Focal seizures are the transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain originating within networks limited to one hemisphere.
Focal seizures can be caused by overt brain lesions (e.g., stroke, tumour), but neuroimaging studies often do not identify any underlying pathology.
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 anticonvulsant medication is the initial and preferred treatment. Choice of medication should be tailored to the needs of the individual patient, taking into account factors such as age, sex, and comorbidities.
When at least two monotherapy trials fail to achieve seizure remission, dual therapy may be tried; use of drugs with different mechanisms of action should be considered to maximise efficacy and minimise toxicity.
Patients in whom seizure remission is not achieved with two monotherapy trials followed by dual therapy are considered to have refractory focal seizures. They should be evaluated to confirm the diagnosis and for consideration of resective epilepsy surgery and/or neuromodulation therapies.
Focal seizures (formerly known as partial seizures) refer to the electrical and clinical manifestations of seizures that arise from one portion of the brain. An electroencephalogram typically indicates a localised discharge over the area of onset, or regions beyond the initial onset as the abnormal electrical activity propagates. Focal seizures can originate from any lobe in the brain. Focal epilepsy of temporal lobe origin is the most frequently recognised focal epilepsy.
Focal aware seizures (formerly known as simple focal seizures) are those in which consciousness is preserved.
Focal impaired awareness seizures (formerly known as complex focal seizures) are characterised by loss of awareness, memory loss for the clinical event, and impaired responsiveness at the time of the event.
Focal seizures may evolve into bilateral tonic-clonic seizures (formerly known as secondarily generalised tonic-clonic seizures). The clinical manifestations of a particular seizure depend on the clinically eloquent structures of the brain that are activated.
The clinical definition of epilepsy includes 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 being unaware of surroundings
Assistant Professor of Clinical Neurology
Department of Neurology, Epilepsy Division
University of Miami, Miller School of Medicine
RR has received consultancy funds from Supernus Pharmaceuticals, Inc.
Professor of Clinical Neurology
Director, Comprehensive Epilepsy Center and Head, Section of Epilepsy
Department of Neurology
University of Miami, Miller School of Medicine
AMK has received honoraria from Eisai laboratories and Neuropace. AMK is an author of a number of references cited in this topic.
Dr Ramses Ribot and Dr Andres M. Kanner would like to gratefully acknowledge Dr Vikram R. Rao, Dr John D. Hixson, and Dr Jeffrey Cohen, previous contributors to this topic.
VRR served as a paid consultant for Neuropace, Inc., manufacturer of the Responsive Neurostimulation (RNS) System. JDH has received research funding and consultancy funds from UCB, Inc. 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.
Use of this content is subject to our disclaimer