Epileptic phenotype of FGFR3-related bilateral medial temporal lobe dysgenesis

Hypochondroplasia (HCH) is a skeletal dysplasia, characterized by short stature and macrocephaly. Clinical symptoms and radiological and histopathological features of HCH are similar, but milder than those seen in achondroplasia. Particularly, HCH patients with Asn540Lys mutation in the FGFR3 gene are reported to have medial temporal lobe dysgenesis and epilepsy.We report a 3-year-old girl who developed recurrent epileptic apnea, which started immediately after birth. The apneic seizures were refractory to antiepileptic medications; ictal electroencephalography showed rhythmic activity originating from the left or right temporal areas and rarely from the right frontal area. Macrocephaly was noted since birth. Neuroimaging revealed bilateral dysgenesis and hypometabolism of the medial temporal structures as well as perfusion changes in the left lateral temporofrontal areas during the ictal period. Clonazepam was initiated and acetazolamide dosage was increased at 6 months, resulting in complete seizure control after 8 months of age. Genetic analysis identified an Asn540Lys (c.1620 C > A) mutation in the FGFR3 gene. Characteristic bone findings on the lumbar spine, iliac bone, and femur were retrospectively confirmed on X-rays during infancy.This was the first report that delineated the epilepsy phenotype in FGFR3-related bilateral medial temporal lobe dysgenesis; such findings would lead to an early diagnosis and better epilepsy management.     

Absence of seizures in Rasmussen encephalitis with active inflammation

Severe focal motor epilepsy is considered a clinical hallmark of Rasmussen encephalitis (RE). The authors report a 6-year-old girl with progressive right sided hemiparesis, loss of language skills, left sided hemispheric atrophy, and brain pathologic features characteristic for RE. The patient did not experience seizures over a 2 year period after symptom onset and for several months during follow-up. This report expands the clinical spectrum of RE and suggests that seizures are not a universal symptom of RE. Our patient’s quite remarkable neurologic deficits along with active inflammation in the absence of epilepsy supports that, at least in some individuals, unilateral hemispheric progressive inflammation can occur without active seizure activity.     

Ictal and postictal semiology in patients with bilateral temporal lobe epilepsy

Bilateral temporal lobe epilepsy is characterized by evidence of seizure onset independently in both temporal lobes. The main aim of the present study was to determine whether patients with evidence of independent bilateral temporal lobe epilepsy (biTLE) can be identified noninvasively on the basis of seizure semiology analysis. Thirteen patients with biTLE, as defined by invasive EEG, were matched with 13 patients with unilateral temporal lobe epilepsy (uniTLE). In all 26 patients, the frequency of predefined clusters of ictal and periictal signs were evaluated: ictal motor signs (IMSs), periictal motor signs (PIMSs), periictal vegetative signs (PIVSs), the frequency of early oroalimentary automatisms (EOAs), and the duration of postictal unresponsiveness (PU). Some other noninvasive and clinical data were also evaluated. A lower frequency of IMSs was noted in the group with biTLE (patients = 46.2%, seizures = 20.7%) than in the group with uniTLE (patients = 92.3%, seizures = 61.0%) (p = 0.030; p < 0.001, respectively). The individual IMS average per seizure was significantly lower in the group with biTLE (0.14; range = 0–1.0) than in the group with uniTLE (0.80; range = 0–2.6) (p = 0.003). Postictal unresponsiveness was longer than 5 min in more patients (75.0%) and seizures (42.9%) in the group with biTLE than in the group with uniTLE (patients = 30.8%, seizures = 18.6%) (p = 0.047; p = 0.002). The frequency of EOAs, PIMSs, PIVSs, and other clinical data did not differ significantly. There is a lower frequency of ictal motor signs and longer duration of postictal unresponsiveness in patients with biTLE.     

Spindle frequency activity may provide lateralizing information in drug-resistant nocturnal mesial frontal lobe epilepsy: A pilot study on the contribution of sleep recordings

PurposeNocturnal frontal lobe epilepsy (NFLE) is characterized by sleep-related paroxysmal motor attacks occurring almost exclusively during non-REM sleep. Surgical treatment may relieve symptoms in drug-resistant patients. However, the identification of the epileptogenic zone, the region to be resected, is frequently challenging because of the absence of lateralizing and localizing information and the lack of informative EEG correlates. The aim of this study was to find asymmetries in the ictal activity that could provide information on the lateralization of the epileptogenic zone.MethodWe retrospectively analyzed the sleep EEG of four patients recorded prior to surgical intervention. The epileptogenic zone was known, as these patients had subsequently undergone successful surgery after bilateral intracerebral stereo-EEG investigation. Sleep EEG during the ictal phase was compared with sleep EEG during the pre-ictal phase.ResultsIn all patients, electrical sources of sigma activity (12–16 Hz) exhibited increased activity during the ictal phase which was higher in the epileptogenic hemisphere. Conversely, increased delta activity (1–4 Hz) was predominant contralateral to the epileptogenic focus in three of four patients.ConclusionSigma activity may have a predictive role in the lateralization of the epileptogenic zone and be useful during the pre-surgical evaluation of patients with NFLE.     

Dysembryoplastic neuroepithelial tumors: Epileptogenicity related to histologic subtypes

ObjectiveTo analyze the electroclinical features and the relationship between the epileptogenic zone (EZ), the tumor and focal cortical dysplasia (FCD) in the three histologic subtypes of dysembryoplastic neuroepithelial tumors (DNTs) (“simple”, “complex” and “non-specific forms”).MethodsWe analyzed electroclinical data from 78 patients (50 males; 3–54 years) operated for intractable epilepsy due to a DNT. We compared EZ extent, defined by stereo-electroencephalography (n = 33), with the tumor and FCD areas, in each DNT subtype.ResultsNon-specific forms (68%) and temporal location were predominant (73%). The main characteristics consisted of late childhood epilepsy onset (median 12 years), drug-resistant partial seizures and EEG abnormalities concordant with tumor location. In all DNT subtypes, intrinsic epileptogenicity was demonstrated by intralesional recordings (n = 30), displaying a depressed background activity interrupted by rapid spikes or polyspikes. EZ co-localized with the tumor in all simple and complex DNTs, but in only 1/3 of non-specific DNTs. The main discordance between the EZ and tumor extent was found in temporal non-specific DNTs associated with extensive FCD.ConclusionThese results are helpful when planning surgery for DNTs.SignificanceIntrinsic epileptogenicity characterizes all DNTs; however, the EZ differs according to histologic subtypes and is particularly widespread in non-specific temporal forms.     

Surgical treatment of hypermotor seizures originating from the temporal lobe

PurposeTo describe the characteristics of electroclinical manifestations in patients with hypermotor seizures (HMSs) originating from the temporal lobe.MethodsWe retrospectively reviewed the data of patients who underwent surgical treatments for seizure to identify patients with HMSs of temporal origin. We systematically reviewed patient seizure histories, imaging reports, video-EEG monitoring data, operative records and pathological findings.ResultsEight of the 9 patients reported auras. The ictal behavior included marked agitation in 5 patients and mild agitation in 4 patients. All of the 9 patients exhibited stiffness or dystonia of the upper limb or contralateral limbs during ictus. Seven of the 9 patients completed intracranial recording and at least 3 seizures were recorded for each patient. The intracranial recordings showed ictal activity originating from mesial temporal lobe in 6 patients and the lateral temporal lobe in 1 patient. The time interval of ictal propagation from the temporal to frontal lobe was 15.0 ± 8.3 s. While the time interval from EEG origination to the beginning of hypermotor behavior was 21.0 ± 8.1 s. Brain MRIs revealed hippocampal sclerosis in 3, neoplastic lesion in 1, and normal images in the remaining 5 patients. Patients were followed for 1–5 years after the anterior temporal lobectomy; 7 patients remained seizure-free throughout follow-up.ConclusionSome HMSs can originate from the temporal lobe. In carefully selected patients, surgical resection may lead to good outcomes.     

Epilepsy in patients with Cornelia de Lange syndrome: A clinical series

PurposeCornelia de Lange (CdLS) syndrome is characterized by multiple congenital anomalies and mental retardation. Epilepsy is a clinical feature found in about 20% of cases, but there are no data about its electroclinical features and long-term outcome.Methodswe describe a clinical series of fourteen Caucasian CdLS paediatric patients who developed epilepsy, with special reference to the long term prognosis.ResultsEpilepsy manifested between age 0.6 and 16.3 years. The majority of patients (64.3%) presented with partial seizures and interictal EEGs mainly revealed focal epileptic paroxysms involving temporal and parietal areas. Thirteen of 14 children became seizure-free with treatment. Valproate monotherapy was used in eight patients (57.1%), controlling seizures in seven. Otherwise monotherapy with topiramate, levetiracetam, carbamazepine and oxcarbazepine appeared to be effective in controlling seizures in four cases. At the end of the follow-up (age range, 7.3–24.2 years; follow-up, 8.2 ± 3.9 years), thirteen patients were seizure free (three still in therapy), while in one patient seizures were not controlled.ConclusionsPartial epilepsy is the most common type of epilepsy in CdLS patients. In the majority of cases the prognosis of this epilepsy is favourable and therapy can be withdrawn after few years of complete seizure control.     

Low resolution electromagnetic tomography analysis of ictal EEG patterns in mesial temporal lobe epilepsy with hippocampal sclerosis

ObjectiveTo investigate the difference in the spatial distribution of scalp initial ictal discharge (IID) patterns in mesial temporal lobe epilepsy with hippocampal sclerosis (HS–MTLE).MethodsScalp ictal EEG data in 22 seizure-free patients after temporal lobectomy with amygdalo-hippocampectomy were classified as follows: a regular 5–9 Hz rhythm with a restricted temporal/subtemporal distribution (type 1, 11 patients), or an irregular 2–5 Hz rhythm with a widespread fronto-temporal distribution (type 2, 11 patients). EEG data were fragmented into segments of 1.28 s, both at ictal onset and at baseline. The LORETA solution of three frequency bands was compared between ictal and baseline using statistical non-parametric mapping (p < 0.01).ResultsThe LORETA solution of 5–9 Hz in type 2 had wider cortical activity in the ipsilateral fronto-temporal area, compared to type 1 with activation of the ipsilateral focal mesial and lateral temporal regions. The LORETA solution of 10–13 Hz in both types showed increased activity in the fronto-temporal area, which was wider in type 2 than type 1. Increased cortical activity of <5 Hz was not observed in type 1, whereas increased cortical activity was observed in the bilateral anterior frontal area in type 2.ConclusionsThe cortical source distribution in HS–MTLE may depend on scalp IID frequency. The neural generators of 5–13 Hz may be important for the formation of the ictal onset zone in both ictal patterns.SignificanceSpatial distributions in HS–MTLE patients differ with scalp IID frequency.     

The evaluation of interictal focal EEG findings in adult patients with absence seizures

PurposeTo investigate the focal interictal EEG abnormalities in adult patients with absence seizures (ASs) and to identify their clinical, EEG and semiological correlates.MethodsFifty patients older than 18 years, diagnosed as having IGE with AS documented with ictal recordings. Interictal focal sharp or spike–waves and strictly focal paroxysmal slow activity were considered as focal EEG features. The patients having focal EEG features were classified as “Group I”, whereas the remaining of them was classified as “Group II”.ResultsWe observed focal findings in 34% of the patients, mainly in frontotemporal (41%), and frontal (29%) regions. There were no significant differences with respect to the clinical parameters such as sex, epilepsy duration, positive family history and the age of the onset between the groups. Psychiatric co-morbidities were significantly higher in Group I when compared to Group II (P = 0.00). Accompanying automatisms were higher in Group I, whereas eye deviation during absences was higher in Group II. In Group I, the asymmetry of the ictal discharges was more frequently observed. Focal EEG features were more frequently seen in juvenile absence epilepsy syndrome, without reaching a significance level.ConclusionThe focal findings in adult absence epilepsy patients could have some unknown etio-pathogenetic and prognostic implications. We emphasize the cautious interpretation of isolated interictal focal EEG abnormalities to prevent a wrong diagnosis of focal epilepsy in patients who may indeed suffer from generalized epilepsy.     

EEG features and epilepsy in MECP2-mutated patients with the Zappella variant of Rett syndrome

ObjectiveTo assess the presence/absence of peculiar EEG features and epilepsy in MECP2-mutated Rett patients with the Zappella–Rett variant (Z-RTT) also known as preserved speech variant.MethodsRetrospective analysis of 16 (age 19.4 ± 8.4 years; range 8–38 years) MECP2 mutated Z-RTT cases, including 11 high or intermediate performance (HIP), and five low-performance (LP) patients was performed. Peculiar EEG features were analyzed as a function of the HIP or LP Z-RTT categories: (1) centro-temporal spikes, (2) multifocal EEG activity, (3) EEG encephalopathy (i.e. multifocal EEG activity associated with the presence of background slowing and diffuse slow activity), (4) spindles and K-complex. Furthermore, we assessed the occurrence of epilepsy.Correlations between electroclinical features and category of Z-RTT genotype (missense or truncation mutation) were also tested.ResultsThe Z-RTT HIP group showed a very abnormal EEG (presence of centro-temporal spikes: p = 0.004808), although the cases studied were not epileptogenic and did not develop encephalopathy. The LP group showed multifocal EEG activity (p = 0.000229), EEG encephalopathy (p = 0.000229) and epilepsy (p = 0.299451). No significant differences between the prevalence of centro-temporal spikes, multifocal EEG activity, EEG encephalopathy, and epilepsy between the patients with the truncation or missense mutation were observed.ConclusionsEEG electrophysiological patterns and epileptogenic susceptibility differ in Z-RTT according to the level of performance (i.e. HIP or LP).SignificanceThese results indicate that HIP and LP Z-RTT should be considered as distinct entities, not only on a clinical basis, but also as it concerns EEG features and epileptogenic susceptibility.These results could offer support in the practical management of patients and family counseling.     

Electroclinical aspects and therapy of Han patients with juvenile myoclonic epilepsy in northern China

ObjectiveThe objective of this study was to assess the electroclinical aspects and treatment of Han patients with juvenile myoclonic epilepsy (JME) in northern China.MethodsOne hundred fifty-six outpatients with JME from six epilepsy centers, between January 2011 and June 2012, were followed up for at least two years. They underwent twenty-four-hour video-EEG recording. Brain imaging was performed using magnetic resonance imaging (MRI). Clinical aspects, electroencephalographic (EEG) features, and antiepileptic drugs (AEDs) received were reviewed.ResultsGeneralized tonic–clonic seizures (GTCS) were found in 150/156 patients. Delay of diagnosis was 4.60 ± 9.92 years. Photosensitivity was more common in eye closure condition during IPS in patients with JME; in addition, patients with JME with myoclonic seizures (MS) and GTCS as seizure types were likely to present photoparoxysmal responses (PPRs). The 82 nontreated patients showed a median latency to first interictal or ictal generalized spike–wave discharge (GSWD) of 50 min (IQR: 22–102 min). The first GSWDs were recorded in 63%, 76%, 90%, and 98% patients within one, two, three, and 4 h, respectively; only 2% of patients had first GSWDs after 4 h. One hundred eleven patients (111/156) chose extended-release valproate (VPA) at daily doses ≤ 1000 mg. The percentages of seizure-free patients among MS, GTCS, and absence seizure (AS) groups were 88.3%, 99.0%, and 94.9%, respectively.ConclusionPhotoparoxysmal responses were more common in patients with JME with MS and GTCS and rare in patients with JME with MS and AS in northern Chinese Han patients. Most patients with JME in northern China chose VPA as first therapeutic choice, and low dose (500 to 1000 mg daily) of extended-release VPA may be an optimal choice for them. Video-EEG monitoring for at least 4 h may be helpful in detecting the first interictal or ictal GSWD in patients with potential JME. Moreover, video-EEG monitoring performed at about 9 o'clock in the morning with patients in the awake state might be useful to find the first GSWD. For JME diagnosis, Class II criteria are more helpful than Class I counterparts, the latter yielding more missed diagnoses.     

Neural network underlying ictal pouting (“chapeau de gendarme”) in frontal lobe epilepsy

In order to determine the anatomical neural network underlying ictal pouting (IP), with the mouth turned down like a “chapeau de gendarme”, in frontal lobe epilepsy (FLE), we reviewed the video-EEG recordings of 36 patients with FLE who became seizure-free after surgery. We selected the cases presenting IP, defined as a symmetrical and sustained (> 5 s) lowering of labial commissures with contraction of chin, mimicking an expression of fear, disgust, or menace. Ictal pouting was identified in 11 patients (8 males; 16–48 years old). We analyzed the clinical semiology, imaging, and electrophysiological data associated with IP, including FDG-PET in 10 and SEEG in 9 cases. In 37 analyzed seizures (2–7/patient), IP was an early symptom, occurring during the first 10 s in 9 cases. The main associated features consisted of fear, anguish, vegetative disturbances, behavioral disorders (sudden agitation, insults, and fighting), tonic posturing, and complex motor activities. The epileptogenic zone assessed by SEEG involved the mesial frontal areas, especially the anterior cingulate cortex (ACC) in 8 patients, whereas lateral frontal onset with an early spread to the ACC was seen in the other patient. Ictal pouting associated with emotional changes and hypermotor behavior had high localizing value for rostroventral “affective” ACC, whereas less intense facial expressions were related to the dorsal “cognitive” ACC. Fluorodeoxyglucose positron emission tomography demonstrated the involvement of both the ACC and lateral cortex including the anterior insula in all cases. We propose that IP is sustained by reciprocal mesial and lateral frontal interactions involved in emotional and cognitive processes, in which the ACC plays a pivotal role.     

An evaluation of lateralizing signs in patients with temporal lobe epilepsy

Resective epilepsy surgery has been accepted as an effective treatment for patients with medically intractable temporal lobe epilepsy (TLE) to control the seizures and to limit cognitive dysfunction. Complete resection of the epileptic zone, and therefore the success of the surgery, depends on the identification of the seizure focus. Reliable lateralizing semiologic signs, together with other presurgical assessments, are of great importance for an accurate identification of the seizure focus. In this respect, this study evaluated the frequency of semiologic signs in medically intractable temporal lobe epilepsy (TLE) together with the lateralizing values and variations according to the age and gender groups. Two hundred seventy-three seizures of 55 patients of the Adult Epilepsy Monitoring Unit of Gazi University Faculty of Medicine with the diagnosis of medically intractable TLE, whose epileptic foci were detected through noninvasive presurgical procedures and seizures were controlled successfully after anterior temporal lobectomy (ATL), were analyzed retrospectively. Seizure semiologies of the patients were evaluated in terms of lateralizing values, and it was inquired whether age/gender causes any variation. Versive head rotation, unilateral dystonic limb posturing, asymmetric tonic limb posturing, and the combination of unilateral hand automatisms and dystonic posturing were determined as the semiologic signs with the highest lateralizing values (90–100%). While hand automatisms were observed frequently in the group with early seizure-onset age (onset age ≤ 2), asymmetric tonic limb posturing was detected as more frequent in the group with later seizure-onset age (onset age > 2; p < .005). In addition to this, semiologic signs were noted to be different between male and female groups; psychic and autonomic auras and ictal emotional signs were associated with women (p < .005).     

Ictal body turning in focal epilepsy

Despite the explanations of many lateralization findings, body turning in focal epilepsy has been rarely investigated. One of the aims of this study was to evaluate the role of ictal body turning in the lateralization of focal epilepsies. The records of 263 patients with focal epilepsy (temporal lobe epilepsy (TLE), n = 178; extratemporal lobe epilepsy (ETLE), n = 85) who underwent prolonged video-EEG monitoring during presurgical epilepsy evaluation were reviewed. Preoperative findings (TLE, n = 16; ETLE, n = 6) and postoperative outcomes (TLE, n = 7) of patients with focal epilepsy with ictal body turning were assessed. For the evaluation of ictal body turning, two definitions were proposed. Nonversive body turning (NVBT) was used to denote at least a 90° nonforced (without tonic or clonic component) rotation of the upper (shoulder) and lower (hip) parts of the body around the body axis for a minimum of 3 s. Versive body turning (VBT) was used to denote at least a 90° forced (with tonic or clonic component) rotation of the upper (shoulder) and lower (hip) parts of the body around the body axis for a minimum of 3 s. Nonversive body turning was observed in 6% (n = 11) of patients with TLE and 2% (n = 2) of patients with ETLE. For VBT, these ratios were 5% (n = 8) and 7% (n = 6) for patients with TLE and ETLE, respectively. Nonversive body turning was frequently oriented to the same side as the epileptogenic zone (EZ) in TLE and ETLE seizures (76% and 80%, respectively). If the amount of NVBT was greater than 180°, then it was 80% to the same side in TLE seizures. Versive body turning was observed in 86% of the TLE seizures, and 55% of the ETLE seizures were found to be contralateral to the EZ. When present with head turning, NVBT ipsilateral to the EZ and VBT contralateral to the EZ were more valuable for lateralization. In TLE seizures, a significant correlation was found between the head turning and body turning onsets and durations. Our study demonstrated that ictal body turning is a rarely observed but reliable lateralization finding in TLE and ETLE seizures, which also probably has the same pathophysiological mechanism as head turning in TLE seizures.     

Cortical excitability varies upon ictal onset patterns in neocortical epilepsy: A cortico-cortical evoked potential study

ObjectiveTo better understand pathological neuronal excitation in epilepsy by comparing cortico-cortical evoked potential (CCEP) responses in regions with different ictal onset patterns: focal paroxysmal fast (PF) and repetitive spiking (RS).MethodsFourteen patients undergoing invasive monitoring (six patients with PF and eight with RS) were studied with CCEPs. A repetitive 1 Hz bipolar electrical stimulus was applied to both the ictal onset region (iCCEP) and to a control region (nCCEP) and CCEPs were recorded from the surrounding electrodes. The two groups were compared by subtracting the amplitude of nCCEP from that of iCCEP (CCEP_{ictal?control}) at each stimulus intensity, and then normalizing the amplitudes of iCCEP at maximum stimulus intensity by dividing by nCCEP (CCEP_{ictal/control}).ResultsThe CCEP response to stimulation in the ictal onset region was significantly larger than to control stimulation for both ictal patterns (paroxysmal fast: P = 0.02, repetitive spiking: P < 0.01), with repetitive spiking group amplitudes higher than the paroxysmal fast group (CCEP_{ictal?control}: P < 0.01 and CCEP_{ictal/control}: P = 0.04).ConclusionsPro-epileptic excitability is more accentuated in regions showing an ictal repetitive spiking pattern than a paroxysmal fast pattern.SignificanceThese findings confirm in a new way that cortical excitability varies depending on the ictal onset pattern.     

Perception of seizure severity and bothersome in refractory focal epilepsy

IntroductionA better understanding of the perception of the severity and bothersome caused by seizure phases (warning, ictal, and postictal phases) can contribute to the orientation strategies for adult people with epilepsy (PWEs).ObjectiveTo assess the seizure severity and bothersome and relate them to the clinical aspects of epilepsy and quality of life (QoL).MethodsThe Seizure Severity Questionnaire (SSQ) was associated with clinical variables and the Neurological Disorders Depression Inventory for Epilepsy (NDDI-E) and the QOLIE–31 of 98 PWEs, with a significance level of P < 0.05.ResultsMost patients reported that seizure warnings helped them prepare for the event, with the postictal phase was the most bother symptom. Higher scores on the SSQ were associated with movements in the ictal phase, a prolonged duration, and the presence of mental and physical effects in the postictal phase. No difference was found in the SSQ, according to the seizure type and frequency. There was an association between the NDDI-E > 15 and the SSQ. Higher scores on the SSQ were significantly related to an NDDI-E > 15 (P = 0.013), in the linear regression model. Seizure severity and bothersome compromise the perception of QoL.ConclusionThe SSQ was useful in the assessment of the perception of seizure severity in PWEs. The postictal phase was the most bothersome one. The perception of seizure severity is associated with the presence of depression. Seizure severity correlates inversely with QoL.     

In vivo human hippocampal cingulate connectivity: A corticocortical evoked potentials (CCEPs) study

ObjectiveTo investigate the human limbic system using cortico-cortical evoked potential (CCEP), which reveals the brain networks.MethodsFive patients with nonlesional medically intractable focal epilepsy with ictal onset outside the limbic system were enrolled. All patients underwent stereoelectroencephalogram electrode implantation in order to delineate the epileptogenic zone. Alternating 1 Hz electrical stimuli were delivered to the hippocampus and posterior cingulate gyrus. A total of sixty stimuli were averaged in each trial to obtain CCEP responses.ResultsHippocampal stimulation elicited prominent CCEP responses in the posterior cingulate gyrus. The latencies of early (N1) and late (N2) negative peak ranged 20–60 ms and 102–175 ms respectively. In addition, CCEP responses were observed in the posterior parahippocampal gyrus, medial superior frontal gyrus (SFG) and orbitofrontal cortex. Stimulation of posterior cingulate contacts induced CCEPs in the hippocampus with N1 and N2 latencies of 25–43 ms and 90–234 ms respectively in all five patients.ConclusionThis finding supports the assertion that the hippocampus is connected with the posterior cingulate gyrus, posterior parahippocampal gyrus, medial SFG and orbitofrontal cortex. The hippocampus and posterior cingulate gyrus have a bidirectional network through the cingulum.SignificanceThe present study provides new insight into the human limbic network.     

Cessation of gamma activity in the dorsomedial nucleus associated with loss of consciousness during focal seizures

RationaleImpaired consciousness during seizures may be mediated by ictal propagation to the thalamus. Functions of individual thalamic nuclei with respect to consciousness, however, are largely unknown. The dorsomedial (DM) nucleus of the thalamus likely plays a role in arousal and cognition. We propose that alterations of firing patterns within the DM nucleus contribute to impaired arousal during focal seizures.MethodsElectroencephalograph data were collected from electrodes within the left DM thalamus and midcingulate cortex (MCC) in a patient undergoing seizure monitoring. Spectral power was computed across ictal states (preictal, ictal, and postictal) and level of consciousness (stupor/sleep vs. awake) in the DM nucleus and MCC.ResultsEighty-seven seizures of multifocal left frontal and temporal onsets were analyzed, characterized by loss of consciousness. At baseline, the left DM nucleus demonstrated rhythmic bursts of gamma activity, most frequently and with greatest amplitude during wakefulness. This activity ceased as ictal discharges spread to the MCC, and consciousness was impaired, and it recurred at the end of each seizure as awareness was regained.The analysis of gamma (30–40 Hz) power demonstrated that when seizures occurred during wakefulness, there was lower DM ictal power (p < 0.0001) and higher DM postictal power (p < 0.0001) relative to the preictal epoch. This spectral pattern was not evident within the MCC or when seizures occurred during sleep.ConclusionsData revealed a characteristic pattern of DM gamma bursts during wakefulness, which disappeared during partial seizures associated with impaired consciousness. The findings are consistent with studies suggesting that the DM nucleus participates in cognition and arousal.     

Do sphenoidal electrodes aid in surgical decision making in drug resistant temporal lobe epilepsy?

ObjectiveThe utility of sphenoidal electrodes (SPh) in analyzing interictal epileptiform discharges (IEDs) and ictal electrography remains controversial, despite its widespread use.MethodsOne hundred and twenty-two consecutive patients with presumed temporal lobe epilepsy (TLE) who underwent presurgical evaluation were prospectively studied. SPh and Silverman’s electrodes were placed, in addition to routine electrodes in 10–20 international system. IEDs and ictal electroencephalography (EEG) were analyzed separately in bipolar and referential montages. The proportion of patients selected for surgery after adjusting for SPh placement based on the earlier ictal onset and IEDs were analyzed.ResultsOf the 8701 IEDs in SPh, only 65% were seen over the scalp bipolar montage; 1392 (16%) IEDs were confined to SPh electrodes, and were not seen at scalp bipolar montage (p < 0.001). Spike amplitudes were highest at SPh (p < 0.001). Of the 592 seizures analyzed, 62 (61%) had simultaneous SPh and scalp onset, while in 26 (25%) SPh onset preceded the scalp.ConclusionsOut of the 35 patients with unilateral mesial temporal sclerosis (MTS) with additional neocortical changes and/or non-lateralized bitemporal IEDs and/or diffuse ictal onset (group 1), 27 were selected for surgery (77%). About 7% was selected for surgery in this group by SPh placement. Also, in patients with bilateral MTS (group 2), 25% (5/20) were chosen for anterior temporal lobectomy, SPh provided an additional benefit in 11% (p < 0.001). Patients with normal magnetic resonance imaging (group 3) and temporal plus epilepsy (group 4) had a lower surgical yield, only 12% and 9.5% could undergo surgery. They were denied surgical candidacy with SPh (p < 0.001).SignificanceOne-third of patients after SPh placement were selected for resective surgery obviating the need for invasive monitoring. The maximum yield was noted in unilateral MTS (associated with additional neocortical features or non-lateralized bilateral temporal interictal IEDs or diffuse ictal onset in scalp EEG) and in bilateral MTS. Those with normal MRI/temporal plus epilepsy could be excluded from direct resective surgery.