Epilepsy.

Epilepsy is a common chronic neurological disorder that is characterized by recurrent unprovoked seizures. These seizures are transient signs and/or symptoms due to abnormal, excessive or synchronous neuronal activity in the brain. About 50 million people worldwide have epilepsy at any one time. Epilepsy is usually controlled, but not cured, with medication, although surgery may be considered in difficult cases. Not all epilepsy syndromes are lifelong – some forms are confined to particular stages of childhood. Epilepsy should not be understood as a single disorder, but rather as a group of syndromes with vastly divergent symptoms but all involving episodic abnormal electrical activity in the brain.

The word epilepsy is derived from the Greek epilepsia, which in turn can be broken in to epi- (upon) and lepsis (to take hold of, or seizure)

The diagnosis of epilepsy requires the presence of recurrent, unprovoked seizures; accordingly, it is usually made based on the medical history. EEG, brain MRI, SPECT, PET, and magnetoencephalography may be useful to discover an etiology for the epilepsy, discover the affected brain region, or classify the epileptic syndrome, but these studies are not useful in making the initial diagnosis.

Long-term video-EEG monitoring for epilepsy is the gold standard for diagnosis, but it is not routinely employed owing to its high cost, low availability and inconvenience.

Convulsive or other seizure-like activity, non-epileptic in origin, can be observed in many other medical conditions. These non-epileptic seizures can be hard to differentiate and may lead to misdiagnosis.

The diagnosis of epilepsy requires that the seizures be unprovoked, with the implication that the provocant is assumed to be something obviously harmful. However, in some epilepsy syndromes, the provocant can reasonably be considered to be part of normal daily life. Examples of these normal provocants include reading, hot water on the head, hyperventilation, and flashing or flickering lights. This last provocant is a special type of reflex epilepsy called photosensitive epilepsy. Although it is commonly assumed that photosensitivity is a common element to all epilepsies, among both patients and the public, only around 3% of people with epilepsy are affected by flickering lights.

Certain environmental factors can lead to an increased likelihood of seizures in someone with epilepsy or in certain syndromes, for example:

• being asleep
• the transition between sleep and wakefulness (hypnogogia)
• tiredness and sleep deprivation
• illness
• constipation
• menstruation
• stress or anxiety
• alcohol consumption
• very severe depression and bipolar disorders

Epilepsy is one of the most common of the serious neurological disorders. Genetic, congenital, and developmental conditions are mostly associated with it among younger patients. The prevalence of active epilepsy is roughly in the range 5–10 per 1000 people. Up to 50 per 1000 people experience nonfebrile seizures at some point in life; epilepsy’s lifetime prevalence is relatively high because most patients either stop having seizures or (less commonly) die.

Children with epilepsy are three to nine times more likely to have mental health problems than healthy children. Although the search for risk factors has often produced inconsistent results, there is evidence that the development of mental health problems in children with epilepsy is moderated and mediated by family risk factors. Attention-deficit/hyperactivity disorder (ADHD) affects three to five times more children with epilepsy than children in the general population, and children with epilepsy also have significantly higher rates of depression and anxiety. There is a strikingly higher prevalence of epilepsy in children with autism, and evidence suggests that epilepsy is a risk factor for autism, independent of other central nervous system problems.

There are many different epilepsy syndromes, each presenting with its own unique combination of seizure type, typical age of onset, EEG findings, treatment, and prognosis.

Infantile spasms (West syndrome) is associated with brain development abnormalities, tuberous sclerosis, and perinatal insults to the brain. It affects infants (as implied by its name), which by definition is between 30 days to 1 year of life. It carries a poor prognosis such that only 5-10% of children with infantile spasms will develop normal to near-normal function, while more than two-thirds will have severe deficits. The typical seizures are characterized by sudden flexor and extensor spasms of head, trunk, and extremities. The key EEG finding in these patients is a hypsarrhythmia, or a high-voltage slow wave with multifocal spikes.

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