Localization of epileptogenic zone in temporal lobe epilepsy by ictal scalp EEG.

Our aim was to evaluate the ability to localize the epileptogenic zone in temporal lobe epilepsy (TLE) by ictal scalp electroencephalogram (EEG). Using simultaneous video recording, we analysed scalp EEG activity during ictal periods in 38 patients (30 patients with medial TLE (MTLE) and eight with lateral TLE (LTLE)). In 14 patients, intracranial ictal EEGs were recorded with depth electrodes, and simultaneous recordings of scalp and intracranial EEG were performed in 11 patients. Scalp EEG showed that, in all 30 patients with MTLE (71 of 72 seizures), an attenuation of background activity was observed before the appearance of ictal activity. Ictal discharges first appeared in the scalp EEG when the ictal discharges reached the lateral part of the temporal lobe on the intracranial EEG. While, in all eight patients with LTLE (25 of 25 seizures), the attenuation of background activity did not occur before the appearance of ictal activity. When the ictal discharges started in the lateral temporal lobe on intracranial EEG, ictal discharges appeared on the scalp. MTLE and LTLE could be diagnosed by the presence or absence of attenuation of background activity with clinical ictal signs before the appearance of ictal discharges.     

Heart rate increase in otherwise subclinical seizures is different in temporal versus extratemporal seizure onset: support for temporal lobe autonomic influence.

Ictal heart rate was investigated in otherwise subclinical epileptic seizures to test the hypothesis as to whether ictal tachycardia is physiological and not a physical or psychological stress response. In addition, we aimed to evaluate the localizing significance of pure ictal tachycardia. We included 21 epilepsy patients, who showed an ictal EEG seizure pattern during 22, otherwise subclinical seizures. All patients underwent ictal video-EEG recordings to evaluate the possibility of resective epilepsy surgery. The changes in heart rate in these patients were investigated in order to determine their relationship to localization and duration of EEG seizure patterns. Ictal tachycardia was observed in 41% of the otherwise subclinical seizures (nine out of 22), and significantly more often in seizures arising from the temporal lobe than from extratemporal regions (62% versus 11%, p < 0.0018). The seizure duration as defined by EEG was significantly positively correlated with an increase of heart rate (p = 0.043). Ictal heart rate can increase as a result of epileptic activation of autonomic cortex, reflecting a temporal lobe autonomic influence. Thus, measurement of heart rate should be included in the evaluation of otherwise subclinical epileptic seizures, because of its localizing value.     

Lack of aura experience correlates with bitemporal dysfunction in mesial temporal lobe epilepsy

The diagnostic value of lack of aura experience in patients with temporal lobe epilepsy (TLE) is unclear. PURPOSE: To evaluate possible factors of bitemporal dysfunction in patients with mesial TLE who did not experience an aura in electroencephalography EEG/video monitoring for epilepsy surgery. METHODS: Ictal scalp EEG propagation patterns of 347 seizures of 58 patients with mesial temporal lobe sclerosis or non-lesional mesial TLE, interictal epileptiform discharges (IED), presence of unilateral mesial temporal lobe sclerosis in visual magnetic resonance imaging (MRI) analysis, prose memory performance, history or not of an aura, and postictal memory or absence of an aura were analyzed. The ictal EEG was categorized as follows. EEG seizure: (a) remaining regionalized, (b) non-lateralized, (c) showing later switch of lateralization or bitemporal asynchronous ictal patterns. RESULTS: Absent aura in monitoring was significantly correlated with absence of unitemporal MRI sclerosis (P=0.004), bitemporal IED (P=0.008), and propagation of the ictal EEG to the contralateral temporal lobe (P=0.001). Other historical data and interictal prose memory performance were not significantly correlated with absent aura. Ten of 11 patients without aura in monitoring also had absent or rare auras in their history. CONCLUSIONS: Lack of aura experience strongly correlates with indicators of bitemporal dysfunction such as bitemporal interictal sharp waves and bitemporal ictal propagation in scalp EEG, and absence of lateralized MRI sclerosis in patients with mesial TLE. The fact that absent auras are not correlated with episodic memory suggests a transient memory deficit, probably because of rapid propagation to the contralateral mesial temporal lobe.     

Ictal magnetoencephalography in temporal and extratemporal lobe epilepsy

PURPOSE: We evaluated visual patterns and source localization of ictal magnetoencephalography (MEG) in patients with intractable temporal lobe epilepsy (TLE) and extratemporal epilepsy (ETE). METHODS: We performed spike and seizure recording simultaneously with EEG and MEG on two patients with TLE and five patients with ETE. Scalp EEG was recorded from 21 channels (10-20 international system), whereas MEG was recorded from two 37-channel sensors. We compared ictal EEG and MEG onset, frequency, and evolution and performed MEG dipole source localization of interictal spikes and early ictal discharges and co-registered dipoles to brain magnetic resonance imaging (MRI). We correlated dipole characteristics with intracranial EEG, surgical resection, and outcome. RESULTS: Ictal MEG lateralized seizure onset in both TLE patients and demonstrated ictal onset, frequency, and evolution in accordance with EEG. Ictal MEG source analysis revealed tangential vertical dipoles in the anterolateral angle in one patient, and anterior dipoles with anteroposterior orientation in the other. Intracranial EEG revealed regional entorhinal seizure onset in the first patient. Both patients became seizure free after temporal lobectomy. In ETE, ictal MEG demonstrated visual patterns similar to ictal EEG and had concordant localization with interictal MEG in all five patients. Two patients underwent surgery. Ictal MEG localization was concordant with intracranial EEG in both cases. One patient had successful outcome after surgery. The second patient did not improve after limited resection and multiple subpial transections. CONCLUSIONS: Ictal MEG can demonstrate ictal onset frequency and evolution and provide useful localizing information before epilepsy surgery.     

Electrophysiologic Analysis of a Chronic Seizure Model After Unilateral Hippocampal KA Injection

PURPOSE: Unilateral intrahippocampal injections of kainic acid (KA) in rats produce spontaneous recurrent limbic seizures and morphologic changes in hippocampus that resemble hippocampal sclerosis in patients with medically refractory mesial temporal lobe epilepsy (MTLE), that form of temporal lobe epilepsy (TLE) associated with hippocampal sclerosis. Interictal in vivo electrophysiologic studies have revealed high-frequency (250-500 Hz) oscillations, termed fast ripples (FRs). These oscillations may uniquely occur in or adjacent to the site of hippocampal KA injection, in areas that generate spontaneous seizures. Similar field potentials also have been demonstrated in the epileptogenic region of patients with TLE. We have now characterized ictal electrographic patterns in this rat model for comparison with those in human TLE and begun to evaluate the role of FRs in the transition to ictus in the KA-treated rat. METHODS: Rats received unilateral intrahippocampal injections of KA and, after the development of spontaneous seizures, were implanted with multiple fixed and moveable microelectrodes for single unit, field potential, and EEG recording. They were then monitored by using video-EEG telemetry for several weeks to capture and evaluate electrographic and behavioral seizure types. Results were correlated with Timm's stain demonstration of mossy fiber sprouting. RESULTS: Low-voltage fast (LVF) and hypersynchronous electrographic ictal-onset patterns were seen in the KA-treated rat that resembled similar ictal-onset patterns in patients with TLE. Hypersynchronous, but not LVF, ictal discharges were associated with recurrent FRs. As in the human, hypersynchronous ictal onsets originated predominantly in hippocampus, whereas LVF ictal onsets more often involved extrahippocampal structures. LVF ictal onsets occurred during wakefulness or paradoxical sleep and were usually associated with motor behavior, whereas hypersynchronous ictal onsets occurred during slow-wave sleep or periods of immobility and were not associated with motor behavior unless there was transition to another ictal electrographic pattern. Mossy fiber sprouting did not correlate with the frequency of ictal EEG discharges exhibited by each rat but was greater in those rats that demonstrated frequent behavioral seizures. CONCLUSIONS: The electrographic features of spontaneous seizures in the KA-treated rat resemble those of patients with medically refractory TLE with respect to EEG pattern and localization. Our data suggest that hypersynchronous ictal onsets represent epileptogenic disturbances in hippocampal circuits, whereas LVF ictal onsets may involve extrahippocampal areas having more direct connections to the motor system. Hypersynchronous seizures may involve the same neuronal mechanisms that generate interictal FRs.     

Correlation between temporal pole MRI abnormalities and surface ictal EEG patterns in patients with unilateral mesial temporal lobe epilepsy.

OBJECTIVE: The objective of this retrospective study is to analyze ictal patterns observed during continuous Video-EEG monitoring in patients with temporal lobe epilepsy (TLE) due to unilateral hippocampal sclerosis (HS), and to correlate these EEG patterns to temporal pole abnormalities observed on magnetic resonance imaging exams. METHODS: We analyzed 147 seizures from 35 patients with TLE and unilateral HS. Ictal patterns were classified and correlated to signal abnormalities and volumetric measures of the temporal poles. Volume differences over 10% were considered abnormal. RESULTS: The most frequent type of ictal pattern was rhythmic theta activity (RTA), encountered in 65.5% of the seizures. Rhythmic beta activity (RBA) was observed in 11% of the seizures, localized attenuation in 8%, interruption of epileptiform discharges in 6%, repetitive discharges in 5.5%, and rhythmic delta activity (RDA) in 4%. Sixty-six percent of the patients presented signal abnormalities in the temporal pole that were always ipsilateral to the HS. Sixty percent presented significant asymmetry of the temporal poles consisting of reduced volume that was also always ipsilateral to HS. Although patients with RTA as the predominant ictal pattern tended to present asymmetry of temporal poles (p=0.305), the ictal EEG pattern did not correlate with temporal pole asymmetry or signal abnormalities. CONCLUSIONS: RTA is the most frequent initial ictal pattern in patients with TLE due to unilateral HS. Temporal pole signal changes and volumetric reduction were commonly found in this group of patients, both abnormalities appearing always ipsilateral to the HS. However, neither temporal pole volume reduction nor signal abnormalities correlated with the predominant ictal pattern, suggesting that the temporal poles are not crucially involved in the process of epileptogenesis.     

The localizing value of ictal EEG in focal epilepsy.

OBJECTIVE: To investigate the lateralization and localization of ictal EEG in focal epilepsy. METHODS: A total of 486 ictal EEG of 72 patients with focal epilepsy arising from the mesial temporal, neocortical temporal, mesial frontal, dorsolateral frontal, parietal, and occipital regions were analyzed. RESULTS: Surface ictal EEG was adequately localized in 72% of cases, more often in temporal than extratemporal epilepsy. Localized ictal onsets were seen in 57% of seizures and were most common in mesial temporal lobe epilepsy (MTLE), lateral frontal lobe epilepsy (LFLE), and parietal lobe epilepsy, whereas lateralized onsets predominated in neocortical temporal lobe epilepsy and generalized onsets in mesial frontal lobe epilepsy (MFLE) and occipital lobe epilepsy. Approximately two-thirds of seizures were localized, 22% generalized, 4% lateralized, and 6% mislocalized/lateralized. False localization/lateralization occurred in 28% of occipital and 16% of parietal seizures. Rhythmic temporal theta at ictal onset was seen exclusively in temporal lobe seizures, whereas localized repetitive epileptiform activity was highly predictive of LFLE. Seizures arising from the lateral convexity and mesial regions were differentiated by a high incidence of repetitive epileptiform activity at ictal onset in the former and rhythmic theta activity in the latter. CONCLUSIONS: With the exception of mesial frontal lobe epilepsy, ictal recordings are very useful in the localization/lateralization of focal seizures. Some patterns are highly accurate in localizing the epileptogenic lobe. One limitation of ictal EEG is the potential for false localization/lateralization in occipital and parietal lobe epilepsies.     

RTTBD‐like activity in association with hippocampal ictal discharges in patients with temporal lobe epilepsy

Aim. To determine clinical and intracranial EEG correlates of rhythmic temporal theta bursts of drowsiness (RTTBD) and assess its clinical significance in patients with temporal lobe epilepsy (TLE). Methods. A retrospective review of simultaneous scalp and intracranial video‐EEG recordings from 28 patients with TLE was evaluated for epilepsy surgery. Scalp RTTBD patterns were identified and their clinical and intracranial EEG correlates were then determined on video‐EEG recording using depth and subdural electrodes. Results. Thirty‐one RTTBD patterns on scalp EEG were observed in six (21%) of the 28 patients. Five (16%) of the RTTBD patterns occurred during wakefulness and 26 (84%) occurred during drowsiness and light sleep. The mean duration of RTTBD was 10 seconds (range: 3‐28 seconds). RTTDB consistently correlated with hippocampal ictal discharges and was time‐locked to the hippocampal seizures in which the ictal discharges evolved into rhythmic theta frequency (4‐7‐Hz) range. Ictal automatisms were observed during five (16%) RTTBD patterns, while cognitive impairment was observed in four (13%) of the 31 RTTBD patterns. Conclusion. Our findings show that scalp EEG correlates of hippocampal ictal discharges can resemble RTTBD and may be associated with ictal symptoms and cognitive impairment, indicating that RTTBD may rarely be an ictal EEG pattern in patients with TLE.     

The localizing value of the abdominal aura and its evolution: a study in focal epilepsies.

OBJECTIVE: To evaluate the localizing value of abdominal aura and its evolution into other seizure types. METHODS: The seizures of 491 consecutive patients with focal epilepsies were prospectively classified according to a recently introduced semiologic seizure classification. All patients underwent prolonged EEG video monitoring and MRI scan. Two hundred twenty-three patients (45%) had temporal lobe epilepsies (TLE); 113 patients (23%) had extratemporal epilepsies; and for 155 (32%) patients, the epilepsy could not be localized to one lobe. RESULTS: Abdominal auras were more frequent with TLE (117 of 223 patients, 52%) than in extratemporal epilepsy (13 of 113 patients, 12%, p < 0.0001) and more frequent in mesial TLE (70 of 110 patients, 64%) than in neocortical TLE (16 of 41 patients, 39%, p = 0.007). No preponderance to one side existed. Abdominal auras were followed by ictal oral and manual automatisms (automotor seizure) in at least one seizure evolution in all patients with TLE (117 patients, 100%). In contrast, only two patients with extratemporal epilepsy (2 of 13 patients, 15%, p < 0.0001) had abdominal auras evolving into automotor seizures. An abdominal aura is associated with TLE with a probability of 73.6%. The evolution of an abdominal aura into an automotor seizure, however, increases the probability of TLE to 98.3%. CONCLUSIONS: These results demonstrate that evolution of abdominal aura into automotor seizure permits differentiation between temporal lobe epilepsy and extratemporal epilepsy, showing that analysis of seizure evolution provides more localizing information than does the frequency of particular seizure types.     

Orbito-frontal epilepsy masquerading as temporal lobe epilepsy-a case report.

Temporal lobectomy fails to control seizures in a considerable percentage of patients who do not have hippocampal sclerosis. One theoretical reason for failure of surgery is that some of these patients may in fact have extratemporal epilepsy. We present a 28-year-old woman with clinical and scalp electroencephalogram (EEG) evidence of right temporal lobe epilepsy (TLE) supported by functional imaging with interictal positron emission tomography (PET) and ictal single-photon emission computerized tomography (SPECT). An invasive EEG monitoring was prompted by the discovery of a small right orbito-frontal lesion on MRI. Monitoring documented seizure onset at the lesion, with rapid right temporal involvement. The patient was almost seizure-free after a lesionectomy. The index of suspicion of orbito-frontal epilepsy should be high in patients with apparent TLE when the scalp EEG and neuroimaging data are not congruent, or if temporal lobe pathology cannot be identified on structural imaging.     

颞叶癫痫的痫性放电传导和临床症状的颅内电极脑电图研究

目的 探讨颞叶癫痫患者痫性放电的传导部位、时间和相应的临床症状变化.方法 对2003年6月至2007年5月确诊为颞叶癫痫并行颅内电极埋置检查的48例患者的颅内电极脑电图和发作期症状进行回顾性分析,通过在双侧海马放置的针状电极和颢叶、额叶等放置的条状皮层电极,找出发作起源部位、早期传导部位、传导时间及发作起始症状和传导后症状.结果 共记录126次临床癫痫发作,105次记录到传导部位,其中同侧颢叶内传导22次,额叶39次,顶枕叶18次,对侧海马10次,16次全脑放电.44.8%传导时间小于2.5 s,55.2%传导时间超过2.5 s,且有17.1%超过5 s.101次发作中出现初始症状,其中82.2%为意识水平下降、自动症、恐惧等;99次记录到传导后新症状,其中出现颞叶外传导者82.2%出现抽动或强直表现.结论 颞叶癫痫放电传导部位主要是同侧的额叶与颞叶内部,但也可直接到对侧海马结构,临床症状与传导位置有关,传导速度多较慢.     

Cardiac rhythm during temporal lobe seizures.

We studied the neuroanatomic correlates of ictal tachycardia in 27 seizures from five patients with unilateral temporal lobe epilepsy being evaluated with bilateral temporal lobe depth electrodes and orbitofrontal subdural electrodes. There were 11 complex partial seizures, three simple partial seizures, and 13 subclinical seizures. For all seizures, heart rate (HR) increased in a graded fashion as new cortical regions anywhere in the brain were recruited into the seizure. HR plateaued at the new level despite EEG frequency changes until the next region became involved. Increases in HR did not correlate with increased duration of seizures but rather with volume of brain involved. Restricted amygdaloid seizure activity was generally insufficient to alter HR. We conclude that the amygdala has a limited role in modulating HR during seizures, and ictal tachycardia depends principally on the volume of cerebral structures recruited into a seizure.     

Interictal regional delta slowing is an EEG marker of epileptic network in temporal lobe epilepsy

Purpose: Several studies have suggested that interictal regional delta slowing (IRDS) carries a lateralizing and localizing value similar to interictal spikes and is associated with favorable surgical outcomes in patients with temporal lobe epilepsy (TLE). However, whether IRDS reflects structural dysfunction or underlying epileptic activity remains controversial. The objective of this study is to determine the cortical electroencephalography (EEG) correlates of scalp‐recorded IRDS, in so doing, to further understand its clinical and biologic significances. Methods: We examined the cortical EEG substrates of IRDS with electrocorticography (ECoG‐IRDS) and delineated the spatiotemporal relationship between ECoG‐IRDS and both interictal and ictal discharges by recording simultaneously scalp and intracranial EEG in 18 presurgical candidates with TLE. Key Findings: Our results demonstrated that ECoG‐IRDS is typically a mixture of delta/theta slowing and spike‐wave potentials. ECoG‐IRDS was predominantly recorded from basal and anterolateral temporal cortex, occasionally in mesial, posterior temporal, and extratemporal regions. Abundant IRDS was most commonly observed in patients with neocortical temporal lobe epilepsy (NTLE), whereas infrequent to moderate IRDS was usually observed in patients with mesial temporal lobe epilepsy (MTLE). The anatomic distribution of ECoG‐IRDS was highly correlated with the irritative and seizure‐onset zones in 10 patients with NTLE. However, it was poorly correlated with the irritative and seizure‐onset zones in the 8 patients with MTLE. Significance: These findings demonstrate that IRDS is an EEG marker of epileptic network in patients with TLE. Although IRDS and interictal/ictal discharges likely arise from the same neocortical generator in patients with NTLE, IRDS in patients with MTLE may reflect a network disease that involves temporal neocortex.     

Speech preservation during language-dominant, left temporal lobe seizures: report of a rare, potentially misleading finding

PURPOSE: To evaluate the prevalence and mechanism of ictal speech in patients with language-dominant, left temporal lobe seizures. METHODS: We retrospectively reviewed the video-EEG telemetry records for the presence of ictal speech in 96 patients with surgically proven left temporal lobe epilepsy and studied the seizure-propagation patterns in three patients who required intracranial EEG recordings for seizure localization. RESULTS: Ictal speech preservation was observed in five patients. One patient's seizures demonstrated rapid propagation of the ictal discharges to the contralateral temporal area where the seizure evolved, resembling a nondominant temporal lobe seizure. The other two patients had ictal discharges that remained confined to the inferomesial temporal areas, sparing language cortex. CONCLUSIONS: Preservation of speech in complex partial seizures of language-dominant, left temporal lobe origin is rare. Based on intracranial EEG recordings, the likely mechanism underlying this potentially misleading clinical finding is the preservation of language areas due to limited seizure-propagation patterns.     

Electroclinical analysis of postictal noserubbing

BACKGROUND: Postictal noserubbing (PIN) has been identified as a good, albeit imperfect, lateralizing and localizing sign in human partial epilepsy, possibly related to ictal autonomic activation. METHODS: PIN was studied prospectively in a group of consecutive patients admitted for video-EEG monitoring, with the laterality of noserubbing correlated with electrographic sites of seizure onset, intra- and interhemispheric spread, and sites of seizure termination. RESULTS: PIN was significantly more frequent in temporal than extratemporal epilepsy (p<0.001; 23/41 (56%) patients and 41/197 (21%) seizures in temporal lobe epilepsy compared with 4/34 (12%) patients and 12/167 (7%) seizures in extratemporal epilepsy). The hand used to rub the nose was ipsilateral to the side of seizure onset in 83% of both temporal and extratemporal seizures. Seizures with contralateral PIN correlated with spread to the contralateral temporal lobe on scalp EEG (p<0.04). All extratemporal seizures with PIN showed spread to temporal lobe structures. One patient investigated with intracranial electrodes showed PIN only when ictal activity spread to involve the amygdala: seizures confined to the hippocampus were not associated with PIN. PIN was not observed in 63 nonepileptic events in 17 patients. Unexpectedly, one patient with primary generalized epilepsy showed typical PIN after 1/3 recorded absence seizures. CONCLUSIONS: This study confirms PIN as a good indicator of ipsilateral temporal lobe seizure onset. Instances of false lateralization and localization appear to reflect seizure spread to contralateral or ipsilateral temporal lobe structures, respectively. Involvement of the amygdala appears to be of prime importance for induction of PIN.     

Clinical implications of scalp ictal EEG pattern in patients with temporal lobe epilepsy

ObjectiveTo determine the clinical implications of scalp ictal EEG pattern in patients with temporal lobe epilepsy (TLE).MethodsScalp EEG ictal patterns were retrospectively determined in 27 consecutive patients with medically refractory temporal lobe epilepsy who underwent phase-1 scalp video-EEG and phase-2 simultaneous scalp and intracranial video-EEG recordings for pre-surgical evaluation.ResultsOf the 192 temporal lobe seizures recorded during phase-1 and phase-2 scalp video-EEG studies, 124 (65%) seizures were associated with theta/alpha (5–9 Hz) ictal onset pattern, and 68 (35%) seizures were associated with delta (2–5 Hz) ictal onset pattern. Fourteen (52%) patients had exclusively theta/alpha ictal onset, 3 (11%) patients had exclusively delta ictal onset, and 10 (37%) patients had mixed theta/alpha and delta ictal onsets. MTLE was observed in 26 patients who had 124 seizures with theta/alpha ictal onset and 59 seizures with delta ictal onset. LTLE was observed in one patient who had 9 seizures with delta ictal onset. Scalp ictal EEG pattern was not significantly correlated with postsurgical seizure outcomes.ConclusionsBoth scalp delta and theta/alpha ictal onset patterns can be commonly found in patients with MTLE.SignificanceScalp delta ictal onset is not a unique EEG pattern for LTLE as commonly believed.     

Interictal EEG and ictal scalp EEG propagation are highly predictive of surgical outcome in mesial temporal lobe epilepsy

PURPOSE: Surgical outcome in patients with mesial temporal lobe sclerosis (MTS) is worse than that in patients with temporal lobe activity (TLE) with tumors. Previous studies of the ictal EEG focused on ictal EEG onset in scalp EEG or ictal EEG propagation in invasive recordings. Ictal EEG propagation with scalp electrodes has not been reported. METHODS: Ictal scalp EEG propagation patterns were studied in 347 seizures of 58 patients with MTS or nonlesional TLE. Interictal epileptiform discharges (IEDs) and the presence of unilateral mesial temporal lobe atrophy in magnetic resonance imaging (MRI) also were studied in these 58 patients. Forty-nine patients were operated on (minimal follow-up of 1 year). RESULTS: Postoperatively, seizure-free outcome was seen in (a) 82.8% of patients with regionalized EEG seizure without contralateral propagation, but in only 45.5% of patients with contralateral propagation (p = 0.007); (b) 84.6% of patients with 100% IED lateralized to one temporal lobe, but in only 52.2% with <100% unitemporal IED (p = 0.015); (c) 88.9% with 100% unitemporal IED and regionalized ictal EEG combined, 73.7% with one of both variables, and only 33.3% with <100% ipsitemporal IED combined with contralateral ictal EEG propagation (p = 0.007). CONCLUSIONS: Switch of lateralization or bitemporal asynchrony in the ictal scalp EEG and bitemporal IED are most probably an index of bitemporal epileptogenicity in MTS and are associated with a worse outcome.     

Ictal Single Photon Emission Computed Tomography in Occipital Lobe Seizures

Summary: Purpose: Ictal single photon emission computed tomography (SPECT) has been evaluated as an adjunctive localizing technique in temporal lobe epilepsies and, to a lesser degree, in some extratemporal epilepsies. The purpose of this study was to determine whether occipital lobe seizures are associated with distinctive ictal cerebral blood perfusion (rCP) patterns.
Methods : SPECT was used with the tracer ^99mTc HMPAO to image ictal rCP in 6 patients in whom clinical, EEG, and imaging data indicated occipital lobe seizures.
Results : Two patterns of rCP were seen. Four patients had hyperperfusion that was restricted to the occipital lobe, and two patients had hyperperfusion of the occipital lobe and the ipsilateral mesial temporal lobe, with hypoperfusion of the lateral temporal lobe. The latter 2 patients had clinical and surface EEG evidence of temporal lobe involvement in the seizure discharge.
Conclusions : Ictal rCP patterns in occipital lobe seizures are distinct from those in temporal lobe seizures and may vary according to whether or not ipsilateral temporal lobe structures are involved in the ictal discharge.     

Ictal spitting in left temporal lobe epilepsy: report of three cases.

PURPOSE: Ictal spitting is rarely reported in patients with epilepsy. More often it is observed in patients with temporal lobe epilepsy (TLE) and is presumed to be a lateralizing sign to language nondominant hemisphere. We report three patients with left TLE who had ictal spitting registered during prolonged video-EEG monitoring. METHODS: Medical charts of all patients with medically refractory partial epilepsy submitted to prolonged video-EEG monitoring in the Epilepsy Unit at UNIFESP during a 3-year period were reviewed, in search of reports of ictal spitting. The clinical, neurophysiological and neuroimaging data of the identified patients were reviewed. RESULTS: Among 136 patients evaluated with prolonged video-EEG monitoring, three (2.2%) presented spitting automatisms during complex partial seizures. All of them were right-handed, and had clear signs of left hippocampal sclerosis on MRI. In two patients, in all seizures in which ictal spitting was observed, EEG seizure onset was seen in the left temporal lobe. In the third patient, ictal onset with scalp electrodes was observed in the right temporal lobe, but semi-invasive monitoring with foramen ovale electrodes revealed ictal onset in the left temporal lobe, confirming false lateralization in surface records. The three patients became seizure-free following left anterior temporal lobectomy. CONCLUSIONS: Ictal spitting is a rare finding in patients with epilepsy, and may be considered a localizing sign of seizure onset in the temporal lobe. It may be observed in seizures originating from the left temporal lobe, and thus should not be considered a lateralizing sign of nondominant TLE.     

Use of cavernous sinus EEG in the detection of seizure onset and spread in mesial temporal lobe epilepsy

PURPOSE: The study goal was to evaluate the clinical usefulness of intravenous EEG recording by placing wire electrodes in the cavernous sinus (CS) and the superior petrosal sinus (SPS) in patients with intractable temporal lobe epilepsy (TLE), with special emphasis on the ictal recording. METHODS: We placed Seeker Lite-10 guide wire as electrodes in the bilateral CS, SPS, or both to simultaneously record both ictal and interictal EEGs with the scalp EEG in five patients with TLE. In addition, in one patient, we averaged interictal scalp and intravascular EEG time-locked to the epileptiform discharge recorded from the CS/SPS-EEG to further delineate the relationship of the spikes between scalp and intravenous recording. RESULTS: In four of five patients, clinically useful recording was obtained to determine ictal focus. We recorded habitual seizures in three patients, and the detailed characteristics of ictal epileptiform discharges were shown. The averaged waveform of interictal epileptiform discharges clarified the spike distribution in the scalp EEGs, which was otherwise undetectable in the single trace. All of the patients completed the intravenous EEG monitoring without any neurological or psychological problems. CONCLUSIONS: The CS/SPS-EEG is a relatively noninvasive method that is useful for the detection of ictal focus and its spreading pattern and thus for the selection of surgical candidate among patients with intractable TLE. Although the number of seizures detected during the short monitoring period may be limited, due to the advantages of its safety and simplicity, it is worth trying for potential surgical candidates before more invasive examinations are applied. A further study with a larger number of patients is needed to estimate its practical risk.