image local brain metabolism in late ictal temporal lobe epilepsy?

Ictal increase in regional cerebral blood flow as judged by single-photon emission tomography (SPET) is a common phenomenon during focal epileptic seizures. Up to 2 min postictally, regional hyperperfusion is a consistent finding with technetium-99m hexamethylpropylene amine oxime (HMPAO) in temporal lobe epilepsy. A new 99mTc-labelled lipophilic cerebral blood flow imaging agent, bicisate, has considerably longer radiochemical stability and yields better image quality than 99mTc-HMPAO. In this report, we present the case of a 21-year-old female patient with temporal lobe complex partial seizures. Magnetic resonance imaging revealed right hippocampal sclerosis. A dose of 550 MBq of 99mTc-bicisate was injected 35 s after the onset of a seizure during intracranial EEG-videotelemetry. At the moment of injection, subdural EEG demonstrated the beginning of late ictal discharges and postictal suppression in the right temporomesial areas. Late ictal SPET images showed marked right fronto-temporo-parietal hypoactivity. The interictal SPET study clearly showed right frontotemporal hypoactivity. These preliminary data suggest that 99mTc-bicisate shows late ictal/early postictal hypoactivity which might represent the primary change in neuronal metabolism rather than the secondary change in cerebral blood flow.

Postictal language assessment and lateralization of complex partial seizures

We performed a prospective study of ictal and postictal language function after 105 temporal lobe complex partial seizures in 26 patients. Seizure localization was verified by a greater than 90% reduction in seizure frequency after temporal lobectomy. At the time of the seizure, the patient was asked to read a test phrase aloud until it was read correctly and clearly. In all 62 seizures originating from the left temporal lobe, the patient took more than 68 seconds to read the test phrase correctly (mean, 321.9 seconds); in 42 of 43 seizures from the right temporal lobe, the patient read the test phrase in less than 54 seconds (mean, 19.7 seconds). Postictal paraphasias occurred in 46 of 62 seizures from the left temporal lobe (11 of 14 patients). In this study, quantifying the time delay in reading a test phrase lateralized seizure onset in all 26 patients tested, proving significantly more accurate than any other single noninvasive presurgical test.