Dynamic cerebral autoregulation during sevoflurane anesthesia: a comparison with isoflurane

OBJECTIVE: To study the incidence and pattern of epilepsy in patients with periventricular leukomalacia (PVLM) in two specialty clinic settings. BACKGROUND: Motor and cognitive deficit as well as epilepsy are common in patients with PVLM. With modern imaging techniques, PVLM is now easily recognized. METHODS: Epileptic seizures and syndromes as well as motor and cognitive deficits were correlated with MRI findings. Two patient populations were studied: Group A-children with cerebral palsy and PVLM presenting to a center for children with motor disability (n = 19); and Group B-epileptic patients with PVLM presenting to a tertiary epilepsy center (n = 12). A single patient with PVLM and epilepsy who underwent extensive investigations, including intracranial EEG telemetry, is reported. RESULTS: In Group A, 47% of patients had epilepsy (9/19). PVLM was found in 1.27% of patients investigated for epilepsy at a tertiary epilepsy center (12/942). The majority of patients in both groups had multiple seizure types, with complex partial seizures being most common. Of patients with seizures (Groups A and B), 85.7% had intractable epilepsy (18/21). Intracranial EEG in the illustrative case demonstrated a multifocal epileptic process with occipitotemporal predominance. CONCLUSIONS: PVLM was an uncommon underlying cause in patients presenting with epilepsy (Group A); however, patients presenting with motor disability and PVLM (Group B) had a high incidence of seizures. PVLM in epileptic patients is associated with multiple seizure types and medically refractory disease.     

Epilepsy and the heart

The relations between epilepsy and heart are complex and expressed in two opposite sides. (1) Cardiac arrhythmias may provoke epileptic seizures but these seizures are, in this case, syncopal attacks. Nevertheless, in the past, these clinical features have been individualized as "cardiac epilepsy" or epilepsy in cardiacs. However, true epileptic seizures could be observed in the course of a syncopal attack and a syncope may complicate the issue of an epileptic seizure. (2) On the other hand, epileptic seizures may provoke severe cardiac arrhythmias. The incidence rate of sudden death in patients with epilepsy is estimated to be 1/1000 patients. The exact neural mechanisms in cardiac arrhythmias seizures could explain only some of the sudden unexpected deaths observed in epileptic patients. The role of antiepileptic drugs on cardiac conduction as well as the effects of seizures or status epilepticus on the myocardium are other enigmatic aspects of the relations between epilepsy and heart.     

Ectopic cerebral tissue in the middle ear. A case report

Most idiopathic generalized epilepsies have an onset in childhood or adolescence, with a moderate second incidence peak in the presenium predominantly in women. This study addressed the question of a later onset. The available literature and the records of four personal data sets (two prospective incidence surveys of epileptic seizures, one prevalence study of epilepsy, and one clinical series of individuals with epilepsy) were screened for patients who had experienced a first generalized convulsive seizure with bilateral spike-wave complexes on EEG after 60 years of age. Reports of first idiopathic generalized tonic-clonic seizures occurring after age 60 were extremely rare and none was found in our four cohorts regardless of the methodology involved. Only five case reports were found, all involving a woman. Two had a family history of seizure disorders and two had had at least one seizure earlier in life. Idiopathic generalized epilepsy of late onset, if this condition actually exists, is likely to be the consequence of a genetic predisposition triggered by acquired epileptogenic factors.     

Latest tests for prostatic neoplasia

Neurofibromatosis 1 is a common, genetically transmitted neurodevelopmental disorder with a high potential to cause subcortical focal brain lesions. Although seizures occasionally complicate neurofibromatosis 1, they have not been characterized adequately in the disease. Other phacomatoses with attendant subcortical focal brain lesions have been associated with an evolution from generalized to focal-onset epilepsy. This evolution may be related to the cortical dysplasias that also appear in such disorders. Cortical dysplasias, although occasionally found in neurofibromatosis 1 epileptic patients, are not as frequent as in other phacomatoses. The authors retrospectively screened 499 neurofibromatosis 1 patients for the prevalence and etiology of seizures, their response to therapy, and the evolution of seizure type over time. The prevalence of epileptic seizures (4.2%) was about twice the prevalence in the general population. There were no significant cortical dysplasias identified radiographically nor was there a relationship among the presence of subcortical focal brain lesions and seizure type, response to treatment, or evolution of epilepsy in the neurofibromatosis 1 population. The authors' data do not suggest an ontogeny of epilepsy in neurofibromatosis 1 that is different from the general epileptic population.     

Regional cerebral blood flow in focal cortical epilepsy

Regional cerebral blood flow (rCBF) was studied in ten patients with focal cortical epilepsy. The blood flow was measured by the intra-arterial injection of xenon 133 (133Xe), and the isotope clearance was recorded by a multidetector scintillation camera with 254 detectors. Three patients were studied both during a seizure and (in the same setting) in the interictal period; six patients were studied only in the interictal period, and one patient was studied only during a seizure. Studies during seizures all showed marked flow increases in areas presumed to participate in the seizure activity. This finding accords with earlier studies. All nine patients studied in the interictal phase showed, either spontaneously or during activation by intermittent light, focal flow increases in areas presumed to comprise the epileptic focus. These interictal hyperemic foci probably reflect subictal neuronal hyperactivity in epileptogenic nervous tissue. Only two of the patients had distinct epileptic electroencephalographic foci. It appears that rCBF studies can be a valuable diagnostic tool in the investigation of cortical epileptogenic lesions.     

Adolescent onset of idiopathic photosensitive occipital epilepsy after remission of benign rolandic epilepsy

PURPOSE: We describe 2 girls, aged 19 years, who experienced a rolandic seizure at ages 4 and 5, respectively, together with the interictal EEG features of benign rolandic epilepsy (BRE). In adolescence both patients developed photosensitive occipital seizures accompanied by spontaneous and photic-induced occipital EEG paroxysms. METHODS: We have been following 33 patients with a history of BRE, between ages 12 and 28 years (mean 17 years). Twenty-one of these patients had experienced their last rolandic seizure before the age of 10 years and 9 of them had been without treatment since age 11 or earlier. In 2 of these 9 patients, other types of seizures recurred after remission of BRE. Clinical, EEG, and evoked potential findings on these 2 patients are presented. RESULTS: After having experienced BRE, both patients suffered partial seizures from age 12, with elementary visual hallucinations, visual blurring, slow head turning, cephalic pain, epigastric discomfort, unresponsiveness, and vomiting. Seizure onset was related to watching TV or exposure to bright light. EEG showed interictal occipital spikes, and a photoparoxysmal response limited to the occipital lobes. Visual evoked potentials were greatly increased in amplitude. One patient had two visual attacks only and remained seizure free after 4 years of follow-up, while the other had seizures controlled by an association of valproate and carbamazepine. CONCLUSIONS: Clinical and neurophysiological characteristics suggest that these two patients may have presented different age-related expressions within the spectrum of a benign seizure susceptibility syndrome rather than sharply distinct epilepsy syndromes.     

Electroclinical manifestations elicited by intracerebral electric stimulation "shocks" in temporal lobe epilepsy

In patients with severe drug-resistant partial epilepsy, undergoing Stereo-EEG investigations, spatial definition of the "epileptogenic area" is mainly based on spontaneous seizures recordings, but also on seizures induced by intracerebral electrical stimulation (ES). Only "trains" ES (TES, 50 pps) are currently used with this aim; "shocks" ES (SES, 1 pps) are principally applied to localize motor pathways. We have shown, during a prospective study concerning 10 temporal lobe epileptic patients, that SES could frequently induce seizures, especially when stimulation is applied in the anterior part of the Ammon's horn. Even if its efficacy seems lower than by TES, this kind of stimulation, in the majority of the cases, does reproduce isolated ictal subjective symptomatology, allowing the visualization of the progressive organisation of ictal electrical discharges, and avoids "unexpected" ("false positive"?) clinical responses.     

Epidemiology in epilepsy. Epilepsy primarily affects small children and the elderly

Epilepsy is one of the commonest neurological/disorders, with peak incidences among the elderly and among children in the first year of life. Approximately 60,000 (0.7 per cent) of the Swedish population, 50,000 adults and 10,000 children, have active epilepsy. Stroke is the aetiology most commonly identified. The majority of those with a first-ever unproven seizure suffer no further seizures. Of those who do have further seizures (i.e., who develop epilepsy), 65-85 per cent eventually become free from seizures, and many of them are able to cease antiepileptic medication. Epilepsy is a heterogeneous disorder. The larger proportion of patients who are otherwise healthy, and who respond readily to antiepileptic treatment and manifest no side effects or only mild ones, are characterised by the best prognosis and are able to terminate treatment within 2-5 years without recurrence. At the other extreme is the smaller group of patients with onset of epilepsy very early in life, and characterised by multiple severe neurological defects, severe daily seizures, resistance (more or less) to all available treatment, and high mortality. In many cases of epilepsy, however, severity and prognosis lie somewhere between these two extremes.     

Seizures associated with propofol anesthesia

Propofol is a new, fast-acting intravenous (i.v.) anesthetic. Involuntary movements or epileptic seizures have occurred during or after propofol-induced anesthesia in approximately 50 reported cases; a third of the patients have had epilepsy. We report 5 patients with seizures in association with propofol anesthesia. A female epileptic patient developed severe status epilepticus; the other patients with short-lasting seizures had no previous epilepsy. Although propofol has been used in treatment of patients of status epilepticus, the risk of precipitation of epileptic seizures warrants consideration especially when planning anesthesia for epileptic patients.     

Pediatric psychopharmacology and the interaction between drugs and the developing brain

Cardiac arrhythmias are frequently seen with epileptic seizures and their occurrence has been proposed as a possible cause for sudden unexpected death in patients with epilepsy. Reported is a case of a 32-year-old man who presented to the emergency department (ED) following a generalized tonic-clonic seizure and subsequently developed sinus bradycardia and asystole following a second, witnessed tonic-clonic event. This case illustrates the potential for life-threatening cardiac arrhythmias in patients with seizures. The importance of hemodynamic monitoring in seizure patients while they are in the ED is emphasized.     

Effects of intracerebroventricular injection of histamine on memory deficits induced by hippocampal lesions in rats

This review was conducted to evaluate the long-term prognosis of children responding to vigabatrin by examining the incidence of increased seizure frequency, loss of efficacy, and appearance of new seizures in a cohort of 196 children (mean age, 68.2 months; range, 2 months to 19 years) with drug-resistant epilepsy, who had received vigabatrin as add-on treatment in clinical trials. The results indicate that an increase in seizure frequency was uncommon, occurring in only 10% of children with highly drug-resistant epilepsy and that it usually appears shortly after the initiation of treatment. It was clearly not dose-dependent and most often occurred in patients with nonprogressive myoclonic epilepsy. No specific seizure type was specially involved and usually the problem reversed on discontinuing vigabatrin. Loss of efficacy was also uncommon (12% of patients), and again no specific seizure type was found to be associated. Epilepsy syndrome does seem to be a better predictor of loss of efficacy because it occurred most often in symptomatic generalized epilepsies and cryptogenic infantile spasms. A total of 21 patients (11%) developed genuinely new types of seizures. Fifteen of these patients developed new partial seizures that had little impact on the patients' overall clinical improvement. The new partial seizures were better tolerated than the initial seizure type which in most cases had disappeared. Approximately 3% of patients experienced new generalized seizures that aggravated their initial condition. These occurred most often in patients with nonprogressive myoclonic epilepsy; therefore vigabatrin should be used with particular caution in such patients.     

Merosin-negative congenital muscular dystrophy, occipital epilepsy with periodic spasms and focal cortical dysplasia. Report of three Italian cases in two families

We report clinical, EEG and neuroimaging findings of three patients in two Italian families with merosin-negative congenital muscular dystrophy (CMD), drug-resistant occipital epilepsy, diffuse persistent cerebral white matter changes and focal cortical dysplasia. Clinical and epilepsy histories, EEG and neuroimaging findings were very similar in all patients. Seizures started in childhood and mainly consisted of periodic spasms, a particular type of partial seizure characterized by clusters of epileptic spasms. The motor expression of the spasms was very mild so that they had been frequently missed or misinterpreted as non-convulsive generalized absence seizures. Interictal EEG showed occipital spike-waves and bilateral synchronous slow spike-wave discharges. Ictal EEG showed prolonged periodic sequences of slow waves with associated fast rhythm complexes, characteristic of periodic spasms. Two patients had normal intelligence, one patient presented moderate mental retardation. Focal cortical dysplasia in the posterior areas of the brain, in addition to marked diffuse white matter alterations, was detected in the magnetic resonance images of all patients. Findings in these patients indicate that in merosin-negative CMD brain involvement can include cortical dysplasia, in addition to white matter changes. In such cases the brain damage can lead to a childhood-onset localization-related symptomatic occipital epilepsy. Epileptic seizures and cortical dysplasia can be, however, difficult to detect in CMD. The clinical semiology of epileptic seizures may in fact be modified because of muscular weakness. This implies that epilepsy may be misdiagnosed or even missed and EEG-polymyographic recordings may be necessary to identify it. Similarly, cortical dysplasia may be very localized and visible by neuroimaging only if it is carefully investigated on the basis of epileptological and EEG-polymyographic findings.     

Brain chimeras for the study of an avian model of genetic epilepsy: structures involved in sound and light-induced seizures

The epileptic homozygotes of the Fayoumi strain of chickens (Fepi) are affected by photogenic reflex epilepsy with complete penetrance. Here we demonstrate that they are equally affected by audiogenic reflex epilepsy induced by intense sound stimulation. All the Fepi display sound-induced seizures from hatching to adulthood consisting of initial 'ictal arousal' and running fits usually followed by generalized clonico-tonic convulsions. A running fit is the preconvulsive motor symptom specifically induced by auditory stimulation while neck myoclonus is the preconvulsive motor symptom specifically induced by photic stimulation. The EEG interictal spikes and spike and waves are suppressed and replaced by a desynchronized trace during the seizures of both kinds. Viable neural chimeras were obtained by graft of embryonic brain vesicles from Fepi donors into normal chick embryos. Transfer of the complete audiogenic and photogenic phenotypes was obtained in chimeras resulting from embryonic substitution of both the prosencephalon and mesencephalon. The substitution of the prosencephalon alone resulted in transfer of interictal paroxysmal EEG activity accompanied by the sound and light-induced desynchronization and 'ictal arousal' with no motor seizures. Chimeras with embryonic substitution of the mesencephalon alone displayed running fits and convulsions induced by sound stimulation but only neck myoclonus following light stimulation. The conclusions are reached that: (i) the Fepi is a model of audiogenic and photogenic reflex epilepsy; (ii) in both types, the seizure initiator and the convulsion generator are localized in the brainstem, although reinforcement from telencephalic visual structures is needed to trigger photogenic generalized convulsions.     

Dizziness, epilepsy and the EEG

EEGs were done on 97 patients with the complaint of dizziness and were compared to a normal control group. In patients with dizziness of a syncopal-like type there was a small but significant increase in the incidence of bitemporal sharp wave discharges. Another group, consisting of 48 patients with seizures was evaluated; 71% had noted dizziness, significantly more than a control group. Most seizure patients experienced dizziness as a syncopal-like sensation with an abrupt onset just before their clinical seizures. The majority also experienced identical episodes of dizziness unassociated with their seizures, possibly as an abortive epileptic phenomenon. Dizziness described as rotational (vertigo) was uncommon in these epileptics.     

Otoneurologic abnormalities in insulin-dependent diabetes

The Authors discuss the role of plasma prolactin concentration as a marker to discriminate epileptic and non epileptic seizures. In 40 children was determined prolactin during the first seizure (30 feverish and 10 non feverish seizures). The analysis of the results shows that during non feverish seizures prolactin concentration in higher, but we don't know if the same seizures are the beginning of epilepsy. So plasma prolactin concentration is a parameter of moderate interest in diagnosis and prognosis in childhood paroxismal disorders.     

Dynamic interactions determine partial thalamic quiescence in a computer network model of spike-and-wave seizures

In vivo intracellular recording from cat thalamus and cortex was performed during spontaneous spike-wave seizures characterized by synchronously firing cortical neurons correlated with the electroencephalogram. During these seizures, thalamic reticular (RE) neurons discharged with long spike bursts riding on a depolarization, whereas thalamocortical (TC) neurons were either entrained into the seizures (40%) or were quiescent (60%). During quiescence, TC neurons showed phasic inhibitory postsynaptic potentials (IPSPs) that coincided with paroxysmal depolarizing shifts in the simultaneously recorded cortical neuron. Computer simulations of a reciprocally connected TC-RE pair showed two major modes of TC-RE interaction. In one mode, a mutual oscillation involved direct TC neuron excitation of the RE neuron leading to a burst that fed back an IPSP into the TC neuron, producing a low-threshold spike. In the other, quiescent mode, the TC neuron was subject to stronger coalescing IPSPs. Simulated cortical stimulation could trigger a transition between the two modes. This transition could go in either direction and was dependent on the precise timing of the input. The transition did not always follow the stimulation immediately. A larger, multicolumnar simulation was set up to assess the role of the TC-RE pair in the context of extensive divergence and convergence. The amount of TC neuron spiking generally correlated with the strength of total inhibitory input, but large variations in the amount of spiking could be seen. Evidence for mutual oscillation could be demonstrated by comparing TC neuron firing with that in reciprocally connected RE neurons. An additional mechanism for TC neuron quiescence was assessed with the use of a cooperative model of gamma-aminobutyric acid-B (GABA(B))-mediated responses. With this model, RE neurons receiving repeated strong excitatory input produced TC neuron quiescence due to burst-duration-associated augmentation of GABA(B) current. We predict the existence of spatial inhomogeneity in apparently generalized spike-wave seizures, involving a center-surround pattern. In the center, intense cortical and RE neuron activity would be associated with TC neuron quiescence. In the surround, less intense hyperpolarization of TC neurons would allow low-threshold spikes to occur. This surround, an "epileptic penumbra," would be the forefront of the expanding epileptic wave during the process of initial seizure generalization. Therapeutically, we would then predict that agents that reduce TC neuron activity would have a greater effect on seizure onset than on ongoing spike-wave seizures or other thalamic oscillations.     

Losing consciousness: role of the venous lactate levels in the diagnosis of convulsive crises

OBJECTIVES: This prospective study was conducted to evaluate the usefulness of venous lactate assay in the diagnosis of generalized seizures. PATIENTS AND METHODS: Over a three month period, 78 consecutive adults admitted to the emergency unit for unconsciousness were included in the study. Three study groups were defined: patients with generalized seizures (n = 22), unconscious patients without seizure (n = 34) and known epileptic patients with unexplained malaises (n = 22). Patients with a disease susceptible of increasing lactate levels were excluded. Peripheral venous blood was drawn to determine lactates, bicarbonates and pH on a blood gas analyzer. All determinations were performed within 5 minutes of blood withdrawal. CPK level was also determined with an enzymatic method. RESULTS: In patients who had seizures, venous lactate levels were higher than those in patients who had no seizures: 4.3 +/- 0.5 mmol/l in generalized seizure patients versus 1.64 +/- 0.1 and 2.2 +/- 1.39 in unconscious patients without seizure and known epileptic patients with unexplained malaise respectively. The threshold lactate level of 2.5 mmol/l given by ROC curves gave a 0.97 specificity and a 0.73 sensitivity. DISCUSSION: The acidosis observed in patients with generalized seizures results from the combined effects of respiratory and metabolic acidosis. High lactate level would be a consequence of hypoxemia, per seizure rise in catecholamines, and aerobic and anaerobic metabolism in muscles during the tonic-clonic phase. In patients presenting in an unconscious state, increased lactate levels, even when determined up to 2 hours after venous blood withdrawal, could be a useful parameter for the diagnosis of epileptic seizure.     

Repair of traumatic orbital wall defects with nasal septal cartilage: report of five cases

PURPOSE: Arachnoid cysts are sometimes encountered in MRIs performed for a variety of reasons. In patients with epilepsy, particularly those with refractory epilepsy, arachnoid cysts are often assumed to be related to their seizure focus. We conducted a study to investigate this putative relationship. METHODS: A retrospective study on the incidence of arachnoid cysts was performed in patients seen in our Epilepsy Clinic who had CT or MRI scans, interictal EEGs or ictal EEGS. Locations of seizure foci in these patients were defined from clinical and electrophysiologic data. RESULTS: Seventeen of 867 patients had arachnoid cysts. Twelve patients had temporal lobe cysts and only 3 of them had temporal lobe seizures. Four patients had frontal lobe cysts and only 1 had frontal lobe seizures ipsilateral to the cyst. One patient had a cerebello-pontine angle cyst and frontal lobe seizures. Thus, clinical manifestations of seizures and EEG findings (interictal and/or ictal) indicated that the seizure focus was adjacent to the cysts in only 4 patients (23.5%). CONCLUSIONS: Our findings suggest that arachnoid cysts are often an incidental finding in patients with epilepsy and do not necessarily reflect the location of the seizure focus.     

Anticonvulsant drug effects in the direct cortical ramp-stimulation model in rats: comparison with conventional seizure models

A modified cortical ramp stimulation (CRS) model has been developed allowing repeated determinations of seizure threshold at short time intervals in individual rats without inducing postictal threshold increases. Anticonvulsant potency of the standard antiepileptic drugs carbamazepine, phenytoin, phenobarbital, valproate, diazepam and ethosuximide in the CRS model was compared with respective drug potencies in two more traditional seizure models with transcorneal stimulus application, i.e., the minimal electroshock seizure threshold (minEST) and the maximal electroshock seizure threshold (maxEST). In the CRS model, two different types of threshold were determined, the threshold for localized seizures (TLS) and the threshold for generalized seizures (TGS). When screw electrodes were implanted over the primary motor cortex, TLS was characterized by unilateral forelimb clonus, tonic abduction of contralateral forelimb, and head adversion. When ramp-shaped stimulation was continued above the TLS current, bilateral clonic forelimb seizures with loss of posture developed, which was defined as TGS. In contrast to TLS, TGS could not be repeatedly determined at short time intervals because of postictal threshold increase. TLS was dose-dependently increased by carbamazepine, phenobarbital, valproate and diazepam, although phenytoin showed a truncated dose-response, and ethosuximide was ineffective. In comparison to TLS, drug-induced increases in TGS were more marked. All drugs dose-dependently increased minEST and, except ethosuximide, maxEST. For comparison of drug potencies, doses increasing seizure thresholds by 20 or 50% were calculated from dose-response curves. Respective comparisons showed marked differences in drug potencies between models, indicating that the CRS method presents a model of another, more pharmacoresistant seizure type than seizure types induced in traditional models, such as transcorneal electroshock. Based on the location of electrodes in the frontal neocortex, the characteristic seizure pattern, and the low pharmacological sensitivity of the seizures to standard antiepileptics, the modified CRS model most likely represents a new model of localization-related seizures occurring in frontal lobe epilepsy and may thus be used in the search for novel drugs with higher efficacy against this difficult-to-treat type of epilepsy.