Tremor, dystonia and other movement disorders

• Movement disorders are failures of regulation in the systems that control posture and voluntary movement: too little movement, too much, or movement that is unstable or patterned.
• Tremor is a rhythmical oscillation. The common diagnostic split is between a bilateral action tremor that has lasted at least three years with no other neurological signs (now the consensus definition of essential tremor) and the tremor of Parkinson disease, which occurs at rest and is combined with bradykinesia, rigidity and gait change.
• Dystonia is sustained or intermittent abnormal postures or movements, often patterned and worsened by voluntary action; the 2013/2025 MDS classification splits it into what is seen and what caused it.
• Botulinum neurotoxin is accepted as first-line treatment for cervical dystonia and is considered first-line for blepharospasm by most movement disorder specialists, with AAN grades by preparation.
• Ataxia is loss of motor coordination; much of it is symptomatic and rehabilitative, while a few conditions (such as Friedreich ataxia) now have approved disease-modifying therapy.
• Wilson disease is an autosomal recessive copper accumulation disorder that can present with tremor and dystonia in adolescence or young adulthood.
• Drug-induced movement disorders (parkinsonism, dystonia, akathisia, tardive dyskinesia, neuroleptic malignant syndrome) are common, distinguishable, and treated differently.

By the end of this page you should be able to:

1. Define, on first principles, tremor, dystonia and ataxia, and give one example of how each looks in a patient.
2. Separate essential tremor from Parkinson disease tremor on history and examination, and say which signs are incompatible with essential tremor.
3. Apply the 2018 Movement Disorder Society tremor classification, including the "ET plus" category, and say why it exists.
4. Classify dystonia on the two MDS axes, recognise its body distributions, and explain why botulinum toxin is first-line for many focal dystonias.
5. Name the common hereditary ataxias in adults, and state the one disease-modifying ataxia drug with regulatory approval.
6. Describe the presentation, diagnostic testing and treatment of Wilson disease, including its scoring system.
7. Distinguish the drug-induced movement disorders, say which respond to anticholinergics and which do not, and name the drugs approved for tardive dyskinesia.
8. Recognise tics and Tourette syndrome, their cross-over into Psychiatry, and the principles of their medical treatment.

Movement disorders are abnormal movements or postures (or both) that arise from the brain circuits that plan, select and refine movement, rather than from weakness, an acute corticospinal lesion or a peripheral nerve problem. They are usually divided into hypokinetic (too little movement, as in parkinsonism) and hyperkinetic (too much, as in chorea, tremor, dystonia, tics, myoclonus and ballism); cerebellar ataxia is a third group, in which coordination and accuracy rather than amount are the problem. Abnormal movements are "positive" signs (something extra is produced) or "negative" signs (automatic behaviour is absent), and the clinical skill lies in matching the phenomenology to the likely anatomy and cause.

Most movement disorders are classified on two axes, a convention that now runs through tremor and myoclonus as well as dystonia: one axis describes what is seen in the clinic (phenomenology), the other describes the cause.

Tremor is a rhythmical, oscillatory, involuntary movement around a joint or axis, usually produced by synchronous bursts of muscle activity alternating between antagonist muscles. The Movement Disorder Society (MDS) 2018 classification works on two axes too: clinical (phenomenology) and aetiology. Its two key observations are (1) essential tremor (ET) is an isolated bilateral upper extremity action tremor lasting at least three years with no other neurological signs such as dystonia, ataxia or parkinsonism ^[1], and (2) many people who otherwise fulfil these criteria have one or more "soft signs" of uncertain significance, and for them a distinct category, ET plus, was created.

A soft sign might be questionable dystonic posturing, a slightly uncertain bradykinesia, impaired tandem walking in an older person, or tremor at rest in someone with otherwise classical ET. Labelling such patients ET plus is a diagnostic placeholder rather than a cure: it records uncertainty and protects the diagnosis from being quietly overstated. In a cohort of patients referred for ET, referral diagnoses were reported as incorrect in nearly half, and the most common alternatives were Parkinson disease and dystonia ^[1]. Misdiagnosis matters because the relatives' questions, genetic advice, treatment and prognosis of an essential tremor are not those of a dystonic tremor or Parkinson disease.

ET plus also reflects the fact that most soft signs are poorly reliable between raters. For example, impaired tandem walking was a soft sign to the first task force; it occurs in about half of ET patients but also in roughly 28% of controls, and is heavily confounded by age (in patients aged 70 or over, about 71% of ET patients and 22% of controls show the change), so it should not be assumed to be clinically connected to the tremor ^[1]. Two or three congruent soft signs, by contrast, can swing the probability of an alternative diagnosis well past one half.

ET is common, and what is called ET has shifted: in a population-based southern Spanish cohort about 85% of elderly people had upper extremity tremor without head or voice tremor, and only 1.6% had isolated head tremor, which the 2018 classification no longer calls ET ^[1]. Isolated voice or head tremor is now much more likely to be dystonic.

The tremor of Parkinson disease is classically a rest (and often re-emergent) tremor, often starting as a pill-rolling flexion-extension of the thumb and fingers, usually unilateral at onset but bilateral as the disease advances, synchronised with chin and leg movement, suppressed by action and reappearing after a delay. True rest tremor is uncommon in ET (less than 15% of clinic patients and under 5% of those identified in population studies) ^[1], and its appearance in someone who also has ET-type features places them in ET plus. Parkinsonian tremor is also often accompanied by re-emergence ("re-emergent tremor") a few seconds after taking up a posture.

The decisive clinical split is the following:

• Essential tremor is an action tremor (postural or kinetic), usually bilateral from the start (though it need not be symmetrical), frequently involves the head and voice, and shows no bradykinesia, rigidity or gait disorder. It is common and often familial. An interesting trap is "cogwheel" rigidity: passive cogwheeling can be felt if tremor is present in a limb that has not relaxed, and it does not exclude ET ^[1].
• Parkinson disease tremor is a rest tremor that is asymmetric at onset, begins in one hand, and is part of a syndrome that includes bradykinesia (slowness with progressive reduction in amplitude - decremented), rigidity and postural instability developing with time. Mild slowing of repeated movements has been reported in ET cohorts (for example, slight kinematic slowness in about 6.6% of clinic patients in one small series ^[1]), but a clinically definite bradykinesia incompatible with ET.
• Dystonic tremor often has a positional or task-specific trigger, may be irregular and jerky, is accompanied by unusual postures or sensory tricks, and may involve one arm or the neck. It is the commonest alternative diagnosis among people referred for ET ^[1].
• Enhanced physiologic tremor is a high-frequency, low-amplitude action tremor with a clear trigger (anxiety, caffeine, beta-adrenergic drugs, alcohol withdrawal, thyrotoxicosis), and mass loading of the hand lowers its frequency by more than 1 Hz, which distinguishes it from mild ET ^[1].

A tremor that is strictly unilateral upper extremity action tremor is too uncommon for ET and should make one think of dystonia or parkinsonism; likewise isolated head tremor is usually dystonic. The diagnostic approach is summarised in the flowchart below.

The 2013 then 2025 Movement Disorder Society consensus defines dystonia as: a movement disorder characterised by sustained or intermittent abnormal movements, postures or both. Dystonic movements and postures are typically patterned and repetitive and may be tremulous or jerky; they are often initiated or worsened by voluntary action and frequently are associated with overflow movements ^[2]. (The 2025 revision added the word "jerky" only.) The phrase "dystonic tremor" is discouraged because it has been used inconsistently to separate a tremulous dystonic movement from a separate tremor accompanying dystonia, and these are not well distinguished in practice ^[2]. A cranial or cervical sensory trick (geste antagoniste) is the classic clue.

Dystonia is classified on two axes ^[2]:

• Axis I (clinical): age of onset (infancy up to 2 years, childhood more than 2 to 12, adolescence more than 12 to 20, early adulthood more than 20 to 40, late adulthood over 40); family history (sporadic, familial, unknown); body distribution (focal, segmental, multifocal, hemidystonia, generalised); temporal course (acute, subacute, gradual; static, progressive, fluctuating; paroxysmal or with diurnal variation); and phenomenology (task-specific, action-induced, present at rest, fixed; with sensory trick, tremulous or jerky). ^[2]
• Axis II (aetiology): genetic; acquired (medicines, toxins, trauma, other); neuroanatomical (focal, multifocal or diffuse lesions); and pathogenesis (developmental, degenerative, metabolic, immune/inflammatory or unknown).

Practical body-distribution examples that matter clinically:

• Focal: one region (cervical torticollis with the neck twisted).
• Segmental: two or three contiguous regions (blepharospasm plus lower face).
• Generalised: trunk and at least two other regions, or three or four limbs. Generalised dystonia beginning in childhood often signals a genetic or metabolic cause and may respond to deep brain stimulation (DBS).
• Combined dystonia: dystonia plus parkinsonism, ataxia, myoclonus, tremor or systemic features; dystonia can also be isolated or focal, and the remainder of the nervous system is normal.

Dystonia in a child, on one side of the body (hemidystonia) or with a second movement disorder, deserves imaging and a search for a secondary, often vascular, cause. Dystonia developing acutely in adulthood is sometimes functional (psychogenic) dystonia, now placed among dystonia mimics, or the result of neuroleptic exposure.

Ataxia is global incoordination of posture, stance, gait and eye movements arising from the cerebellum and its connections (and, importantly, the vestibular nuclei, proprioceptive pathways and thalamocortical circuits). It is characterised by errors in timing and scaling of movement rather than weakness: the movements are inaccurate, uncoordinated and often irregularly broken up. Clinically one speaks of cerebellar, sensory (proprioceptive) and vestibular ataxia - from the lesion location - and of hereditary, acquired (stroke, toxic, autoimmune, structural, paraneoplastic, infectious) and sporadic (unknown) forms.

Adult-onset primary cerebellar ataxias are divided into sporadic and autosomal dominant causes (the spinocerebellar ataxias, SCA, now more than 50 subtypes) and autosomal recessive forms, of which Friedreich ataxia is the commonest hereditary ataxia in Europeans ^[7]. Friedreich ataxia is caused by a GAA repeat expansion in the FRDA (FXN) gene, producing frataxin deficiency; it becomes apparent before age 25 years in most, and presents with progressive gait ataxia, dysarthria, areflexia and often hypertrophic cardiomyopathy and diabetes ^[7]. Episodic ataxia type 2 (CACNA1A, EA2) causes recurrent attacks of ataxia with vertigo and visual symptoms, typically in young adults. Other adult-onset recessive conditions include ataxia-telangiectasia variants and cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS). Multiple system atrophy of the cerebellar type (MSA-C) is an acquired degenerative (sporadic) adult-onset cerebellar ataxia combined with autonomic failure.

The clinical examination of ataxia includes gait (wide-based, tandem and toe-to-heel tasks), heel-to-shin, rapid alternating movements, finger-to-nose (look for intention tremor, dysmetria), rebound (Holmes sign), cerebellar dysarthria (scanning speech), downbeating and gaze-evoked nystagmus, oculomotor apraxia and pupillary abnormalities. Brain MRI, genetic testing, paraneoplastic and inflammatory screens, and structural survey identify the rest.

A tic is a sudden, rapid, recurrent, non-rhythmic, usually suppressible movement or vocalisation that is preceded by a premonitory sensory urge. Tourette syndrome is a childhood-onset condition of multiple motor tics and at least one vocal tic lasting more than one year ^[4]. Chronic (persistent) motor or vocal tic disorders have only one modality. Simple tics involve one muscle group (a blink, a shoulder jerk); complex tics can look deliberate (touching, jumping, copropraxia) but are involuntary. Many tics become embedded in stereotypies or habits, and distinguishing them from stereotypes (repetitive, usually rhythmic, purposeless movements typical of neurodevelopmental disorders) and from compulsions (deliberately performed to neutralise an obsession) is the point of clinical interest. Tics cross-check Psychiatry: they are part of the neurodevelopmental axis and commonly occur alongside obsessive-compulsive disorder and attention-deficit hyperactivity disorder. In specialist series, comorbid behavioural disorder is reported in up to 90% of patients with Tourette syndrome over a lifetime ^[4], and it is often the comorbidity rather than the tic that dominates quality of life. Sleep disorders, anxiety and mood disturbance also cluster.

In school-age children, Tourette syndrome has consistent prevalence figures of 0.4 to 1.5%, and chronic tic disorders 0.9 to 2.8% ^[4]. There are few adult population estimates; one diagnosed-prevalence study was around one case per 1,000 ^[4].

Cross-check Psychiatry also means using psychiatric concepts in neurology: screen any patient on a dopamine receptor blocking drug for drug-induced movement disorders (below), and refer the tics themselves to a psychiatrist or movement disorder neurologist when the burden is high.

These arise from dopamine receptor blocking agents (DRBAs) used as antipsychotics, or from serotonergic, metoclopramide, complementary and recreational compounds ^[8]. Antipsychotic prescribing in the United States increased from 2.2 million prescriptions in 1997 to 6.1 million in 2018 ^[8], so awareness of these disorders is a daily task for all clinicians. They are conventionally divided by phenomenology and time of onset ^[8]:

• Drug-induced parkinsonism (DIP): Hypokinetic syndrome (bradykinesia, rigidity, tremor) starting days to weeks after starting or raising a DRBA. Usually bilateral, with postural tremor and the pill-rolling absent at rest. It subsides on stopping, dose reduction or switching (weeks; occasionally months), may unmask underlying Parkinson disease (^[8] reporting up to 15% persistence), and is treated with anticholinergics short-term if needed.
• Acute dystonia: Oculogyric crisis, retrocollis, jaw deviation/clamping, torticollis and, rarely, laryngeal involvement, within hours of initiation or dose escalation. Risk is higher with intramuscular high-potency first-generation antipsychotics and in young men. Treated with intramuscular diphenhydramine or benztropine, then oral anticholinergy for one to two days if the drug is withdrawn and several days if not.
• Akathisia: A sense of inner restlessness with repetitive, purposeless movements (pacing, weight-shifting, leg swinging). Anticholinergics do not help reliably; a beta blocker, a benzodiazepine or reducing the offending drug does.
• Tardive dyskinesia (TD): Orofacial stereotypies (lip smacking, tongue protrusion, grimacing) and writhing limb or trunk movements developing after three or more months of exposure, more often in older women. Anticholinergics are contraindicated (they can worsen TD). Treat with valbenazine (40, 60 or 80 mg daily, target dose 80 mg) or deutetrabenazine (6, 9 or 12 mg twice daily, or 6, 12 or 24 mg once-daily extended release; titrate from 12 mg daily in 6 mg weekly steps, target 24 to 48 mg per day, mean about 39 mg per day), which are the approved vesicular monoamine transporter 2 (VMAT2) inhibitors. ^[8]
• Tardive dystonia: produces abnormal postures in delayed fashion; treated with VMAT2 inhibitors or, in some cases, relatively high doses of anticholinergics, botulinum toxin or surgical modification.
• Neuroleptic malignant syndrome: Rigidity, fever, autonomic instability, altered mental state, high creatine kinase. Antipsychotics are stopped, supportive care is given, and benzodiazepines, dopamine agonists, dantrolene or electroconvulsive therapy can be tried. Anticholinergics are contraindicated because they impair sweating and heat dissipation.
• Other recognised disorders include serotonin syndrome (hyperthermia, clonus, hyperreflexia, diarrhoea, mydriasis), tardive akathisia and tardive parkinsonism.

A useful teaching distinction is that dopamine blockade lowers dopamine signalling, which can be offset by anticholinergics (DIP, dystonia), while tardive/hyperkinetic disorders imply receptor up-regulation in the opposite direction, so anticholinergics can worsen them ^[8]. Screening for these disorders (a structured examination such as the Abnormal Involuntary Movement Scale at least every 12 months, or every 6 months in high-risk patients) is recommended in patients receiving DRBAs ^[8].

Chorea is a brief, flowing, dance-like, unpredictable movement; ballism is its large-amplitude unilateral form and points acutely to the subthalamic nucleus. Myoclonus is a brief, shock-like, involuntary jerk; it comes in cortical, subcortical and spinal types. Hemifacial spasm is arrhythmic twitching of one side of the face. Stereotypies and akathisia are often confounded in schizophrenia and neurodevelopmental disorders. Catatonia is a disorder of motor posture, reactivity and negativism rather than a movement disorder proper. Drug-induced chorea is recognised with levodopa and, rarely, with anticonvulsants.

Movement disorders are consistently underdiagnosed in clinical practice. Referral diagnoses of ET are reportedly wrong in nearly half of people sent to a movement disorders clinic, and dystonia and Parkinson disease account for most of the wrong calls ^[1]. Childhood Tourette syndrome is present in about 0.4 to 1.5% of school-age children, with chronic tic disorders 0.9 to 2.8% ^[4], while adult diagnosed prevalence is around one per 1,000 ^[4]. The rise in antipsychotic prescribing means drug-induced parkinsonism and TD are now common outpatient findings ^[8]. Wilson disease has a worldwide prevalence of about one in 30,000, with about one in 90 healthy carriers ^[6]. Episodic ataxias and spinocerebellar ataxias are individually rare but together represent a sizable part of neurological genetics clinics.

• Tremor. A family history is usual in ET; the genetic basis remains incomplete (ET genes have lower penetrance and overlaps with other tremor disorders). Common acquired causes include enhanced physiologic tremor (beta-adrenergic drugs, alcohol withdrawal, thyrotoxicosis, hypoglycaemia), toxic, vascular and degenerative causes. Tremor is one of the first clues to Parkinson disease, whose origin is degenerative (alpha-synuclein pathology) with genetic forms.
• Dystonia. Around nine in ten adult-onset focal dystonias have no identifiable cause. Risk factors are young adult onset, repetitive skilled tasks (task-specific writer's cramp, musician's dystonia), neuroleptic exposure, and structural lesions (for hemidystonia). Genetic dystonias involve many genes and involve age groups from infancy upward.
• Ataxia. Cerebellar ataxia has a very broad aetiology: vascular (posterior circulation stroke), toxic (alcohol, phenytoin, toluene, chemotherapy), paraneoplastic and autoimmune cerebellitis, structural compression of the posterior fossa, infection (post-encephalitic, prion), hereditary (SCA, ataxia telangiectasia, Friedreich ataxia), and metabolic (vitamin E deficiency, Refsum disease, mitochondrial disease, Wilson disease). Family history, age, tempo (acute vs chronic), imaging, and autoantibodies separate them.
• Tics. A hereditary predisposition (polygenic, rare single-gene findings) underlies Tourette syndrome. Precipitants and aggravators include infection, stress and fatigue; tics usually peak in childhood or early adolescence and decline in most people by adulthood.
• Wilson disease. Autosomal recessive ATP7B mutation, an enzyme that incorporates copper into ceruloplasmin and exports excess into bile. Consanguinity increases prevalence markedly (1 in 3,000 to 1 in 10,000 in high-consanguinity communities) ^[6]. Onset is usually 3 to 40 years, with cases reported into the eighth decade ^[6].
• Drug-induced disorders. The DRBA dose, potency, age, female sex and cumulative exposure are the major risk factors; high-potency first-generation drugs are the worst offenders for dystonia and NMS; TD risk rises with age over 55 years, female sex, mood disorder and cumulative antipsychotic exposure ^[8].

Movement is produced by a hierarchy: intention is shaped by the basal ganglia, calibrated by the cerebellum, constrained by corticospinal output and modulated by brainstem reflexes. Disruption at each level gives a different phenotype.

• Parkinsonism (hypokinetic). Degeneration of dopaminergic neurons in the substantia nigra pars compacta reduces striatal dopamine; the direct pathway is less active and the indirect pathway more active. The result is poverty of movement, rigidity and tremor.
• Tremor. ET is thought to reflect dysfunction of the corticobulbocerebellothalamocortical loop: the tremor emerges from oscillatory entrainment of this circuit, and it normalises partially with thalamic deep brain stimulation or alcohol ^[1]. Parkinsonian tremor is more associated with basal ganglia dopaminergic loss. Dystonic tremor comes from abnormal sensorimotor integration in the basal ganglia-thalamo-cortical and cerebellar networks.
• Dystonia. The leading model is impaired sensorimotor integration and aberrant plasticity (the "maladaptive plasticity" hypothesis), with abnormal inhibitory and efference-copy circuits, sometimes with discrete basal ganglia lesions. X-linked and acquired causes sit alongside this.
• Ataxia. Cerebellar Purkinje cell loss (or, in Friedreich ataxia, mitochondrial frataxin deficiency) degrades the predicted motor response; sensory ataxia degrades the afferent signal on which prediction relies. Clinically this is why ataxia worsens on eye closure (Romberg) in sensory forms and why fine repetitive movements are uneven.
• Tics. Abnormal cortico-striato-thalamo-cortical circuits interact with limbic and dopaminergic systems; premonitory urges build and wax, tics are voluntarily suppressible briefly, and dopaminergic drugs can worsen them.
• Drug-induced disorders. DRBAs block striatal D2 receptors. Acute effects (DIP and dystonia) reflect dopamine-acetylcholine imbalance on medium spiny and cholinergic interneurons, which anticholinergics partly correct; TD reflects receptor up-regulation and hypersensitivity with enhanced dopamine signalling, so anticholinergics are unhelpful or harmful ^[8].

• Onset and course. Onset age is critical: dystonia in infancy or childhood, or hemidystonia at any age, suggest a structural or genetic cause; ET starting in late adolescence and worsening in the sixth/seventh decade is the norm; Parkinson disease generally starts in late adulthood (typically after the sixth decade).
• Tremor characteristics. What activates it (rest, posture, action, specific task), distribution over time, progression, aggravators and relievers (alcohol, sleep, stress, caffeine), and family history. Ask specifically about rest tremor, because it reclassifies the patient.
• Distribution and task specificity. The body part where a movement occurs: neck (torticollis), eyelids (blepharospasm), blink, voice, hand posture, writing or instrument playing. Dystonia's timing (task-specific vs action-induced vs at rest vs fixed) is part of the Axis I vocabulary ^[2].
• Associated features. Involuntary muscle twitches, sensory trick, head tremor, balance, slowness of movement, swallowing, speech and falls.
• Medications. Neuroleptics, metoclopramide, gastrointestinal prokinetics, antipsychotics (including off-label use), valproate, acute stressors and recent toxin exposure.
• Psychiatric load. OCD, ADHD, anxiety, tics, impulsive behaviour, depression and sleep disorder.
• Low-resource questions. Alcohol intake, exposure to manganese/copper, Wilson family history.

A vignette: A 64-year-old woman is referred with "essential tremor" of the right hand. On examination her right hand has an action tremor, but the right little finger adopts a curled posture on action and a slight head tilt is maintained by a shoulder elevation. Her voice sounds strained. She qualifies as ET plus, and the posturing plus strained voice make dystonic tremor more likely than isolated ET.

• Tremor examination. Inspection at rest, in protruded posture and on action (finger-nose, finger-to-nose, wing-beating, water-cup) for each limb; head, voice and chin; the distribution and asymmetry; speed and rhythm; intention component (approaching a target); and suppressibility/entrainment (functional). Postural arm position with the head extended and rotated can reveal a dystonic postural tremor. Hands hanging unsupported produce more tremor than supported forearms.
• Signs incompatible with ET (examine for them): bradykinesia (finger tapping, pronation-supination), rigidity (passive, and cogwheel that is not simply tremor), asymmetric tremor, sensory trick, unusual postures, rest tremor (use a fully supported forearm; false positives are common if the hand hangs or is only partially supported), highly asymmetric upper limb tremor, and impaired tandem glide in young or middle-aged patients.
• Dystonia examination. Distribution and which muscles; whether the abnormality is absent at rest and brought out by a task; mirror movements in the contralateral hand; sensory tricks; hypertrophied overused muscles. The examination is standardised by video and by rating scales.
• Ataxia examination. Gait (wide-based, tandem, toe-walk, toe-to-heel), heel-to-shin, finger-to-nose, rapid alternating movements, dysarthria, eye movements including downbeat and gaze-evoked nystagmus, deep tendon reflexes, vibration/proprioception, Romberg, tremor and truncal sway.
• ** tic examination:** suppression, premonitory urge discussion (for older children), assessment of comorbidity.

The central differential diagnosis for tremor has been summarised already; the broader movement disorder differential also separates by tempo, distribution and associated features, as in the table.

• Basic work-up for all patients. Full general examination (thyroid, liver, metabolism); detailed medication and toxin history; family history and a video in native posture; a baseline structured Parkinson and ataxia exam; brain MRI in atypia, onset under 40 years, rapid progression, ataxia or hemidystonia; and bloods including full blood count, liver function tests, Wilson testing whenever it is relevant (young or middle age at onset, neuropsychiatric or hepatic features), thyroid function, vitamin B12/folate/beta-glycoprotein, drug levels if relevant, and autoimmune screen.
• Tremor work-up. No test clinches ET; MRI excludes structural causes, neurovascular compression is rarely diagnostic, and physiological tremor frequency study helps mild cases and mass-load testing. Dopamine transporter imaging (DAT) is used in selected cases where the question is Parkinsonian disease versus ET, but it is fallible.
• Dystonia work-up. Electromyography and neurophysiology (blink reflex recovery, temporal somatosensory discrimination) can help distinguish dystonic tremor from ET, but they are not needed for most patients. Botulinum toxin injection requires careful mapping of muscle patterns.
• Ataxia work-up. MRI of posterior fossa and spinal cord, genetic testing (trinucleotide repeat ataxias, Friedreich's ataxia as first pass in typical cases, panel/whole-exome if the clinical category is unexplained), and targeted tests for vitamin E deficiency, gliadin antibodies, thyroid, Wilson disease (ceruloplasmin and urinary copper), and malignancy. SARA (Scale for the Assessment and Rating of Ataxia) and ICARS quantify severity and track time course.
• Tics. No laboratory test. Clinical diagnosis; examination for associated comorbidity.
• Drug-induced disorders. Check offending drug, its dose and duration; screen for parkinsonism, blood pressure, pulse; consider neuroimaging if red flags or asymmetric. VMAT2 inhibitor treatment is managed by psychiatrist/neurologist.

• Tremor (MDS 2018). ET is an isolated bilateral upper extremity action tremor lasting at least three years, with or without tremor elsewhere, and no other neurological signs ^[1]. ET plus adds soft signs. All of these are phenomenology-based; the aetiological axis describes cause.
• Tics (DSM-five and clinical). Tourette syndrome: multiple motor and at least one vocal tic for more than one year, with onset under 18 years; not attributable to substances or other conditions; tic-specific severity scale (Yale Global Tic Severity Scale, YGTSS) is standard in trials ^[4].
• Dystonia axes. Axis I phenotype (age, family history, body distribution, temporal features, phenomenology, isolated vs combined) and Axis II aetiology (genetic/acquired/anatomical/pathogenic mechanism) ^[2]. There are no numeric staging criteria but severity scores (BFM-Fahn-Marsden Dystonia Rating Scale, Global Dystonia Rating Scale, Tsui scale for cervical dystonia) are used in trials.
• Leipzig score (Wilson disease). The criteria score is as follows: KF ring +2; typical neurological symptoms +2; atypical +1; 24-hour urinary copper >100 micrograms +2; 40 to 100 micrograms +1; serum ceruloplasmin below 0.1 g/L +2; 0.1 to 0.2 g/L +1; hepatic copper >250 micrograms/g +1; hemolysis +1; two gene mutations +4; one mutation +1. Score 4 or more confirms, 3 is probable, and 2 or less is unlikely ^[6].
• Lesion-induced dystonia or suspected Wilson disease is usually also confirmed by MRI/pre-motor or targeted genetic testing.
• Ataxia severity. Several validated scales are used to quantify ataxia: the Scale for the Assessment and Rating of Ataxia (SARA) and the International Cooperative Ataxia Rating Scale (ICARS) are the most commonly used; rehabilitation trials report small but meaningful SARA point reductions (see the trial tables in the review) ^[7].

Management is built around (1) the correct phenomenological label and underlying cause, (2) functional impact, and (3) the patient's values. Since many movement disorders are lifelong rather than curable, patient education, structured exercise and psychological support become part of the prescription.

• Essential tremor. When symptoms interfere with living, commonly used oral agents are propranolol (a non-selective beta blocker; contraindicated in asthma, bradyarrhythmia and AV block) and primidone (a barbiturate anticonvulsant; sedation, nausea and imbalance are common) ^[1]. Exact dosing schedules, titration rates and durations vary by guideline and by patient tolerance, so local formularies should be followed; a variety of other agents (topiramate, gabapentin, pregabalin, benzodiazepines, levetiracetam and botulinum toxin for selected patterns) have mixed or second-line evidence. For severe, drug-resistant tremor, deep brain stimulation (thalamus, VIM), focused ultrasound thalamotomy are surgical options. A common quality-of-life trap is that alcohol suppresses tremor in many patients, sometimes for hours, which leads to misleading self-medication; treatment is pharmacological and surgical, not alcohol.
• Parkinson disease. Treat with levodopa (combined with a dopa decarboxylase inhibitor) and/or dopamine agonists; MAO-B inhibitors; adjunctive therapy; regular multidisciplinary review; and exercise and physiotherapy. NICE guidance emphasises timely initiation and review, avoiding unnecessary early over-reliance on high-dose agonists in patients with impulse-control vulnerability, and systematic management of non-motor symptoms ^[5].
• Dystonic tremor. The cause localises often to the neck/cranio-facial muscles; eminently injectable with botulinum toxin (below). Do not give anti-parkinsonian or antitremor drugs.

Dystonia is usually treated by its distribution ^[3]:

• Focal and many segmental dystonias. Botulinum neurotoxin (BoNT) is the treatment of choice. The AAN 2016 guideline update (Retired, but the most widely cited edition) states that BoNT is accepted as first-line treatment for cervical dystonia, and that most movement disorder specialists consider BoNT first-line for blepharospasm ^[3]. BoNT is a neurotoxin that, when injected into a dystonic muscle, blocks acetylcholine release at the neuromuscular junction; benefit in published trials lasted about 10 to 16 weeks. Key recommendations by preparation: for cervical dystonia, abobotulinumtoxinA and rimabotulinumtoxinB should be offered (Level A), and onabotulinumtoxinA and incobotulinumtoxinA should be considered (Level B); for blepharospasm, onabotulinumtoxinA and incobotulinumtoxinA should be considered (Level B) and abobotulinumtoxinA may be considered (Level C) ^[3]. Local practice will differ. Toxin units are not interchangeable between preparations, and dosing follows muscle anatomy, strength, distribution and technique. Side effects of BoNT include local weakness, dysphagia (notably with cervical injections: about 23% with 240 units and about 11% with 120 units of incobotulinumtoxinA in one trial) ^[3], dry eyes, periorbital haematoma and ptosis (up to 13% to 54% risk difference) ^[3]. Repeat injection is usually planned when effect wears off (efficacy in trials ranged from about 10 to 16 weeks per preparation). Specific adjunctive approaches include anticholinergics (trihexyphenidyl) careful low doses, baclofen, benzodiazepines, and deep brain stimulation to the globus pallidus for generalised or severe segmental dystonia. Sensory tricks can be maximised. Surgery changes posture only after the muscles have been mapped.

• Generalised or severe dystonia. Medical therapy plus DBS (usually globus pallidus interna) for disabling dystonia when pharmacotherapy fails.

• Combined dystonia. Treat the underlying cause (e.g. copper chelation for Wilson disease), then by distribution.

• Neuroleptic-induced acute dystonia is treated as a drug-induced disorder (below), not with routine BoNT.

There is no universal cure for most adult ataxias; management follows five principles ^[7]: (1) treat the cause (stop alcohol and drugs; gluten-free if gluten-related; replace vitamin E; immune therapy for autoimmune/paraneoplastic; pancreatic/ malignancy screening); (2) multidisciplinary rehabilitation (physiotherapy, balance and gait training with evidence for benefit, occupational and speech therapy); (3) symptomatic medicines (riluzole, 4-aminopyridine for episodic ataxia type 2 (reducing attacks from about 6.5 to 1.65 per interval in one small study), amantadine is used for drug-induced parkinsonism rather than ataxia; acetazolamide 250 to 500 mg daily for SCA6); (4) disease-modifying progress - omaveloxolone (150 mg daily) was approved for Friedreich ataxia after the MOXIe trial showed a mean 2.40-point mFARS improvement versus placebo at 48 weeks and a 55% reduction in progression over three years, and gene-targeted therapies (ASOs, viral vectors, gene editing) are advancing; (5) psychosocial and palliative (sleep, bladder, communication, carers). Ataxia scales (SARA, ICARS) quantify and track change. Note: pharmacologically, much of this rests on small trials and expert consensus rather than on large RCTs.

Cross-check Psychiatry for all that follows. Most children with tics do not need drugs: psychoeducation, reduction of stress and fatigue, management of comorbidity, and sleep are the foundations. When distress or impairment requires more ^[4]:

• Behavioral therapy with a strong evidence base: Comprehensive Behavioural Intervention for Tics (CBIT) is more likely than supportive psychotherapy to reduce tic severity.
• Medical treatments with moderate evidence: haloperidol, risperidone (watch weight gain and prolactin), aripiprazole (watch weight and sedation, ECG if concern), tiapride, clonidine (combination with methylphenidate for tics with ADHD), and onabotulinumtoxinA injections for localised troublesome tics. ^[4]
• Lower evidence / alternatives: pimozide (ECG/QT risk, prolonged QT), ziprasidone, metoclopramide, guanfacine, topiramate. Atomoxetine probably does not worsen tics.
• Deep brain stimulation of globus pallidus (moderate evidence) or thalamus for disabling, treatment-resistant tics in adults, and habit reversal/cognitive behavioural therapy.
• Side-effect monitoring is mandatory, particularly drug-induced movement disorders and metabolic effects (weight, lipids, prolactin) ^[4].

Wilson disease (hepatolenticular degeneration) is autosomal recessive copper accumulation from mutation in the ATP7B gene, which prevents copper incorporation into ceruloplasmin and biliary excretion; copper accumulates first in liver, then brain (especially basal ganglia, cerebellar connections) and cornea ^[6]. It can present as an adolescent or young adult with a "wing-beating" tremor, dystonia, dysarthria, parkinsonism, psychiatric illness, hepatitis or cirrhosis ^[6]. A tremor that looks unlike other essential tremor but with a young age, K-F ring or hepatic abnormality should trigger testing.

Diagnostic approach ^[6]:

• Presence of Kayser-Fleischer rings (corneal copper deposits visible on slit-lamp) and sunflower cataracts.
• Low serum ceruloplasmin; raised free (depending on timing of testing) and 24-hour urinary copper excretion (>100 micrograms/day in most symptomatic patients and 40 to 100 micrograms in presymptomatic/children; urine collection schemas vary by guideline).
• High hepatic copper (>250 micrograms/g dry weight).
• Leipzig score as in the table. Score 4 or more confirms (18 to 68% neurologic in different series), 3 is probable, 2 or less is unlikely.
• Two ATP7B mutations may add four points and confirm the diagnosis.
• Brain MRI for basal ganglia (putamen, midbrain "face of the giant panda" sign), more often T2 signal changes in the striatum.
• The penicillamine challenge test (>1,600 micrograms copper excreted per 24 hours after two 500 mg penicillamine doses) is sometimes used, particularly in children, but is not recommended routinely in many authorities. ^[6]

Treatment ^[6]:

• Lifelong therapy maintains a negative copper balance: chelators (D-penicillamine, trientine) increase urinary copper excretion; zinc salt reduces intestinal absorption; low-copper diet avoids shellfish, liver, mushrooms, nuts and chocolate.
• Chelators are typically used during the initial (detoxification) phase; zinc or low-dose chelator maintenance follows, with close neurological review in the first months.
• Hepatic disease and acute liver failure may require transplantation, which corrects the defect in hepatocytes.
• Adequate hydration, pregnancy and drug side-effect monitoring accompany care; zinc is often used where chelators are unavailable.
• Guideline editions differ between the European and American approaches, and evidence differs on split-lamp and MRI criteria; refer patients to hepatology and neurology. (Dates: EASL 2012 recommendations; the 2022 AASLD clinical practice guidance referenced in recent reviews builds on them.)

Management differs by phenotype ^[8] and must be individualised:

• Drug-induced parkinsonism: Reduce dose, switch or stop the offending agent if possible; short-term anticholinergics (benztropine, trihexyphenidyl) at the lowest effective dose, tapering weeks to months; amantadine may be preferred in older patients or when anticholinergics are problematic. An extended-release amantadine preparation is approved for drug-induced extrapyramidal reactions.
• Acute dystonic reactions: Intramuscular diphenhydramine or benztropine; thereafter oral anticholinergics for one to two days after withdrawal, or several days if the antipsychotic is continued, at the lowest dose, tapered off when the regimen changes. ^[8]
• Akathisia: Reduce offending drug, change antipsychotic, or use a beta blocker, low-dose mirtazapine or benzodiazepine, remembering drug interactions. Anticholinergics are not recommended.
• Tardive dyskinesia: Anticholinergics are contraindicated (may worsen). Use a VMAT2 inhibitor (valbenazine or deutetrabenazine) for moderate-to-severe TD or for milder TD with functional impact; antipsychotic cessation early, particularly in young patients. APA guideline recommends structured assessments such as the Abnormal Involuntary Movement Scale at least every 12 months, and every 6 months in high-risk patients.
• Tardive dystonia: VMAT2 inhibitor or relatively high-dose anticholinergics in some, botulinum toxin for focal forms, antipsychotic modification, surgery in selected cases.
• NMS: Stop offending drug, supportive care, and benzodiazepines, dantrolene, dopaminergic agents or electroconvulsive therapy as needed. Anticholinergics are contraindicated. Prevention is a safer prescription record: avoid prophylactic anticholinergics except for prevention of acute dystonia in at-risk patients on high potency parenteral first-generation antipsychotics, and avoid or monitor carefully in older adults.
• Anticholinergics can be safely tapered to reduce burden over one to four months when a reduction in cognitive, bladder and bowel risk is appropriate. Always weigh the risk of re-emergence of the underlying disorder.

Across movement disorders, complications include:

• Falls and fractures; aspiration and poor swallowing; decline in activities of daily living; and social exclusion because of a visible movement, all of which dominate quality of life in progressive disorders.
• Tardive syndromes and neuroleptic malignant syndrome are preventable complications of antipsychotic use that can be long-lasting or life-threatening once they occur.
• Untreated Wilson disease leads to cirrhosis, haemolytic episodes and fixed neurological disability.
• Dystonia can develop fixed contracture and muscle hypertrophy if untreated, with a substantial psychosocial burden.

• ET may progress slowly or stay mild; many older patients never seek treatment; treatment is symptomatic.
• Parkinson disease (with a tremor-predominant phenotype) often has a slower course than akinetic-rigid forms, and is (eventually) dominated by non-motor complications.
• Tourette syndrome often peaks at ages eight to twelve and improves in most adolescents and young adults; adult persistence is associated with severity and comorbidity.
• Ataxias are mostly progressive, although EA2 and thiamine/vitamin-responsive ataxias are exceptions.
• Acute dystonias resolve completely. Tardive dyskinesia may remit on withdrawal early, but often persists.
• Wilson disease is treatable; the earlier it is caught the better the long-term outcome.

• Children. Tics are common and need reassurance. Dystonia in childhood suggests a genetic/metabolic (or secondary) origin. Rhabdomyoma of the heart is a different entity.
• Pregnancy. Drug choices change: propranolol can be continued (it causes bradycardia/low birth weight considerations), botulinum toxin and levodopa pass with caution, anticholinergics are less favoured, Wilson disease management often shifts to zinc as pregnancy adds chelation concerns; pregnancy is usually managed by a multidisciplinary team.
• Older adults. Akathisia mimics anxiety; drug-induced disorders are most dangerous here (anticholinergic burden), review medication doses carefully.
• Consanguineous families or high recurrence. Wilson disease screening of siblings with family genetic testing (Leipzig score, ATP7B variants) during a heterozygote work-up is vital.

• Ensure a transthoracic ultrasound for "mitral stenosis" that doesn't fit, or unexplained stroke; in movement disorders, MRI plus a copper test is the key for Wilson disease.
• Where botulinum toxin is unavailable, low-dose anticholinergics for dystonia and physiotherapy remain the mainstays for focal dystonia management in resource-poor clinics.
• In countries with high consanguinity, suspect Wilson disease early in young people with unexplained neuropsychiatric or hepatic illness; zinc salts can be a practical alternative where chelators are unavailable. Family screening is low-cost and high-yield.
• In drug-induced disorders, the first step is to stop and explain (not prescribe), when possible, plus review anticholinergics and dosing; avoid polypharmacy.
• Ataxia care should focus on rehabilitation, falls prevention, independence, communication and cerebellar gait training, even without disease-modifying drugs.

Within the MedGrasp library this topic connects, in plain text, to Parkinson disease and movement disorders; tics and Tourette syndrome and the accompanying Psychiatry topics (obsessive-compulsive disorder and attention-deficit hyperactivity disorder); Wilson disease as a separate topic; ataxia as a separate topic; stroke and cerebellar disease; drug safety and antipsychotic use; and the general neurological examination and neuroimaging topics. These related topics are not linked electronically in this curriculum-gap file.