The effects of myoclonus in an individual can vary depending on the form and the overall health of the individual. In severe cases, particularly those indicating an underlying disorder in the brain or nerves, movement can be extremely distorted and limit ability to normally function, such as in eating, talking, and walking. In these cases, treatment that is usually effective, such as clonazepam and sodium valproate, may instead cause adverse reaction to the drug, including increased tolerance and a greater need for increase in dosage. However, the prognosis for more simple forms of myoclonus in otherwise healthy individuals may be neutral, as the disease may cause few to no difficulties. Other times the disease starts simply, in one region of the body, and then spreads.

Research on myoclonus is supported through the National Institute of Neurological Disorders and Stroke (NINDS). The primary focus of research is on the role of neurotransmitters and receptors involved in the disease. Identifying whether or not abnormalities in these pathways cause myoclonus may help in efforts to develop drug treatments and diagnostic tests. Determining the extent that genetics play in these abnormalities may lead to potential treatments for their reversal, potentially correcting the loss of inhibition while enhancing mechanisms in the body that would compensate for their effects.

The diagnosis can be confirmed when the characteristic centrotemporal spikes are seen on electroencephalography (EEG). Typically, high-voltage spikes followed by slow waves are seen. Given the nocturnal activity, a sleep EEG can often be helpful. Technically, the label "benign" can only be confirmed if the child's development continues to be normal during follow-up. Neuroimaging, usually with an MRI scan, is only advised for cases with atypical presentation or atypical findings on clinical examination or EEG.

The disorder should be differentiated from several other conditions, especially centrotemporal spikes without seizures, centrotemporal spikes with local brain pathology, central spikes in Rett syndrome and fragile X syndrome, malignant Rolandic epilepsy, temporal lobe epilepsy and Landau-Kleffner syndrome.

The only currently available method to diagnose Unverricht–Lundborg disease is a genetic test to check for the presence of the mutated cystatin B gene. If this gene is present in an individual suspected of having the disease, it can be confirmed. However, genetic tests of this type are prohibitively expensive to perform, especially due to the rarity of ULD. The early symptoms of ULD are general and in many cases similar to other more common epilepsies, such as juvenile myoclonic epilepsy. For these reasons, ULD is generally one of the last options doctors explore when looking to diagnose patients exhibiting its symptoms. In most cases, a misdiagnosis is not detrimental to the patient, because many of the same medications are used to treat both ULD and whatever type of epilepsy the patient has been misdiagnosed with. However, there are a few epilepsy medications that increase the incidence of seizures and myoclonic jerks in patients with ULD, which can lead to an increase in the speed of progression, including phenytoin, fosphenytoin, sodium channel blockers, GABAergic drugs, gabapentin and pregabalin.

Other methods to diagnose Unverricht–Lundborg disease are currently being explored. While electroencephalogram (EEG) is useful in identifying or diagnosing other forms of epilepsy, the location of seizures in ULD is currently known to be generalized across the entire brain. Without a specific region to pinpoint, it is difficult to accurately distinguish an EEG reading from an individual with ULD from an individual with another type of epilepsy characterized by generalized brain seizures. However, with recent research linking ULD brain damage to the hippocampus, the usefulness of EEG as a diagnostic tool may increase.

Magnetic Resonance Imaging (MRI) is also often used during diagnosis of patients with epilepsy. While MRIs taken during the onset of the disease are generally similar to those of individuals without ULD, MRIs taken once the disease has progressed show characteristic damage, which may help to correct a misdiagnosis.

While ULD is a rare disease, the lack of well defined cases to study and the difficulty in confirming diagnosis provide strong evidence that this disease is likely under diagnosed.

Myoclonic epilepsy refers to a family of epilepsies that present with myoclonus. When myoclonic jerks are occasionally associated with abnormal brain wave activity, it can be categorized as myoclonic seizure. If the abnormal brain wave activity is persistent and results from ongoing seizures, then a diagnosis of myoclonic epilepsy may be considered.

To date, there is no single, universal treatment that has been found to cure myoclonus dystonia. However, there are several treatment methods that have been found to be effective for helping to reduce the symptoms associated with the syndrome.

Many drugs used to treat myoclonus dystonia do not have a significant impact individually, but when combined, can work on different brain mechanisms to best alleviate symptoms. The method of treatment used depends on the severity of the symptoms presented in the individual, and whether the underlying cause of the syndrome is known.

PME accounts for less than 1% of epilepsy cases at specialist centres. The incidence and prevalence of PME is unknown, but there are considerable geography and ethnic variations amongst the specific genetic disorders. One cause, Unverricht Lundborg Disease, has an incidence of at least 1:20,000 in Finland.

Unverricht–Lundborg disease is also known as EPM1, as it is a form of progressive myoclonic epilepsy (PME). Other progressive myoclonic epilepsies include myoclonus epilepsy and ragged red fibers (MERRF syndrome), Lafora disease (EPM2a or EMP2b), Neuronal ceroid lipofuscinosis (NCL) and sialidosis. Progressive myoclonic epilepsies generally constitute only a small percentage of epilepsy cases seen, and ULD is the most common form. While ULD can lead to an early death, it is considered to be the least severe form of progressive myoclonic epilepsy.

The prognosis for Rolandic seizures is invariably excellent, with probably less than 2% risk of developing absence seizures and less often GTCS in adult life.

Remission usually occurs within 2–4 years from onset and before the age of 16 years. The total number of seizures is low, the majority of patients having fewer than 10 seizures; 10–20% have just a single seizure. About 10–20% may have frequent seizures, but these also remit with age.

Children with Rolandic seizures may develop usually mild and reversible linguistic, cognitive and behavioural abnormalities during the active phase of the disease. These may be worse in children with onset of seizures before 8 years of age, high rate of occurrence and multifocal EEG spikes.

The development, social adaptation and occupations of adults with a previous history of Rolandic seizures were found normal.

Benign neonatal sleep myoclonus (BNSM) is the occurrence of myoclonus (jerky movements) during sleep. It is not associated with seizures.

Occurs in the first few weeks of life, usually resolves in first 2–3 months of life. Often worries parents because they appear like seizures, but they are not. Features that can help distinguish this condition from seizures include: The myoclonic movements only occur during sleep, when baby is woken up the myoclonic movements stop, normal EEG, normal neurological examination, normal developmental examination. The myoclonic jerks occur during non-REM sleep

A wide array of phenomena may resemble epileptic seizures, which may lead to people who do not have epilepsy being misdiagnosed. Indeed, a significant percentage of people initially diagnosed with epilepsy will later have this revised. In one study, the majority of children referred to a secondary clinic with "fits, faints and funny turns" did not have epilepsy, with syncope (fainting) as the most common alternative. In another study, 39% of children referred to a tertiary epilepsy centre did not have epilepsy, with staring episodes in mentally challenged children as the most common alternative. In adults, the figures are similar, with one study reporting a 26% rate of misdiagnosis.

Differentiation of a non-epileptic attack from an epileptic seizure includes the patient keeping their eyes closed and rarely causing themselves harm (both more common in non-epileptic attacks)

This is an autosomal recessive disorder in which the body is deficient in α-neuraminidase.

The International League Against Epilepsy (ILAE) define an epileptic seizure as "a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain." Epileptic seizures can occur in someone who does not have epilepsy – as a consequence of head injury, drug overdose, toxins, eclampsia or febrile convulsions, for example.

Medically, when used on its own, the term seizure implies an epileptic seizure. The lay use of this word can also include sudden attacks of illness, loss of control, spasm or stroke. Where the physician is uncertain as to the diagnosis, the medical term paroxysmal event and the lay terms spells, funny turns or attacks may be used.

Juvenile myoclonic epilepsy is responsible for 7% of cases of epilepsy. Seizures usually begin around puberty and usually have a genetic basis. Seizures can be stimulus-selective, with flashing lights being one of the most common triggers.

A detailed family history should be obtained from at least three generations. In particularly a history to determine if there has been any neonatal and childhood deaths: Also a way to determine if any one of the family members exhibit any of the features of the multi-system disease. Specifically if there has been a maternal inheritance, when the disease is transmitted to females only, or if there is a family member who experienced a multi system involvement such as: Brain condition that a family member has been record to have such asseizures, dystonia, ataxia, or stroke like episodes.The eyes with optic atrophy, the skeletal muscle where there has been a history of myalgia, weakness or ptosis. Also in the family history look for neuropathy and dysautonomia, or observe heart conditions such ascardiomyopathy. The patients history might also exhibit a problem in their kidney, such as proximal nephron dysfunction. An endocrine condition, for example diabetes and hypoparathyroidism. The patient might have also had gastrointestinal condition which could have been due to liver disease, episodes of nausea or vomiting. Multiple lipomas in the skin, sideroblastic anemia and pancytopenia in the metabolic system or short stature might all be examples of patients with possible symptoms of MERRF disease.

Treatment of primary dystonia is aimed at reducing symptoms such as involuntary movements, pain, contracture, embarrassment, and to restore normal posture and improve the patient’s function. This treatment is therefore not neuroprotective. According to the European Federation of Neurological Sciences and Movement Disorder Society, there is no evidence-based recommendation for treating primary dystonia with antidopaminergic or anticholinergic drugs although recommendations have been based on empirical evidence. Anticholinergic drugs prove to be most effective in treating generalized and segmental dystonia, especially if dose starts out low and increases gradually. Generalized dystonia has also been treated with such muscle relaxants as the benzodiazepines. Another muscle relaxant, baclofen, can help reduce spasticity seen in cerebral palsy such as dystonia in the leg and trunk. Treatment of secondary dystonia by administering levodopa in dopamine-responsive dystonia, copper chelation in Wilson’s disease, or stopping the administration of drugs that may induce dystonia have been proven effective in a small number of cases. Physical therapy has been used to improve posture and prevent contractures via braces and casting, although in some cases, immobilization of limbs can induce dystonia, which is by definition known as peripherally induced dystonia. There are not many clinical trials that show significant efficacy for particular drugs, so medical of dystonia must be planned on a case-by-case basis. Botulinum toxin B, or Myobloc, has been approved by the US Food and Drug Administration to treat cervical dystonia due to level A evidential support by the scientific community. Surgery known as GPi DBS (Globus Pallidus Pars Interna Deep Brain Stimulation) has come to be popular in treating phasic forms of dystonia, although cases involving posturing and tonic contractions have improved to a lesser extent with this surgery. A follow-up study has found that movement score improvements observed one year after the surgery was maintained after three years in 58% of the cases. It has also been proven effective in treating cervical and cranial-cervical dystonia.

Because OMS is so rare and occurs at an average age of 19 months (6 to 36 months), a diagnosis can be slow. Some cases have been diagnosed as having been caused by a virus. After a diagnosis of OMS is made, an associated neuroblastoma is discovered in half of cases, with median delay of 3 months.

The interictal EEG pattern is usually normal.

Treatment of tics present in conditions such as Tourette’s syndrome begins with patient, relative, teacher and peer education about the presentation of the tics. Sometimes, pharmacological treatment is unnecessary and tics can be reduced by behavioral therapy such as habit-reversal therapy and/or counseling. Often this route of treatment is difficult because it depends most heavily on patient compliance. Once pharmacological treatment is deemed most appropriate, lowest effective doses should be given first with gradual increases. The most effective drugs belong to the neuroleptic variety such as monoamine-depleting drugs and dopamine receptor-blocking drugs. Of the monoamine-depleting drugs, tetrabenazine is most powerful against tics and results in fewest side effects. A non-neuroleptic drug found to be safe and effective in treating tics is topiramate. Botulinum toxin injection in affected muscles can successfully treat tics; involuntary movements and vocalizations can be reduced, as well as life-threatening tics that have the potential of causing compressive myelopathy or radiculopathy. Surgical treatment for disabling Tourette’s syndrome has been proven effective in cases presenting with self-injury. Deep Brain Stimulation surgery targeting the globus pallidus, thalamus and other areas of the brain may be effective in treating involuntary and possibly life-threatening tics.

The diagnosis varies from individual to individual, each is evaluated and diagnosed according to their age, clinical phenotype and pressed inheritance pattern. If the Individual has been experiencing myoclonus the doctor will run a series of genetic studies to determine if its a mitochondrial disorder.

The molecular genetic studies are run to identify the reason of for the mutations underlying the mitochondrial dysfunction. This approach will avoid the need for a muscle biopsy or an exhaustive metabolic evaluation. After the sequencing the mitochondrial genomes, four points mutations in the genome can be identified which are associated with MERRF: A8344G, T8356C, G8361A, and G8363A. The point mutation A8344G is mostly associated with MERRF, in a study published by Paul Jose Lorenzoni from the Department of neurology at University of Panama stated that 80% of the patients with MERRF disease exhibited this point mutation. The remaining mutations only account for 10% of cases, and the remaining 10% of the patients with MERRF did not have an identifiable mutation in the mitochondrial DNA.

If a patient does not exhibit mitochondrial DNA mutations, there are other ways that they can be diagnosed with MERRF. They can go through computed tomography (CT) or magnetic resonance imaging (MRI).The classification for the severity of MERRF syndrome is difficult to distinguish since most individuals will exhibit multi-symptoms. For children with complex neurologic or multi-system involvement, as the one described below, is often necessary.

Between 10 and 30% of people who have status epilepticus die within 30 days. The great majority of these people have an underlying brain condition causing their status seizure such as brain tumor, brain infection, brain trauma, or stroke. However, people with diagnosed epilepsy who have a status seizure also have an increased risk of death if their condition is not stabilized quickly, their medication and sleep regimen adapted and adhered to, and stress and other stimulant (seizure trigger) levels controlled.

However, with optimal neurological care, adherence to the medication regimen, and a good prognosis (no other underlying uncontrolled brain or other organic disease), the person—even people who have been diagnosed with epilepsy—in otherwise good health can survive with minimal or no brain damage, and can decrease risk of death and even avoid future seizures.

Prevention of tardive dyskinesia is achieved by using the lowest effective dose of a neuroleptic for the shortest time. However, with diseases of chronic psychosis such as schizophrenia, this strategy must be balanced with the fact that increased dosages of neuroleptics are more beneficial in preventing recurrence of psychosis. If tardive dyskinesia is diagnosed, the causative drug should be discontinued. Tardive dyskinesia may persist after withdrawal of the drug for months, years or even permanently. Some studies suggest that physicians should consider using atypical antipsychotics as a substitute to typical antipsychotics for patients requiring medication. These agents are associated with fewer neuromotor side effects and a lower risk of developing tardive dyskinesia.

Recent studies have tested the use of melatonin, high dosage vitamins, and different antioxidants in concurrence with antipsychotic drugs (often used to treat schizophrenia) as a way of preventing and treating tardive dyskinesia. Although further research is needed, studies reported a much lower percentage of individuals developing tardive dyskinesia than the current prevalence rate for those taking antipsychotic drugs.

Currently there are no clinically established laboratory investigations available to predict prognosis or therapeutic response.

Tumors in children who develop OMS tend to be more mature, showing favorable histology and absence of n-myc oncogene amplification than similar tumors in children without symptoms of OMS. Involvement of local lymph nodes is common, but these children rarely have distant metastases and their prognosis, in terms of direct morbidity and mortality effects from the tumor, is excellent. The three-year survival rate for children with non-metastatic neuroblastoma and OMS was 100% according to Children’s Cancer Group data (gathered from 675 patients diagnosed between 1980 and 1994); three-year survival in comparable patients with OMS was 77%. Although the symptoms of OMS are typically steroid-responsive and recovery from acute symptoms of OMS can be quite good, children often suffer lifelong neurologic sequelae that impair motor, cognitive, language, and behavioral development.

Most children will experience a relapsing form of OMS, though a minority will have a monophasic course and may be more likely to recover without residual deficits. Viral infection may play a role in the reactivation of disease in some patients who had previously experienced remission, possibly by expanding the memory B cell population. Studies have generally asserted that 70-80% of children with OMS will have long-term neurologic, cognitive, behavioral, developmental, and academic impairment. Since neurologic and developmental difficulties have not been reported as a consequence of neuroblastoma or its treatment, it is thought that these are exclusively due to the immune mechanism underlying OMS.

One study concludes that: ""Patients with OMA and neuroblastoma have excellent survival but a high risk of neurologic sequelae. Favourable disease stage correlates with a higher risk for development of neurologic sequelae. The role of anti-neuronal antibodies in late sequelae of OMA needs further clarification"."

Another study states that: ""Residual behavioral, language, and cognitive problems occurred in the majority"."

Definitions vary, but currently it is defined as one continuous, unremitting seizure lasting longer than five minutes, or recurrent seizures without regaining consciousness between seizures for greater than five minutes. Previous definitions used a 30-minute time limit.

NCSE is believed to be under-diagnosed.

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.