In the early stages, it can be difficult to distinguish progressive myoclonic epilepsy from benign idiopathic generalised epilepsies, such as juvenile myoclonic epilepsy. With PME, the initial effectiveness of anticonvulsant treatment diminishes as seizures become more frequent and neurological decline progresses. However, these can also be signs of anticonvulsant intoxication. The myoclonus in PME is usually severe and is the prominent seizure type.

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.

Myoclonic seizures involve brief involuntary muscle twitching, and may become frequent enough to be disabling. Tonic-clonic seizures have two phases: the tonic phase may last a few seconds and involves the muscles tensing, and may lead to the person falling down; the clonic phase involves a convulsion of rapidly alternating muscle tensing and relaxing. Neurological dysfunction includes difficulty coordinating muscle movements (ataxia) and a decline in cognitive ability (dementia).

The only sign of BFNE are seizures, generally tonic-clonic, which occur within the first week of life. Seizures often begin as apnea, cyanosis, and hypertonia and last less than 1 minute.

People with BFNE are not more likely to develop epileptic seizures later in life.

Benign neonatal seizures include two disorders benign idiopathic neonatal seizures and benign familial neonatal seizures. They are not classified as epilepsy. Anticonvulsants are not needed. And those affected do not develop epilepsy when they grow up.

Generalized seizures can be either absence seizures, myoclonic seizures, clonic seizures, tonic-clonic seizures or atonic seizures.

Generalized seizures occur in various seizure syndromes, including myoclonic epilepsy, familial neonatal convulsions, childhood absence epilepsy, absence epilepsy, infantile spasms (West's syndrome), Juvenile Myoclonic Epilepsy and Lennox-Gastaut syndrome.

Generalized epilepsy, also known as primary generalized epilepsy or idiopathic epilepsy, is a form of epilepsy characterised by generalised seizures with no apparent cause. Generalized seizures, as opposed to focal seizures, are a type of seizure that impairs consciousness and distorts the electrical activity of the whole or a larger portion of the brain (which can be seen, for example, on electroencephalography, EEG).

Generalized epilepsy is "primary" because the epilepsy is the originally diagnosed condition itself, as opposed to "secondary" epilepsy, which occurs as a symptom of a diagnosed condition.

The epileptic seizures which can be observed in infants with West syndrome fall into three categories, collectively known as infantile spasms. Typically, the following triad of attack types appears; while the three types usually appear simultaneously, they also can occur independently of each other:

- "Lightning attacks": Sudden, severe myoclonic convulsions of the entire body or several parts of the body in split seconds, and the legs in particular are bent (flexor muscle convulsions here are generally more severe than extensor ones).

- "Nodding attacks": Convulsions of the throat and neck flexor muscles, during which the chin is fitfully jerked towards the breast or the head is drawn inward.

- "Salaam or jackknife attacks": a flexor spasm with rapid bending of the head and torso forward and simultaneous raising and bending of the arms while partially drawing the hands together in front of the chest and/or flailing. If one imagined this act in slow motion, it would appear similar to the Muslim ceremonial greeting (Salaam), from which this type of attack derives its name.

Epileptic spasms, also known as infantile spasms, juvenile spasms, or West syndrome is an uncommon-to-rare epileptic disorder in infants, children and adults. It is named after the English physician, William James West (1793–1848), who first described it in an article published in The Lancet in 1841. The original case actually described his own son, James Edwin West (1840–1860). Other names for it are "generalized flexion epilepsy", "infantile epileptic encephalopathy", "infantile myoclonic encephalopathy", "jackknife convulsions", "massive myoclonia" and "Salaam spasms". The term "infantile spasms" can be used to describe the specific seizure manifestation in the syndrome, but is also used as a synonym for the syndrome itself. West syndrome in modern usage is the triad of infantile spasms, a pathognomonic EEG pattern (called hypsarrhythmia), and developmental regression – although the international definition requires only two out of these three elements.

The syndrome is age-related, generally occurring between the third and the twelfth month, generally manifesting around the fifth month. There are various causes. The syndrome is often caused by an organic brain dysfunction whose origins may be prenatal, perinatal (caused during birth) or postnatal.

Benign familial neonatal seizures (BFNS), formerly called benign familial neonatal convulsions (BFNC), is a rare autosomal dominant inherited form of seizures. It manifests in newborns, normally within the first 7 days of life, as tonic-clonic seizures. Infants are otherwise normal between attacks and develop without incident. Attacks normally spontaneously cease within the first 15 weeks of life. Lifetime susceptibility to seizures is increased, as 16% of those diagnosed with BFNE earlier in life will go on to have seizures versus a 2% lifetime risk for the general population. There are three known genetic causes of BFNE, two being the voltage-gated potassium channels KCNQ2 (BFNC1) and KCNQ3 (BFNC2) and the third being a chromosomal inversion (BFNC3). There is no obvious correlation between most of the known mutations and clinical variability seen in BFNE.

FHM signs overlap significantly with those of migraine with aura. In short, FHM is typified by migraine with aura associated with hemiparesis and, in FHM1, cerebellar degeneration. This cerebellar degeneration can result in episodic or progressive ataxia. FHM can also present with the same signs as benign familial infantile convulsions (BFIC) and alternating hemiplegia of childhood. Other symptoms are altered consciousness (in fact, some cases seem related to head trauma), gaze-evoked nystagmus and coma. Aura symptoms, such as numbness and blurring of vision, typically persist for 30–60 minutes, but can last for weeks and months. An attack resembles a stroke, but unlike a stroke, it resolves in time. These signs typically first manifest themselves in the first or second decade of life.

During generalized febrile seizures, the body will become stiff and the arms and legs will begin twitching. The child loses consciousness, although their eyes remain open. Breathing can be irregular. They may become incontinent (wet or soil themselves); they may also vomit or have increased secretions (foam at the mouth). The seizure normally lasts for less than five minutes. The child's temperature is usually greater than .

The specific and familial association of BIFE and PKC defines a novel clinical entity : the infantile convulsions and choreoathetosis syndrome. The first observation was made in four families where children were affected with nonfebrile convulsions at age 3–12 months.Partial epileptic seizures started with a psychomotor arrest and a deviation of the head and eyes to one side, followed inconstantly by unilateral jerks.In some cases, seizures generalized secondarily. None of the interictal electroencephalograms showed epileptiform abnormalities, and magnetic-resonance imaging were normal. These convulsions had a favorable outcome. At 5–8 years of age affected children developed abnormal movements. They presented with twisting movements of the hands of a reptilian type when stressed or embarrassed. They also developed jerky movements of the legs after running. Initially, abnormal movements were intermediate in speed between quick and slow, typical of paroxysmal choreoathetosis. Combinations of abnormal movements involving the arms, legs, trunk and occasionally the head were observed. The attacks lasted only a few minutes, occurring with a frequency of 5-30 episodes per day and were not accompanied by unconsciousness. In all patients, abnormal movements disappeared at 25–30 years of age without any treatment. Since the first report similar clinical presentations have been published which confirm the specificity of the ICCA syndrome.

A febrile seizure, also known as a fever fit or febrile convulsion, is a seizure associated with a high body temperature but without any serious underlying health issue. They most commonly occur in children between the ages of 6 months and 5 years. Most seizures are less than five minutes in duration and the child is completely back to normal within sixty minutes of the event.

Febrile seizures may run in families. The diagnosis involves verifying that there is not an infection of the brain, there are no metabolic problems, and there have not been prior seizures that have occurred without a fever. There are two types of febrile seizures: simple febrile seizures and complex febrile seizures. Simple febrile seizures involve an otherwise healthy child who has at most one tonic-clonic seizure lasting less than 15 minutes in a 24-hour period. Blood testing, imaging of the brain or an electroencephalogram (EEG) is typically not needed for the diagnosis. Examination to determine the source of the fever is recommended. In otherwise healthy looking children a lumbar puncture is not necessarily required.

Neither anti-seizure medication nor anti-fever medication are recommended in an effort to prevent further simple febrile seizures. In the few cases that last greater than five minutes a benzodiazepine such as lorazepam or midazolam may be used. Outcomes are generally excellent with similar academic achievements to other children and no change in the risk of death for those with simple seizures. There is tentative evidence that children have a slight increased risk of epilepsy at 2%. Febrile seizures affect two to five percent of children before the age of five. They are more common in boys than girls. After a single febrile seizure there is a 15 to 70% chance of another one.

The defining characteristic of BPT is a tilting of an infant’s head in recurrent episodes, for varying periods of time. Furthermore, the child’s trunk may bend in the same direction as the head, giving the baby an overall curved shape; this complaint is known as tortipelvis. In addition to this, the individual may also, but not necessarily, experience vomiting, pallor, ataxia, agitation, infantile migraine, unsteadiness of gait upon learning to walk, general malaise and nystagmus.

The periods in which the child’s head is tilted and other symptoms appear can last anywhere from a few minutes to a few weeks, with a frequency of anywhere from two per year to two per month.

Familial hemiplegic migraine (FHM) is an autosomal dominant type of hemiplegic migraine that typically includes weakness of half the body which can last for hours, days or weeks. It can be accompanied by other symptoms, such as ataxia, coma and paralysis. There is clinical overlap in some FHM patients with episodic ataxia type 2 and spinocerebellar ataxia type 6, benign familial infantile epilepsy, and alternating hemiplegia of childhood. There are 3 known loci for FHM. FHM1, which accounts for approximately 50% of FHM patients, is caused by mutations in a gene coding for the P/Q-type calcium channel α subunit, CACNA1A. FHM1 is also associated with cerebellar degeneration. FHM2, which accounts for <25% of FHM cases, is caused by mutations in the /-ATPase gene ATP1A2. FHM3 is a rare subtype of FHM and is caused by mutations in a sodium channel α-subunit coding gene, SCN1A. These three subtypes do not account for all cases of FHM, suggesting the existence of at least one other locus (FHM4). Many of the non-familial cases of hemiplegic migraine (sporadic hemiplegic migraine) are also caused by mutations at these loci. A fourth gene that has been associated with this condition is the proline rich transmembrane protein 2 (PRRT2) - an axonal protein associated with the exocytosis complex. A fifth gene associated with this condition is SLC4A4 which encodes the electrogenic NaHCO3cotransporter NBCe1.

There are also non-familial cases of hemiplegic migraine, termed sporadic hemiplegic migraine. These cases seem to have the same causes as the familial cases and represent de novo mutations. Sporadic cases are also clinically identical to familial cases with the exception of a lack of family history of attacks.

The classic presentation of Todd's paresis is a transient weakness of a hand, arm, or leg after focal seizure activity within that limb. The weakness may range in severity from mild to complete paralysis.

When seizures affect areas other than the motor cortex, other transient neurological deficits can take place. These include sensory changes if the sensory cortex is involved by the seizure, visual field defects if the occipital lobe is involved, and aphasia if speech, comprehension or conducting fibers are involved.

Postictal paresis (PP), although familiar to neurologists, has not been well-studied. One retrospective observational study evaluated 328 selected patients from ages 16 to 57 years who had prolonged video-electroencephalogram (EEG) monitoring for medically intractable epilepsy and focal seizure onset; those with nonepileptic seizures, status epilepticus, and Lennox-Gastaut syndrome were excluded. The following observations were made:

- PP occurred in 44 patients (13.4 percent)

- PP was always unilateral and always contralateral to the seizure focus

- The mean duration of PP was 174 seconds (range 11 seconds to 22 minutes)

Of all seizures followed by PP, the following features were noted:

- Obvious ictal motor activity was seen in 78 percent (Todd's paresis is more common after any clonic seizure activity)

- Very slight ictal motor activity was seen in 10 percent

- No ictal motor activity was seen in nearly 10 percent

- The most common ictal lateralizing sign was unilateral clonic activity in 56 percent

- Ictal dystonic posturing occurred in 48 percent

- Ictal limb immobility occurred in 25 percent

The results of this study are valuable because few other data exist on the frequency, duration, and seizure characteristics associated with PP. However, the study is likely biased by the inclusion only of patients with medically intractable seizures who had undergone video-EEG monitoring, and the results may not extrapolate to a general epilepsy population.

Other post-ictal neurological findings that do not involve activity of the area affected by the seizure have been described. They are thought to be caused by a different mechanism than Todd's paresis, and including paralysis of the contralateral limb, and rare genetic causes of hemiplegia and seizures.

Benign paroxysmal torticollis (BPT) is a rare medical disorder affecting infants.

Infantile convulsions and choreoathetosis (ICCA) syndrome is a neurological genetic disorder with an autosomal dominant mode of inheritance. It is characterized by the association of benign familial infantile epilepsy (BIFE) at age 3–12 months and later in life with paroxysmal kinesigenic choreoathetosis. The ICCA syndrome was first reported in 1997 in four French families from north-western France and provided the first genetic evidence for common mechanisms shared by benign infantile seizures and paroxysmal dyskinesia. The epileptic origin of PKC has long been a matter of debates and PD have been classified as reflex epilepsies.Indeed, attacks of PKC and epileptic seizures have several characteristics in common, they both are paroxysmal in presentation with a tendency to spontaneous remission, and a subset of PKC responds well to anticonvulsants. This genetic disease has been mapped to chromosome 16p-q12. More than 30 families with the clinical characteristics of ICCA syndrome have been described worldwide so far.

Paroxysmal kinesigenic choreathetosis (PKC) also called paroxysmal kinesigenic dyskinesia (PKD) is a hyperkinetic movement disorder characterized by attacks of involuntary movements, which are triggered by sudden voluntary movements. The number of attacks can increase during puberty and decrease in a person's 20s to 30s. Involuntary movements can take many forms such as ballism, chorea or dystonia and usually only affect one side of the body or one limb in particular. This rare disorder only affects about 1 in 150,000 people with PKD accounting for 86.8% of all the types of paroxysmal dyskinesias and occurs more often in males than females. There are two types of PKD, primary and secondary. Primary PKD can be further broken down into familial and sporadic. Familial PKD, which means the individual has a family history of the disorder, is more common, but sporadic cases are also seen. Secondary PKD can be caused by many other medical conditions such as multiple sclerosis (MS), stroke, pseudohypoparathyroidism, hypocalcemia, hypoglycemia, hyperglycemia, central nervous system trauma, or peripheral nervous system trauma. PKD has also been linked with infantile convulsions and choreoathetosis (ICCA) syndrome, in which patients have afebrile seizures during infancy (benign familial infantile epilepsy) and then develop paroxysmal choreoathetosis later in life. This phenomenon is actually quite common, with about 42% of individuals with PKD reporting a history of afebrile seizures as a child.

The most significant issue regarding the Todd's paresis is its differentiation from a stroke. The issue is further complicated by the fact that some strokes trigger a focal seizure during the acute phase. A Todd's paresis in this context may overestimate the extent of neurological deficit due to the vascular process itself resulting in erroneous decisions with regards to acute stroke therapy such as thrombolysis. For this reason a seizure during an acute stroke is generally accepted to be a relative contraindication to thrombolytic therapy, especially in the absence of documented cerebrovascular occlusion using vascular imaging techniques.

An infant with Todd's paresis does not necessarily preclude the diagnosis of a febrile convulsion. This view is as a result of a recent study that showed the incidence of Todd's paresis to be in 0.4% of infants that have been diagnosed with a febrile convulsion.

Paroxysmal kinesigenic dyskinesia is diagnosed using a strict set of guidelines. These criteria were studied and confirmed by Bruno et al. in a study of 121 individuals with PKD. The age at onset is between 1 and 20 years old. The attacks of involuntary movements last less than one minute and have a known trigger, usually a sudden voluntary movement. For example, if a PKD patient stands up or begins walking after being sedentary for a period of time, or a person goes from a walk to a run, it can trigger an attack. Persons with PKD do not lose consciousness during attacks and have a full memory of the entire attack. Lastly, people with the disorder have a good response to medication and are usually prescribed anticonvulsants. The study also found that patients with familial PKD exhibit symptoms that follow the diagnostic criteria closely, while sporadic PKD individuals may deviate slightly. Prior to criteria for diagnosis being set out, many patients with PKD were often diagnosed with some form of epilepsy. Many patients also experience an aura, similar to those experienced with epilepsy, preceding their attacks. Some patients describe it as a tingling sensation in the affected limb or “butterflies in their stomach.” Some individuals also have precipitants, such as stress and anxiety, that make it more likely for attacks to occur.

The above diagnostic criteria also set PKD apart from the other paroxysmal dyskinesias, which include paroxysmal nonkinesigenic dyskinesia (PNKD) and paroxysmal exercise-induced dyskinesia (PED). While PKD attacks last less than one minute, PNKD attacks last a few minutes to a few hours, and as the name suggests, the attacks do not occur because of a sudden voluntary movement like PKD. Additionally, PKD can almost always be managed with drug therapy, while PNKD is not as responsive to anticonvulsants. PED, on the other hand, separates itself from PKD in that it is caused by prolonged exercise. Attacks from PED will cease soon after exercise is stopped.

The physical manifestations of TSC are due to the formation of hamartia (malformed tissue such as the cortical tubers), hamartomas (benign growths such as facial angiofibroma and subependymal nodules), and very rarely, cancerous hamartoblastomas. The effect of these on the brain leads to neurological symptoms such as seizures, intellectual disability, developmental delay, and behavioral problems. Symptoms also include trouble in school and concentration problems.

Onset is usually confined to infancy and early childhood, with peak prevalence at 18–36 months. In rare cases, particularly where the child is severely mentally impaired, onset may extend to adolescence.

The classical symptoms of the syndrome are spasmodic torticollis and dystonia. Nodding and rotation of the head, neck extension, gurgling, writhing movements of the limbs, and severe hypotonia have also been noted.

Spasms may last for 1–3 minutes and may occur up to 10 times a day. Ingestion of food is often associated with occurrence of symptoms; this may result in reluctance to feed. Associated symptoms, such as epigastric discomfort, vomiting (which may involve blood) and abnormal eye movements have been reported. Clinical signs may also include anaemia.

About 50% of people with TSC have learning difficulties ranging from mild to significant, and studies have reported that between 25% and 61% of affected individuals meet the diagnostic criteria for autism, with an even higher proportion showing features of a broader pervasive developmental disorder. A 2008 study reported self-injurious behavior in 10% of people with TSC. Other behaviors and disabilities, such as ADHD, aggression, behavioral outbursts, and OCD can also occur. Lower IQ is associated with more brain involvement on MRI.

Three types of brain tumours may be associated with TSC:

- Giant cell astrocytoma: (grows and blocks the cerebrospinal fluid flow, leading to dilatation of ventricles causing headache and vomiting)

- Cortical tubers: after which the disease is named

- Subependymal nodules: form in the walls of ventricles

Classic intracranial manifestations of TSC include subependymal nodules and cortical/subcortical tubers.

The tubers are typically triangular in configuration, with the apex pointed towards the ventricles, and are thought to represent foci of abnormal neuronal migration. The T2 signal abnormalities may subside in adulthood, but will still be visible on histopathological analysis. On magnetic resonance imaging, TSC patients can exhibit other signs consistent with abnormal neuron migration such as radial white matter tracts hyperintense on T2WI and heterotopic gray matter.

Subependymal nodules are composed of abnormal, swollen glial cells and bizarre multinucleated cells which are indeterminate for glial or neuronal origin. Interposed neural tissue is not present. These nodules have a tendency to calcify as the patient ages. A nodule that markedly enhances and enlarges over time should be considered suspicious for transformation into a subependymal giant cell astrocytoma, which typically develops in the region of the foramen of Monro, in which case it is at risk of developing an obstructive hydrocephalus.

A variable degree of ventricular enlargement is seen, either obstructive (e.g. by a subependymal nodule in the region of the foramen of Monro) or idiopathic in nature.