Dramatic changes in artistic preference after left temporal lobectomy.
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Adult↗
Biomedical subjects
Edouard Hirsch
Publications and source records attributed to Edouard Hirsch.
Antiepileptic drug-induced pharmacodynamic aggravation of seizures: does valproate have a lower potential?
Thirty-five years since its introduction into clinical use, valproate (valproic acid) has established itself as one of the most widely used antiepileptic drugs (AEDs). In recent years, there has been a growing awareness of the potential aggravation of seizure disorders by AEDs. Such aggravation may be due to a variety of factors that include a paradoxical pharmacodynamic effect. In order to address this important safety aspect of AED treatment, we reviewed all available published evidence in search of factors related to seizure aggravation during valproate therapy. We analysed the 20 available publications, which outline about 99 case reports (in some papers, the exact number was not specified) of aggravation of seizures associated with valproate. Almost all of these cases occurred in a specific clinical context known to be linked to seizure aggravation, such as overdose, encephalopathy, hepatopathy or metabolic disorders. However, we found no consistent evidence of pure pharmacodynamic aggravation in the absence of any of the above quoted factors. In view of the large number of patients treated worldwide with valproate, the number of reported cases of seizure aggravation in patients taking the drug in the literature is low. Conditions in which worsening of seizures as a result of valproate use may occur are well known and often avoidable. Thus, unlike most AEDs, including the newer ones, valproate appears to have a very low potential for pharmacodynamic paradoxical seizure aggravation. This knowledge is in accordance with long-standing clinical experience and practice.
Anticonvulsants↗
Levetiracetam: preliminary efficacy in generalized seizures.
Levetiracetam is a novel antiepileptic drug (AED) with proven efficacy against partial seizures, but there is limited information about its effectiveness against generalized seizures. In animal models, levetiracetam protects against seizures in audiogenic susceptible rodents, and it is effective in the Genetic Absence Epilepsy Rat from Strasbourg, a model of absence seizures. In these models, levetiracetam has a therapeutic index that is higher than those of other AEDs. A number of small open-label studies suggest that levetiracetam reduces seizure frequency in patients with generalized seizures, including primarily generalized seizures and myoclonic seizures. Case reports provide additional information regarding the potential efficacy of levetiracetam in postanoxic, post-encephalitic and progressive myoclonus. Although random-ized controlled studies of patients with generalized seizures have not yet been conducted, on the basis of available information, levetiracetam may be prom-ising in the treatment of generalized seizures.
Animals↗
Co-occurrence of infantile epileptic seizures and childhood paroxysmal choreoathetosis in one family: clinical, EEG, and SPECT characterization of episodic events.
The co-occurrence of infantile convulsions and childhood paroxysmal choreoathetosis (ICCA syndrome) has recently been reported in several families. The pattern of familial clustering observed is consistent with a single locus mutation which has been mapped onto the pericentromeric region of chromosome 16. We studied the main clinical, electroencephalogram (EEG), and single photon emission computed tomography (SPECT) characteristics of episodic events in a new family presenting clinical features similar to that described in the ICCA syndrome. In the first year of life, a mother and her two daughters suffered from rare afebrile seizures lasting from 30 seconds to 15 minutes. Ictal EEG recording in one daughter at 7 months of age showed bilateral polyspikes with a posterior predominance. In the three patients, epileptic seizures regressed within a few weeks, and never reoccurred. At the age of 7 and 12 years, respectively, the two daughters presented daily brief (20 seconds to 1 minute) involuntary choreoathetotic episodes. In 10 of these attacks, EEG did not show any epileptiform abnormalities. In both sisters, an ictal SPECT was performed during a choreoathetotic episode. Subtracting the ictal SPECT from the interictal SPECT coregistered to magnetic resonance imaging (MRI) revealed significant modifications in the local cerebral perfusion in the sensorimotor cortex, the supplementary motor areas, and pallidum. Carbamazepine completely suppressed paroxysmal dyskinesias. These observations, together with literature data, suggest that in this syndrome, depending on brain maturation, the same genetic abnormality may result in different paroxysmal neurological symptoms.
Athetosis↗
Antiepileptic effect of high-frequency stimulation of the subthalamic nucleus (corpus luysi) in a case of medically intractable epilepsy caused by focal dysplasia: a 30-month follow-up: technical case report.
OBJECTIVE AND IMPORTANCE: Currently, some forms of epilepsy are resistant to both pharmacological and surgical interventions. As a result, there is a need for new therapeutic strategies. Because the nigral system modulates neuronal excitability in animal models of epilepsy, we considered therapeutic high-frequency stimulation of the subthalamic nucleus (STN). We were encouraged by the known relationship between the STN and the nigral system, as well as by our experience with high-frequency stimulation of the STN in Parkinsonian patients. CLINICAL PRESENTATION: A 5-year-old girl with pharmacologically resistant, inoperable epilepsy caused by focal centroparietal dysplasia underwent implantation with a permanent electrode in the left STN and was chronically stimulated. To date, we have followed up this patient for 30 months postoperatively. TECHNIQUE: High-frequency stimulation of the STN induced a significant voltage-dependent reduction (by 80%) in the number and severity of seizures. In addition, consistent improvement in both motor and cognitive functions was noted as a result of reduced postictal states. The effect was more prominent for seizures occurring in clusters (89% reduction) and during the day (88% reduction) than for those that occurred during sleep (53% reduction). CONCLUSION: This is the first report of epilepsy control using chronic high-frequency stimulation of the STN. Preliminary observations in three other operated patients (at 2, 12, and 18 mo) confirm these data. We think that high-frequency stimulation of the STN may hold significant future potential as a treatment for epilepsy, similar to its established role in the treatment of Parkinson's disease. This finding opens completely new experimental and therapeutic avenues for the treatment of surgically and medically intractable epilepsy.
Brain↗
Correlation between PET and SISCOM in temporal lobe epilepsy.
UNLABELLED: The subtraction of interictal from ictal SPECT coregistered to 3-dimensional (3D) MRI (SISCOM) and (18)F-FDG PET are 2 techniques that are involved in the definition of the epileptogenic zone in refractory partial temporal lobe epilepsy (TLE). The aim of this study was compare, region by region, the functional patterns obtained by both strategies, SISCOM and PET, in patients with unilateral TLE. METHODS: Perfusion data using SISCOM and metabolic data using (18)F-FDG PET scans were acquired from 17 patients with unilateral TLE. The functional metabolism and perfusion maps were overlaid onto a 3D rendering of the patient's anatomic MRI scans. RESULTS: The functional patterns that were observed with PET and SISCOM were found mainly in the ipsilateral and contralateral temporal lobes, in the orbitofrontal and insular cortices. Despite the high rate of concordance, in some cases discrepancies could be observed between PET and SISCOM abnormalities: In the mesial regions, as in the anterior neocortex, PET abnormalities were found more frequently than SISCOM changes. SISCOM abnormalities were found more frequently in the posterior temporal neocortex. In the extratemporal cortex, SISCOM abnormalities were more widespread. CONCLUSION: The marked rate of concordance between PET and SISCOM abnormalities observed in relatively extensive regions shows that, in TLE, seizures were generated and spread in metabolically abnormal regions.
Adult↗
Epilepsy and neuroprotection: an illustrated review.
Multiple types of insults, such as status epilepticus, hypoxia and trauma, may alter the central nervous system. Strategies to protect the brain against insults remain a very difficult and challenging problem. Damage to the central nervous system can be modulated via excessive excitatory and reduced inhibitory neurotransmission. In addition, increased sodium and calcium loading through impaired voltage-sensitive channels, as well as alterations in the acid-base balance can contribute to both excitotoxic and apoptotic cell death. Epilepsy treatment has always been related to neuroprotection, since it aims to reduce the duration or totally suppress seizures. Although the debate on the capacity of simple seizures to induce neuronal injury is still ongoing, no doubt persists on the disastrous effects of prolonged episodes of status. The next step would be to prevent epilepsy. Several animal models have been used to study the various aspects of the epileptogenic process. In humans, one of the most compelling examples of a series of epileptogenic events is temporal lobe epilepsy (TLE). Temporal lobe epilepsy is often attributed to prolonged febrile convulsions in childhood resulting in mesial temporal sclerosis. However, the relationship between TLE, seizures in childhood and hippocampal sclerosis may not be apparent as initially believed. Furthermore, it is well recognized that in a number of patients there is a delay from a specific insult to the onset of seizures. This "latent period" could be an opportunity for effective intervention, provided that the underlying mechanisms are understood and that appropriate means for a beneficial modification of the disease process become available. The present review discusses the various steps of temporal lobe epilepsy and provides illustrations of the various mechanisms implicated in neuronal death. Data from animal models is also presented and illustrated with video sequences. Finally, on the basis of what is known on mechanisms of action of available antiepileptic drugs, some suggestions are put forward. Basic science and research are guided by clinical queries and from ongoing dialogue. The present illustrated review deals with only a small part of the important amount of work related to epilepsy and neuroprotection. As such it is necessarily schematic or even simplistic. The review is designed to inform clinicians about the basic issues related to the subject, thus allowing them to follow the ongoing debate and participate with pertinent questions. (Published with video sequences).
Animals↗
Seizures and the basal ganglia: a review of the clinical data.
This article attempts an overview of the clinical and electrophysiological evidence supporting the involvement of the basal ganglia in epileptic seizures. In contrast to animal data, evidence for a role of these structures in human epilepsies is lacking. However, from the theoretical point of view, it remains conceivable that, given their strong interconnectivity, basal ganglia could be functionally linked to the cerebral cortex during an epileptic seizure. Several clinical ictal aspects have been suggested to be compatible with the involvement of basal ganglia, namely, ictal dystonic posturing during temporal lobe seizures, rotatory seizures and paroxysmal dyskinesia-like seizures. On the other hand, basal ganglia dysfunction may also influence some aspects of epilepsy, as suggested by pure basal ganglia pathology such as Parkinson's disease, or the described effect of an acute basal ganglia lesion in epileptic patients. The data discussed in this review may stimulate further research to link basic scientific data to human epilepsies, and lead to the development of novel therapeutical solutions.
Animals↗
Deep brain stimulation in epilepsy with particular reference to the subthalamic nucleus.
Alternative methods, for the treatment of medically refractory epileptic patients, who cannot be treated by resective surgery, such as chronic deep brain neurostimulation, are under development. Such methods have been used in the cerebellum, various thalamic nuclei, and in the caudate nucleus. In Grenoble, encouraged by the suppressive effects of pharmacological or electrical inhibition of the STN on different types of seizure in animal models of epilepsy, and by our experience with STN high frequency stimulation (HFS) in patients with movement disorders, we have evaluated the high frequency stimulation of the subthalamic nucleus (STN HFS). STN HFS was performed in five patients suffering from medically intractable seizures and considered unsuitable for resective surgery. A 67% to 80% reduction in seizure frequency was observed in three patients, with a partial symptomatic epilepsy of the central region. An additional patient suffering from severe myoclonic epilepsy (Dravet syndrome) also responded to STN HFS, with a weaker reduction of seizure frequency. The fifth patient who suffered from an autosomal dominant frontal lobe epilepsy with insulo-frontal seizures did not show any improvement. These results suggest that stimulation of STN could be a promising treatment for patients with drug-resistant epilepsy who would not benefit from conventional surgery.
Adolescent↗