LA CONSULTA SEMANAL

 

DICIEMBRE 2000

 

 

CONSULTA

Etiología de convulsiones

 

Am Fam Physician 2000 Sep 1;62(5):1109-16 [Texto completo]
A practical approach to uncomplicated seizures in children.
McAbee GN, Wark JE
University of Medicine and Dentistry of New Jersey, Stratford, USA.
Uncomplicated seizures and epilepsy are common in infants and children. Family physicians should be aware of certain epilepsy syndromes that occur in children, such as febrile seizures, benign focal epilepsy of childhood, complex partial epilepsy, juvenile myoclonic epilepsy and video game-related epilepsy. Not all uncomplicated childhood seizures require neuroimaging or treatment. Febrile seizures, rolandic seizures and video game-related seizures are childhood epileptic syndromes that are typically not associated with brain structural lesions on computed tomography or magnetic resonance imaging, and are often not treated with anticonvulsant drugs. Juvenile myoclonic epilepsy does not require neuroimaging but does require treatment because of a high rate of recurrent seizures. Complex partial epilepsy often requires both neuroimaging and treatment. Although seizures are diagnosed primarily on clinical grounds, all children with a possible seizure (except febrile seizures) should have an electroencephalogram. Interictal EEGs may be normal. Computed tomography has demonstrated abnormalities in 7 to 19 percent of children with new-onset seizures. The yield of magnetic resonance imaging for specific childhood seizure types is not known, but it is the preferred modality of neuroimaging for many clinical presentations. Most children's seizures treated with anticonvulsants are controlled by the first drug selected. The value of "therapeutic' serum drug levels is questionable in the management of uncomplicated childhood seizures.

Publication Types:
  Review
  Review, tutorial


Rev Neurol 2000 Jun;30 Suppl 1:S85-9 [Texto completo]
[Reflex epilepsies].
[Article in Spanish]
Salas-Puig J, Mateos V, Amorin M, Calleja S, Jimenez L
Servicio de Neurologia, Hospital General de Asturias, Oviedo, Espana.jsalasp@meditex.es
INTRODUCTION: Reflex seizures are provoked by a specific sensory stimulus. Approximately 6% of all epileptic patients have reflex seizures. For identification of these seizures it is necessary to take a directed history and make an EEG study whilst the patient is being exposed to the stimulus, which will confirm the diagnosis. DEVELOPMENT: Many stimuli are effective in provoking reflex seizures, the commonest are visual. Amongst the various epileptic syndromes there are different types of epilepsies with reflex seizures which generally correspond to idiopathic generalized epilepsies. The physiopathogenic mechanisms are usually complex. The cerebral cortex corresponding to the function which induces the epileptic crisis is hyperexcitable, and is the cause of an identifiable lesion or dysfunction without an underlying lesion. CONCLUSION: The diagnostic importance of reflex seizures is that when some formerly drug-resistant patients can control the mechanism which triggers off their seizures they attain good control of them.
Publication Types:
  Review
  Review, tutorial


Rev Neurol 2000 Jun;30 Suppl 1:S81-4 [Texto completo]
[Photogenic epilepsy].
[Article in Spanish]
Salas-Puig J, Parra J, Fernandez-Torre JL
Servicio de Neurologia, Hospital General de Asturias, Oviedo, Espana.jsalasp@meditex.es
INTRODUCTION: The commonest reflex seizures are those induced by visual stimuli, and amongst these, those provoked by intermittent luminous stimulus. DEVELOPMENT: A directed anamnesis and suitable intermittent light stimulation are important during electroencephalographic studies for the confirmation of the diagnosis of photosensitive epilepsy. The photogenic epilepsies, that is those in which all the epileptic seizures are provoked by visual stimuli, form a small group of epilepsies within the idiopathic generalized epilepsies with their onset during adolescence. These seizures have had great social impact, since media diffusion of the possibility of their appearance whilst watching television or playing video games. CONCLUSION: The correct diagnosis and preventive measures, together with the correct anti-epileptic treatment are in favour of a good prognosis in the great majority of patients.
Publication Types:
  Review
  Review, tutorial


Rev Neurol 2000 Jun;30 Suppl 1:S42-6 [Texto completo]
[Clinical aspects of epileptic ion channel disorders].
[Article in Spanish]
Campos-Castello J, Canelon de Lopez M, Garcia-Fernandez M
Servicio de Neuropediatria, Hospital Clinico Universitario San Carlos, Madrid, Espana. jcampos@hcsc.insalud.es
OBJECTIVE: One of the recent findings in the investigation of epileptogenesis is the localization of new gene situses and mutations of the ion channels. The pathology of these ion channel disorders is responsible for a considerable number of disorders affecting the central nervous and musculoskeletal systems. Their clinical expression is often paroxystic. Mutations cause inactivation of the channel, which depending of the degree, conditions the phenotype of the disorder. DEVELOPMENT: We studied the main ion channel disorders related to simply inherited idiopathic epileptic syndromes in which four genes have been codified to date: benign familial neonatal convulsions, generalized epilepsy with febrile seizures plus and autosomal dominant nocturnal frontal lobe epilepsy. CONCLUSIONS: The ion channels, both voltage dependent and receptor channels, are involved in the genesis of idiopathic epileptics syndromes. Their importance is due to their contribution to the understanding of epileptogenesis and its application to the investigation of drugs which modify the initial cause of the seizure. At present, it may be affirmed that the idiopathic epilepsies, or at least some of them, seem to form a family of ion channel disorders.
Publication Types:
  Review
  Review, tutorial


Rev Neurol 2000 Jun;30 Suppl 1:S25-41 [Texto completo]
[Ion channels and epilepsy].
[Article in Spanish]
Armijo JA, de las Cuevas I, Adin J
Servicio de Farmacologia Clinica, Hospital Universitario Marques de Valdecilla, Universidad de Cantabria, Santander, Espana. facasj@humv.es
OBJECTIVE: We review the role of ligand-gated ion channels and voltage-gated ion channels as a substrate for the epileptogenesis and as targets in the development of new antiepileptic drugs. DEVELOPMENT: Voltage-gated calcium channels are involved in the release of neurotransmitters, in the sustained depolarization-phase of paroxysmal depolarisation shifts (PDS), and in the generation of absences; they are also the genetic substrate of generalized tonic-clonic convulsions and absence-like pattern seen in some mice. The voltage-gated potassium channel has been implicated in the hyperpolarization-phase of PDS, it is the genetic substrate of the long QT syndrome, benign neonatal epilepsy, and episodic ataxia/myokymia syndrome, and it is the target of some antiepileptic drugs which activate this channel. The voltage-gated sodium channel is the target of most of the classical and newer antiepileptic drugs; it is also the substrate for generalized epilepsy with febrile seizures plus. The sodium channel of the nicotinic acetylcholine receptor is the substrate for nocturnal frontal lobe epilepsy. The sodium channels of the AMPA and KA glutamate receptors have been proposed as substrate for juvenile absence epilepsy and are a target for new antiepileptic drugs which inhibit it. The calcium channel of the NMDA glutamate receptor has been implicated in the sustained depolarization-phase of PDS and in epileptogenesis after kindling and is a main target for new antiglutamate drugs. The chloride channel of the GABAA receptor is responsible for the rapid hyperpolarization of PDS, it has been involved in epileptogenesis after kindling, it may be the substrate of the Angelman syndrome, and it is activated by many classical and new antiepileptic drugs. CONCLUSION: The knowledge of the role of the ion channels in the epilepsies is allowing the design of new and more specific therapeutic strategies.
Publication Types:
  Review
  Review, tutorial


BMJ 2000 Jan 8;320(7227):94-7 [Texto completo]
Cross sectional study of reporting of epileptic seizures to general practitioners.
Dalrymple J, Appleby J
Schools of Health, University of East Anglia, Norwich NR4 7TJ. j.dalrymple@uea.ac.uk
OBJECTIVE: Comparison of reporting of recent epileptic seizures by patients to a doctor and anonymously. DESIGN: Cross sectional study of patients with epilepsy by comparison of paired questionnaires. SETTING: Rural and urban general practices in Norfolk. PARTICIPANTS: 122 patients aged over 16 years and able to self complete a questionnaire who were recruited by 31 general practitioners when attending for review of their epilepsy. MAIN OUTCOME MEASURE: The difference in reported occurrence of seizure to general practitioners and in a linked anonymous questionnaire. RESULTS: 18 patients failed to report a seizure in the past year to their general practitioner (uncontrolled epilepsy). 40% (24/60) of people with epilepsy who anonymously reported a seizure in the past year held a driving licence, but only six revealed this to their general practitioner. The unemployment rate was 34%, substantially higher than the 9% in the general population. Measures of anxiety, depression, and stigmatization were higher in patients with uncontrolled epilepsy. CONCLUSIONS: A significant proportion of patients with epilepsy under-report their seizures. Recognition of underreporting is important if patients are to benefit from adequate and appropriate treatment. General practitioners' ability to treat epilepsy is hampered by their role in regulating the rights of epileptic patients to hold a driving licence or access certain occupations.


Geriatrics 1999 Dec;54(12):31, 34, 39-40 passim
Strategies for successful management of older patients with seizures.
Eisenschenk S, Gilmore R
Department of Neurology, University of Florida, J Hillis Miller Health Center, Gainesville, USA.
The incidence of seizures increases dramatically with age, making epilepsy in the older patient a common clinical presentation in the primary care practice. In the case of a single seizure or when the underlying cause can be corrected, antiepileptic drug (AED) therapy may not be warranted. For recurrent seizures, single AED therapy should be initiated at a low dose and gradually titrated upward. Control of seizure frequency is dependent on appropriate AED selection and compliance, drug-drug interactions, and minimization of side effects. Monitoring of AED serum levels is imperative for effective AED therapy. Conventional AEDs remain the standard initial anticonvulsants for epilepsy in older patients. The newer AEDs have demonstrated efficacy as adjunctive therapy and may offer reduced side-effect profiles and fewer drug-drug interactions.
Publication Types:
  Review
  Review, tutorial
Comments:
  Comment in: Geriatrics 2000 Feb;55(2):16, 19


Postgrad Med J 1999 Jul;75(885):387-90
HIV infection and seizures.
Garg RK
Department of Neurology, Banaras Hindu University, Varanasi, India.
New-onset seizures are frequent manifestations of central nervous system disorders in patients infected with human immunodeficiency virus (HIV). Seizures are more common in advanced stages of the disease, although they may occur early in the course of illness. In the majority of patients, seizures are of the generalised type. Status epilepticus is also frequent. Associated metabolic abnormalities increase the risk for status epilepticus. Cerebral mass lesions, cryptococcal meningitis, and HIV-encephalopathy are common causes of seizures. Phenytoin is the most commonly prescribed anticonvulsant in this situation, although several patients may experience hypersensitivity reactions. The prognosis of seizure disorders in HIV-infected patients depends upon the underlying cause.
Publication Types:
  Review
  Review, tutorial
Comments:
  Comment in: Postgrad Med J 2000 Aug;76(898):523-4


Rev Neurol 1999 May 1-15;28(9):846-9 [Texto completo]
[Symptomatic epilepsy: review of 208 patients].
[Article in Spanish]
Santos S, Mauri JA, Lopez del Val J, Tejero C, Morales F
Servicio de Neurologia, Hospital Clinico Universitario Lozano Blesa, Zaragoza, Espana.
OBJECTIVE: To determine the main etiological mechanisms of symptomatic epilepsy and its frequency according to age. PATIENTS AND METHODS: We made a retrospective analysis of 208 patients admitted during a period of four and a half years, studying the variables: age, sex and type of seizures: simple partial, secondarily generalized partial, complex partial, tonic-clonic, generalized tonic, and also EEG and neuroimaging. RESULTS: The main etiological mechanisms found were: vascular (31.25%), alcoholic (12.01%), intracranial disorders (9.61%), traumatic (5.28%), degenerative (5.28%), infectious (2.88%) and cryptogenic (33.65%). In the last group there was an outstandingly large proportion of patients with silent infarcts. When considering vascular epilepsy, those seizures occurring during the acute phase of the stroke (24/65) are differentiated from those of late onset (41/65). In the latter there was a marked predominance of ischemic etiology (48.78% corresponded to extensive infarcts in the territory of the middle cerebral artery; 36.58% were associated with partial infarcts) probably because of the greater frequency of ischemic stroke as compared with hemorrhagic stroke. After the acute phase, the latency was of 10.68 +/- 0.43 months and the most frequent seizures were tonic-clonic (48.78%). CONCLUSION: In persons under 30 years of age, etiology is multifactorial; between 30 and 50 years of age alcoholic epilepsy (39.53%) and traumatic epilepsy (11.62%) predominate; over the age of 50 years the cause was vascular in 43.5%. In the latter age group there was a high proportion of patients with heraldic seizures.


N Engl J Med 1999 May 20;340(20):1565-70
Patients with refractory seizures.
Devinsky O
Department of Neurology, New York University Medical Center, New York 10016,
USA. od4@is4.nyu.edu
Publication Types:
  Review
  Review, tutorial


Rev Neurol 1999 Jan 1-15;28(1):32-5 [Texto completo]
[Etiology of epilepsy in adolescents].
[Article in Spanish]
Prats JM, Garaizar C
Unidad de Neuropediatria, Hospital de Cruces, Barakaldo, Vizcaya, Espana.
OBJECTIVE: To review the etiology of epilepsies in adolescent patients treated at the Child Neurology Clinic, during the years 1995-1997. PATIENTS AND METHODS: All 13 years old patients, or older, were selected and considered adolescents. RESULTS AND CONCLUSIONS: A total of 863 patients with epileptic seizures were reviewed. Among them, 225 were epileptic adolescents and another 8 were adolescents with a single seizure or with several seizures clustering into a single event. Among the former, 163 suffered from partial epilepsy and 62 from generalized epilepsy. Partial epilepsies were distributed as: idiopathic (69), remote symptomatic (49) and cryptogenic (45). Generalized epilepsies were: idiopathic (22), cryptogenic (16) and cryptogenic-remote symptomatic (24). The latter included the Lennox-Gastaut syndrome, West syndrome, polymorphic epilepsy, etc. The etiology of these patients and related literature are reviewed in order to study the proper nosologic location of these entities.


Emerg Med Clin North Am 1999 Feb;17(1):203-20, ix-x
Evaluation of the patient with seizures: an evidence based approach.
Bradford JC, Kyriakedes CG
Department of Emergency Medicine, Northeastern Ohio Universities College of Medicine, Rootstown, USA.
Statistics tell us that as many as 1 in 20 members of the population will suffer a seizure at some point in their lifetime, a figure which becomes even more likely if one lives to the age of 80. Thus, a careful evidence based approach to the patient with seizure is immensely useful to the emergency physician. The authors evaluate current studies on the subject, discuss seizures as they relate to specific patient groups, and, ultimately, make recommendations on this important subject.
Publication Types:
  Review
  Review, tutorial


Acad Emerg Med 1998 Sep;5(9):905-11
New-onset generalized seizures in patients with AIDS presenting to an emergency department.
Pesola GR, Westfal RE
Department of Emergency Medicine, Saint Vincents Hospital, New York, NY 10011, USA.
OBJECTIVE: To determine the etiology of new-onset generalized seizures in patients with AIDS presenting to an ED. Patients without HIV infection with a first-time seizure were used as a comparison group. With these data, the current American College of Emergency Physicians (ACEP) guidelines on the workup of new-onset seizures were applied to determine whether they could safely be used in patients with AIDS. METHODS: The authors conducted a retrospective review of all patients with new-onset generalized seizures who presented to an academic medical center hospital ED in New York City over 2 years. A standard ED medical evaluation with history, physical examination, and routine laboratory studies-including at least a panel 7 chemistry, serum magnesium, and complete blood count-was performed. RESULTS: The causes of new-onset seizures in 26 patients with AIDS were idiopathic (8), HIV encephalopathy (8), CNS toxoplasmosis (5), alcohol withdrawal (2), progressive multifocal leukoencephalopathy (2), and CNS lymphoma (1). In 120 patients without HIV infection, idiopathic (43) and alcohol withdrawal (29) were the most common diagnoses. Six patients with AIDS had CNS lesions necessitating immediate admission to the hospital (5 with toxoplasmosis and 1 with lymphoma). Only 2 of 6 had findings on initial ED examination that would have suggested admission under current guidelines written for patients without HIV infection. The 4 patients with no findings were 3 with CNS toxoplasmosis and 1 with CNS lymphoma. CONCLUSION: Four of 26 AIDS patients with immediately treatable CNS lesions could have been sent home for outpatient evaluation of their seizures on the basis of current guidelines for non-HIV-infected patients. However, the updated 1997 ACEP guidelines now include emergent brain neuroimaging studies on patients who have or are suspected of having AIDS. This study helps to strengthen this recommendation. Based on these findings, the authors suggest a neuroimaging study with a lumbar puncture, if indicated, in the ED or inpatient admission workup for all patients with AIDS or suspected AIDS presenting with new-onset generalized seizures.


Lancet 1998 Aug 1;352(9125):397-9 [Texto completo]
Aetiology of transient global amnesia.
Lewis SL
Department of Neurological Sciences, Rush-Presbyterian-St Luke's Medical Center, Chicago, IL 60612, USA. slewis@neuro.rush.edu
The pathophysiology of transient global amnesia (TGA) has been obscure since the definition of this syndrome more than 30 years ago. Current hypotheses include migraine, seizure, or transient cerebral arterial ischaemia. However, none of these potential mechanisms explain both the absence of other neurological signs or symptoms during TGA, and its frequent precipitating activities: many of which would be expected to result in marked increases in venous return from the arms to the superior vena cava. Patients with TGA also commonly have a Valsalva manoeuvre at the onset of attacks. I suggest that a Valsalva manoeuvre, blocking venous return through the superior vena cava, may allow brief retrograde transmission of high venous pressure from the arms to the cerebral venous system, resulting in venous ischaemia to the diencephalon or mesial temporal lobes and to TGA.
Publication Types:
  Review
  Review, tutorial
Comments:
  Comment in: Lancet 1998 Nov 7;352(9139):1557-8


Lancet 1998 Aug 1;352(9125):383-90 [Texto completo]
Medical causes of seizures.
Delanty N, Vaughan CJ, French JA
Department of Neurology, Hospital of the University of Pennsylvania, Philadelphia 19104-4283, USA. normandy@mail.med.upenn.edu
Seizures are commonly encountered in patients who do not have epilepsy. Factors that may provoke such seizures include organ failure, electrolyte imbalance, medication and medication withdrawal, and hypersensitive encephalopathy. There is usually one underlying cause, which may be reversible in some patients. A full assessment should be done to rule out primary neurological disease. Treatment of seizures in medically ill patients is aimed at correction of the underlying cause with appropriate short-term anticonvulsant medication. Phenytoin is ineffective in the management of seizures secondary to alcohol withdrawal, and in those due to theophylline or isoniazid toxicity. Control of blood pressure is important in patients with renal failure and seizures. Non-convulsive status epilepticus should be considered in any patient with confusion or coma of unclear cause, and electroencephalography should be done at the earliest opportunity. Most ill patients with secondary seizures do not have epilepsy, and this should be explained to patients and their families. Only those patients with recurrent seizures and uncorrectable predisposing factors need long-term treatment with anticonvulsant medication.
Publication Types:
  Review
  Review, tutorial
Comments:
  Comment in: Lancet 1998 Oct 24;352(9137):1390


Am Fam Physician 1998 Apr 1;57(7):1589-600, 1603-4 [Texto completo]
Management of seizures and epilepsy.
Marks WJ Jr, Garcia PA
Northern California Comprehensive Epilepsy Center, University of California, San Francisco 94143-0138, USA.
While the evaluation and treatment of patients with seizures or epilepsy is often challenging, modern therapy provides many patients with complete seizure control. After a first seizure, evaluation should focus on excluding an underlying neurologic or medical condition, assessing the relative risk of seizure recurrence and determining whether treatment is indicated. Successful management of patients with recurrent seizures begins with the establishment of an accurate diagnosis of epilepsy syndrome followed by treatment using an appropriate medication in a manner that optimizes efficacy. The goal of therapy is to completely control seizures without producing unacceptable medication side effects. Patients who do not achieve complete seizure control should be referred to an epilepsy specialist, since new medications and surgical treatments offer patients unprecedented options in seizure control.
Publication Types:
  Review
  Review, tutorial


N Engl J Med 1998 Feb 12;338(7):429-34
Risk of recurrent seizures after two unprovoked seizures.
Hauser WA, Rich SS, Lee JR, Annegers JF, Anderson VE
G.H. Sergievsky Center, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
BACKGROUND: Patients with a single unprovoked seizure have about a 35 percent risk of recurrence in the subsequent five years. We studied the risk of recurrence after two unprovoked seizures. METHODS: We prospectively followed 204 patients with a first unprovoked seizure from the day of the initial seizure. Information was obtained from patients (and verified by a review of their medical records) about the dates and circumstances of any subsequent seizures. The risk of a second, third, and fourth seizure was estimated by the Kaplan-Meier method. RESULTS: Of the 204 patients, 63 had a second seizure, 41 a third seizure, and 26 a fourth seizure. The mean age of the patients was 36 years, 10 percent were less than 16 years of age, 70 percent were male, 71 percent had epilepsy of unknown cause, and 66 percent had generalized seizures. The risk of a second unprovoked seizure was 33 percent. Among those with a second seizure, the risk of a third unprovoked seizure was 73 percent; among those with a third unprovoked seizure, the risk of a fourth was 76 percent. Most recurrences occurred within one year of the second or third seizure. The risk of a third seizure was higher in those with a presumed cause of epilepsy (relative risk, 1.9; 95 percent confidence interval, 1.0 to 3.4). CONCLUSIONS: Although only about one third of patients with a first unprovoked seizure will have further seizures within five years, about three quarters of those with two or three unprovoked seizures have further seizures within four years.
Comments:
  Comment in: N Engl J Med 1998 Jul 9;339(2):128-9; discussion 129-30
  Comment in: N Engl J Med 1998 Jul 9;339(2):129; discussion 129-30


Lancet 1997 Apr 5;349(9057):1009-12
First tonic-clonic seizures in childhood.
Wallace SJ
Department of Child Health, University Hospital of Wales, Cardiff, UK.
Publication Types:
  Review
  Review, tutorial

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