ArticlesEpileptology of the first-seizure presentation: a clinical, electroencephalographic, and magnetic resonance imaging study of 300 consecutive patients
Introduction
A first seizure is a sudden frightening event for the individual, for onlookers, and for family members, and diagnosis of such events is common in everyday clinical practice. At least 4% of people will have one or more non-febrile seizures in their lifetime.1, 2 Initial clinical assessment seldom gives a specific diagnosis, and this leads to uncertainty about prognosis and further management. It is important to distinguish between epileptic and non-epileptic attacks such as convulsive syncope, and seizures provoked by metabolic derangements and poisons, because the latter two do not have the medical and social consequences of epilepsy. Previous studies of the risk of recurrence after a first tonic-clonic seizure have had conflicting results,3, 4, 5 although a meta-analysis has suggested that the 2-year risk of reccurence is greater than 40%.6
In the management of patients with established epilepsy, the concept of epilepsy syndromes based on age at onset, seizure type or types, electroencephalographic (EEG) findings, and aetiology, has been an important advance.7 Broadly, epilepsies are classed as either generalised or partial, with several subcategories in each class. Knowledge of an individual patient's epilepsy syndrome allows assessment of prognosis and choice of the most effective antiepileptic drug. However, in clinical practice and research, patients with first seizures are generally regarded as a relatively homogeneous group and there is no attempt to identify the specific syndrome. There are no guidelines for best practice in management of these patients. The role of EEG, and its diagnostic yield, are unknown, especially if EEG is done soon after the seizure. Magnetic resonance imaging (MRI) is now the investigation of choice in patients with chronic epilepsy,8 but its diagnostic yield in first-seizure cases is not known.
We undertook a prospective study of patients who presented with a first seizure, to assess the diagnostic use of early EEG, sleep-deprived EEG, and MRI. We aimed to devise an improved strategy for the clinical and laboratory investigation of patients with this common problem.
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Patients
We recruited patients from around 500 000 people served by the Austin and Repatriation Medical Centre—the tertiary referral hospital for the north-east sector of Melbourne, Australia. The study was approved by the centre's Human Research Ethics Committee. Patients were referred to us from the emergency departments of the centre, and four satellite hospitals, and by local general practitioners and specialists. Patients were also recruited from the centre's neurology clinics and EEG department. A
Patients
300 patients (170 male, 130 female) were enrolled over 30·5 months (March, 1994, to October, 1996) from 496 referrals. Most excluded patients had non-epileptic events, such as syncope or convulsive syncope, or provoked seizures (table 1). The patients enrolled were aged 5–83 years (mean 31·2 [SD 18·7], median 25·6), and the study group included 59 children aged under 16 years (20% of the total study group). 68% of patients were referred from hospital emergency departments and 23% were referred
Discussion
We aimed to develop a comprehensive, rapid diagnostic strategy for patients who present to hospital emergency departments with an unprovoked first seizure. This term, as commonly used, refers to a first tonic-clonic seizure, which is the dramatic and generally recognised type of seizure that usually brings a patient to medical attention. However, a first recognised seizure may not be the patient's first epileptic event. In our study group, 17% of those who presented with their first recognised
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