Hyperkinetic syndrome: what is it?

Hyperkinesias are involuntary, excessive movements that occur when the basal ganglia and associated cortical-subcortical networks are disrupted. These include tremor, dystonia, chorea, myoclonus, and tic disorders, each with its own causes, symptoms, and treatment approaches. Correctly recognizing the phenomenology is the first step to an accurate diagnosis. [1]

In parallel, "hyperkinetic disorder" exists as a former term for attention-deficit/hyperactivity disorder in children in the International Classification of Diseases, Tenth Revision. In the International Classification of Diseases, Eleventh Revision, this diagnosis is called "attention-deficit/hyperactivity disorder" and does not refer to motor hyperkinesias. It is important not to confuse these different clinical categories. [2]

Another source of confusion is outdated concepts such as "hyperkinetic cardiac syndrome" or "vegetative-vascular dystonia." Modern cardiology uses the terms "high cardiac output" and "high-output heart failure," which have specific causes such as thyrotoxicosis or anemia and are confirmed by objective hemodynamics. [3]

In the following, I will sequentially analyze the codes for two editions of the International Classification of Diseases, epidemiology, causes and risk factors, pathogenesis, symptoms, classification and forms, complications, indications for consulting a doctor, diagnosis, differential diagnosis, modern treatment, prevention, prognosis and answers to frequently asked questions.

Code according to ICD-10 and ICD-11

In the International Classification of Diseases, Tenth Revision, codes for motor hyperkinesias are distributed under the section "Extrapyramidal and other movement disorders." Thus, tremor has the code G25.0, dystonia - G24, Huntington's chorea - G10, tic disorders - F95, and "hyperkinetic disorders" as a synonym for attention deficit hyperactivity disorder - F90. [5]

In the International Classification of Diseases, Eleventh Revision, motor hyperkinesias are structured in the "Movement Disorders" block: disorders associated with tremor are grouped 8A04, dystonic disorders - 8A02, choreic - 8A01, tic - 8A05, myoclonic - 8A06. Attention deficit hyperactivity disorder is located in the neurodevelopmental section and is coded 6A05 with presentation clarifications. [6]

Table 1. Correspondence between the main clinical entities and codes

Clinical essence	ICD-10	ICD-11
Essential tremor	G25.0	8A04 Tremor-related disorders
Dystonia	G24.x	8A02 Dystonic disorders
Huntington's chorea	G10	8A01 Choreic disorders; genetically confirmed Huntington's disease
Tics and Tourette syndrome	F95.x	8A05 Tic disorders
Attention deficit hyperactivity disorder	F90.x	6A05 Attention deficit hyperactivity disorder

A note on terminology. In everyday speech, "hyperkinetic syndrome" can mean various things, but in coding, it is important to choose a precise nosology rather than an umbrella term, otherwise, diagnosis, routing, and statistics will suffer.

Epidemiology

Essential tremor is one of the most common motor hyperkinesias. According to meta-analyses, its prevalence ranges from approximately 0.3 percent to over 1 percent in the general population, increasing in the elderly. This makes tremor a key nosology for primary care and neurologists. [8]

The prevalence of primary dystonia, according to pooled estimates, is approximately 16 cases per 100,000 population, with rates varying depending on study design and dystonia phenotype. Significant regional differences and underreporting of mild forms are observed. [9]

Tourette syndrome and tic disorders are most often diagnosed in childhood. Current estimates put the prevalence of Tourette syndrome in the pediatric population at approximately 0.5 percent, while combined estimates for the broader group of tic disorders put it at up to 1 in 162 children. [10]

Attention deficit hyperactivity disorder (ADHD) occurs in approximately 7.6 percent of children and 5.6 percent of adolescents in population studies, and persists in a significant proportion of adults, accounting for approximately 3 percent by conservative estimates. It is a distinct neurodevelopmental disorder and is not related to motor hyperkinesias. [11]

Table 2. Prevalence estimates (population benchmarks)

Essence	Approximate prevalence
Essential tremor	0.3-1.3 percent; higher after age 65
Primary dystonia	about 16 per 100,000
Tourette syndrome	about 0.5 percent in children
Tic disorders in general	up to 1 in 162 children
Attention deficit hyperactivity disorder	5.6-7.6 percent in children and adolescents; about 3 percent in adults

Reasons

Hyperkinetic movement disorders can be primary, meaning without an identifiable structural cause, as in essential tremor or isolated focal dystonia, or secondary, when hyperkinesis is caused by a metabolic, toxic, infectious, autoimmune, or genetic process. The key goal for the clinician is to recognize reversible and potentially treatable causes. [12]

Tics and Tourette syndrome develop against a background of genetically determined dysregulation of the cortico-striatal-thalamo-cortical circuits, with the influence of neurotransmitter systems, primarily dopamine. Comorbid conditions are often present, including obsessive-compulsive and anxiety disorders, and attention deficit disorder. [13]

Chorea can be a consequence of Huntington's disease, autoimmune processes, drug side effects, and metabolic disorders. Huntington's chorea is characterized by dominant inheritance with expanded repeats in the huntingtin gene. [14]

Attention deficit hyperactivity disorder is associated with dysregulation of catecholaminergic systems and changes in frontostriatal and frontocerebellar networks, as supported by neuroimaging and molecular studies.[15]

Risk factors

Risk factors for secondary hyperkinesias include liver disease, copper metabolism disorders, thyrotoxicosis, exposure to neuroleptics and other drugs that affect the dopaminergic system, heavy metal intoxication, and immune system disorders. Early detection of these conditions can alter the outcome. [16]

Heredity, family history, and adverse perinatal factors play a significant role in tic disorders. Psychoemotional stressors increase the severity of tics but are not their primary cause. [17]

Genetic variants, repetitive microtrauma, occupational stress, and certain medications play a role in dystonia. Individual sensory triggers, such as light or sound, can provoke spasms in some patients. [18]

For attention deficit hyperactivity disorder, risk factors are considered to be a combination of genetic predisposition and environmental influences, including nicotine exposure during pregnancy and an adverse early developmental environment.[19]

Table 3. Common risk factors and modifiable effects

Group	Examples
Metabolic and systemic	Wilson's disease, thyrotoxicosis, hyperparathyroidism
Medicinal	Dopamine blockers, antidepressants with risk of dyskinesia, antiemetics
Infectious and autoimmune	Postinfectious chorea, autoimmune encephalitis
Genetic	Huntington's chorea, monogenic forms of dystonia
Psychosocial modifiers	Stress, sleep deprivation, environmental stimuli

Pathogenesis

Motor hyperkinesias reflect an imbalance between the direct and indirect pathways of the basal ganglia, leading to a decrease in the "inhibitory" influence on motor programs and excessive motor activity. Modern studies complement the classical model with a more complex architecture of loops and plasticity. [20]

In tics, disruptions in the cortico-striatal-thalamo-cortical circuits, including sensorimotor and limbic components, are considered key, explaining the phenomenon of precursors and the feeling of relief after performing a tic. Changes in the dopaminergic and cholinergic systems maintain pathological patterns. [21]

In dystonia, abnormal sensorimotor interactions, overrepresentation of cortical maps, and deficits in "sensory inhibition tricks" are detected. Deep-brain neuromodulation, such as stimulation of the globus pallidus, can rewire these networks. [22]

In attention deficit hyperactivity disorder, the role of catecholamines, norepinephrine and dopamine, as well as frontostriatal and frontocerebellar networks influencing attention, reaction time and behavioral control has been demonstrated. [23]

Symptoms

Essential tremor is characterized by rhythmic, oscillatory movements while maintaining a posture or performing an action. The arms, head, and voice are most often involved. Symptoms often worsen with anxiety and subside with rest and small doses of ethanol, which is of diagnostic, but not therapeutic, value. [24]

Dystonia is characterized by involuntary muscle contractions leading to repetitive movements and abnormal postures. Patients often describe a "pulling" or "twisting" sensation and find individual sensory techniques that reduce the spasm. [25]

Chorea is rapid, irregular, "dancing" movements that "flow" from one muscle group to another and appear to be voluntary. In Huntington's disease, they are associated with cognitive and psychiatric symptoms. [26]

Tics are sudden, brief, stereotypical movements or sounds accompanied by a feeling of increasing internal tension and relief after their execution. The intensity of tics fluctuates throughout the day and increases with stress or fatigue. [27]

Classification, forms and stages

Phenomenologically, tremors, dystonia, chorea, myoclonus, and tics are distinguished. Within each subtype, forms are differentiated based on distribution, frequency, amplitude, provoking factors, and associated symptoms. This classification helps determine the appropriate investigation and treatment. [28]

Based on etiology, primary, genetic, and secondary forms are distinguished. Secondary forms require an active search for reversible causes, including metabolic disorders, drug effects, and autoimmune processes. [29]

Staging is primarily used for progressive diseases, such as Huntington's disease, where motor, cognitive, and behavioral domains are considered, as well as confirmation of genetic status. Staging determines prognosis and the choice of interventions. [30]

Attention deficit hyperactivity disorder is classified according to the presentation of symptoms as predominantly inattentive, predominantly hyperactive-impulsive, and combined, as recorded in the International Classification of Diseases, Eleventh Revision. [31]

Table 4. Brief guide to clinical subsyndromes

Subsyndrome	Key Features	Common first lines of therapy
Essential tremor	Action and posture, symmetry, involvement of hands, head, voice	Propranolol, primidone, and, if resistant, high-intensity focused ultrasound or deep thalamic stimulation
Focal dystonia	Pathological postures, "sensory tricks"	Botulinum toxin type A injections, in case of generalization - deep stimulation of the globus pallidus
Chorea	Rapid irregular movements, "flowing"	Monoamine transporter-2 inhibitors, atypical antipsychotics as needed
Tiki	Motor and vocal phenomena, precursors	Behavioral therapy of complex behavioral intervention for tics, alpha-agonists, in severe cases - antipsychotic drugs
Attention deficit hyperactivity disorder	Attention deficit, hyperactivity, impulsivity	Psychoeducation and school interventions, stimulants or atomoxetine, prolonged-release guanfacine

Complications and consequences

With severe hyperkinesis, daily skills are impaired, quality of life declines, the risk of falls and injuries increases, and work limitations arise. Long-term forms increase the risk of anxiety and depressive disorders. [32]

Drug therapy carries risks of side effects, ranging from sedation and orthostatic hypotension to extrapyramidal complications. This requires individualized dosage adjustments and regular monitoring. [33]

In Huntington's disease, complications include progressive cognitive impairment, dysphagia, cachexia, and high caregiving and psychological burden on the family, necessitating multidisciplinary management.[34]

Untreated people with attention deficit hyperactivity disorder have increased risks of academic failure, trauma, comorbid mood disorders, and substance use, while a combination of medication and behavioral therapy reduces these risks.[35]

When to see a doctor

If new involuntary movements appear that interfere with writing, gait, speech, or sleep, you should consult a neurologist. It's important not to attribute the symptoms to "nerves" or self-medicate without diagnosis. [36]

If already known hyperkinesia suddenly worsens, weakness, confusion or fever are added, this is a reason for an urgent assessment of a possible metabolic, drug or infectious cause. [37]

In familial cases of chorea or early onset of symptoms, medical genetic counseling and targeted molecular testing are discussed, taking into account ethical standards. [38]

If signs of attention deficit hyperactivity disorder are present and interfere with learning, work, and relationships, a neurodevelopmental specialist or child psychiatrist should be consulted for a full evaluation and treatment options. [39]

Diagnostics

The first step is a phenomenological description of the hyperkinesia: rhythm, frequency, distribution, triggers, suppressibility, presence of precursors, and the influence of sleep. This allows one to suspect tremor, dystonia, chorea, myoclonus, or tics. [40]

The second step is a basic laboratory screening for reversible causes: copper and ceruloplasmin levels if Wilson's disease is suspected, thyroid hormones, vitamin B12 levels, liver and kidney function tests, and a review of medications and substances. If indicated, copper metabolism in a 24-hour urine sample and slit-lamp ophthalmoscopy are added. [41]

The third step is neuroimaging. Magnetic resonance imaging of the brain is indicated for atypical onset, rapid progression, and focal neurological symptoms. When differentiating tremors, dopamine transporter testing with single-photon emission computed tomography is used as an auxiliary test when distinguishing degenerative parkinsonism from benign action tremor. [42]

The fourth step is genetic and specialized diagnostics as indicated: confirmation of Huntington's disease, genetic panels for early-onset dystonia, and expanded metabolic panels in pediatrics. Referral for testing is made after consultation regarding the implications of the results. [43]

Table 5. Step-by-step diagnostic route

Step	Target	What are we doing?	What are we looking for?
Phenomenology	Determine the type of hyperkinesis	Neurological examination, video recording	Rhythm, frequency, suppression, precursors
Basic tests	Find reversible causes	Copper, ceruloplasmin, thyroid hormones, vitamin B12, liver and kidney function	Wilson's disease, thyrotoxicosis, deficiencies
Visualization	Rule out structural causes	Magnetic resonance imaging, if indicated, dopamine transporter study	Foci, degeneration, exclusion of Parkinsonism
Special tests	Confirm the nosology	Genetics, copper metabolism in urine, ophthalmoscopy	Huntington's disease, Kayser-Fleischer rings

Differential diagnosis

Action tremor is often confused with parkinsonian rest tremor. Distinctive features include a predominance of tremors during posture and action, higher frequency, symmetry, and head involvement in benign forms. Classic parkinsonian tremor is pronounced at rest, diminishes with movement, and is asymmetrical. [44]

Dystonic tremor can mimic essential tremor, but is accompanied by abnormal postures and is reduced by sensory input. Myoclonus is characterized by brief "jerks" and variability, while chorea is characterized by irregular, "flowing" movements that masquerade as voluntary. [45]

Tics are distinguished by their precursors and subjective relief after the tic, as well as their partial suppressibility. This distinguishes them from myoclonus and choreic movements, which patients are unable to suppress by willpower. [46]

Table 6. Key differences in tremors

Sign	Tremor during action	Parkinsonian tremor	Dystonic tremor
Situation	Holding the pose and action	Peace	Postures with dystonia
Symmetry	Often symmetrical	More often asymmetrical	Asymmetry with poses
Head involvement	Often	Rarely	Often with cervical dystonia
Sensory trick	No	No	Yes

Treatment

Modern management of essential tremor begins with trigger modification, educational strategies, and, if necessary, pharmacotherapy. First-line medications include propranolol and primidone, gradually titrated to a tolerated, effective dose. In cases of intolerance or insufficient response, topiramate or atenolol are considered. In cases of drug resistance, neurosurgical approaches are considered. [47]

Instrumental methods for intractable tremor include deep stimulation of the ventral intermediate nucleus of the thalamus and magnetic resonance focused ultrasound thalamotomy. Both technologies reduce tremor, but differ in their risk profile and reversibility of effect. The choice depends on individual preference, anatomy, and associated conditions. The decision is made by a multidisciplinary team. [48]

For focal dystonia, the first-line treatment is local injections of botulinum toxin type A, administered under electromyography or ultrasound guidance. This method reduces hyperactivity in specific muscles and improves function for twelve to sixteen weeks, after which injections are repeated. For generalized forms and severe cervical variants, deep stimulation of the globus pallidus interna is indicated. Selection of muscles and dosages requires an experienced team. [49]

Drug-induced dyskinesias and choreic hyperkinesias respond to monoamine transporter-2 inhibitors such as tetrabenazine and deutetrabenazine; valbenazine has evidence of efficacy and a milder psychiatric profile in some patients. In Huntington's chorea, atypical antipsychotics are added if behavioral symptom control is required. Regular monitoring for depression and suicide risk is essential. [50]

Mild to moderate cases of tics and Tourette's syndrome are optimally treated non-pharmacologically: a comprehensive behavioral intervention for tics teaches recognition of precursors and replacement responses. If drug therapy is required, alpha-adrenergic agonists, such as clonidine or extended-release guanfacine, are started, especially when combined with inattention and hyperactivity. If the effect is insufficient, atypical antipsychotics, such as aripiprazole, are indicated, with monitoring for metabolic and neurological risks. Botulinum toxin injections are possible for limited, focal tics. [51]

If Wilson's disease is suspected, therapy is initiated immediately after diagnosis, as delays worsen the prognosis. Copper chelators, such as penicillamine, triiodothiomolybdate, and zinc supplementation are used according to current recommendations, with monitoring of liver function and side effects. Family screening is mandatory. [52]

Rehabilitation and occupational therapy are important for all forms of hyperkinesis. Teaching point strategies, postural stabilization, adapting writing and grasping skills, selecting cutlery, and selecting daily living tools reduce the impact of symptoms. Physical therapy programs improve coordination and reduce fatigue, especially when combined with cognitive-behavioral stress management techniques. [53]

For attention deficit hyperactivity disorder, psychoeducation, school and work adaptations, and behavioral approaches are fundamental. Pharmacotherapy includes stimulants based on methylphenidate or amphetamines, as the most effective, as well as non-stimulant options, including atomoxetine and extended-release guanfacine, according to clinical guidelines. Prescription decisions are made taking into account age, comorbidities, side effect profile, and family preferences. [54]

Safety monitoring is part of treatment. For alpha-agonists, heart rate and blood pressure are monitored; for antipsychotics, body weight, glucose, and lipids; and for monoamine transporter-2 inhibitors, mood and sleep. With neurostimulation, efficacy, side effects, and the need for parameter adjustments are regularly assessed. [55]

Finally, in resistant cases, consultations at movement centers, participation in clinical trials, and consideration of new technologies are helpful. These include bilateral staged approaches to focused ultrasound for tremor, improved targeting algorithms for deep stimulation, and new monoamine transporter-2 inhibitor molecules. The choice is made after weighing the benefits and risks, taking into account the patient's goals. [56]

Prevention

Primary prevention involves reducing exposure to medications and toxins known to trigger hyperkinesias, as well as monitoring endocrine and metabolic conditions. It is important to promptly correct sleep deprivation and stress triggers. [57]

Secondary prevention focuses on maintaining function and preventing falls, including workplace ergonomics, writing aids and hand stabilization, and training in relaxation and breathing strategies. Individual exercises are coordinated with a physical therapist. [58]

For families at risk for Huntington's disease, medical genetic counseling with discussion of family planning is recommended. For attention deficit hyperactivity disorder, early identification and family and school interventions to prevent secondary complications are important. [59]

Periodic review of diagnosis and therapy is necessary due to the natural variability of symptoms and the emergence of new treatment technologies. This reduces the risk of overmedication and improves quality of life. [60]

Forecast

Essential tremor often has a slowly progressive course with fluctuating severity and good chances of symptom control with combined strategies. Quality of life improves with early access to rehabilitation and, if necessary, neuromodulation. [61]

Focal dystonia often stabilizes with regular botulinum therapy, while generalized forms benefit from deep stimulation. Relapses are managed by adjusting the dosage and precisely selecting the muscles for injection. [62]

Tics decrease in a significant proportion of adolescents by adulthood, but persist in some and require supportive interventions. Early behavioral therapy improves long-term outcomes. [63]

Huntington's disease remains a progressive neurodegenerative disorder, but symptomatic therapy and a multidisciplinary approach slow functional decline and improve quality of life. Family support is critical. [64]

FAQ

Are "hyperkinetic syndrome" and attention-deficit/hyperactivity disorder the same thing? No. The former describes excessive movements, the latter a neurodevelopmental disorder of attention and behavior. In the International Classification of Diseases, Eleventh Revision, attention-deficit/hyperactivity disorder is coded separately. [65]

Is it possible to cure tremor permanently? No therapy promises a complete cure for essential tremor, but a combination of medications, rehabilitation, and, when indicated, neurosurgery can keep symptoms under control in most patients. [66]

What is the difference between deep tissue stimulation and focused ultrasound? The former is reversible and customizable, while the latter is a single, irreversible ablation. Both approaches are effective for resistant tremor, but have different risk profiles and indications. [67]

Is it true that tics are a "habit"? No. They are a neurological condition with distinct neural network mechanisms, not a conscious habit. Behavioral therapy helps people learn to manage tics, but it doesn't reduce them to "habits." [68]

Should attention deficit hyperactivity disorder be treated with diet alone? Evidence for the effectiveness of strict diets is limited and mixed. The mainstay of treatment is psychoeducation, behavioral and educational measures, and medications with proven effectiveness, individually tailored to the individual. [69]

Where is the line between action tremor and parkinsonian tremor? It is determined clinically; sometimes additional studies, such as dopamine transporter imaging, are helpful. The final decision is made by a neurologist after an examination. [70]

Table 7. “What to do” for the main subsyndromes

Situation	Basic tactics	When to expand
Tremor with dysfunction	Titrate propranolol or primidone, teach strategies	Resistance, side effects, severe limitation - assessment for neuromodulation
Focal dystonia	Botulinum toxin every three to four months	Generalized forms and severe cervical - deep stimulation
Chorea	Monoamine amine transporter type 2 inhibitors, atypical antipsychotics if necessary	Severe psychiatric symptoms, dysphagia, increased risk of falls
Tiki	Comprehensive behavioral intervention for tics, including alpha agonists if needed	Severe disability - antipsychotic drugs, local botulinum toxin
Attention deficit hyperactivity disorder	Psychoeducation, school interventions, stimulants, or atomoxetine	Intolerance, comorbidity, need for non-stimulant strategies