Symptomatic and Probably Symptomatic Focal Epilepsies
Focal (anatomical, topographical, or localization-related) epilepsies are defined by seizures that emanate from an anywhere within the brain. These may be , , and cryptogenic (synonym: probably symptomatic).
symptoms, particularly at onset, are determined by localization and not by etiology. Anatomical origins of some epilepsies are difficult to assign to specific localizations or lobes and this is often the case with seizures originating from clinically silent epileptogenic regions.
The new ILAE diagnostic scheme considers ‘symptomatic (or probably symptomatic) focal epilepsies’ as a separate group from ‘idiopathic focal epilepsies’. This is because prognosis and treatment of idiopathic focal epilepsies differ significantly from the symptomatic ones. There is now concrete evidence to accept, diagnose, and treat certain focal epilepsies on the basis of etiology rather than simply localization. Mesial with hippocampal sclerosis, among the more common and most distinct epileptic syndromes, is a striking example of this.
The ILAE Commission (1989) classifies focal epilepsies according to their topographical/anatomical origin as:
The epileptic syndromes and their significance
A major advance in recent epileptology is the recognition of epileptic syndromes that allows an accurate diagnosis and management of seizure disorders.[1-3]
Medical diagnosis is the identification of a disease by investigation of its symptoms and history, which provides a solid basis for the treatment and prognosis of the individual patient. An accurate diagnosis is the golden rule in medicine, and epilepsies should not be an exception to this. Like in any other disease, the recognition of non-fortuitous clustering of symptoms and signs in epilepsies requires the study of detailed clinical and laboratory data.[1-3] However, often in current practice, the diagnosis is limited to either epilepsy or seizures, which is unsatisfactory because this cannot provide guidance on important items such as severity of the disease, prognosis, short- and long-term therapeutic decisions, and genetics (research and counselling), which are all factors that crucially affect personal, family, and social life; education; and career choices of patients. Defining the type of epilepsy should now be considered mandatory as it offers the best guide to both management and prognosis. Most epileptic syndromes and diseases are well defined and easy to diagnose. The benefits of syndromic diagnosis over seizure/symptom diagnosis or an inclusive diagnosis such as epilepsy far outweigh any morbidity from incorrect categorization that may arise in difficult cases.
Important clinical features of a include the type of seizures, their localization, frequency, sequence of events, circadian distribution, precipitating factors, age at onset, mode of inheritance, physical or mental symptoms and signs, prognosis, and response to treatment.
Epilepsies or epilepsy?
The clinical and practical significance of the syndromic diagnosis of epilepsies is well illustrated by 3 common epileptic disorders. childhood focal epilepsies, (), and hippocampal epilepsy have nothing in common other than the fact that they may all be complicated by generalized tonic clonic seizures (GTCS), which are primarily GTCS in JME and secondarily GTCS in benign childhood focal epilepsies and hippocampal epilepsy.
Furthermore, the short-and long-term treatment strategies are entirely different for each disorder: benign childhood focal epilepsies may or may not require medication for a few years, appropriate anti-epileptic drug (AED) treatment is lifelong in JME while neurosurgery may be life-saving for patients with hippocampal epilepsy. What may be a life-saving drug such as carbamazepine for hippocampal epilepsy may be ill-advised for JME.
It should not be difficult to distinguish an intelligent child with benign focal seizures or childhood absence epilepsy from a child with Kozhevnikov-Rasmussen, Lennox-Gastaut, Down, or or a child with severe post-traumatic cerebral damage, brain anoxia, or catastrophic progressive myoclonic epilepsy. Describing all these children as simply having epilepsy just because they have seizures offers no more benefit than a diagnosis of febrile illness irrespective of cause, which may be a mild viral illness, a life-threatening acute bacterial , or a malignancy. Inappropriate generalizations with regard to terminology, diagnosis, and treatment are the single most important factor of mismanagement in epilepsies.
C. P. Panayiotopoulos, MD, PhD, FRCP
For details and bibliography for these syndromes see the reference book: Panayiotopoulos CP. A clinical guide to epileptic syndromes and their treatment. Second edition. London:Springer; 2007.
This page was adapted from:
The educational kit on epilepsies
Originally published by MEDICINAE
Reviewed and revised June 2008 by Steven C. Schachter, MD
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