Electrical and clinical manifestations of seizures that arise from one portion of the brain. May evolve to bilateral tonic-clonic seizures.
Underlying structural brain abnormalities are known to cause a localised epileptiform focus, but idiopathic cases may occur.
History taking is the most important aspect of diagnosis. Supportive tests, although helpful, need not be abnormal for a diagnosis of focal seizures.
Monotherapy with antiepileptic medication is the preferred treatment. When polytherapy is required, this should be approached rationally, by considering the combination of different mechanisms of action and different adverse-event profiles.
Patients with 2 failed monotherapy trials followed by a failed trial of polytherapy are considered to have refractory focal seizures and should be assessed for the possibility of resective epilepsy surgery.
Focal (or partial) seizures refer to the electrical and clinical manifestations of seizures that arise from one portion of the brain. The electroencephalogram (EEG) typically indicates a localised discharge over the area of onset. Focal seizures most commonly arise from the temporal lobe. Simple focal seizures are those in which consciousness is preserved. New terminology suggests that these should now be called 'focal aware' seizures. Complex focal seizures include memory loss for the clinical event and impaired responsiveness at the time of the event. New terminology suggests that these should now be called 'focal impaired awareness' seizures. Focal seizures may evolve into secondary generalised seizures. The clinical manifestations of a particular seizure depend on the portion of the brain that is activated.
In 2009, a task force supported by the International League Against Epilepsy (ILAE) issued a report revising the system of terminology and classification used for the description of individual seizures and epilepsy syndromes. The clinical definition of epilepsy was revised in 2014 to include any of the following conditions: 1) at least two unprovoked seizures occurring >24 hours apart; 2) one unprovoked seizure and a probability of further seizures similar to the general recurrence risk (at least 60%) after two unprovoked seizures, occurring over the next 10 years; 3) diagnosis of an epilepsy syndrome.
History and exam
- presence of risk factors
- movement of one side of the body or one specific body part
- premonitory sensation or experience (fear, epigastric sensation, déjà vu, jamais vu)
- automatisms (picking at clothes, smacking of the lips)
- temporary aphasia
- staring and loss of contact with the environment
University of California, San Francisco
VRR is an author of a number of references cited in this monograph. He served as a paid consultant for NeuroPace, Inc., manufacturer of the Responsive Neurostimulation (RNS) System.
University of California, San Francisco
JDH has received research funding and consultancy funds from UCB Inc.
Dr Vikram R. Rao and Dr John D. Hixson would like to gratefully acknowledge Dr Jeffrey Cohen, a previous contributor to this monograph. JC declares that he has no competing interests.
Brigham and Women's Hospital
Associate Professor of Neurology
Harvard Medical School
At the time of review, EB declared that between 2004 and 2009, he received speaking honoraria from UCB Pharma, Novartis, Abbott Laboratories, GlaxoSmithKline, and Pfizer. He received consulting fees from UCB Pharma, Genzyme, and Spherics, and research funding from UCB Pharma. Unfortunately, we have since been made aware that EB is deceased.
Pediatrics and Neurology
Baylor College of Medicine
Comprehensive Epilepsy Program
Texas Children's Hospital
AAW declares that he has no competing interests.
Division of Pediatric Neurology
Columbia University College of Physicians and Surgeons
Muscular and Neurodegenerative Diseases Unit
"G Gaslini" Institute
Federico II University
PS declares that he has no competing interests.
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