Classification of Seizures and Epilepsy
Stanley R. Resor, Henn Kutt in The Medical Treatment of Epilepsy, 2020
The current classification contains two important physiological concepts. First, that seizures are fundamentally of two types: those onset limited to a part of one cerebral hemisphere (partial or focal seizure), and those which seem to involve the brain diffusely from the beginning (generalized seizures). Second, that the clinical expression of seizures is determined as much by the sequence of spread of electrical discharge within the brain as by the site at which the ictal discharge originates. Variations in the seizure pattern exhibited by a given individual often reflect variable spread of the electrical discharge. Both generalized and partial seizures are subdivided into various subtypes. For partial seizures, the most important subdivision is based upon whether consciousness its preserved or lost. In simple partial seizures, consciousness is maintained, whereas in complex partial seizures, consciousness is impaired. Simple partial seizures can evolve into complex partial seizures, and partial seizures may evolve into generalized seizures. In fact, in adults most generalized seizures have a focal onset.
Basic mechanisms
Timothy Betts, Lyn Greenhill in Managing Epilepsy with Women in Mind, 2005
'Partial seizures are those in which, in general, the first clinical electroencephalographic changes indicate initial activation of a system of neurones limited to part of one cerebral hemisphere. A partial seizure is currently classified primarily on the basis of whether or not consciousness is impaired during the attack. When consciousness is not impaired, the seizure is classified as a simple partial seizure. When consciousness is impaired the seizure is classified as a complex partial seizure. Impaired consciousness is defined as the inability to respond normally to exogenous stimuli by virtue of altered awareness and/or responsiveness'.
The nervous system
Laurie K. McCorry, Martin M. Zdanowicz, Cynthia Y. Gonnella in Essentials of Human Physiology and Pathophysiology for Pharmacy and Allied Health, 2019
Focal seizures occur in a specific area (foci) of the brain. Focal seizures are further divided into two subcategories based on the presentation of the seizure: Simple partial seizure: No loss of consciousness, patients are fully aware the seizure is occurringSymptoms depend upon the region of the brain affected by the seizure and may include sensory disturbances (altered sensations, tastes, smells, vision), motor disturbances (abnormal movements on the contralateral side), autonomic disturbances (flushing, diaphoresis, tachycardia).Complex partial seizure: Patients exhibit impaired consciousnessOften referred to as psychomotor seizures to reflect the motor and psychic manifestationsSymptoms may include automatisms that are repetitive behaviors such as hand rubbing, swallowing, grimacing or walking in circles. Complex visual, and auditory hallucinations may occur. Patients often report a feeling of déjà vu.
The Revised Definition and Classification of Epilepsy for Neurodiagnostic Technologists
Published in The Neurodiagnostic Journal, 2018
Robert S. Fisher, Anna M. Bonner
The names of the seizures have changed in a 2017 classification that revises the 1981 classification. The primary division continues to be based upon focal origin of the seizure in one hemisphere of the brain versus generalized onset in both hemispheres. Consciousness has been maintained as an important classifier of focal seizures, but awareness is used as a more easily understood surrogate marker for consciousness. The prior term “complex partial seizure” is now a “focal impaired awareness seizure.” The prior “simple partial seizure” is now a “focal aware seizure.” Focal seizures can be further subdivided into motor and nonmotor onset categories. Generalized seizures are not classified according to awareness, since awareness is impaired for most, and are categorized as either motor or absence (nonmotor) seizures. If onset is unknown, some seizures can still be classified under the heading for unknown-onset seizures.
Autistic spectrum disorder and epilepsy: diagnostic challenges
Published in Expert Review of Neurotherapeutics, 2019
Anna Loussouarn, Blandine Dozières-Puyravel, Stéphane Auvin
The ILAE framework for epilepsy lists three levels of classification [8] (Figure 1). First, seizure types are classified as either focal-onset, generalized-onset, or with an unknown-onset [9] (Figure 1). Second, epilepsy is classified by the seizure type previously identified as either focal, generalized, or combined generalized and focal seizure types (Figure 1). Third, when a specific epilepsy syndrome can be identified, the epilepsy syndrome can be classified (Figure 1). At each level, classification aims to identify one or several etiological factors, according to therapeutic considerations, such as genetic, structural, metabolic, immune, infectious, or unknown etiology [8] (Figure 1).
The inhibitory effect of functional lesions on eloquent brain areas: from research bench to operating bed
Published in International Journal of Neuroscience, 2018
These findings are consistent with the theory of maladaptive effect of injured neurons [10]. This theory claims that injured neurons that were previously normal inhibit the plasticity and reorganization of surrounding neural networks. The evidences for the disturbing effect of an injured neuron on its surrounding network come from the observations of motor weakness after an episode of focal seizure (Todd's phenomenon) [16], and the aphasia following seizures in Landau–Kleffner syndrome [17]. This theory was debated as an explanation for the recoveries shown after surgeries recently performed on the cortical lesions located in the cortical eloquent areas [10,11].
Related Knowledge Centers
- Cerebral Hemisphere
- Deja Vu
- Hypoesthesia
- Paresthesia
- Parietal Lobe
- Occipital Lobe
- Frontal Lobe
- Temporal Lobe
- Seizure
- Lobes of The Brain
- Déjà Vu