Prior automatic posture and activity identification improves physical activity energy expenditure prediction from hip-worn triaxial accelerometry

Accelerometry is increasingly used to quantify physical activity (PA) and related energy expenditure (EE). Linear regression models designed to derive PAEE from accelerometry-counts have shown their limits, mostly due to the lack of consideration of the nature of activities performed. Here we tested whether a model coupling an automatic activity/posture recognition (AAR) algorithm with an activity-specific count-based model, developed in 61 subjects in laboratory conditions, improved PAEE and total EE (TEE) predictions from a hip-worn triaxial-accelerometer (ActigraphGT3X+) in free-living conditions. Data from two independent subject groups of varying body mass index and age were considered: 20 subjects engaged in a 3-h urban-circuit, with activity-by-activity reference PAEE from combined heart-rate and accelerometry monitoring (Actiheart); and 56 subjects involved in a 14-day trial, with PAEE and TEE measured using the doubly-labeled water method. PAEE was estimated from accelerometry using the activity-specific model coupled to the AAR algorithm (AAR model), a simple linear model (SLM), and equations provided by the companion-software of used activity-devices (Freedson and Actiheart models). AAR-model predictions were in closer agreement with selected references than those from other count-based models, both for PAEE during the urban-circuit (RMSE = 6.19 vs 7.90 for SLM and 9.62 kJ/min for Freedson) and for EE over the 14-day trial, reaching Actiheart performances in the latter (PAEE: RMSE = 0.93 vs. 1.53 for SLM, 1.43 for Freedson, 0.91 MJ/day for Actiheart; TEE: RMSE = 1.05 vs. 1.57 for SLM, 1.70 for Freedson, 0.95 MJ/day for Actiheart). Overall, the AAR model resulted in a 43% increase of daily PAEE variance explained by accelerometry predictions.

NEW & NOTEWORTHY Although triaxial accelerometry is widely used in free-living conditions to assess the impact of physical activity energy expenditure (PAEE) on health, its precision and accuracy are often debated. Here we developed and validated an activity-specific model which, coupled with an automatic activity-recognition algorithm, improved the variance explained by the predictions from accelerometry counts by 43% of daily PAEE compared with models relying on a simple relationship between accelerometry counts and EE.

An original piecewise model for computing energy expenditure from accelerometer and heart rate signals

OBJECTIVE

Activity energy expenditure (EE) plays an important role in healthcare, therefore, accurate EE measures are required. Currently available reference EE acquisition methods, such as doubly labeled water and indirect calorimetry, are complex, expensive, uncomfortable, and/or difficult to apply on real time. To overcome these drawbacks, the goal of this paper is to propose a model for computing EE in real time (minute-by-minute) from heart rate and accelerometer signals.

APPROACH

The proposed model, which consists of an original branched model, uses heart rate signals for computing EE on moderate to vigorous physical activities and a linear combination of heart rate and counts per minute for computing EE on light to moderate physical activities. Model parameters were estimated from a given data set composed of 53 subjects performing 25 different physical activities (light-, moderate- and vigorous-intensity), and validated using leave-one-subject-out. A different database (semi-controlled in-city circuit), was used in order to validate the versatility of the proposed model. Comparisons are done versus linear and nonlinear models, which are also used for computing EE from accelerometer and/or HR signals.

MAIN RESULTS

The proposed piecewise model leads to more accurate EE estimations ([Formula: see text], [Formula: see text] and [Formula: see text] J kg^-1 min^-1 and [Formula: see text], [Formula: see text], and [Formula: see text] J kg^-1 min^-1 on each validation database).

SIGNIFICANCE

This original approach, which is more conformable and less expensive than the reference methods, allows accurate EE estimations, in real time (minute-by-minute), during a large variety of physical activities. Therefore, this model may be used on applications such as computing the time that a given subject spent on light-intensity physical activities and on moderate to vigorous physical activities (binary classification accuracy of 0.8155).

Localised impedance monitoring device for the remote clinical assessment of home-based dialysis patients

BioImpedance Spectroscopy (BIS) has been clinically used to determine the hydrational status of patients undergoing haemodialysis (HD). In the present project we are developing a calf-localised, integrated impedimetric device to periodically and conveniently measure and transmit information on the hydrational status of home-based patients to a remote clinic. Surprisingly, we have found that simple postural changes before or during measurement lead to significant fluid shifts in the lower leg that are as important and as long lasting as the effects of haemodialysis. These must be taken into account if potentially hazardous errors are not to be made in assessing a patient's hydrational status.

Personalization of a compartmental physiological model for an artificial pancreas through integration of patient's state estimation

Artificial Pancreas (AP) are developed for patients with Type 1 diabetes. This medical device system consists in the association of a subcutaneous continuous glucose monitor (CGM) providing a proxy of the patient's glycaemia and a control algorithm offering the real-time modification of the insulin delivery with an automatic command of the subcutaneous insulin pump. The most complex algorithms are based on a compartmental model of the glucoregulatory system of the patient coupled to an approach of MPC (Model-Predictive-Control) for the command. The automatic and unsupervised control of insulin regulation constitutes a major challenge in AP projects. A given model with its parameterization on the shelf will not directly represent the patient's data behavior and the personalization of the model is a prerequisite before using it in a MPC. The present paper focuses on the personalization of a compartmental showing a method where taking into account the estimation of the patient's state in addition to the parameter estimation improves the results in terms of mean quadratic error.

Wearable impedance monitoring system for dialysis patients

This paper describes the development and the validation of a prototype wearable miniaturized impedance monitoring system for remote monitoring in home-based dialysis patients. This device is intended to assess the hydration status of dialysis patients using calf impedance measurements. The system is based on the low-power AD8302 component. The impedance calibration procedure is described together with the Cole parameter estimation and the hydric volume estimation. Results are given on a test cell to validate the design and on preliminary calf measurements showing Cole parameter variations during hemodialysis.

A wireless patch for sleep respiratory disorders applications

This paper presents a conformable wireless patch and its mobile application for physical activity, spO2 and pCO2 recording associated to digital biomarkers that aim at providing the clinicians with a reliable computer-aided diagnosis tool for rapid and continuous monitoring of sleep respiratory disorders. Each part of the system is described and results are presented and discussed. The reflectance sp02 sensor has been tested in vivo on several body sites and several subjects then compared to a reference device. The electrochemical tcpO2 sensor has been validated in vitro. Based on these physiological parameters, the proposed algorithms to automatically identifying sleep respiratory events are compared to a reference index.

The epidemiology of seizure disorders in infancy and childhood: definitions and classifications

Seizures are one of the most common neurological symptoms that occur in infancy and childhood. They represent many different disorders with many different causes. Neonatal seizures occur in ~1.5% of neonates, febrile seizures in 2-4% of young children, and epilepsy in up to 1% of children and adolescents. Seizures provoked by other acute insults such as head trauma also occur although their precise frequency in children is hard to estimate. Ultimately, seizures are symptoms of various neurological insults and conditions. Although neonatal seizures, febrile seizures, and epilepsy overlap to a degree in that children with neonatal or febrile seizures are at increased risk of epilepsy, these different disorders have somewhat different risk factors and their own epidemiology. Furthermore, to the extent that environmental (e.g., infections, malnutrition) and medical system factors (vaccinations, prenatal care) and population genetics play roles, very different risks and patterns are seen in different areas of the world. Within each of these sets of disorders, designated as neonatal or febrile seizures and epilepsy, there are many highly specific conditions that, especially in the case of epilepsy, may have considerable implications for treatment and prognosis and consequently may require care from a specialist.

Arrhythmogenic seizures

Arrhythmogenic seizures may represent one of the mechanisms implicated in sudden unexpected death in epilepsy. Various cardiac changes can be observed during epileptic seizures. However, reports of well-documented, life-threatening cardiac arrhythmias in the literature are scarce. The pathogenesis of these arrhythmias and speculations about the cortical localization of cardioarrhythmogenic triggers are reviewed.

Psychiatric comorbidity in patients evaluated for chronic epilepsy: a differential role of the right hemisphere?

INTRODUCTION

Psychiatric disorders are known to occur frequently in chronic epilepsy. The aim of this study is to investigate the prevalence of psychiatric comorbidity and its relationship to regional cerebral dysfunction in patients admitted to a tertiary epilepsy center for epilepsy surgery.

METHODS

217 patients were investigated. A presurgical workup was performed and allowed precise localization of the epileptogenic focus in 156 patients. Sixty-one patients had multifocal or generalized discharges. After 1-3 psychiatric interviews, a psychiatric diagnosis was made (DSM-IV classification).

RESULTS

Psychiatric comorbidity was found in 85 patients (39%), more often in those with right or bilateral hemispheric dysfunction (74%, p = 0.04) with no difference between temporal or extratemporal foci location frequency. Additionally, patients with psychiatric disorders were less likely to undergo epilepsy surgery compared to 'epilepsy-only' patients (p = 0.003), despite similar good outcome in patients with and without psychiatric comorbidity.

CONCLUSIONS

Right-sided or bilateral foci seem to represent a risk factor for psychiatric comorbidity in epilepsy, although we did not find any particular association between a psychiatric syndrome and focus localization. Recognition and treatment of psychiatric comorbidity is of major importance since its presence may interfere with patient's decision making for epilepsy surgery treatment.

Mortality of epilepsy in developing countries

During the last two decades, there has been a renewed interest in studying epidemiology of epilepsy in developing countries. While there are data on prevalence of epilepsy from many developing countries, there is very little information on the mortality of epilepsy in these same populations. This is because incidence studies of epilepsy are difficult to perform, death certificates are unreliable and often unavailable, and the cause of death is difficult to determine. We report on several studies of mortality in epilepsy in developing countries: Ecuador; the Parsi community of Bombay; a semiurban community in Vasai, India; Mali; Martinique; and Africa. Overall, these studies in general illustrate excess mortality among people with epilepsy when compared with the general population.

[Current epilepsy treatment in adults]

The prevalence of epilepsy is about 1%. Only two thirds of these patients respond satisfactorily to an antiepileptic drug (AED) treatment. New AED did not clearly improve this overall efficacy, but often show a better tolerability as compared to old AED. This may allow a more targeted choice, especially in some delicate clinical situations, such as for the treatment of women in childbearing age, or patients receiving other drugs with possible pharmacokinetic interactions. Invasive approaches should be considered early in the course of treatment-resistant epilepsy, and may offer a complete seizure remission in selected cases. On the background of recent acquisitions from the literature, the pros and cons of different treatment options are presented. This is followed by the discussion of some clinical relevant situations.

[Epidemiology of drug-resistant epilepsies]

BACKGROUND

To evaluate the incidence and the prevalence of drug-resistant epilepsies and risk factors in relation with this condition.

METHODS

The epidemiological approach of drug-resistant epilepsies come up against two major difficulties: the lack of a rigorous and consensus definition of this condition and its elusive evaluation which is indirectly appreciated with many studies concerning the remission of seizures in heterogeneous population of patients with or without treatment.

RESULTS

The majority of papers on this topic report a hard core of 20 p. 100 of patients who continue to have seizures under treatment. This percentage has to be discussed because many factors can influence the exact number of patients with refractory epilepsy: the age of the first seizure, the seizure type, the cause of the seizures, the effective therapeutic interventions. This percentage did not seem to have been modified since the use of "new" anti-epileptic drugs and the development of epilepsy surgery. The main problem is to appreciate when refractoriness is really present and how long does it takes to declare that this condition has a self-perpetuating progression. Thank to the data from an abundant literature we can put forward that nearly 10 p. 100 of the incident cases could become refractory and that 1 to 2 /1 000 persons are drug resistant epilepsies, of which partial epilepsies represent 60 p. 100 of the cases. This rate allows to think that in France 5 000 to 12 000 patients may require a surgical evaluation and that annual need for surgery would be 500 patients per year.

CONCLUSIONS

Data on drug-resistant epilepsies in France are lacking and it seems essential to put in place in our country a population-based incidence study including the risk factors of intractability in order to confirm these epidemiological data. The results of such a study would help to convince the political authorities to encourage the development of surgical structures.

EEG-mediated diagnosis of an unusual presentation of SSPE

OBJECTIVE

To highlight the role of EEG in the diagnosis of SSPE.

METHODS

EEG was performed in an 18 month old girl who had a 1 week history of repeated episodes of sudden flexion of the head and trunk and frequent falls.

RESULTS

EEG abnormalities consisted of stereotyped, generalized and synchronous high amplitude periodic complexes. These abnormalities correlated with brief episodes of axial and upper limb atonia on electromyogram examination. They persisted during sleep although abnormal movements disappeared. Biological results and cerebral MRI confirmed the diagnosis of subacute sclerosing panencephalitis.

CONCLUSIONS

This case is exceptional because of the age of the patient, the clinical presentation and the mode of contamination and it highlights the role of EEG in this diagnosis.

[Acute repetitive giratory seizures as a manifestation of nonketotic hyperglycemia]

This 71 years old women without any history of epilepsy had diabetes mellitus. She was admitted for repetitive giratory seizures in relation with non-ketotic hyperglycaemia. The EEG showed right centro-parietal paroxysmal slow activity. Symptomatology disappeared within 48 hours after insulin therapy. One month later, she presented with a left hemiplegia in relation with a right sylvian infraction. The role of focal transitory ischaemia in connection with hyperglycaemia is discussed.

Bodyweight gain and anticonvulsants: a comparative review

Bodyweight gain is a common and frequent undesirable effect associated with the use of anticonvulsant drugs. This has been observed for many years with valproic acid (sodium valproate) and carbamazepine, and also, more recently, with some of the newer anticonvulsants such as vigabatrin and gabapentin. Very often bodyweight gain in children, adolescents and adults with epilepsy taking such anticonvulsants results in cosmetic adverse effects. On the other hand, bodyweight gain is disturbing to general health, with a possible increase in the risk of diabetes mellitus or heart disease. Other potential adverse effects, such as the association of obesity with polycystic ovaries, have been reported with the use of valproic acid. Potential mechanisms of anticonvulsant-associated bodyweight gain are not yet clear and differ between drugs used. The involvement of lowered blood glucose level, which may stimulate eating through an effect on the hypothalamus, constitutes one of the possible mechanisms. Lowered blood glucose levels may result from a competition between the binding of the drug and long chain fatty acids. An increased availability of the latter stimulates insulin production and lowers the serum glucose levels. Another possible explanation for lowered blood glucose may be a deficiency in carnitine directly caused by the drug, that would result in a reduction of fatty acid metabolism and an increase in glucose consumption. An enhancing effect of gamma-aminobutyric acid-mediated neurotransmission may increase appetite for carbohydrates and reduce energy expenditure. An antidiuretic hormone-like effect or effects on norepinephrine (noradrenaline) or serotonin-mediated neurotransmission are more rarely considered. Many studies on anticonvulsant-associated bodyweight gain illustrate how we could better define the risk factors for the development of anticonvulsant-induced bodyweight gain and uncover the mechanisms behind it.

Symptomatic postictal cardiac asystole in a young patient with partial seizures

This report describes a patient with complex partial seizures arising from the right temporal lobe who developed symptomatic sinus arrest following the end of his seizure activity. A ventricular pacemaker was implanted and was documented to function appropriately, preventing development of bradycardia associated symptoms during subsequent seizures. Possibly relevant cerebral structures are briefly discussed.

SPECT in periodic lateralized epileptiform discharges (PLEDs): a form of partial status epilepticus?

Periodic lateralized epileptiform discharges (PLEDs) are a well defined electroencephalographic entity but whether PLEDs represent an ictal condition or not remains debated. Much work has been done using electroencephalography (EEG) but new approaches using cerebral perfusion imaging may give more information about this question. We aimed to evaluate if PLEDs were associated with high regional cerebral blood flow (rCBF). We studied 18 patients with PLEDs and different pathologies, and performed brain single-photon-emission computed tomography (SPECT) during and, for three cases, after the disappearance of PLEDs. Qualitative variations and locations of rCBF were compared with PLEDs. Association with seizures and type of seizures were also assessed. SPECT showed high rCBF in 18/18 patients (100%). The location of PLEDs and high rCBF matched in 17/18 cases (94%). In the three cases where SPECT was performed after PLEDs disappeared, the high rCBF had cleared (100%). Eighteen cases (100%) presented seizures before recording of PLEDs, mainly motor (partial motor or generalized tonic-clonic). Where there was a decreased rCBF (related to a lesion) there was little relationship to PLEDs and all patients with decreased rCBF had an adjacent increased rCBF. These results confirm preliminary case reports. Hyperperfusion adds further to the argument that PLEDs may be related to a form of partial status epilepticus.

Newly diagnosed unprovoked epileptic seizures: presentation at diagnosis in CAROLE study. Coordination Active du Réseau Observatoire Longitudinal de l' Epilepsie

PURPOSE

We describe first unprovoked seizures and newly diagnosed epilepsies at initial presentation, with a special emphasis on epilepsy syndromes, in a large cohort recruited in the mid-1990s in France.

METHODS

The French Foundation for Research on Epilepsy set up a network to conduct a prospective study of patients with newly diagnosed unprovoked seizures. Information was provided by 243 child or adult neurologists. Four neurologists classified each case according to the International League Against Epilepsy (ILAE) criteria. First-seizure patients and patients with previously undiagnosed seizures were compared.

RESULTS

Between May 1, 1995, and June 30, 1996, 1,942 patients aged from 1 month to 95 years were identified: 926 (47.7%) with a single seizure and 1,016 (52.3%) with newly diagnosed epilepsy. All but 17 patients had EEGs. In the first-seizure and newly-diagnosed-epilepsy groups, neuroimaging studies were performed in 78.2 and 68.3% of patients, and medication prescribed in 54.1 and 89.6%, respectively. There were significant differences between the two groups with respect to age at onset and diagnosis, sex, etiology, several specific syndromes, as well as the type and presentation of initial seizure. In patients for whom the first seizure was convulsive, only sex, multiple seizures in a day or status epilepticus, and cryptogenic localization-related syndrome differed between the two groups.

CONCLUSIONS

Approximately half of patients who first came to attention for an unprovoked seizure already met epidemiologic criteria for epilepsy. There were significant differences between the types of patients with a first seizure and those with newly diagnosed epilepsy. One or several seizures at diagnosis did not influence the diagnostic assessment of the patients but had a strong influence on the initiation of treatment.

Severe but reversible encephalopathy associated with cefepime

In this study, a report has been made of 19 cases of severe encephalopathy in patients with renal impairment who were treated during the last three years for various infections with cefepime, a new parenteral cephalosporin antibiotic. All patients (aged 57 to 91 years) presented a prolonged confusional state associated with diffuse rhythmic non-reactive triphasic sharp waves on the EEG. All the electroclinical symptomatology disappeared within 24-48 hours after discontinuation of drug administration. A clear relation was found between encephalopathy and cefepime intake. These observations underline the fact that the cefepime dosage should be reduced in renally impaired patients.

Incidence of status epilepticus in French-speaking Switzerland: (EPISTAR)

BACKGROUND

To determine the incidence, risk factors, and case fatality rate of status epilepticus (SE) in the French-speaking part of Switzerland.

METHODS

Between October 1, 1997 and September 30, 1998 all cases of SE referred to all the hospitals in the six cantons of the French-speaking part of Switzerland were identified by physicians working in emergency rooms, intensive care units, and electroencephalography departments; neurologists; and pediatricians from all hospitals in the area. Each case was validated and classified according to seizure type and etiology.

RESULTS

Over 1 year, 172 cases were identified, of whom 74 had a history of epilepsy (42.4%). The crude and standardized annual incidence rate were 9.9/100,000 (95% CI, 8.4 to 11.4) and 10.3/100,000 (95% CI, 8.7 to 11.9). The incidence rate was higher among children < 1 year of age and adults > 65 years, and among men than women. There were 108 cases of acute symptomatic SE (incidence: 6.2 per 1000), 49 cases of remote symptomatic SE, and 15 cases of unknown etiology. Case fatality rate was 7.6%.

CONCLUSIONS

The standardized incidence rate of SE in the French-speaking part of Switzerland was lower than that reported in Rochester, MN (18.3/100,000) and in the white population of Richmond, VA (20/100,000). The discrepancy may stem from the lack of a homogeneous, rigorous, and pragmatic definition of SE and the efficient management of acute repetitive seizures in this area.

Left temporal rhythmic electrical activity: a correlate for psychosis? A case report

It is well recognized that epileptic patients are at higher risk for acute or chronic psychotic states than non-epileptic subjects. Here we present intracranial depth electrode recordings during a psychotic episode in a 20-year-old woman who was referred for presurgical evaluation. Unrelated to her seizures, she presented acoustic hallucinations and delusions and became agitated for a duration of 18-24 hours. During this period, a new unusual pattern of sharp slow waves was seen semi-rhythmically every 2-3 sec from left anterior neocortical temporal areas. Her condition responded well to a treatment with Haloperidol, but not with Benzodiazepines. Ictal and interictal scalp- and depth-EEG recordings outside the psychotic episode as well as MRI-based volumetry, PET, SPECT and neuropsychological testing gave evidence of bilateral temporal and frontal dysfunction. This case report suggests that psychosis in epileptic patients may be based on a bilateral cerebral dysfunction linked together in a pathological network, but with a focal (here: left temporal) driving mechanism.

[Drug resistant status epilepticus]

Refractory epileptic state (RES) is defined by severe seizures that are resistant to antiepileptic drug treatment. Diagnostic errors such as pseudo-seizures and encephalopathies with triphasic waves must be distinguished at an early stage from cases of RES. The latter are symptomatic of a focal brain lesion or severe systemic disease, most frequently metabolic in origin. The treatment of such conditions is aimed at correction of the underlying cause. A nosographic issue that is still a subject of discussion and which requires further study, i.e., PLEDS, will also be discussed in this article.

Encephalopathy with epileptic spasms resolved with corticoids in a 69 year-old patient

A 69 year-old man with a history of recent temporal lobe seizures, presented with progressive coma and frequent epileptic spasms. Ictal EEG, PET and SPECT alterations were strikingly similar to those described in infantile spasms. Conventional antiepileptic drugs were ineffective but the introduction of corticoids induced a dramatic improvement with disappearance of the spasms. The etiology remains unknown. Epileptic spasms may occur in the elderly. If conventional antiepileptic drugs are ineffective, corticoids should be tried immediately.

Distinct behavioral and EEG topographic correlates of loss of consciousness in absences

PURPOSE

To describe the behavioral and EEG topographic correlates of absences with 3-Hz generalized spike-waves and partitioned impairment of consciousness.

METHODS

Two adult women had so-called "phantom" absences, characterized by brief and mild impairments of consciousness that were previously inconspicuous to both patient and physician. Neuropsychological examination was performed under video-EEG monitoring during absence status. EEG topographic mapping of spike-wave discharges was obtained in the two cases.

RESULTS

Only mild attentional and executive disturbances were observed during absence status despite prolonged discharges. Spike-wave bursts were associated with selective impairment in the initiation of response and self-generated action, whereas short-term storage of external information during discharges was fully preserved. This is consistent with a predominant involvement of frontomesial cortex demonstrated by topographic mapping of spike-wave discharges in the two cases. By contrast, in two other patients with typical absences and a complete lack of retention for information given during the discharges, topographic mapping found a more lateral frontal involvement by spike-wave activity.

CONCLUSIONS

Different types of absence seizures may impair distinct components of conscious behavior. A predominant involvement of frontomesial thalamocortical circuitry may underlie an "inconspicuous" disorder of consciousness as seen in phantom absences with selective loss of initiation and goal-oriented behavior, whereas involvement of more lateral frontal areas in typical absences may additionally disrupt working memory processes.

[The difficulty of defining and classifying status epilepticus]

Status epilepticus (SE) can theoretically be described using a simple definition based on physiopathological mechanisms: any seizure of epileptic nature, partial or generalized, convulsive or non-convulsive, lasting over a period of more than 30 minutes; or repeated seizures lasting for a period of over 30 minutes without recovery of consciousness. In the context of a historical review of various definitions, the validity of this definition is assessed and questioned. The heterogeneous nature of this condition is evidenced in daily clinical practice and by the results of epidemiologic studies. In the present study, the authors propose a more pragmatic and heuristic classification, taking into account not only clinical but also electroencephalographic data, as well as the particular nature of the epileptic syndrome when this is known.

Clinical correlates and prognosis in early spindle coma

OBJECTIVE

To determine the prognostic significance of spindle coma (SC) according to etiology and EEG reactivity.

METHODS

We reviewed 15 patients with SC due to various causes within 8 days of coma to determine the prognostic significance of this EEG pattern.

RESULTS

The outcome among survivors was favorable: among 13 survivors, 9 were independent in all activities of daily living (ADLs) at 6 months; 3 were dependent in all ADLs; and one remained in coma. EEG reactivity to noxious stimuli best predicted outcome: All patients (whatever the coma etiology) with EEG reactivity survived; conversely, not all patients without EEG reactivity died.

CONCLUSION

In our patients, EEG reactivity independent of etiology predicted survival, neurological examination did not predict outcome. Most SC survivors had a meaningful recovery achieving all ADLs. From the literature, the cause of SC was predictive of outcome: encephalopathy, seizures and trauma had the best prognosis while hypoxia, CRA and structural lesions carried the worst. Literature review revealed that 23% of patients [56/242] died or remained in a persistent vegetative state (PVS). Best outcomes occurred when SC was due to drugs, encephalopathy or seizures: (0/14 died or were in a PVS). With trauma 15% [25/169] died or were in a PVS). Intermediate outcomes occurred with hypoxia and cardio-respiratory arrest (CRA): 33% [7/21] died or were in a PVS. The gravest outcomes occurred with brain-stem and cerebral infarctions, and tumors: 73% [22/30] died or were in a PVS.

The contributing factors to medical cost of epilepsy: an estimation based on a French prospective cohort study of patients with newly diagnosed epileptic seizures (the CAROLE study). Active Coordination of the Longitudinal Observational Network in Epilepsy

Epilepsy is a common neurological condition with significant resource implications. An estimation was performed in France of the direct medical cost of patients presented with newly diagnosed seizures and followed during the first two years after diagnosis. This estimation was based on the service utilization data collected from French prospective cohort study (CAROLE: 1942 patients enrolled). Costs were estimated in a societal perspective in 1998 value. The impact on the costs of different factors like age, aetiologic categorization and severity of seizures (type and number of seizures), and treatment by anti-epileptic drugs (AEDs) was analysed. The mean annual direct epilepsy-related costs per patient were estimated to be 14 305 F and 3766 F for the first and the second year of follow-up respectively, 68% and 40% of the costs were devoted to inpatient care. Costs during the first year were highly sensitive to aetiologic categorization of seizures at inclusion and to other clinical parameters. Second-year costs had a much lower variance and were sensitive to frequency of seizures and the fact of being treated or not by AEDs. Our data emphasize the importance of seizure control as means of reducing the costs of epilepsy especially during the first year of follow-up.

Non convulsive status epilepticus following intrathecal fluorescein injection

We report a case of non convulsive status epilepticus after an intrathecal injection of fluorescein. The clinical presentation was a confusional state--the epileptic origin of which was confirmed by the electroencephalogram. This rare and relatively benign complication should not bring about worry concerning the fluorescein test used for the diagnosis of a dural defect and the identification of the site of a CSF leak.

EPIMART: prospective incidence study of epileptic seizures in newly referred patients in a French Carribean island (Martinique)

PURPOSE

To identify, in the population living in the island of Martinique, persons who had their first epileptic seizure or first came to medical attention because of an epileptic seizure.

METHODS

Between May 1, 1994, and April 30, 1995, we collected all suspected cases of provoked and unprovoked epileptic seizures admitted to the hospitals or addressed to the private neurologists or pediatricians of the island.

RESULTS

Three hundred nine cases were collected. Rate of initial diagnosis of provoked and nonprovoked seizures (standardized to the U.S. population): 77.7/100,000, with a bimodal distribution of the cases with age (86 in 0- to 10-year age group and 203 in patients older than 60 years). Sixty-three cases were classified as provoked seizures (incidence, 16.4/100,000). Alcohol consumption, stroke, and cranial trauma were the most frequent causes (30.1, 20.6, and 18.7%, respectively). Two hundred forty-six cases were classified as unprovoked seizures (incidence, 64.1): seizures with a stable condition, 74 cases (I, 19.3); seizures with an evolutive condition, 17 cases (I, 4.5); seizures of unknown etiology, 155 cases (I, 40.4). These figures must be considered as the minimal rate.

CONCLUSIONS

The global incidence rate of newly referred persons with a diagnosis of epileptic seizures in this study is clearly higher than those observed in industrialized countries but lower than those in developing countries. The major risk factors are represented by alcohol consumption, followed by stroke, cranial trauma, and infectious diseases.

[Sudden death of epileptic patients]

DEFINITION

Sudden unexpected death in an epileptic patient which no likely cause--head trauma, drowning, grand mal, bronchial aspiration, suffocation--and no anatomic or toxicologic condition which could clearly explain the death. A seizure reported by witnesses or suspected from clinical signs observed prior to death and compatible with the definition raises the problematic of the relationship with sudden death.

INCIDENCE AND RISK FACTORS

Sudden death is estimated to occur in 1 out of 450 to 2000 epileptic patients, giving an annual incidence of 0.55 to 9.3 per 1000 patients. Such a wide incidence range can be explained by the difficulties in providing a rigorous definition of sudden death and more importantly by the heterogeneous nature of the population at risk. The risk of sudden death is clearly related to the severity of the epilepsy. It is observed in young adults with symptomatic, often difficult to treat epilepsy. Death is frequently observed during sleep.

PATHOPHYSIOLOGICAL HYPOTHESES

The circumstances of sudden death in the epileptic patient illustrate the complex relationships existing between seizures and irreversible cardiorespiratory dysfunction. Neurogenic lung edema is frequently observed at autopsy and has been confirmed by experimental data. Experimental work and clinical observations would suggest that central apnea, associated with cardiac dysrhythmia could be involved. Other risk factors, including sleep, compliance to treatment, arrhythmogenic effect of certain antiepileptics and the consequences of repeated seizures on the myocardium may also play a role.

Etiology, neurologic correlations, and prognosis in alpha coma

OBJECTIVE

To determine the factors affecting prognosis in alpha coma (AC).

METHODS

Retrospective review of 36 study patients, 36 control coma patients matched for age and etiology, and meta-analysis of 335 cases in the world literature.

RESULTS

Principal causes were cardiorespiratory arrest (CRA) (21 patients); infection, metabolic dysfunction, head trauma (3 each); and drugs, stroke and hypoxia (2 each). Outcome was predicated by EEG reactivity to noxious stimuli. Fourteen of the 15 patients with reactive EEGs, had measurable outcome, 8 awoke - all but two had etiologies other than CRA. Fourteen of 19 patients without EEG reactivity died; two had support discontinued and 3 awoke. Following CRA, 16/21 patients died and 3 had support discontinued. Only 3 patients made a good recovery - all with toxic or metabolic etiologies. Literature meta-analysis of 335 cases showed that overall, AC carried a poor prognosis (76% died). CRA (226 cases) had an 88% mortality; strokes (29 cases), a 90% mortality; hypoxia without cardiac arrest (28 cases), a 61% mortality; drug-induced AC (25 cases), an 8% mortality.

CONCLUSIONS

Although the cause of AC largely predicts outcome, EEG reactivity in AC predicted survival: most patients with reactivity awoke; most of those without, died. Few survivors had meaningful recovery.

Semantically-triggered reading epilepsy: an experimental case study

Primary reading epilepsy (PRE) is a rare syndrome in which epileptic seizures are electively provoked by reading. Cognitive neuropsychology has demonstrated the existence of at least two pathways for reading, the sublexical pathway involved in converting graphemes to phonemes, and the lexical pathway used when meaning is conveyed. Which of these specific pathways is relevant in triggering epileptic discharges remains largely unknown. We report the case of a patient suffering from PRE in which the two routes were distinguished on the basis of the reading material employed. Significantly less epileptic discharges were observed when the patient read non-words than words. In view of our findings, we tentatively contrast a lexical form of PRE, triggered by the activation of semantic knowledge structures, with a sublexical form, triggered by non-word reading. Evidence from the literature suggests that the former is characterized by bilateral EEG activating patterns, whereas the latter involves preferentially the left hemisphere.

Idiopathic generalized epilepsy of late onset

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.

[Monotherapy and polytherapy use of anti-epileptic drugs. Development of views]

The evolution of our approach to the treatment of epilepsy has occurred in three stages: at the turn of the century, when epilepsy was increasingly entering into the mainstream of Neurology, pharmacotherapy of epilepsy was limited to the bromides. Subsequently, phenobarbital used in 1912 and then phenytoin, discovered in 1932, remained, for many years, the only therapeutic options. To increase the chances of complete suppression of seizures, it appeared logical to use both medications together. This approach was used for many years despite the advent of carbamazepine and sodium valproate. In 1976, the first studies appeared indicating the advantages of using monotherapy from the start. Not only did this approach show itself to be effective, but there was a marked decrease in the incidence of side-effects engendered by polytherapy. Nevertheless, despite o carefully instituted monotherapy, between 20 and 30 p. cent of patients still had seizures refractory to treatment. A new era in antiepileptic drug development has created new hope in the management of epilepsy. Based on a better understanding of the disease process and scientific development in molecular biology, we are able to provide a more rational polypharmacy, taking into account their pharmacodynamic interactions and their relatively high cost.

[Epileptic seizures, epilepsy and risk factors. Experiences with an investigation in Martinique. Epimart Group]

A prospective incidence study was carried out in the French Caribbean island of Martinique between May 1st 1994 and April 31st 1995. incidence was 80.6 (77.7 when standardized with 1990 U.S. population). This incidence was higher than that observed in the Swiss canton of Geneva where the same methodology was used. The individualized risk factors of first provoked and unprovoked seizures in Martinique were alcoholism, head trauma and cerebro-vascular accidents.

The problem of intractability: the continuing need for new medical therapies in epilepsy

Treatment of epilepsy, one of the most common neurologic disorders, has evolved from "institutional" polytherapy to "dogmatic" monotherapy, and, most recently, to "rational" polypharmacy. The introduction of bromides for the treatment of epilepsy was followed first by phenobarbital and then by phenytoin as therapeutic options. Although attempts to combine medications were legion, none was supported by studies that demonstrated the benefit of such combinations. The issue of adverse effects became a principal argument in favor of monotherapy. Monotherapy, using newly developed drugs, avoided problems due to drug interactions but was ineffective in 20-30% of patients. A greater understanding of basic disease mechanisms and developments in molecular biology have led to an increased number of effective drugs for the estimated 6-12% of patients with epilepsy whose condition is intractable. Clinical research continues to build on the work of basic scientists in attempting to develop treatments based on a desire to move beyond the palliative and to affect the causative mechanisms of the disease. Novel medical approaches now under exploration include the use of drugs with complementary mechanisms of action, stimulation of various components of the nervous system, biochemical manipulations, focal intracerebral drug perfusion, and gene therapy.

[Epilepsy and psychiatric disorders: epidemiological data]

Data about psychiatric disorders associated with epilepsy as well as their risk factors are heterogeneous. The overall prevalence of psychiatric disturbances in epileptic patients can be estimated between 20 and 30 per cent. It is the highest in pharmocoresistant cases seen in specialized centers. Psychotic disorders, depression, and suicide are the three most common among interictal disturbances. Psychoses affect 2 to 9 per cent of patients and are more frequent in cases with aura or altered consciousness, such as in complex partial seizures and absences. They correlate positively with the multiplicity of seizures but often inversely with their frequency. Temporal lobe epilepsy is associated with schizo phrenic-like and paranoid types of psychosis, but frontal lobe epilepsy is also common. A putative association with predominant left or bilateral EEG abnormalities in cases with partial epilepsy remains to be confirmed, as well as the frequency of underlying structural lesions. Depressive disorders affect 20 to 60 per cent of patients. While their occurrence with partial complex seizures and left hemisphere foci is common, the role of temporal lobe involvement still appears controversial. Depression prevails in cases with seizures that occasionally, albeit rarely, secondarily generalize and correlates with the duration of the disease, intractable seizures, and polypharmacy. A genetic factor is likely to play a role. Suicides rates are increased, encountered in 0.2-0.5 per cent of patients and causing deaths in 3-7 per cent of them. The overall risk might be the highest during the first years after diagnosis of epilepsy, as well as in patients with temporal lobe foci, depression, or psychosis. Great variability and discordance in results show the major difficulties encountered in epidemiologic studies. Most of these problems relate to the classification of epileptic disorders as well as that of psychiatric disorders, the variability in the methods and measures which are used, and frequent bias in the selection of patients. We review here data about the frequency of major psychiatric disorders in epileptic patients or the frequency of epileptic disorders in psychiatric patients, and also possible risk factors related to the epileptic disease and its evolution.

[Effect of antiretroviral treatment on early electroencephalographic and otoneurologic manifestations in HIV infection and prognostic importance of verified perturbations]

Electrophysiologic tests may be abnormal in asymptomatic HIV-1-infected individuals. Our study was aimed at determining whether these findings have a prognostic value and could be corrected by antiviral treatment. In 18 patients, followed for 34 or 43 months, these findings were not progressive. Only one patient developed Aids dementia complex (ADC). Three have died (one with normal, two with abnormal tests at baseline). To study the effect of antiviral treatment, another group of seven asymptomatic patients was included into a cross-over double-blind study with either eight weeks zidovudine or eight weeks placebo, separated by eight more weeks without treatment. Electrophysiological evaluation was also performed in a group of 15 patients before antiviral therapy with zidovudine or didanosine was started and again after a mean of three and 13 months treatment. Results did not suggest that treatment reverses early electroencephalographic and otoneurological changes seen in HIV-1 infection.