Efficacy of mGlu2 -positive allosteric modulators alone and in combination with levetiracetam in the mouse 6 Hz model of psychomotor seizures.

OBJECTIVE: The metabotropic glutamate receptor subtype 2 (mGlu2 ) possesses both orthosteric and allosteric modulatory sites, are expressed in the frontal cortex and limbic structures, and can affect excitatory synaptic transmission. Therefore, mGlu2 is a potential therapeutic target in the treatment of epilepsy. The present study seeks to evaluate the anticonvulsant potential of mGlu2 -acting compounds. METHODS: The anticonvulsant efficacy of two selective mGlu2 -positive allosteric modulators (PAMs) (JNJ-42153605 and JNJ-40411813/ADX71149) and one mGlu2/3 receptor agonist (LY404039) were evaluated alone and in combination with the antiseizure drug levetiracetam (LEV) in the mouse 6 Hz model. RESULTS: In the 6 Hz (32 mA stimulus intensity) model, median effective dose (ED50 ) values were determined for JNJ-42153605 (3.8 mg/kg), JNJ-40411813 (12.2 mg/kg), and LY404039 (10.9 mg/kg). At the 44 mA stimulus intensity, ED50 values were determined for JNJ-42153605 (5.9 mg/kg), JNJ-40411813 (21.0 mg/kg), LY404039 (14.1 mg/kg), and LEV (345 mg/kg). In addition, subprotective doses of each mGlu2 -acting compound, administered in combination with various doses of LEV, were able to shift the 6 Hz 44 mA ED50 for LEV by >25-fold. When JNJ-42153605 was administered at varying doses in combination with a single dose of LEV (10 mg/kg), the potency of JNJ-42153605 was increased 3.7-fold. Similarly, when a moderately effective dose of LEV (350 mg/kg) was administered in combination with varying doses of JNJ-40411813, the potency of JNJ-40411813 was increased approximately 14-fold. Plasma levels of JNJ-40411813 and LEV were not different when administered alone or in combination, suggesting that increases in potency are not due to pharmacokinetic effects. SIGNIFICANCE: These studies suggest a potential positive pharmacodynamic effect of mGlu2 -acting compounds in combination with LEV. If this effect is translated in a clinical setting, it can support a rational polypharmacy concept in treatment of epilepsy patients.

Effects of WIN 55,212-2 (a non-selective cannabinoid CB1 and CB 2 receptor agonist) on the protective action of various classical antiepileptic drugs in the mouse 6 Hz psychomotor seizure model.

The aim of this study was to characterize the influence of WIN 55,212-2 (WIN--a non-selective cannabinoid CB1 and CB2 receptor agonist) on the anticonvulsant effects of various classical antiepileptic drugs (clobazam, clonazepam, phenobarbital and valproate) in the mouse 6 Hz-induced psychomotor seizure model. Limbic (psychomotor) seizure activity was evoked in albino Swiss mice by a current (32 mA, 6 Hz, 3 s stimulus duration) delivered via ocular electrodes. Drug-related adverse effects were ascertained by use of the chimney test (evaluating motor performance), step-through passive avoidance task (assessing learning) and grip-strength test (evaluating skeletal muscular strength). Total brain concentrations of antiepileptic drugs were measured by fluorescence polarization immunoassay to ascertain any pharmacokinetic contribution to the observed antiseizure effect. Results indicate that WIN (5 mg/kg, administered intraperitoneally) significantly enhanced the anticonvulsant action of clonazepam (P < 0.001), phenobarbital (P < 0.05) and valproate (P < 0.05), but not that of clobazam in the mouse 6 Hz model. Moreover, WIN (2.5 mg/kg) significantly potentiated the anticonvulsant action of clonazepam (P < 0.01), but not that of clobazam, phenobarbital or valproate in the 6 Hz test in mice. None of the investigated combinations of WIN with antiepileptic drugs was associated with any concurrent adverse effects with regard to motor performance, learning or muscular strength. Pharmacokinetic experiments revealed that WIN had no impact on total brain concentrations of antiepileptic drugs in mice. These preclinical data would suggest that WIN in combination with clonazepam, phenobarbital and valproate is associated with beneficial anticonvulsant pharmacodynamic interactions in the mouse 6 Hz-induced psychomotor seizure test.

Partial rhombencephalosynapsis and Chiari type II malformation in a child: a true association supported by DTI tractography.

Partial rhombencephalosynapsis (PRECS) has been recently reported in association with Chiari II (CII). However, its existence as a true malformation is challenged due to the anatomical changes potentially induced by CII. The aim of this report was to investigate the contribution of midbrain/hindbrain tractography in this setting. A 13-year-old boy with a known CII malformation and operated myelomeningocele was referred for brain imaging after a first complex partial seizure. In addition to the classical features of CII, MRI showed partially fused cerebellar hemispheres and multiple supratentorial abnormalities. Diffusion tensor imaging (DTI) color map and tractography showed absent transverse fibers on the midsection of the cerebellum, scarce fibers of the middle cerebellar peduncle (MCP), absence of the middle pontine crossing tract, and fibers running vertically in the medial part of the cerebellum. Vertical mediocerebellar fibers are a feature of classical RECS and the paucity or absence of MCP fibers is mainly described in CII. In our patient, DTI and FT therefore demonstrated structural characteristics of both RECS and CII confirming their potential coexistence and suggesting possible shared embryological pathway.

Periventricular nodular heterotopia functionally couples with the overlying hippocampus.

Patients with periventricular nodular heterotopia (PVNH) often have severe epilepsy. However, it is unclear how the heterotopia contributes to epileptogenesis. Recently, electrophysiologic studies using intraoperative depth electrodes have indicated that interaction between the heterotopia and overlying cortex is crucial for seizure onset. We performed an in vitro physiologic study using slices of resected brain from a 22-year-old man with PVNH, who manifested medically refractory mesial temporal lobe epilepsy. Preoperative evaluation indicated that the right mesial temporal structure and PVNH were the epileptogenic focus. The resected tissue was immediately immersed in cold artificial cerebrospinal fluid, and then slices of the brain tissue including the heterotopic nodules and overlying hippocampus were prepared. We electrically stimulated the incubated slices, and the elicited neural activities were analyzed as changes in the flavoprotein fluorescence signals. When we stimulated either the heterotopic nodule or the overlying hippocampus, clear functional coupling of neural activities between these structures was observed. The coupling response evoked by stimulation of the subiculum and developing within the heterotopic nodule was enhanced by application of bicuculline. Therefore, activities of the hippocampus and the nodule are closely correlated.

Epileptogenic networks in two patients with hypothalamic hamartoma.

Hypothalamic hamartomas (HH) are typically associated with gelastic seizures but also implicated in the genesis of other seizure types. In order to identify networks involved in seizure generation, we performed EEG-fMRI in two adult patients with HH, the first with predominantly gelastic seizures and the second with complex partial and no typical gelastic seizures. The ictal and interictal analysis of the patient with gelastic seizures revealed the involvement of the HH, the cingulate gyrus, the precuneus and the prefrontal cortex. The interictal analysis of the patient with complex partial seizures, showed changes in blood oxygen-level dependent signal over the temporal lobes, the base of the frontal lobe, the cingulate, the precuneus and the prefrontal cortex, but not the HH. The differences in the neural networks implicated may account for differences in clinical manifestation of seizures owing to HH.

Emergence of complex partial epilepsy-like experiences following closed head injuries: personality variables and neuropsychological profiles.

To pursue Richard Roberts' epileptic spectrum disorder (ESD) and the emergence of complex partial epilepsy-like experiences, items and total scores for the ESD Inventory were examined for 185 patients who had sustained mechanical impacts (and were diagnosed with or without neuropsychological impairment) and a reference group (n=68) of university students. Results from neuropsychological, personality, neurological screening, and interview data supported the role of temporal lobe origins for these experiences. The incidences of these experiences were sufficient to adversely affect adaptation and to produce psychiatric profiles. Although only 70% of the patients who were impaired versus not impaired could be differentiated by items from the ESD Inventory, >95% of the patients with scores >100 on the ESD Inventory displayed abnormal scores on more than four Minnesota Multiphasic Personality Inventory scales. These results support Roberts' ESD concept and strongly suggest that persistent, subclinical occurrence of these experiences could be the cause or major correlate of neuropsychological impairment for these patients.

Adult-onset angiocentric glioma of epithelioid cell-predominant type of the mesial temporal lobe suggestive of a rare but distinct clinicopathological subset within a spectrum of angiocentric cortical ependymal tumors.

Angiocentric glioma (AG) is defined as an epilepsy-associated stable or slowly growing cerebral tumor primarily affecting children and young adults, histologically consisting mainly of monomorphic, bipolar spindle-shaped cells and occasional round to monopolar columnar epithelioid cells, showing angiocentric growth pattern and features of ependymal differentiation. We describe two clinicopathologically unusual cases of AG. Case 1 is a 54-year-old woman with a 10-year history of complex partial seizures. MRI revealed non-enhancing T1-low, T2/fluid-attenuated inversion recovery (FLAIR)-high intensity signal change in the left hippocampus and amygdala. After selective amygdalohippocampectomy, she had rare non-disabling seizures on medication for over 50 months (Engel's class I). Case 2 is a 37-year-old man with a 3-year history of complex partial seizures. MRI revealed non-enhancing T1-low, T2/FLAIR-high intensity signal change in the left uncus and amygdala. After combined amygdalohippocampectomy and anterior temporal lobectomy, he has been seizure-free for over 11 months. Histologically the tumors in both cases consisted mainly of infiltrating epithelioid cells (GFAP- ∼±, S-100-) with perinuclear epithelial membrane antigen (EMA)-positive dots and rings, showing conspicuous single- and multi-layered angiocentric arrangements. Occasional tumor cells showed spindle-shaped morphology (GFAP+, S-100+) with rare EMA-positive dots aligned radially and longitudinally along parenchymal blood vessels. Focal solid areas showed a Schwannoma-like fascicular arrangement with rare EMA-positive dots and/or sheets of epithelioid cells with abundant EMA dots. Electron microscopic investigation demonstrated features of ependymal differentiation. These cases, together with a few similar cases previously reported, appear to represent a rare but distinct clinicopathological subset of AG characterized by adult-onset, mesial temporal lobe localization and epithelioid cell-predominant histology.

[Insular psammomatous meningioma presenting intractable complex partial seizures].

We describe a 30-year-old female with intractable symptomatic epilepsy caused by an insular calcified mass, which was histologically proved as psammomatous meningioma. Seizures were described as consciousness impairment, motionless stare and automatism. After total removal of the tumor with a neuronavigation system and motor evoked potential (MEP) monitoring, seizures completely disappeared without neurological deficit. We emphasize that insular meningioma presents complex partial seizures which mimic medial temporal lobe epilepsy and seizures are controlled by total resection of the tumor.

Functional definition of seizure provides new insight into post-traumatic epileptogenesis.

Experimental animals' seizures are often defined arbitrarily based on duration, which may lead to misjudgement of the syndrome and failure to develop a cure. We employed a functional definition of seizures based on the clinical practice of observing epileptiform electrocorticography and simultaneous ictal behaviour, and examined post-traumatic epilepsy induced in rats by rostral parasagittal fluid percussion injury and epilepsy patients evaluated with invasive monitoring. We showed previously that rostral parasagittal fluid percussion injury induces different types of chronic recurrent spontaneous partial seizures that worsen in frequency and duration over the months post injury. However, a remarkable feature of rostral parasagittal fluid percussion injury is the occurrence, in the early months post injury, of brief (<2 s) focal, recurrent and spontaneous epileptiform electrocorticography events (EEEs) that are never observed in sham-injured animals and have electrographic appearance similar to the onset of obvious chronic recurrent spontaneous partial seizures. Simultaneous epidural-electrocorticography and scalp-electroencephalography recordings in the rat demonstrated that these short EEEs are undetectable by scalp electrocorticography. Behavioural analysis performed blinded to the electrocorticography revealed that (i) brief EEEs lasting 0.8-2 s occur simultaneously with behavioural arrest; and (ii) while behavioural arrest is part of the rat's behavioural repertoire, the probability of behavioural arrest is greatly elevated during EEEs. Moreover, spectral analysis showed that EEEs lasting 0.8-2 s occurring during periods of active behaviour with dominant theta activity are immediately followed by loss of such theta activity. We thus conclude that EEEs lasting 0.8-2 s are ictal in the rat. We demonstrate that the assessment of the time course of fluid percussion injury-induced epileptogenesis is dramatically biased by the definition of seizure employed, with common duration-based arbitrary definitions resulting in artificially prolonged latencies for epileptogenesis. Finally, we present four human examples of electrocorticography capturing short (<2 s), stereotyped, neocortically generated EEEs that occurred in the same ictal sites as obvious complex partial seizures, were electrographically similar to rat EEEs and were not noted during scalp electroencephalography. When occurring in the motor cortex, these short EEEs were accompanied by ictal behaviour detectable with simultaneous surface electromyography. These data demonstrate that short (<2 s) focal recurrent spontaneous EEEs are seizures in both rats and humans, that they are undetectable by scalp electroencephalography, and that they are typically associated with subtle and easily missed behavioural correlates. These findings define the earliest identifiable markers of progressive post-traumatic epilepsy in the rat, with implications for mechanistic and prophylactic studies, and should prompt a re-evaluation of the concept of post-traumatic silent period in both animals and humans.

Epilepsy surgery for refractory epilepsy due to encephalocele: a case report and review of the literature.

The management of medically intractable epilepsy is frequently assisted by the identification of structural abnormalities made possible by modern imaging techniques. The association between meningoencephaloceles and epileptic seizures is well reported in the literature. We report a patient with refractory right frontal lobe epilepsy caused by a right nasal meningoencephalocele who was rendered seizure free by endoscopic nasal excision and skull base repair, obviating the need for resective epilepsy surgery. Epilepsy patterns associated with encephalocele and their management are reviewed.

[Clinical aspects of epilepsy in children with periventricular leukomalacia].

UNLABELLED: We investigated the frequency and characteristics of epilepsy in 63 children (39 males and 24 females) with cerebral palsy caused by periventricular leukomalacia, who were born preterm at <34 weeks' gestation and followed for more than five years (duration: 5-18 years, mean: 9.6 years). While seven (11%) of the 63 patients had febrile convulsions (FC), 11 (17%) were associated with symptomatic localization-related epilepsy (SLRE) and 8 (13%) with West syndrome (WS). The gestational ages of the WS group were significantly (p<0.05) longer than in FC group. The DQ of the SLRE and WS groups were significantly (p<0.01) lower than in the N-S group. The frequency of spastic quadriplegia was 19%, 29%, 36%, 50% in the N-S, FC, SLRE, WS groups, respectively. Among the 11 SLER patients, 5 had one seizure type, while 3 had two and 3 had three seizure types. The seizure patterns included complex partial seizures (CPS) in 8, secondarily generalized partial epileptic seizures in 8, and simple partial seizures in 4. One patients in the WS group developed CPS, and another patient developed epilepsy undetermined after infancy. Regarding the main localizing symptoms of SLRE, oculogyric seizures were observed in 7 patients and hemi-facial seizures were observed in 8 patients. In all WS patients, the location of the epileptiform discharges was in the parieto-occipital area, while 8 of 11 patients with SLES had it in the central area. IN CONCLUSION: 30% of all patients with PVL were associated with epilepsy. WS developed in 13% during early infancy and SLRE developed in 17% after infancy. The most common epileptic seizure in the patients with PVL was complex partial seizure.

Magnetic resonance imaging abnormalities associated with vigabatrin in patients with epilepsy.

PURPOSE: Vigabatrin used to treat infantile spasms (IS) has been associated with transient magnetic resonance imaging (MRI) abnormalities. We carried out a retrospective review to better characterize the frequency of those abnormalities in IS and in children and adults treated with vigabatrin for refractory complex partial seizures (CPS). METHODS: Medical records and 332 cranial MRIs from 205 infants (aged 16 years) with CPS were re-reviewed. Prespecified MRI abnormalities were defined as any hyperintensity on T(2)-weighted or fluid-attenuated inversion-recovery (FLAIR) sequences with or without diffusion restriction not readily explained by a radiographically well-characterized pathology. MRIs were read by two neuroradiologists blinded to treatment group. The incidence and prevalence of MRI abnormalities associated with vigabatrin were estimated. RESULTS: Among infants with IS, the prevalence of prespecified MRI abnormalities was significantly higher among vigabatrin-treated versus vigabatrin-naive subjects (22% vs. 4%; p < 0.001). Of nine subjects in the prevalence population with at least one subsequent determinate MRI, resolution of MRI abnormalities occurred in six (66.7%)-vigabatrin was discontinued in four. Among adults and children treated with vigabatrin for CPS, there was no statistically significant difference in the incidence or prevalence of prespecified MRI abnormalities between vigabatrin-exposed and vigabatrin-naive subjects. DISCUSSION: Vigabatrin is associated with transient, asymptomatic MRI abnormalities in infants treated for IS. The majority of these MRI abnormalities resolved, even in subjects who remained on vigabatrin therapy.

Cholecystokinin-8 sulfate modulates the anticonvulsant efficacy of vigabatrin in an experimental model of partial complex epilepsy in the rat.

PURPOSE: We evaluated the possible additive effect induced by the administration of the anticonvulsant vigabatrin (VGB) and cholecystokinin-8 sulfate (CCK-8S) on an experimental model of partial complex seizures (maximal dentate gyrus activation, MDA). Moreover, the functional involvement of gamma-aminobutyric acid (GABA) neurotransmission was tested by iontophoretically administering bicuculline (GABA receptor antagonist) in the dentate gyrus. METHODS: Urethane anesthetized rats were pretreated with VGB (50, 100 or 200 mg/kg, i.p.) or CCK-8S (8 nmol/kg, i.p.) alone or coadministered with VGB (50 mg/kg, i.p.). Dentate gyrus epileptic activity was obtained through the repetitive electrical stimulation of the angular bundle. MDA latency, duration, and poststimulus afterdischarge (AD) duration were evaluated. The extracellular activity of some dentate neurons was recorded before and during bicuculline iontophoresis. RESULTS: Only the higher dose of VGB reduced the mean duration of dentate MDA and AD. CCK-8S significantly decreased the number of animals exhibiting MDA responses, characterized by increased latency and shorter duration. The coadministration of CCK-8S and VGB (50 mg/kg) significantly increased the anticonvulsant effects, either reducing the number of responding animals or decreasing both MDA and AD durations. During bicuculline iontophoresis, all the modifications induced on the MDA-related activity of dentate neurons by the pretreatments (VGB and/or CCK-8S) were abolished. DISCUSSION: The results indicate that CCK-8S significantly enhances the VGB-induced anticonvulsant effect in the MDA model of partial epilepsy, probably through an increase of GABA cerebral levels. Such increased anticonvulsant effect becomes evident by using VGB at a lower dose.

Complex partial status epilepticus revealing anti-NMDA receptor encephalitis.

Encephalitis with anti-NMDA receptor antibodies is a recently-recognised form of paraneoplastic encephalitis characterized by a prodromal phase of unspecific illness with fever resembling viral disease, followed by memory loss, psychiatric features, seizures, disturbed consciousness, prominent abnormal movements and autonomic imbalance. Association with ovarian teratoma is common. Neurological outcome can be good, especially when surgery is performed at an early stage. Here, we report a case of anti-NMDA receptor encephalitis associated with ovarian teratoma presenting with inaugural complex partial status epilepticus. The nature of abnormal movements at early stages was unclear and abnormal movements were misinterpreted as the recurrence of partial epileptic seizures. Despite its rarity, all clinicians treating epilepsy and movement disorders should be familiar with anti-NMDA receptor encephalitis, that appears to be a very severe but curable disease.

Dysembryoplastic neuroepithelial tumor: a clinicopathological study of 32 cases.

Dysembryoplastic neuroepithelial tumor (DNT) is a relatively newly described entity and is an important cause of intractable epilepsy. We report 32 cases of DNT who were operated and treated in our hospital over a period of 12 years. Immunostaining for various proliferative markers and tumor suppressor gene proteins was done to assess the proliferative potential of these tumors. The most common presentation was partial complex seizures followed by generalized tonic-clonic seizures, focal motor seizures, and myoclonus. The most common location was temporal lobe followed by frontal and in one patient lesion was multifocal. All patients were seizure free at the last postoperative follow-up which varies from 12 to 96 months with mean of 33.7 months. Microscopic examination showed classical histology comprising of intracortical multinodular microcystic lesions with floating neurons. Proliferative indices were very low (<1%) and tumor suppressor gene protein expression was not seen in the present study. Cortical dysplasia of the surrounding brain was observed in 37.3% of cases.

Esophageal tear in a patient undergoing stereotactic brain biopsy under general anesthesia.

Injuries of the esophagus with resultant mediastinitis have been reported following endotracheal intubation. Herein, we report a case of esophageal perforation that resulted from difficulty with intubation in a patient with a stereotactic head frame. A 52-year-old woman underwent a stereotactic brain biopsy of a left temporal tumor. After a stereotactic head frame was applied, intubation for anesthesia required three attempts. On postoperative day 2, she complained of worsening dysphagia and chest pain. A 4-mm tear in the right posterior cervical esophagus was discovered and repaired. Esophageal perforation may arise from limited neck extension imposed by a stereotactic head frame. Unexplained dysphagia postoperatively is the hallmark of this rare complication.

[Anticonvulsant hypersensitivity syndrome: an entity to be remembered]. / Síndrome de hipersensibilidad a anticomiciales: una entidad para recordar.

Anticonvulsant hypersensitivity syndrome is an unpredictable, potentially fatal drug reaction to aromatic anticonvulsants such as carbamazepine, phenytoin and phenobarbital. The hallmark features include fever, eosinophilia, rash and involvement of one or more internal organs. Clearly established diagnostic criteria and treatment guidelines are lacking. A high index of suspicion is required to identify this syndrome, allowing early withdrawal of the drug and avoiding re-exposure. We report an illustrative case of anticonvulsant hypersensitivity syndrome and review the published literature.

Seizure characteristics and control following resection in 332 patients with low-grade gliomas.

OBJECT: Seizures play an important role in the clinical presentation and postoperative quality of life of patients who undergo surgical resection of low-grade gliomas (LGGs). The aim of this study was to identify factors that influenced perioperative seizure characteristics and postoperative seizure control. METHODS: The authors performed a retrospective chart review of all cases involving adult patients who underwent initial surgery for LGGs at the University of California, San Francisco between 1997 and 2003. RESULTS: Three hundred and thirty-two cases were included for analysis; 269 (81%) of the 332 patients presented with >or=1 seizures (generalized alone, 33%; complex partial alone, 16%; simple partial alone, 22%; and combination, 29%). Cortical location and oligodendroglioma and oligoastrocytoma subtypes were significantly more likely to be associated with seizures compared with deeper midline locations and astrocytoma, respectively (p=0.017 and 0.001, respectively; multivariate analysis). Of the 269 patients with seizures, 132 (49%) had pharmacoresistant seizures before surgery. In these patients, seizures were more likely to be simple partial and to involve the temporal lobe, and the period from seizure onset to surgery was likely to have been longer (p=0.0005, 0.0089, and 0.006, respectively; multivariate analysis). For the cohort of patients that presented with seizures, 12-month outcome after surgery (Engel class) was as follows: seizure free (I), 67%; rare seizures (II), 17%; meaningful seizure improvement (III), 8%; and no improvement or worsening (IV), 9%. Poor seizure control was more common in patients with longer seizure history (p<0.001) and simple partial seizures (p=0.004). With respect to treatment-related variables, seizure control was far more likely to be achieved after gross-total resection than after subtotal resection/biopsy alone (odds ratio 16, 95% confidence interval 2.2-124, p=0.0064). Seizure recurrence after initial postoperative seizure control was associated with tumor progression (p=0.001). CONCLUSIONS: The majority of patients with LGG present with seizures; in approximately half of these patients, the seizures are pharmacoresistant before surgery. Postoperatively, >90% of these patients are seizure free or have meaningful improvement. A shorter history of seizures and gross-total resection appear to be associated with a favorable prognosis for seizure control.