It is not possible to make a generalised prognosis for development due to the variability of causes, as mentioned above, the differing types of symptoms and cause. Each case must be considered individually.

The prognosis for children with idiopathic West syndrome are mostly more positive than for those with the cryptogenic or symptomatic forms. Idiopathic cases are less likely to show signs of developmental problems before the attacks begin, the attacks can often be treated more easily and effectively and there is a lower relapse rate. Children with this form of the syndrome are less likely to go on to develop other forms of epilepsy; around two in every five children develop at the same rate as healthy children.

In other cases, however, treatment of West syndrome is relatively difficult and the results of therapy often dissatisfying; for children with symptomatic and cryptogenic West syndrome, the prognosis is generally not positive, especially when they prove resistant to therapy.

Statistically, 5 out of every 100 children with West syndrome do not survive beyond five years of age, in some cases due to the cause of the syndrome, in others for reasons related to their medication. Only less than half of all children can become entirely free from attacks with the help of medication. Statistics show that treatment produces a satisfactory result in around three out of ten cases, with only one in every 25 children's cognitive and motoric development developing more or less normally.

A large proportion (up to 90%) of children suffer severe physical and cognitive impairments, even when treatment for the attacks is successful. This is not usually because of the epileptic fits, but rather because of the causes behind them (cerebral anomalies or their location or degree of severity). Severe, frequent attacks can (further) damage the brain.

Permanent damage often associated with West syndrome in the literature include cognitive disabilities, learning difficulties and behavioural problems, cerebral palsy (up to 5 out of 10 children), psychological disorders and often autism (in around 3 out of 10 children). Once more, the cause of each individual case of West syndrome must be considered when debating cause and effect.

As many as 6 out of 10 children with West syndrome suffer from epilepsy later in life. Sometimes West syndrome turns into a focal or other generalised epilepsy. Around half of all children develop Lennox-Gastaut syndrome.

It is still unknown which bio-chemical mechanisms lead to the occurrence of West syndrome. It is conjectured that it is a malfunction of neurotransmitter function, or more precisely, a malfunction in the regulation of the GABA transmission process. Another possibility being researched is a hyper-production of the Corticotropin-releasing hormone (CRH). It is possible that more than one factor is involved. Both hypotheses are supported by the effect of certain medications used to treat West syndrome.

Cases of epilepsy have been historically divided into three different groups: symptomatic, cryptogenic, and unknown. The International League Against Epilepsy (ILAE) recommended in 2011 to abandon these terms for reasons of clarity and instead try to place individual cases into one of the following 3 groups: genetic, structural/metabolic, and unknown. The new terms are more immediately clear in their meaning, except that the structural and metabolic group includes cases that have a genetic component that does not always directly lead to the condition. Only the genetic grouping has a known direct genetic cause. "Unknown" cases may be of "unknown" genetic, structural, metabolic, or other unknown cause.

The old terminology was defined by the ILAE as follows:

- symptomatic: the epilepsy is the consequence of a known or suspected disorder of the central nervous system.

- cryptogenic: this refers to a disorder whose cause is hidden or occult. Cryptogenic epilepsies are presumed to be symptomatic.

- idiopathic: there is no underlying cause other than a possible hereditary predisposition.

The remainder of this section will refer to the older terminology.

The mortality rate ranges from 3–7% in a mean follow up period of 8.5 to 9.7 years. Death is often related to accidents.

The causes of epilepsy in childhood vary. In about ⅔ of cases, it is unknown.

- Unknown 67.6%

- Congenital 20%

- Trauma 4.7%

- Infection 4%

- Stroke 1.5%

- Tumor 1.5%

- Degenerative .7%

The cause of FIRES is not known. It does not happen twice in the same family, but the medical community does not know if it is genetic. It happens in boys more than girls. After the initial status, life expectancy is not affected directly. Issues such as overdose of medications or infections at a food tube site are examples of things that would be secondary to the status.

LGS is seen in approximately 4% of children with epilepsy, and is more common in males than in females. Usual onset is between the ages of three and five. Children can have no neurological problems prior diagnosis, or have other forms of epilepsy. West syndrome is diagnosed in 20% of patients before it evolves into LGS at about 2 years old.

No single cause of OS has been identified. In most cases, there is severe atrophy of both hemispheres of the brain. Less often, the root of the disorder is an underlying metabolic syndrome. Although it was initially published that no genetic connection had been established, several genes have since associated with Ohtahara syndrome. It can be associated with mutations in "ARX", "CDKL5", "SLC25A22", "STXBP1", "SPTAN1", "KCNQ2", "ARHGEF9", "PCDH19", "PNKP", "SCN2A", "PLCB1", "SCN8A", and likely others.

Treatment outlook is poor. Anticonvulsant drugs and glucocorticoid steroids may be used to try to control the seizures, but their effectiveness is limited. Most therapies are related to symptoms and day-to-day living.

The National Institute of Health Office and Rare Disease Research characterizes PCDH19 gene-related epilepsy as a rare disorder. Rare diseases, by definition, are diseases that affect fewer than 200,000 people in the United States. Since the mutation associated with PCDH19 gene-related epilepsy was only recently identified in 2008, the true incidence of the disease is generally unknown.

Although formal epidemiologic data is not available, results from diagnostic screening indicates that approximately 1 out of 10 girls who have seizure onset before five years of age may have PCDH19 gene mutations. Additionally, PCDH19 screening of several large cohorts of females with early onset febrile-related epilepsy has resulted in a rate of approximately 10% of mutation-positive individuals.

Seizures in cats are caused by various onsets. Cats can have reactive, primary (idiopathic) or secondary seizures. Idiopathic seizures are not as common in cats as in dogs however a recent study conducted showed that of 91 feline seizures, 25% were suspected to have idiopathic epilepsy. In the same group of 91 cats, 50% were secondary seizures and 20% reactive.

Ohtahara syndrome (OS), also known as early infantile epileptic encephalopathy with burst-suppression (EIEE), is a progressive epileptic encephalopathy. The syndrome is outwardly characterized by tonic spasms and partial seizures, and receives its more elaborate name from the pattern of burst activity on an electroencephalogram (EEG). It is an extremely debilitating progressive neurological disorder, involving intractable seizures and severe mental retardation. No single cause has been identified, although in many cases structural brain damage is present.

Benign familial infantile epilepsy (BFIE), also known as benign familial infantile seizures (BFIS) or benign familial infantile convulsions (BFIC) is an epilepsy syndrome. Affected children, who have no other health or developmental problems, develop seizures during infancy. These seizures have focal origin within the brain but may then spread to become generalised seizures. The seizures may occur several times a day, often grouped in clusters over one to three days followed by a gap of one to three months. Treatment with anticonvulsant drugs is not necessary but they are often prescribed and are effective at controlling the seizures. This form of epilepsy resolves after one or two years, and appears to be completely benign. The EEG of these children, between seizures, is normal. The brain appears normal on MRI scan.

A family history of epilepsy in infancy distinguishes this syndrome from the non-familial classification (see benign infantile epilepsy), though the latter may be simply sporadic cases of the same genetic mutations. The condition is inherited with an autosomal dominant transmission. There are several genes responsible for this syndrome, on chromosomes 2, 16 and 19. It is generally described as idiopathic, meaning that no other neurological condition is associated with it or causes it. However, there are some forms that are linked to neurological conditions. One variant known as infantile convulsions and choreoathetosis (ICCA) forms an association between BFIE and paroxysmal kinesigenic choreoathetosis and has been linked to the PRRT2 gene on chromosome 16. An association with some forms of familial hemiplegic migraine (FHM) has also been found. Benign familial infantile epilepsy is not genetically related to benign familial neonatal epilepsy (BFNE), which occurs in neonates. However, a variation with seizure onset between two days and seven months called "benign familial neonatal–infantile seizures" (BFNIS) has been described, which is due to a mutation in the SCN2A gene.

Consistent risk factors include:

- Severity of seizures, increased refractoriness of epilepsy and presence of generalized tonic-clonic seizures: the most consistent risk factor is an increased frequency of tonic–clonic seizures.

- Poor compliance. Lack of therapeutic levels of anti-epileptic drugs, non-adherence to treatment regimens, and frequent changes in regimens are risk factors for sudden death.

- Young age, and early age of seizures onset.

- Male gender

- Poly-therapy of epilepsy. It remains unclear whether this is an independent risk factor or a surrogate marker for severity of epilepsy.

- Being asleep during a seizure is likely to favour SUDEP occurrence.

People with epilepsy are at an increased risk of death. This increase is between 1.6 and 4.1 fold greater than that of the general population and is often related to: the underlying cause of the seizures, status epilepticus, suicide, trauma, and sudden unexpected death in epilepsy (SUDEP). Death from status epilepticus is primarily due to an underlying problem rather than missing doses of medications. The risk of suicide is increased between two and six times in those with epilepsy. The cause of this is unclear. SUDEP appears to be partly related to the frequency of generalized tonic-clonic seizures and accounts for about 15% of epilepsy related deaths. It is unclear how to decrease its risk. The greatest increase in mortality from epilepsy is among the elderly. Those with epilepsy due to an unknown cause have little increased risk. In the United Kingdom, it is estimated that 40–60% of deaths are possibly preventable. In the developing world, many deaths are due to untreated epilepsy leading to falls or status epilepticus.

Idiopathic epilepsy does not have a classification due to the fact there are no known causes of these seizures, however both reactive and symptomatic secondary epilepsy can be placed into classifications.

The number cases of PRES that occur each year is not known. It may be somewhat more common in females.

West syndrome is a triad of developmental delay, seizures termed infantile spasms, and EEG demonstrating a pattern termed hypsarrhythmia. Onset occurs between three months and two years, with peak onset between eight and 9 months. West syndrome may arise from idiopathic, symptomatic, or cryptogenic causes. The most common cause is tuberous sclerosis. The prognosis varies with the underlying cause. In general, most surviving patients remain with significant cognitive impairment and continuing seizures and may evolve to another eponymic syndrome, Lennox-Gastaut syndrome. It can be classified as idiopathic, syndromic, or cryptogenic depending on cause and can arise from both focal or generalized epileptic lesions.

Though the underlying cause of CBPS is unknown, it is thought to arise from improper migration of neuroblasts (neuronal stem cells) to the cerebral cortex in the embryonic brain. This causes the layers of the cerebral cortex to not form properly, and too many small folds (gyri) to form on the surface of the brain. This condition is called bilateral perisylvian polymicrogyria. The sulci, deep grooves on the brain, may also not form correctly. Cranial nerves are affected and cause muscle paralysis and spasms in the face and throat.

A 2008 study, found a relationship between the PCDH19 gene and early onset female seizures, with subsequent studies confirming the relationship.

PCDH19 gene-related epilepsy can arise as a single case in a family, due to a de novo error in cell replication, or it can be inherited. In a large series of cases in which inheritance was determined, half of the PCDH19 mutations occurred de novo, and half were inherited from fathers in good health, and who had no evidence of seizures or cognitive disorders.

Men and women can transmit the PCDH19 mutation, although females, but not males, usually, but not always, exhibit symptoms, which can be very mild. Females with a mutation have a 50% chance of having children who are carriers. Men have a 100% chance of transmitting the mutation to a daughter and 0% chance to a son.

Although males do not generally exhibit PCDH19 gene-related history such as cluster seizures, in a study involving four families with PCDH19 gene mutations, 5 of the fathers had obsessive and controlling tendencies. The linkage of chromosome Xq22.1 to PCDH19 gene-related epilepsy in females was confirmed in all of the families.

The inheritance pattern is very unusual, in that men that carry the PCDH19 gene mutation on their only X-chromosome are typically unaffected, except in rare instances of somatic mosaicism. Alternatively, approximately 90% of women, who have the mutation on one of their two X-chromosomes, exhibit symptoms. It has been suggested that the greater occurrence of PCDH19-epilepsy in females may relate to X-chromosome inactivation, through a hypothesized mechanism termed ‘‘cellular interference’’.

A 2011 study found instances where patients had PCDH19 mutation, but their parents did not. They found that "gonadal mosaicism” of a PCDH19 mutation in a parent is an important molecular mechanism associated with the inheritance of a mutated PCDH19 gene.

Congenital bilateral perisylvian syndrome (CBPS) is a rare neurological disease characterized by paralysis of certain facial muscles and epileptic seizures.

Febrile infection-related epilepsy syndrome (FIRES) is a form of epilepsy that affects children three to fifteen years old. A healthy child that may have been ill in the last few days or with a lingering fever goes into a state of continuous seizures. The seizures are resistant to seizure medications and treatments, though barbiturates may be administered. Medical diagnostic tests may initially return no clear diagnosis and may not detect any obvious swelling on the brain. The syndrome is very rare: it may only affect 1 in 1,000,000 children.

Many cases resolve within 1–2 weeks of controlling blood pressure and eliminating the inciting factor. However some cases may persist with permanent neurologic impairment in the form of visual changes and seizures among others. Though uncommon, death may occur with progressive swelling of the brain (cerebral edema), compression of the brainstem, increased intracranial pressure, or a bleed in the brain (intracerebral hemorrhage). PRES may recur in about 5-10% of cases; this occurs more commonly in cases precipitated by hypertension as opposed to other factors (medications, etc.).

Most people with PNES (75%) are women, with onset in the late teens to early twenties being typical.

Some studies have reported an elevated frequency of childhood abuse in people with PNES. However, others that have controlled for other demographic factors have failed to find a higher rate of reported childhood abuse than in a comparable groups with organic disease (usually epilepsy).

A number of studies have also reported a high incidence of abnormal personality traits or personality disorders in people with PNES such as borderline personality. However, again, when an appropriate control group is used, the incidence of such characteristics it not always higher in PNES than in similar illnesses arising due to organic disease (e.g., epilepsy).

Other risk factors for PNES include having a diagnosis of epilepsy, having recently had a head injury or recently undergone neurosurgery.

Early myoclonic encephalopathy (EME) is an epilepsy syndrome where myoclonic seizures develop in the neonatal period. After several months, the seizure pattern may develop to infantile spasms (West syndrome). Various genetic and metabolic disorders are responsible. The seizures are resistant to treatment. The neurology is very abnormal and patients often do not live beyond one year.

Cases of epilepsy may be organized into epilepsy syndromes by the specific features that are present. These features include the age at which seizures begin, the seizure types, and EEG findings, among others. Identifying an epilepsy syndrome is useful as it helps determine the underlying causes as well as what anti-seizure medication should be tried.

The ability to categorize a case of epilepsy into a specific syndrome occurs more often with children since the onset of seizures is commonly early. Less serious examples are benign rolandic epilepsy (2.8 per 100,000), childhood absence epilepsy (0.8 per 100,000) and juvenile myoclonic epilepsy (0.7 per 100,000). Severe syndromes with diffuse brain dysfunction caused, at least partly, by some aspect of epilepsy, are also referred to as epileptic encephalopathies. These are associated with frequent seizures that are resistant to treatment and severe cognitive dysfunction, for instance Lennox-Gastaut syndrome and West syndrome.

Epilepsies with onset in childhood are a complex group of diseases with a variety of causes and characteristics. Some people have no obvious underlying neurological problems or metabolic disturbances. They may be associated with variable degrees of intellectual disability, elements of autism, other mental disorders, and motor difficulties. Others have underlying inherited metabolic diseases, chromosomal abnormalities, specific eye, skin and nervous system features, or malformations of cortical development. Some of these epilepsies can be categorized into the traditional epilepsy syndromes. Furthermore, a variety of clinical syndromes exist of which the main feature is not epilepsy but which are associated with a higher risk of epilepsy. For instance between 1 and 10% of those with Down syndrome and 90% of those with Angelman syndrome have epilepsy.

In general, genetics is believed to play an important role in epilepsies by a number of mechanisms. Simple and complex modes of inheritance have been identified for some of them. However, extensive screening has failed to identify many single rare gene variants of large effect. In the epileptic encephalopathies, de novo mutagenesis appear to be an important mechanism. De novo means that a child is affected, but the parents do not have the mutation. De novo mutations occur in eggs and sperms or at a very early stage of embryonic development. In Dravet syndrome a single affected gene was identified.

Syndromes in which causes are not clearly identified are difficult to match with categories of the current classification of epilepsy. Categorization for these cases is made somewhat arbitrarily. The "idiopathic" (unknown cause) category of the 2011 classification includes syndromes in which the general clinical features and/or age specificity strongly point to a presumed genetic cause. Some childhood epilepsy syndromes are included in the unknown cause category in which the cause is presumed genetic, for instance benign rolandic epilepsy. Others are included in "symptomatic" despite a presumed genetic cause (in at least in some cases), for instance Lennox-Gastaut syndrome. Clinical syndromes in which epilepsy is not the main feature (e.g. Angelman syndrome) were categorized "symptomatic" but it was argued to include these within the category "idiopathic". Classification of epilepsies and particularly of epilepsy syndromes will change with advances in research.

The lack of generally recognized clinical recommendations available are a reflection of the dearth of data on the effectiveness of any particular clinical strategy, but on the basis of present evidence, the following may be relevant:

- Epileptic seizure control with the appropriate use of medication and lifestyle counseling is the focus of prevention.

- Reduction of stress, participation in physical exercises, and night supervision might minimize the risk of SUDEP.

- Knowledge of how to perform the appropriate first-aid responses to seizure by persons who live with epileptic people may prevent death.

- People associated with arrhythmias during seizures should be submitted to extensive cardiac investigation with a view to determining the indication for on-demand cardiac pacing.

- Successful epilepsy surgery may reduce the risk of SUDEP, but this depends on the outcome in terms of seizure control.

- The use of anti suffocation pillows have been advocated by some practitioners to improve respiration while sleeping, but their effectiveness remain unproven because experimental studies are lacking.

- Providing information to individuals and relatives about SUDEP is beneficial.