The First Seizure: A Diagnostic Challenge
Virtual Special Editions are collections of targeted papers curated by a Guest Editor. Here Dr Jose Francisco Tellez-Zenteno Royal University Hospital, Saskatoon (author of the Editor’s Choice article in Volume 49) and Lady Diana Ladino Hospital Pablo Tobón Uribe – University of Antioquia, Colombia talk about “The First Seizure: A Diagnostic Challenge”.
According to the new epilepsy definition, diagnosis can be made if tests after a single unprovoked seizure lead to the determination that the patient is at high risk (60%) of seizure recurrence over the next 10 years. The challenge in evaluating a patient after a single unprovoked seizure consist in the identification of those patients that will go on to develop recurrent seizures from those who will have only a single seizure in their lifetime. In this special edition we present a series of papers published in Seizure: European Journal of Epilepsy exploring assessment of a first seizure. In one of the papers we have summarized current literature regarding epidemiology, recurrence, modalities of diagnosis and treatment (Syed et al. 2017).
The first seizure is a dramatic event with profound implications for patients. The initial evaluation focuses on an accurate description of the episode. Ictal cry during the tonic phase, cyanosis, frothing at the mouth, lateral tongue biting, posterior shoulder dislocations without a clear history of direct trauma, absence of ictal pallor, post-ictal unconsciousness for greater than five minutes, confusion, anterograde amnesia, and complain of sore limb muscles are specific signs of a convulsion. A careful scrutiny for previously unrecognized seizures is important. Half of patients with an apparent “first seizure” have had previous seizures, so their diagnosis is epilepsy (Nowacki and Jirsch, 2017).
Upwards of 10–60% of patients with single unprovoked seizures have epileptiform abnormalities on EEG. The yield of conventional EEG after a seizure demonstrated a sensitivity and specificity of interictal epileptiform discharge (IED) for seizure recurrence of 17% and 95% respectively. The presence of abnormalities depends upon seizure; absence seizures for instance are associated with IED in 90%, atonic or myoclonic seizures in 80% and complex partial seizures in 60%. Additionally, there is evidence suggesting that the yield for recording IED is highest in the time period shortly after the seizure (<72 hours), in prolonged sleep-deprived video-EEG monitoring, and with consecutive EEGs (at least 3 serial studies). The use of portable EEG in the assessment of single unprovoked seizures is still unclear, although some studies show a higher determination of IED than sleep deprived and routine EEG (Debicki, 2017). In their article Crocker et al. (2017) describe the goal of neuroimaging as to identify a lesion that can explain the seizure. Neuroimaging can be abnormal in 50% of patients with new-onset focal seizures. Furthermore, CT scan and MRI may show abnormalities that portend further seizures and therefore establish a diagnosis of epilepsy.
The series of articles in this supplement make an important contribution on the understanding of relevant factors about diagnosis and treatment. As usual in medicine, in every single case we have to cautiously weigh up the potential pros and cons of either avoidance or initiation of AEDs. Authors believe patients debuting with status epilepticus, seizure flurries, semiology indicating focal epilepsy, neurological deficit on examination (Olmes and Hamer, 2017) and a high personal risk in case of seizure relapse due to professional circumstances (Steinhof, 2017) could need immediate treatment.