Clinical factors associated with post-ictal headache in patients with epilepsy

OBJECTIVES: To determine the incidence of post-ictal headaches (PIH) and clinical risk factors associated with the occurrence of PIH in patients with localization-related epilepsy. MATERIALS AND METHODS: The subjects were 77 patients with temporal lobe epilepsy (TLE), 34 patients with occipital lobe epilepsy (OLE), and 50 patients with frontal lobe epilepsy (FLE). The subjects were directly asked whether headaches occurred just after seizures. Medical charts were reviewed to ascertain the clinical characteristics of epilepsy in these patients. RESULTS: The incidence of PIH was 23% for TLE, 62% for OLE, and 42%, for FLE. The risk of PIH was significantly higher for OLE than for TLE or FLE, and for patients with generalized tonic-clonic seizures. Younger age at onset of epilepsy was also a risk factor for PIH. CONCLUSION: The occurrence of PIH may be related to the region of epileptic focus and the region of spread of epileptic discharges.     

Ictal head turning in frontal and temporal lobe epilepsy

Purpose: To quantitatively evaluate the difference of ictal head turning movements between patients with temporal lobe epilepsy (TLE) and frontal lobe epilepsy (FLE). Methods: We investigated 38 seizures of 31 patients with unilateral TLE and 22 seizures of 14 patients with unilateral FLE where head turning occurred in the seizure evolution. The head movements were defined as ipsilateral or contralateral in reference to the lateralization of the patient’s focal epilepsy syndrome. Head movements were quantified by either referencing the head position with manually placed markers or by automatic detection of infrared marked reference points. The time of onset, duration, and angular speed of the head movements were computed, and interindividual and intraindividual analyses were performed. Key Findings: All of the TLE seizures had both contralateral and ipsilateral head turning, whereas all FLE had contralateral head turning; only 6 of 22 seizures were associated with ipsilateral head turning. Ipsilateral head turning always preceded contralateral head turning in both TLE and FLE. The head turning occurred significantly sooner after clinical seizure onset in FLE than in TLE patients (ipsilateral 0.5 vs. 16.0 s, contralateral: 4.5 vs. 21.3 s; p < 0.001). Furthermore, the duration of head turning was shorter in FLE for contralateral head turning (4.1 s) than in TLE (contralateral 6.0 s, p < 0.01); the ipsilateral head turning in the two groups did not differ (3.0 vs. 2.9 s) in duration. The angular speed of head turning did not differ for ipsilateral and for contralateral head turning in FLE and TLE. Significance: Quantitative analysis of head turning demonstrates significant differences between patients with FLE and TLE. These differences likely represent differences in spread of epileptic activity. This information may be useful in the seizure evaluation of patients considered for resective epilepsy surgery.     

鉴别额叶癫痫及颞叶癫痫的临床症状学提示

目的:比较额叶癫痫(FLE)及颞叶癫痫(TLE)的临床症状学区别。方法:纳入2005年10月至2007年3月我院癫痫中心门诊临床诊断为额叶癫痫患者190名,颞叶癫痫患者257名。纳入病例满足发作间期脑电图至少一次具有局限于额叶或颞叶的放电或发作期脑电图明确提示额或颞叶起源;排除所有发作间期脑电图正常、存在多灶或定位不清的脑电异常及影像学检查具有额或颞叶以外的局灶损害者。由两位不知道患者脑电图和影像学结果的临床医生单独分析患者发作情况(先兆、复杂部分发作(CPS)、继发全面强直阵挛发作(SGTC))。用χ2检验统计数据。结果:提示颞叶癫痫最有意义的先兆是经验现象和胃气上升感(P<0.01)。情感表现在TLE中更常见(P<0.05)。口咽自动症与手部自动症是颞叶癫痫患者的典型CPS表现(P<0.01)。而躯体自动症,偏转性强直-肢体与头眼及SGTC、姿势性强直,局部阵挛发作,发作时伴随出声、植物神经症状是额叶癫痫患者的典型CPS表现(P<0.01)。发笑、震颤症状在二类中均可出现,以额叶居多(P<0.05)。言语终止,自言自语,单纯凝视发作对于二者的鉴别意义不大。额叶癫痫组具有两种以上CPS发作的病例更多(P<0.01)。结论:额叶癫痫与颞叶癫痫的症状学特征是不同的,对于临床诊断有重要价值。     

Hyperorality in epileptic seizures: periictal incomplete Klüver-Bucy syndrome

PURPOSE: To analyze systematically hyperorality associated with epileptic seizures and its relation to the localization of epileptic activity. METHODS: To identify patients with periictal hyperorality, we reviewed video-recordings of 269 patients (aged 6-59 years) who had consecutively undergone presurgical evaluations including ictal video-EEG recordings and high-resolution magnetic resonance imaging (MRI) and had had epilepsy surgery because of intractable frontal (FLE) or temporal lobe epilepsy (TLE). Periictal hyperorality was defined if patients put or unambiguously intended to put nonfood items into their mouths during or after at least one of the reviewed seizures. For the further analysis, we included only patients with periictal hyperorality. We reviewed their medical records and reexamined their ictal video-EEG recordings. RESULTS: We identified eight patients (six women) aged 8-59 years who had hyperorality during or after seizures. Seven patients had TLE, and one patient had frontal lobe epilepsy (FLE). Three of these patients underwent right-sided surgery, whereas five patients had surgery on the left. Three patients exhibited ictal and five showed postictal hyperorality. Interictal EEG suggested bilateral interictal epileptiform discharges (IEDs) in three patients; in two other patients, no IEDs were detected. Ictal EEG suggested bilateral involvement in six cases. Patients with unilateral epileptiform activity had left TLE. CONCLUSIONS: Periictal hyperorality is a rare phenomenon occurring in 3% of the investigated epilepsy population. We suggest that periictal hyperorality is an ictal-postictal mental disturbance, an incomplete Klüver-Bucy syndrome. In most patients, bilateral seizure activity plays an important role in the pathomechanism, but it would appear that left-sided epileptic activity without contralateral involvement also can cause periictal hyperorality.     

Structures involved at the time of temporal lobe spikes revealed by interindividual group analysis of EEG/fMRI data

Purpose: We measured metabolic changes associated with temporal lobe (TL) spikes using combined electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). We selected 18 patients with temporal lobe epilepsy (TLE) who underwent a 2‐h simultaneous EEG–fMRI and had unilateral or bilateral independent TL spikes for interindividual group analysis, in order to identify consistent blood oxygenation level dependent (BOLD) responses to TL spikes. Methods: EEG was postprocessed and spikes were visually identified. fMRI data were preprocessed with motion correction, spatial smoothing, and removal of low frequency drifts. Spike timings were used as events for fMRI statistical analysis. Four hemodynamic response functions were used to account for variability in the BOLD response. Results: Group analysis revealed common areas of BOLD activations and deactivations. The hemodynamic response function (HRF) peaking 3 s after the spike showed activation involving ipsilaterally the mesial temporal structures (presumably the hippocampus), putamen/globus pallidus, inferior insula, and superior temporal gyrus. The HRF peaking at 5 s showed activations involving ipsi‐ and contralaterally the superior temporal gyrus and inferior insula. Both HRFs showed bilateral posterior cingulate deactivations. Discussion: We disclosed involvement of a network of activated areas during unilateral TL spikes, including ipsilateral mesial temporal structures, basal ganglia, and bilateral neocortical temporal regions. Despite the low temporal resolution of fMRI we demonstrated that contralateral temporal involvement occurred later than ipsilateral activation. This contralateral change took place in the absence of visible EEG changes. The posterior cingulate deactivation may reflect the interconnections between this region and other limbic structures. It may also partially correspond to a suspension of the default mode network, as previously described for TL spikes.     

How cerebral cortex protects itself from interictal spikes: The alpha/beta inhibition mechanism

Interactions between interictal epileptiform discharges (IEDs) and distant cortical regions subserve potential effects on cognition of patients with focal epilepsy. We hypothesize that “healthy” brain areas at a distance from the epileptic focus may respond to the interference of IEDs by generating inhibitory alpha and beta oscillations. We predict that more prominent alpha‐beta oscillations can be found in patients with less impaired neurocognitive profile. We performed a source imaging magnetoencephalography study, including 41 focal epilepsy patients: 21 with frontal lobe epilepsy (FLE) and 20 with mesial temporal lobe epilepsy. We investigated the effect of anterior (i.e., frontal and temporal) IEDs on the oscillatory pattern over posterior head regions. We compared cortical oscillations (5–80 Hz) temporally linked to 3,749 IEDs (1,945 frontal and 1,803 temporal) versus an equal number of IED‐free segments. We correlated results from IED triggered oscillations to global neurocognitive performance. Only frontal IEDs triggered alpha‐beta oscillations over posterior head regions. IEDs with higher amplitude triggered alpha‐beta oscillations of higher magnitude. The intensity of posterior head region alpha‐beta oscillations significantly correlated with a better neuropsychological profile. Our study demonstrated that cerebral cortex protects itself from IEDs with generation of inhibitory alpha‐beta oscillations at distant cortical regions. The association of more prominent oscillations with a better cognitive status suggests that this mechanism might play a role in determining the cognitive resilience in patients with FLE.     

Temporal lobe interictal epileptic discharges affect cerebral activity in "default mode" brain regions

A cerebral network comprising precuneus, medial frontal, and temporoparietal cortices is less active both during goal-directed behavior and states of reduced consciousness than during conscious rest. We tested the hypothesis that the interictal epileptic discharges affect activity in these brain regions in patients with temporal lobe epilepsy who have complex partial seizures. At the group level, using electroencephalography-correlated functional magnetic resonance imaging in 19 consecutive patients with focal epilepsy, we found common decreases of resting state activity in 9 patients with temporal lobe epilepsy (TLE) but not in 10 patients with extra-TLE. We infer that the functional consequences of TLE interictal epileptic discharges are different from those in extra-TLE and affect ongoing brain function. Activity increases were detected in the ipsilateral hippocampus in patients with TLE, and in subthalamic, bilateral superior temporal and medial frontal brain regions in patients with extra-TLE, possibly indicating effects of different interictal epileptic discharge propagation.     

Hemodynamic correlates of epileptiform discharges: an EEG-fMRI study of 63 patients with focal epilepsy

Using continuous EEG-correlated fMRI, we investigated the Blood Oxygen Level Dependent (BOLD) signal correlates of interictal epileptic discharges (IEDs) in 63 consecutively recruited patients with focal epilepsy. Semi-automated spike detection and advanced modeling strategies are introduced to account for different EEG event types, and to minimize false activations from uncontrolled motion. We show that: (1) significant hemodynamic correlates were detectable in over 68% of patients in whom discharges were captured and were highly, but not entirely, concordant with site(s) of presumed seizure generation where known; (2) deactivations were less concordant and may non-specifically reflect the consequential or downstream effects of IEDs on brain activity; (3) a striking pattern of retrosplenial deactivation was observed in 7 cases mainly with focal discharges; (4) the basic hemodynamic response to IEDs is physiological; (5) incorporating information about different types of IEDs, their durations and saturation effects resulted in more powerful models for the detection of fMRI correlates; (6) focal activations were more likely when there was good electroclinical localization, frequent stereotyped spikes, less head motion and less background EEG abnormality, but were also seen in patients in whom the electroclinical focus localization was uncertain. These findings provide important new information on the optimal use and interpretation of EEG-fMRI in focal epilepsy and suggest a possible role for EEG-fMRI in providing new targets for invasive EEG monitoring.     

Frontal lobe epilepsy

About one-quarter of patients with refractory focal epilepsies have frontal lobe epilepsy (FLE). The typical seizure semiology for FLE includes unilateral clonic, tonic asymmetric or hypermotor seizures. Interictal electroencephalograms (EEG) usually reveal interictal epileptiform discharges and rhythmical midline theta, which has localizing value. The usefulness of ictal EEG recordings is limited by frequent muscle artifacts in motor seizures and because a large portion of the frontal lobe cortex is “hidden” to scalp electrodes. Ictal single photon emission CT and positron emission tomography are able to localize FLE in about one-third of patients only. A pre-surgical evaluation should include, whenever possible, a subclassification of FLE as dorsolateral frontal, mesial frontal or basal frontal lobe epilepsy to allow a minimal cortical resection. A review of the typical findings of seizure semiology, interictal and ictal EEG regarding the different FLE subtypes is given. Etiology, medical treatment and surgery are also discussed.     

Frequency of bitemporal independent interictal epileptiform discharges in temporal lobe epilepsy

PURPOSE: Bitemporal interictal epileptiform discharges (IEDs) occur in < or =42% of scalp EEGs in patients with temporal lobe epilepsy (TLE) studied with routine EEGs or partial analysis of long-term recordings. METHODS: Twenty-eight patients with TLE demonstrating exclusively unilateral temporal IEDs on routine EEGs underwent 24-h continuous recording. The entire record was visually inspected for epileptiform discharges. We used continuous EEG to assess the significance of long-term recording in detecting bilateral IEDs. RESULTS: Twenty-two patients had left temporal IEDs; 21 had right temporal IEDs. Seventeen (61%) patients had IEDs originating from both the right and left temporal lobes. The probability of detecting bilateral independent IEDs was correlated with the duration of continuous EEG recording. There was no correlation between the number of IEDs originating from one side and the probability of detecting independent IEDs on the other side. The frequencies of IEDs were not correlated with the length of time since onset of epilepsy. CONCLUSIONS: The findings suggest that when long-term recordings are performed, the incidence of bilateral discharges in TLE is higher than previously reported in the literature and supports the view that TLE is commonly a bilateral disease.     

A study of the relationship between the seizure focus and 1H-MRS in temporal lobe epilepsy and frontal lobe epilepsy

Several studies of temporal lobe epilepsy (TLE) patients have investigated the relationship between the seizure focus and 1H magnetic resonance spectroscopy (1H-MRS). There have also been a few reports in other types of partial epilepsy. We examined the relationship between the seizure focus and the reduction in N-acetylaspartate: creatine (NAA : Cr) ratio using 1H-MRS in both TLE and frontal lobe epilepsy (FLE) patients. We studied 21 patients with unilateral TLE and seven patients with unilateral FLE. We used a 1.5 Tesla magnetic resonance unit (Signa Horizon; General Electric). Approximately 15 x 15 x 20 mm3 voxel of interest (VOI) was placed over the anterior portion of the bilateral hippocampus in the TLE patients, and the anterodorsal position of bilateral frontal lobe in the FLE patients. The seizure focus was identified by interictal scalp electro-encephalogram (EEG). In the TLE patients the NAA : Cr ratios were reduced in the seizure focus, while in the FLE patients they were not always reduced in the seizure focus. In the TLE patients the coincidence rate between the seizure focus and the reduction in the NAA:Cr ratio was 90% (19 of 21 patients), while in the FLE patients the coincidence rate was only 57% (four of seven patients).     

Multi-center study on post-ictal headache in patients with localization-related epilepsy

The nature of post-ictal headache (PIH) remains unclear. A multicenter study was conducted in order to evaluate frequency and risk factors for PIH. The subjects consisted of 97 patients with temporal lobe epilepsy (TLE), 65 patients with frontal lobe epilepsy (FLE) and 37 patients with occipital lobe epilepsy (OLE). The subjects were asked about PIH at each institute. Clinical factors of epilepsy were reviewed for each patient and correlated with PIH. Post-ictal headache occurred in 41% of TLE patients, 40% of FLE patients and 59% of OLE patients. Logistic regression analysis revealed that the risk of PIH was significantly higher in OLE than in FLE. In contrast, there were no significant differences in the incidence of PIH between TLE and either OLE or FLE patients. Post-ictal headache occurred significantly more frequently in subjects with generalized tonic-clonic seizure (GTCS) than in those without GTCS. Other clinical factors, such as sex, age, age at onset, duration of illness, seizure frequency, family history of headache and interictal headache were found to have no associations with PIH. A difference was found in the incidence of PIH depending on classification of epilepsy, but only to a relatively slight extent. It was also found that GTCS was significantly related to PIH. These results suggest that both the location of epileptogenic focus and the involvement of certain cerebral areas in the spread of seizure discharges may be closely related to PIH.     

Frontal lobe epileptic seizures are accompanied by elevated pitch during verbal communication

The objective of our study was to assess alterations in speech as a possible localizing sign in frontal lobe epilepsy. Ictal speech was analyzed in 18 patients with frontal lobe epilepsy (FLE) during seizures and in the interictal period. Matched identical words were analyzed regarding alterations in fundamental frequency (?o) as an approximation of pitch. In patients with FLE, ?o of ictal utterances was significantly higher than ?o in interictal recordings (p = 0.016). Ictal ?o increases occurred in both FLE of right and left seizure origin. In contrast, a matched temporal lobe epilepsy (TLE) group showed less pronounced increases in ?o, and only in patients with right‐sided seizure foci. This study for the first time shows significant voice alterations in ictal speech in a cohort of patients with FLE. This may contribute to the localization of the epileptic focus. Increases in ?o were interestingly found in frontal lobe seizures with origin in either hemisphere, suggesting a bilateral involvement to the planning of speech production, in contrast to a more right‐sided lateralization of pitch perception in prosodic processing.     

Theory of mind in frontal and temporal lobe epilepsy: cognitive and neural aspects

Purpose: Theory of mind (ToM) is an important prerequisite to social behavior. This study evaluated ToM in patients with temporal (TLE) or frontal lobe epilepsy (FLE) aiming to determine the cognitive aspects, severity, and pathophysiologic mechanisms of ToM impairment in focal epilepsy. Methods: One hundred thirty‐eight patients with TLE (n = 109) or FLE (n = 29) and 69 healthy subjects underwent the Faux Pas task (FPT), which evaluates the recognition and comprehension of others’ mental states, and neuropsychological tests for other cognitive functions. Key Findings: Factor analysis of all test scores yielded two ToM factors (Recognizing faux pas, FP; Excluding nonexistent FP) distinct from the Control, Language, Matching, and Praxis factors. With respect to healthy subjects, both TLE and FLE patients showed correct exclusion of nonexistent FPs but significantly lower recognition and comprehension of real FPs. FLE patients were also impaired with respect to TLE patients. In the whole patient group, schooling and group membership predicted ToM impairment. In FLE patients, the comprehension of mental states was predicted by disease duration, whereas TLE patients’ comprehension of affects and intentions was associated with early age of seizure onset and medial temporal lobe sclerosis (MTLS). Significance: Focal epilepsy impairs advanced ToM abilities. FLE may affect online performances owing to long‐lasting dysfunctions of the prefrontal areas. MTLS may provoke selective ToM deficits due to medial temporal damage, prefrontal dysfunctions, or early interference with cognitive development. Future studies are needed to determine the implications of ToM impairment on behavior and quality of life.     

Connectivity of the supplementary motor area in juvenile myoclonic epilepsy and frontal lobe epilepsy

Purpose: Subtle structural abnormalities of frontal lobe gray and white matter have been described in cryptogenic frontal lobe and idiopathic generalized epilepsies. The supplementary motor area (SMA) has a role in motor control, and its involvement during frontal lobe epileptic seizures is characterized by a typical asymmetric tonic posturing. Moreover, motor networks are dysfunctional in juvenile myoclonic epilepsy (JME). We tested the hypothesis that SMA structural connectivity is altered in focal frontal lobe epilepsy (FLE) and JME compared to healthy controls. Methods: Diffusion tensor imaging (DTI) and probabilistic tractography were used to map the structural connectivity of the SMA, defined by motor functional magnetic resonance imaging (MRI), in 15 patients with JME, 36 patients with FLE, and 18 healthy controls. Key Findings: Structural connectivity of the SMA was significantly reduced in JME compared to controls (reduced fractional anisotropy and increased mean diffusivity). In FLE there was no significant difference compared to controls, and in all groups there was stronger connectivity in the left hemisphere (higher fractional anisotropy) compared to the right. There was no difference in SMA connectivity between patients with medial or lateral frontal lobe epileptic foci. Significance: Reduced white matter connectivity is the structural correlate of functional frontal lobe abnormalities in JME. In FLE, the structural connectivity of the SMA was preserved, suggesting a robust motor network that is not compromised by longstanding epilepsy involving the medial frontal lobes.     

Temporal and extratemporal BOLD responses to temporal lobe interictal spikes

PURPOSE: Simultaneous EEG and functional MRI (fMRI) allows measuring metabolic changes related to interictal spikes. Our objective was to investigate blood oxygenation level-dependent (BOLD) responses to temporal lobe (TL) spikes by using EEG-fMRI recording. METHODS: We studied 35 patients who had a diagnosis of temporal lobe epilepsy (TLE) and active TL spiking on routine scalp EEG recording. Two-hour sessions of continuous EEG-fMRI were recorded, and spikes were identified after offline artifact removal and used as events in the fMRI analysis. Each type of spike was analyzed separately, as one EEG-fMRI study. We determined significant (p < 0.05) positive (activation) and negative (deactivation) BOLD responses for each study. RESULTS: Twenty-seven patients had spikes during scanning (19 unilateral and eight bilateral). From a total of 35 fMRI studies, 29 (83%) showed BOLD responses: 14 had both activations and deactivations; 12, activations only; and three, deactivations only. Six (17%) showed no responses. Nineteen studies had mainly neocortical TL activation: Sixteen (84%) of 19 concordant with spikes, 12 of 16 with concomitant activation of the contralateral TL, and 16 of 19 with additional extratemporal activation; few showed exclusively mesial TL activation. Seventeen studies showed deactivation, either extratemporal plus temporal (n = 8) or exclusively extratemporal (n = 9). CONCLUSIONS: BOLD responses to TL spikes occurred in 83% of studies, predominated in the spiking temporal lobe, and manifested as activation or deactivation. Responses often involved the contralateral homologous cortex at the time of unilateral spikes and were frequently observed in extratemporal regions, suggesting that TL epileptic spikes can affect neuronal activity at a distance through synaptic connections.     

Magnetoencephalography to confirm epileptiform discharges mimicking small sharp spikes in temporal lobe epilepsy

ObjectiveTo determine whether magnetoencephalography (MEG) can identify epileptiform discharges mimicking small sharp spikes (SSSs) on scalp electroencephalography (EEG) in patients with temporal lobe epilepsy (TLE).MethodsWe retrospectively reviewed simultaneous scalp EEG and MEG recordings of 83 consecutive patients with TLE and 49 with extra-TLE (ETLE).ResultsSSSs in scalp EEG were detected in 15 (18.1%) of 83 TLE patients compared to only two (4.1%) of 49 ETLE patients (p = 0.029). Five of the 15 TLE patients had MEG spikes with concurrent SSSs in EEG, but neither of the 2 ETLE patients. Three of these 5 TLE patients had additional interictal epileptiform discharges (IEDs) in EEG and MEG. Equivalent current dipoles (ECDs) of MEG spikes with concurrent SSSs and IEDs showed no difference in temporal lobe localization and horizontal orientation, whereas ECD moments were smaller in MEG spikes with concurrent SSSs than those with IEDs.ConclusionsSSSs were more common in TLE than in ETLE. At least some morphologically diagnosed SSSs are true but low-amplitude epileptiform discharges in TLE which can be identified with simultaneous MEG.SignificanceSimultaneous MEG is useful to identify epileptiform discharges mimicking SSSs in patients with TLE.     

Ipsilateral and contralateral MRI volumetric abnormalities in chronic unilateral temporal lobe epilepsy and their clinical correlates

PURPOSE: To assess the presence, extent, and clinical correlates of quantitative MR volumetric abnormalities in ipsilateral and contralateral hippocampus, and temporal and extratemporal lobe regions in unilateral temporal lobe epilepsy (TLE). METHODS: In total, 34 subjects with unilateral left (n = 15) or right (n = 19) TLE were compared with 65 healthy controls. Regions of interest included the ipsilateral and contralateral hippocampus as well as temporal, frontal, parietal, and occipital lobe gray and white matter. Clinical markers of neurodevelopmental insult (initial precipitating insult, early age of recurrent seizures) and chronicity of epilepsy (epilepsy duration, estimated number of lifetime generalized seizures) were related to magnetic resonance (MR) volume abnormalities. RESULTS: Quantitative MR abnormalities extend beyond the ipsilateral hippocampus and temporal lobe with extratemporal (frontal and parietal lobe) reductions in cerebral white matter, especially ipsilateral but also contralateral to the side of seizure onset. Volumetric abnormalities in ipsilateral hippocampus and bilateral cerebral white matter are associated with factors related to both the onset and the chronicity of the patients' epilepsy. CONCLUSIONS: These cross-sectional findings support the view that volumetric abnormalities in chronic TLE are associated with a combination of neurodevelopmental and progressive effects, characterized by a prominent disruption in ipsilateral hippocampus and neural connectivity (i.e., white matter volume loss) that extends beyond the temporal lobe, affecting both ipsilateral and contralateral hemispheres.     

Depression in temporal lobe epilepsy surgery patients: an FDG-PET study

PURPOSE: Depression is common in temporal lobe epilepsy (TLE) and after temporal lobectomy, and its etiology is obscure. In nonepileptic depression (including depression associated with other neurologic disorders), a consistent PET imaging finding is frontal lobe hypometabolism. Many TLE patients have hypometabolism involving frontal regions. Thus in data available from routine clinical assessments in an epilepsy surgery unit, we tested the hypothesis that the pattern of hypometabolism, particularly in the frontal lobe, may be associated with the depression seen in patients with TLE and TLE surgery. METHODS: We studied 23 medically refractory TLE patients who underwent anterior temporal lobectomy and who had preoperative FDG-PET scanning. All patients had pre- and postoperative psychiatric assessment. By using statistical parametric mapping (SPM-99), patterns of hypometabolism were compared between patients who had a preoperative history of depression (n=9) versus those who did not (n=14) and between those in whom postoperative depression developed (n=13) versus those in whom it did not (n=10). A significant region of hypometabolism was set at p<0.001 for a cluster of >or=20 contiguous voxels. RESULTS: Patients with a history of depression at any time preoperatively showed focal hypometabolism in ipsilateral orbitofrontal cortex compared with those who did not (t=4.64; p<0.001). Patients in whom depression developed postoperatively also showed hypometabolism in the ipsilateral orbitofrontal region (t=5.10; p<0.001). CONCLUSIONS: Although this study is methodologically limited, and other explanations merit consideration, orbitofrontal cortex dysfunction, already implicated in the pathophysiology of nonepileptic depression, may also be relevant to the depression of TLE and temporal lobectomy.     

Changes in Regional Cerebral Blood Flow Beyond the Temporal Lobe in Unilateral Temporal Lobe Epilepsy

Summary: Purpose: Single photon emission computed tomography (SPECT) is widely used to evaluate functional abnormalities during the epileptic event. Changes in regional cerebral blood flow (rCBF) are well defined in patients with temporal lobe epilepsy (TLE) undergoing surgical resection. Nonetheless, the interpretation of ictal abnormalities in CBF beyond the temporal lobes has not been carefully addressed.
Methods : We assessed 4 patients with pathologically proven unilateral TLE who had significant ipsilateral frontal hypoperfusion in ictal studies with no other abnormalities but chronic epilepsy accounting for such findings. Patients were assessed as candidates for surgery by interictal EEG, neuropsychological studies, brain magnetic resonance imaging, scalp electrode video-EEG monitoring, and ictal SPECT.
Results : Characteristic hyperperfusion was evident over the temporal lobe ipsilateral to the EEG focus, with significant hypoperfusion over the frontal region in 3 patients. In patient 4, frontal hypoperfusion was not statistically significant.
Conclusions : SPECT demonstrated relative rCBF changes beyond the epileptogenic zone in unilateral TLE. Our findings provide further insight into the pathophysiological changes underlying this condition.