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Epilepsy is a common neurological disorder that is characterized by a predisposition to having epileptic seizures and can take many clinical forms and have a veritable Augean stable of etiologies.
Epilepsy is defined by the International League Against Epilepsy (ILAE) as 1:
at least two or more unprovoked (or reflex) seizures occurring more than 24 hours apart; or
one unprovoked (or reflex) seizure and a probability of further seizures similar to the general recurrence risk after two unprovoked seizures, occurring over the next 10 years; or
diagnosis of an epilepsy syndrome
Epilepsy is very common, with approximately 3% of the population affected at some point in their life 2.
The hallmark clinical feature of epilepsy is that of epileptic seizures, which may have a variety of semiologies depending on the type of seizure and epilepsy. However, there are other important clinical features that may accompany epileptic seizures in epilepsy 3:
physical effects/complications of epileptic seizures, e.g. injury, death, neurocognitive deterioration
social effects/complications: e.g. lower education levels, lower employment rates with fewer options, limitations on recreational activities, stigmatisation
medication side-effects, e.g. neurocognitive deterioration, weight gain, rash, osteoporosis
Epilepsy is classified by the International League Against Epilepsy (ILAE) according to a three-level framework 4:
seizure type 5
focal (preferred term to 'partial') onset
may have awareness (preferred term to 'simple partial') or impaired awareness (preferred term to 'complex partial' or 'dyscognitive')
may be motor onset or non-motor onset (e.g. sensory, autonomic)
may progress from focal to bilateral tonic-clonic seizures
may be motor seizures, e.g. tonic-clonic (preferred term to 'grand mal') seizure, clonic seizure, tonic seizure, myoclonic-tonic-clonic seizure, myoclonic-atonic seizure, atonic seizure
may be non-motor or absence (preferred term to 'petit mal') seizure
combined generalized and focal
There are a myriad of etiologies, however, in adults with new onset of seizures ~50% will not have a determinable cause 2. The International League Against Epilepsy (ILAE) have proposed the following etiological classification 4:
MRI brain is the radiographic modality of choice 2. Please see articles on specific conditions listed above for imaging features. There are a number of MRI protocols that can be used to investigate patients with seizures.
If perfusion neuroimaging is performed during a seizure, it can be useful for localizing the epileptogenic focus 6,7.
May show an area of hypometabolism corresponding to the epileptogenic focus. Largely replaced by MRI but can be used in conjunction for localization of the epileptogenic foci 8.
Translocator protein (TSPO) is a molecular marker for glial activation and neuroinflammation. Quantification of TSPO using PET has been recently used to study epileptogenic foci. For example, increased TSPO levels can be seen in the epileptogenic foci within temporal lobes in patients with temporal lobe epilepsy 9,10.
Treatment and prognosis
Management of epilepsy is potentially complex, and may involve 2,3:
lifestyle restrictions, e.g. driving restrictions, restrictions on employment, limiting exposure to drugs and alcohol
antiseizure medications, either as monotherapy or in combination, and ketogenic diet
note that describing these medications as 'antiseizure' is the ILAE preferred terminology to 'antiepileptic' or 'anticonvulsive' 11
epilepsy surgery, e.g. stereo EEG, surgical resection, neuromodulation therapies
specific management of psychosocial effects/complications