History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors include history of febrile seizures; previous central nervous system infection, stroke, tumour, or trauma; history of dementia, mental retardation, and/or cerebral palsy; vascular malformations; family history of seizures, as well as prior seizure events.
movement of one side of the body or one specific body part
A focal seizure is characterised by localised brain activity, which is represented by motor activity of the head (presenting as forced head and gaze deviation to one side) or dystonic posturing of a hand. The epileptogenic area is in the hemisphere contralateral to the side of the head/gaze deviation and/or the dystonic hand.
premonitory sensation or experience (fear, epigastric sensation, déjà vu, jamais vu)
A premonitory sensation or sequence of sensations more likely indicates a focal seizure most often associated with temporal lobe origin.
automatisms (picking at clothes, smacking of the lips)
Suggests a focal impaired awareness seizure.
temporary aphasia
A postictal aphasia can be seen after focal seizures that involve the language centres. This does not necessarily imply that the seizure originated in the dominant hemisphere, as a seizure can originate in the non-dominant hemisphere and propagate to the dominant hemisphere, causing a postictal aphasia.
If the first symptom is expressive and/or receptive aphasia, the epileptogenic area most likely originated in the dominant hemisphere. If the patient speaks during the seizure, the epileptogenic area is likely to be in the non-dominant hemisphere.
staring and being unaware of surroundings
Suggests a focal impaired awareness seizure.
Other diagnostic factors
common
postictal focal neurological deficit (Todd's paralysis, aphasia)
A postictal paralysis or weakness on one side of the body suggests a focal seizure and generally indicates that the seizure focus is contralateral to the side of the deficit.
persistent focal neurological deficit
Associated with central nervous system dysfunction, and suggests the presence of focal seizures.
May also indicate a recent or previous stroke. On examination, there may be visual loss, language dysfunction, and sensory neglect, associated with weakness or numbness of one side of the body.
uncommon
poor memory
Although there are many causes of poor memory, one possibility is the presence of undiagnosed or uncontrolled focal impaired awareness seizures.
stigmata of neurocutaneous syndromes
Some physical signs (neurocutaneous findings) may suggest an underlying neurological disease associated with seizures. For instance, the presence of ash-leaf spots, shagreen patches, facial angiofibromas, and/or periungual fibromas is often indicative of tuberous sclerosis. Café au lait spots, axillary freckling, and/or fibromas are suggestive of neurofibromatosis. Port-wine stain is associated with Sturge-Weber syndrome.
Risk factors
strong
febrile seizure
The risk of developing epilepsy is greater if there is a history of febrile seizures.[29][30]
A distinction is often made between simple febrile seizures (generalised, <15 minutes, in a neurologically normal child aged between 6 months and 6 years, not due to meningoencephalitis) and complex febrile seizures (multiple or focal, and lasting >15 minutes). Unprovoked focal-onset seizures are more likely to be associated with complex febrile seizures.[31]
Febrile seizures may contribute to the development of mesial temporal sclerosis (loss of neurons and scarring of the temporal lobe associated with certain brain injuries, closely related to temporal lobe epilepsy), but it has not yet been determined if this is causative or a result of the seizures.[32]
traumatic brain injury
The more severe the head injury, the greater the risk of developing seizures. Penetrating head injuries carry the greatest risk.[8] Closed head injury (skull fracture or >30 minutes of unconsciousness or amnesia) leads to a significantly increased risk for the development of seizures.[9] Risk may be slightly elevated even if amnesia lasts less than 30 minutes.[10]
The presumed mechanism is trauma-induced injury or scar that sets up an epileptogenic focus.
central nervous system (CNS) infection
The more complicated the CNS infection, the more likely it is to contribute to seizure development. Meningoencephalitis has been associated with a 16-fold increased risk for focal seizure, bacterial meningitis a fourfold increased risk, and aseptic meningitis a twofold increased risk.[33] The presumed mechanism is an inflammatory process involving the CNS.
Focal epilepsy can result from infections with parasites such as neurocysticercosis, toxoplasmosis, and malaria. Neurocysticercosis is a common cause of epilepsy worldwide; it should be considered in any patient who grew up or has spent time in an area of the world known to have high rates of neurocysticercosis, notably Latin America, Africa, and India.[11][34]
stroke
Risk of developing focal epilepsy is at least 3 times higher after a stroke.[18]
The presumed mechanism is central nervous system cortical injury. The risk is higher with haemorrhagic than with ischaemic stroke.[19] Clinically undetectable cerebrovascular disease can present with seizures, and these may be a warning sign of a future stroke.[35]
brain tumour
The tumour (especially if infiltrative) may result in the development of an epileptogenic focus.
Epilepsy is common in patients with glioneuronal tumours and glioma, and is also associated with meningioma and brain metastases.[12] Low-grade tumours seem to be more epileptogenic than high-grade tumours.[12][13] One case series suggested that 28% of patients undergoing surgery for brain tumours experience seizures.[14]
intellectual disability and/or cerebral palsy
One study found that in children with intellectual disability alone, the cumulative risk of developing seizures by age 22 years was 5%. In children with intellectual disability and cerebral palsy, the cumulative risk rose to 38%.[21] Children with a postnatal injury in addition to intellectual disability had a cumulative risk for seizure development (post injury) of 66%.[21] The more severe the brain insult, the more likely the development of an epileptogenic focus.
dementia
Both Alzheimer's disease and non-Alzheimer's dementia have been associated with seizure development.[20]
family history of seizures
Family history is related to the development of focal epilepsy, although this is not a simple relationship. Some syndromes are thought to be due to inheritance of a single gene (familial temporal lobe epilepsy), while others have a complex inheritance (idiopathic focal epilepsies and cryptogenic/symptomatic focal epilepsies).[22][23]
intracranial vascular malformations
Seizures are a common presentation in patients with intracranial vascular malformations such as arteriovenous malformations and cavernous angiomas. Seizures may occur de novo or be secondary to intracerebral haemorrhage.[17]
malformations of cortical development (MCDs)
MCDs are characterised by abnormal cortical structures or heterotopic grey matter resulting from disrupted cerebral cortex formation. The cause is mostly genetic, but infectious, vascular, and metabolic aetiologies have also been reported. It is estimated that 25% to 40% of treatment-resistant childhood epilepsy is attributable to MCDs, and that at least 75% of patients with MCDs have epilepsy.[15][16]
weak
male sex
Slightly more common in males.
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