Rapid-onset dystonia parkinsonism

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Rapid-onset dystonia parkinsonism (sometimes referred to as RDP) is a rare movement disorder. "Rapid-onset" refers to the abrupt appearance of signs and symptoms over a period of hours to days. Dystonia is a condition characterized by involuntary, sustained muscle contractions. Parkinsonism can include tremors, unusually slow movement (bradykinesia), rigidity, an inability to hold the body upright and balanced (postural instability), and a shuffling walk that can cause falls.

Rapid-onset dystonia parkinsonism causes movement abnormalities that can make it difficult to walk, talk, and carry out other activities of daily life. In people with this disorder, dystonia affects the arms and legs, causing muscle cramping and spasms. Facial muscles are often affected, resulting in problems with speech and swallowing. People with rapid-onset dystonia and parkinsonism may also have headaches; seizures; a distorted view of reality (psychosis); or difficulty processing, learning, and remembering information (cognitive impairment).

The movement abnormalities associated with rapid-onset dystonia parkinsonism tend to begin near the top of the body and move downward. They affect the facial muscles first, then the arms, and finally the legs.

The signs and symptoms of rapid-onset dystonia parkinsonism most commonly appear in adolescence or young adulthood. In some affected individuals, signs and symptoms can be triggered by an infection, physical stress (such as prolonged exercise), emotional stress, or alcohol consumption. The signs and symptoms tend to stabilize within about a month, but they typically do not improve much after that. In some people with this condition, the movement abnormalities abruptly worsen during a second episode several years later.

Some people with rapid-onset dystonia parkinsonism have been diagnosed with anxiety, social phobias, depression, and seizures. It is unclear whether these disorders are related to the genetic changes that cause rapid-onset dystonia parkinsonism.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

Rapid-onset dystonia parkinsonism is caused by variants (also called mutations) in the ATP1A3 gene. This gene provides instructions for making one part of a larger protein called Na+/K+ ATPase, also known as the sodium pump. This protein is critical for the normal function of nerve cells (neurons) in the brain. It transports charged atoms (ions) into and out of neurons, which is an essential part of the signaling process that controls muscle movement.

Variants in the ATP1A3 gene reduce activity of the Na+/K+ ATPase or make the protein unstable. Studies suggest that the defective protein is unable to transport ions normally, which disrupts the electrical activity of neurons in the brain. However, it is unclear how a malfunctioning Na+/K+ ATPase causes the movement abnormalities characteristic of rapid-onset dystonia parkinsonism.

The signs and symptoms of rapid-onset dystonia parkinsonism can occur in people who do not have variants in the ATP1A3 gene. The genetic cause of the disorder is unknown in these individuals. Researchers believe that a variant in at least one other gene, which has not been identified, can cause this disorder.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person inherits the variant from one affected parent. Other cases result from new (de novo) variants in the gene that occur during the formation of reproductive cells (eggs or sperm) in an affected individual's parent or during early embryonic development. These affected individuals have no history of the disorder in their family.

Not everyone who has an ATP1A3 gene variant will develop the signs and symptoms of rapid-onset dystonia parkinsonism. It is unclear why some people with a gene variant develop movement abnormalities while others do not.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Rapid-onset dystonia parkinsonism appears to be a rare disorder, although its exact prevalence is unknown. It has been diagnosed in individuals and families from the United States, Europe, and Korea.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Bradykinesia · Frequent (79-30%)

Bradykinesia literally means slow movement, and is used clinically to denote a slowness in the execution of movement (in contrast to hypokinesia, which is used to refer to slowness in the initiation of movement).

Craniofacial dystonia · Frequent (79-30%)

A form of focal dystonia affecting the face and especially the jaw that is induced by the act of speaking. It is an involuntary contraction of the masticatory muscles, resulting in dysarthria or dysphagia.

Drooling · Frequent (79-30%)

Drooling is the overflowing of saliva from the mouth.

Dysarthria · Frequent (79-30%)

Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.

Dysphagia · Frequent (79-30%)

Difficulty in swallowing.

Gait ataxia · Frequent (79-30%)

A type of ataxia characterized by the impairment of the ability to coordinate the movements required for normal walking. Gait ataxia is characteirzed by a wide-based staggering gait with a tendency to fall.

Hypomimic face · Frequent (79-30%)

A reduced degree of motion of the muscles beneath the skin of the face, often associated with reduced facial crease formation.

Limb dystonia · Frequent (79-30%)

A type of dystonia (abnormally increased muscular tone causing fixed abnormal postures) that affects muscles of the limbs.

Other findings in the same source

From: Orphanet

Additional reported features include Motor delay (Frequent (79-30%)); Mutism (Frequent (79-30%)); Parkinsonism (Frequent (79-30%)); Postural instability (Frequent (79-30%)); Torticollis (Frequent (79-30%)); Anxiety (Occasional (29-5%)); Cerebellar atrophy (Occasional (29-5%)); Depression (Occasional (29-5%)); Emotional lability (Occasional (29-5%)); Resting tremor (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Rapid-onset dystonia parkinsonism is Neurology, with a neurologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which nervous-system findings help explain the symptoms?
• Would an assessment of walking, communication or daily function be helpful?
• Are rehabilitation or other specialist services relevant?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Rapid-onset dystonia parkinsonism. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.