Although essential tremor is often mild, people with severe tremor have difficulty performing many of their routine activities of daily living. ET is generally progressive in most cases (sometimes rapidly, sometimes very slowly), and can be disabling in severe cases.

An increased risk of tardive dyskinesia has been associated with smoking in some studies, although a negative study does exist. There seems to be a cigarette smoke-exposure-dependent risk for TD in antipsychotic-treated patients. Elderly patients are also at a heightened risk for developing TD, as are females and those with organic brain injuries or diabetes mellitus and those with the negative symptoms of schizophrenia. TD is also more common in those that experience acute neurological side effects from antipsychotic drug treatment. Racial discrepancies in TD rate also exist, with Africans and African Americans having higher rates of TD after exposure to antipsychotics. Certain genetic risk factors for TD have been identified including polymorphisms in the genes encoding the D, 5-HT and 5-HT receptors.

ET is one of the most common neurological diseases, with a prevalence of approximately 4% in persons age 40 and older and considerably higher among persons in their 60s, 70s, 80s, with an estimated 20% of individuals in their 90s and over. Aside from enhanced physiological tremor, it is the most common type of tremor and one of the most commonly observed movement disorders.

Two other types, primary ciliary dyskinesia and biliary dyskinesia, are caused by specific kinds of ineffective movement of the body, and are not movement disorders.

Spastic thrusting of hip area can occur in Sodemytopic Parkinson's.

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.

Surgery, such as the denervation of selected muscles, may also provide some relief; however, the destruction of nerves in the limbs or brain is not reversible and should be considered only in the most extreme cases. Recently, the procedure of deep brain stimulation (DBS) has proven successful in a number of cases of severe generalised dystonia. DBS as treatment for medication-refractory dystonia, on the other hand, may increase the risk of suicide in patients. However, reference data of patients without DBS therapy are lacking.

All PD associated subtypes have genetic contributions and are likely to run in a families genetic history due to dominant allele mutations. Mutations of identified genes have been leading areas of research in the study and treatment of paroxysmal dyskinesia. PKD, PNKD, and PED are classified as separate subtypes because they all have different presentations of symptoms, but also, because they are believed to have different pathologies.

Interestingly, studies on diseases that are similar in nature to PD have revealed insights into the causes of movement disorders. Hypnogenic paroxysmal dyskinesia is a form of epilepsy affecting the frontal lobe. Single genes have been identified on chromosomes 15, 20, and 21, which contribute to the pathology of these epilepsy disorders. Utilizing new knowledge about pathologies of related and similar disease can shed insight on the causal relationships in paroxysmal dyskinesia.

Paroxysmal Dyskinesia is not a fatal disease. Life can be extremely difficult with this disease depending on the severity. The prognosis of PD is extremely difficult to determine because the disease varies from person to person. The attacks for PKD can be reduced and managed with proper anticonvulsants, but there is no particular end in sight for any of the PD diseases. PKD has been described to cease for some patients after the age of 20, and two patients have reported to have a family history of the disease where PKD went into complete remission after the age of 23. With PNKD and PED, at this time, there is no proper way to determine an accurate prognosis.

Myoclonic dystonia or Myoclonus dystonia syndrome is a rare movement disorder that induces spontaneous muscle contraction causing abnormal posture. The prevalence of myoclonus dystonia has not been reported, however, this disorder falls under the umbrella of movement disorders which affect thousands worldwide. Myoclonus dystonia results from mutations in the SGCE gene coding for an integral membrane protein found in both neurons and muscle fibers. Those suffering from this disease exhibit symptoms of rapid, jerky movements of the upper limbs (myoclonus), as well as distortion of the body's orientation due to simultaneous activation of agonist and antagonist muscles (dystonia).

Myoclonus dystonia is caused by loss-of-function-mutations in the epsilon sarcoglycan gene (SGCE). The disease is dominantly inherited, however SGCE is an imprinted gene, so only the paternal allele is expressed. Therefore, children suffering from this disease inherit the mutation from the father. If the mutated allele is inherited from the mother, the child is not likely to exhibit symptoms.

While no cure has been found for myoclonus dystonia, treatment options are available to those suffering from the disease. Ethanol often ameliorates the symptoms well, and so the syndrome is also called "Alcohol-responsive dystonia". Alcohol may be substituted by benzodiazepines, such as clonazepam, which work through the same mechanism. Deep brain stimulation (DBS) is another viable option that can alleviate symptoms without the unwanted side effects of medications, and has been successful in treating other movement disorders.

A 1969 study of torsion dystonia patients found an average IQ 10 points higher than controls matched for age, sex and ethnic background.

"Primary dystonia" is suspected when the dystonia is the only sign and there is no identifiable cause or structural abnormality in the central nervous system. It is suspected to be caused by a pathology of the central nervous system, likely originating in those parts of the brain concerned with motor function, such as the basal ganglia, and the GABA (gamma-aminobutyric acid) producing Purkinje neurons. The precise cause of primary dystonia is unknown. In many cases it may involve some genetic predisposition towards the disorder combined with environmental conditions.

"Secondary dystonia" refers to dystonia brought on by some identified cause, such as head injury, drug side effect (e.g. tardive dystonia), or neurological disease (e.g. Wilson's disease).

Meningitis and encephalitis caused by viral, bacterial, and fungal infections of the brain have been associated with dystonia. The main mechanism is inflammation of the blood vessels, causing restriction of blood flow to the basal ganglia. Other mechanisms include direct nerve injury by the organism or a toxin, or autoimmune mechanisms.

Environmental and task-related factors are suspected to trigger the development of focal dystonias because they appear disproportionately in individuals who perform high precision hand movements such as musicians, engineers, architects, and artists. Chlorpromazine can also cause dystonia, which can be often misjudged as a seizure.

Neuroleptic drugs often cause dystonia, including oculogyric crisis.

Misfunction of the sodium-potassium pump may be a factor in some dystonias. The - pump has been shown to control and set the intrinsic activity mode of cerebellar Purkinje neurons. This suggests that the pump might not simply be a homeostatic, "housekeeping" molecule for ionic gradients; but could be a computational element in the cerebellum and the brain. Indeed, an ouabain block of - pumps in the cerebellum of a live mouse results in it displaying ataxia and dystonia. Ataxia is observed for lower ouabain concentrations, dystonia is observed at higher ouabain concentrations. A mutation in the - pump (ATP1A3 gene) can cause rapid onset dystonia parkinsonism. The parkinsonism aspect of this disease is thought to be attributable to malfunctioning - pumps in the basal ganglia; the dystonia aspect is thought to be attributable to malfunctioning - pumps in the cerebellum (that act to corrupt its input to the basal ganglia) possibly in Purkinje neurons.

Cerebellum issues causing dystonia is described by Filip et al. 2013: "Although dystonia has traditionally been regarded as a basal ganglia dysfunction, recent provocative evidence has emerged of cerebellar involvement in the pathophysiology of this enigmatic disease. It has been suggested that the cerebellum plays an important role in dystonia etiology, from neuroanatomical research of complex networks showing that the cerebellum is connected to a wide range of other central nervous system structures involved in movement control to animal models indicating that signs of dystonia are due to cerebellum dysfunction and completely disappear after cerebellectomy, and finally to clinical observations in secondary dystonia patients with various types of cerebellar lesions. It is proposed that dystonia is a large-scale dysfunction, involving not only cortico-basal ganglia-thalamo-cortical pathways, but the cortico-ponto-cerebello-thalamo-cortical loop as well. Even in the absence of traditional "cerebellar signs" in most dystonia patients, there are more subtle indications of cerebellar dysfunction. It is clear that as long as the cerebellum's role in dystonia genesis remains unexamined, it will be difficult to significantly improve the current standards of dystonia treatment or to provide curative treatment."

Acute dystonia is a sustained muscle contraction that sometimes appears soon after administration of antipsychotic medications. Any muscle in the body may be affected, including the jaw, tongue, throat, arms, or legs. When the throat muscles are involved, this type of dystonia is called an acute laryngospasm and is a medical emergency because it can impair breathing. Older antipsychotics such as Haloperidol or Fluphenazine are more likely to cause acute dystonia than newer agents. Giving high doses of antipsychotics by injection also increases the risk of developing acute dystonia.

Methamphetamine, other amphetamines and dopaminergic stimulants including cocaine and pemoline can produce choreoathetoid dyskinesias; the prevalence, time-frame and prognosis are not well established. Amphetamines also cause a dramatic increase in choreoathetoid symptoms in patients with underlying chorea such as Sydenham’s, Huntington’s, and Lupus. Long-term use of amphetamines may increase the risk of Parkinson's disease (PD): in one retrospective study with over 40,000 participants it was concluded that amphetamine abusers generally had a 200% higher chance of developing PD versus those with no history of abuse; the risk was much higher in women, almost 400%. There remains some controversy as of 2017.

Levodopa-induced dyskinesia (LID) is evident in patients with Parkinson's disease who have been on levodopa () for prolonged periods of time. LID commonly first appears in the foot, on the most affected side of the body. There are three main types that can be classified on the basis of their course and clinical presentation following an oral dose of :

- Off-period dystonia – correlated to the akinesia that occurs before the full effect of sets in, when the plasma levels of are low. In general, it occurs as painful spasms in the foot. Patients respond to therapy.

- Diphasic dyskinesia – occurs when plasma L-DOPA levels are rising or falling. This form occurs primarily in the lower limbs (though they can happen elsewhere) and is usually dystonic (characterized by apparent rigidity within muscles or groups thereof) or (characterized by involuntary movement of muscles) and will not respond to dosage reductions.

- Peak-dose dyskinesia – the most common form of levodopa-induced dyskinesia; it correlates with the plateau plasma level. This type usually involves the upper limbs more (but could also affect the head, trunk and respiratory muscles), is choreic (of chorea), and less disabling. Patients will respond to reduction but may be accompanied by deterioration of parkinsonism. Peak-dose L-DOPA-induced dyskinesia has been suggested to be associated with cortical dysregulation of dopamine signaling.

Pisa syndrome is predominantly caused by a prolonged administration or an overly dosed administration of antipsychotic drugs. Although antipsychotic drugs are known to be the main drugs that are concerned with this syndrome, several other drugs are reported to have caused the syndrome as well. Certain antidepressants, psychoactive drugs, and antiemetics have also been found to cause Pisa syndrome in patients.

Drugs found to have caused Pisa Syndrome:

- Atypical antipsychotic drugs- ex. clozapine, aripiprazole

- Tricyclic antidepressants- ex. clomipramine

- Psychoactive drugs

- Antiemetic drugs

- Cholinesterase inhibitors

- Galantamine

Based on the drugs that caused Pisa syndrome, it has been implicated that the syndrome may be due to a dopaminergic-cholinergic imbalance or a serotonergic or noradrenergic dysfunction. For the development of Pisa syndrome that cannot be alleviated by anticholinergic drugs, it has been considered that asymmetric brain functions or neural transmission may be the underlying mechanism. How these drugs interact with the biochemistry of the brain to cause the syndrome is unknown and a topic of current research.

Extrapyramidal symptoms are most commonly caused by typical antipsychotic drugs that antagonize dopamine D2 receptors. The most common typical antipsychotics associated with EPS are haloperidol and fluphenazine. Atypical antipsychotics have lower D2 receptor affinity or higher serotonin 5-HT2A receptor affinity which lead to lower rates of EPS. However, some research has shown that atypical antipsychotics are just as likely as conventional antipsychotics to cause EPS.

Other anti-dopaminergic drugs, like the antiemetic metoclopramide, can also result in extrapyramidal side effects. Short and long-term use of antidepressants such as selective serotonin reuptake inhibitors (SSRI), serotonin-norepinephrine reuptake inhibitors (SNRI), and norepinephrine-dopamine reuptake inhibitors (NDRI) have also resulted in EPS. Specifically, duloxetine, sertraline, escitalopram, fluoxetine, and bupropion have been linked to the induction of EPS. Other causes of extrapyramidal symptoms can include brain damage and meningitis.

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.

There are very few reported cases of PED, there are approximately 20 reported sporadic cases of PED and 9 PED families but there is some dispute on the exact number of cases. In addition it appears that PED becomes less severe with aging. Prior to onset of a PED episode some patients reported onset of symptoms including sweating, pallor, and hyperventilation. In brain scans it was observed that patients suffering form frequent PEDs there was increased metabolism in the putamen of the brain and decreased metabolism in the frontal lobe. Another study using subtraction single photon emission computed tomographic (SPECT) imaging technique which was coregistered with an MRI on a patient presented with PED symptoms showed increased cerebral perfusion in the primary somatosensory cortex area, and a mild increase in the region of the primary motor cortex and cerebellum. While all these correlations are not fully understand as to what exactly is happening in the brain it provides areas of interest to study further to hopefully understand PED more fully.

Anticholinergic drugs have been reported to be extremely effective in 40% of the patients with the Pisa syndrome. Patients with Pisa syndrome that is resistant to anticholinergic drugs is mostly resolved by the reduction of the administration of the antipsychotic drugs as previously mentioned. While the specific pathology underlying idiopathic Pisa syndrome is unknown, the administration of anticholinergic drugs has provided resolution in known cases.

The medical treatment of essential tremor at the Movement Disorders Clinic at Baylor College of Medicine begins with minimizing stress and tremorgenic drugs along with recommending a restricted intake of beverages containing caffeine as a precaution, although caffeine has not been shown to significantly intensify the presentation of essential tremor. Alcohol amounting to a blood concentration of only 0.3% has been shown to reduce the amplitude of essential tremor in two-thirds of patients; for this reason it may be used as a prophylactic treatment before events during which one would be embarrassed by the tremor presenting itself. Using alcohol regularly and/or in excess to treat tremors is highly unadvisable, as there is a purported correlation between tremor and alcoholism. Alcohol is thought to stabilize neuronal membranes via potentiation of GABA receptor-mediated chloride influx. It has been demonstrated in essential tremor animal models that the food additive 1-octanol suppresses tremors induced by harmaline, and decreases the amplitude of essential tremor for about 90 minutes.

Two of the most valuable drug treatments for essential tremor are propranolol, a beta blocker, and primidone, an anticonvulsant. Propranolol is much more effective for hand tremor than head and voice tremor. Some beta-adrenergic blockers (beta blockers) are not lipid-soluble and therefore cannot cross the blood–brain barrier (propranolol being an exception), but can still act against tremors; this indicates that this drug’s mechanism of therapy may be influenced by peripheral beta-adrenergic receptors. Primidone’s mechanism of tremor prevention has been shown significantly in controlled clinical studies. The benzodiazepine drugs such as diazepam and barbiturates have been shown to reduce presentation of several types of tremor, including the essential variety. Controlled clinical trials of gabapentin yielded mixed results in efficacy against essential tremor while topiramate was shown to be effective in a larger double-blind controlled study, resulting in both lower Fahn-Tolosa-Marin tremor scale ratings and better function and disability as compared to placebo.

It has been shown in two double-blind controlled studies that injection of botulinum toxin into muscles used to produce oscillatory movements of essential tremors, such as forearm, wrist and finger flexors, may decrease the amplitude of hand tremor for approximately three months and that injections of the toxin may reduce essential tremor presenting in the head and voice. The toxin also may help tremor causing difficulty in writing, although properly adapted writing devices may be more efficient. Due to high incidence of side effects, use of botulinum toxin has only received a C level of support from the scientific community.

Deep brain stimulation toward the ventral intermediate nucleus of the thalamus and potentially the subthalamic nucleus and caudal zona incerta nucleus have been shown to reduce tremor in numerous studies. That toward the ventral intermediate nucleus of the thalamus has been shown to reduce contralateral and some ipsilateral tremor along with tremors of the cerebellar outflow, head, resting state and those related to hand tasks; however, the treatment has been shown to induce difficulty articulating thoughts (dysarthria), and loss of coordination and balance in long-term studies. Motor cortex stimulation is another option shown to be viable in numerous clinical trials.

In most cases, PED is familial, but can also be sporadic. In familial cases, pedigrees examined have shown PED to be an autosomal-dominant inheritance trait. PED also has been associated with Parkinson's disease, epilepsy and migraines, although the exact relationship between these is unknown.

A suspected contributor to familial PED is a mutation in the GLUT1 gene, SLC2A1, which codes for the transporter GLUT1, a protein responsible for glucose entry across the blood–brain barrier. It is not thought that the mutation causes a complete loss of function of the protein but rather only slightly reduces the transporter's activity. In a study of PED patients, a median CSF/blood glucose ratio of .52 compared to a normal .60 was found. In addition, reduced glucose uptake by mutated transporters compared with wild-type in Xenopus oocytes confirmed a pathogenic role of these mutations.

Another recent study was performed to continue to look at the possible connection between PED and mutations on the SLC2A1 gene which codes for the GLUT1 transporter. While PED can occur in isolation it was also noted that it occurs in association with epilepsy as well. In this study the genetics of a five-generation family with history of PED and epilepsy were evaluated. From the results it was noted that most of the mutations were due to frameshift and missense mutations. When looking at homologous GLUT1 transporters in other species it was noted that serine (position 95), valine (position 140), and asparagine (position 317) were highly conserved and therefore mutations in these residues would most likely be pathogenic. Therefore, these are areas of interest when looking at what could lead to PED.All mutations that were observed appeared to only affect the ability of GLUT1 to transport glucose and not the ability for it to be inserted in the membrane. The observed maximum transport velocity of glucose was reduced anywhere from 3 to 10 fold.

A study was performed to determine if the mutation known for the PNKD locus on chromosome 2q33-35 was the cause of PED. In addition, other loci were observed such as the familial hemiplegic migraine (FHM) locus on chromosome 19p, or the familial infantile convulsions and paroxysmal choreoathetosis (ICCA). All three of these suspected regions were found to not contain any mutations, and were therefore ruled out as possible candidates for a cause of PED.

DRPLA is a rare trinucleotide repeat disorder (polyglutamine disease) that can be juvenile-onset ( 40 years). Late adult-onset DRPLA is characterized by ataxia, choreoathetosis and dementia. Early adult-onset DRPLA also includes seizures and myoclonus. Juvenile-onset DRPLA presents with ataxia and symptoms consistent with progressive myoclonus epilepsy

(myoclonus, multiple seizure types and dementia). Other symptoms that have been described include cervical dystonia, corneal endothelial degeneration autism, and surgery-resistant obstructive sleep apnea.

This condition is very rare, only affecting one in two million people. It is more common in females than in males. There are several hundred cases in the United States, 25 known cases in the United Kingdom, and less than that in Australia and New Zealand.

Anticholinergic drugs are used to control neuroleptic-induced EPS, although akathisia may require beta blockers or even benzodiazepines. If the EPS are induced by an antipsychotic, EPS may be reduced by dose titration or by switching to an atypical antipsychotic, such as aripiprazole, ziprasidone, quetiapine, olanzapine, risperidone, or clozapine. These medications possess an additional mode of action that is believed to negate their effect on the nigrostriatal pathway, which means they are associated with fewer extrapyramidal side-effects than "conventional" antipsychotics (chlorpromazine, haloperidol, etc.), although some research has shown that second generation neuroleptics cause EPS at the same rate as the first generation drugs.

Commonly used medications for EPS are anticholinergic agents such as benztropine (Cogentin), diphenhydramine (Benadryl), and trihexyphenidyl (Artane). Another common course of treatment includes dopamine agonist agents such as pramipexole. These medications reverse the symptoms of extrapyramidal side effects caused by antipsychotics or other drugs that either directly or indirectly inhibit dopaminergic neurotransmission.

Studies are yet to be undertaken on the optimum dosage of the causative drugs to reduce their side effects (extrapyramidal symptoms (EPS)).

When other conditions lead to spasmodic torticollis, it is said that the spasmodic torticollis is secondary. A variety of conditions can cause brain injury, from external factors to diseases. These conditions are listed below:

- Perinatal (during birth) cerebral injury

- Kernicterus

- Cerebrovascular diseases

- Drug induced

- Central nervous system tumor

- Peripheral or central trauma

- Infectious or post infectious encephalopathies

- Toxins

- Metabolic

- Paraneoplastic syndromes

- Central pontine myelinolysis

Secondary spasmodic torticollis is diagnosed when any of the following are present: history of exogenous insult or exposure, neurological abnormalities other than dystonia, abnormalities on brain imaging, particularly in the basal ganglia.

The disease is more commonly found amongst Ashkenazi Jews. The occurrence of torsion dystonia in the Ashkenazi Jewish population as stated by the Department of Epidemiology and Public Health of Yale University School of Medicine in New Haven, CT; "Reports dating to the beginning of this century describe Ashkenazi Jewish (AJ) families with multiple cases of ITD either in siblings (Schwalbe 1908; Bernstein 1912; Abrahamson 1920) or in parents and offspring (Wechsler and Brock 1922; Mankowsky and Czerny 1929; Regensberg 1930). The first comprehensive evaluation of the mode of inheritance of ITD in Jewish and non-Jewish families was described by Zeman and Dyken (1967), who concluded that the disorder was inherited as an autosomal dominant with incomplete penetrance in both populations. Although they concluded that the gene frequency was higher in the AJ population than in non-Jews, no difference in mode of inheritance or disease mechanism was construed."

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.