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Movement disorder

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"Movement disorder" covers a lot of ground, so here is a map of the topic. Then I'll ask which part you want in depth.
Topic breakdown
  1. Classification: hypokinetic (parkinsonism) versus hyperkinetic disorders
  2. Parkinson disease and atypical parkinsonism (MSA, PSP, CBD, Lewy body disease)
  3. Tremor (essential, parkinsonian, dystonic, cerebellar, functional)
  4. Dystonia (focal, generalized, drug-induced)
  5. Chorea, Huntington disease, and other choreas (Sydenham, drug-induced)
  6. Tics and Tourette syndrome
  7. Myoclonus, ataxia, and restless legs syndrome
  8. Drug-induced movement disorders (tardive dyskinesia, akathisia, neuroleptic malignant syndrome)
  9. Wilson disease and other metabolic or genetic causes
  10. Treatment (levodopa, DBS, botulinum toxin, VMAT2 inhibitors)
Brief overview
Movement disorders are neurological syndromes with too much or too little movement that are not caused by weakness or spasticity. They mostly arise from dysfunction of the basal ganglia and their cortical, thalamic and cerebellar circuits.
  • Hypokinetic disorders show bradykinesia and rigidity, as in parkinsonism. Parkinson disease is the commonest cause, from loss of dopaminergic neurons in the substantia nigra pars compacta.
  • Hyperkinetic disorders show excess involuntary movement. These include tremor, dystonia, chorea, tics, myoclonus and stereotypies.
  • Diagnosis is mostly clinical. You identify the phenomenology first: what the movement looks like, whether it is at rest or on action, and whether it is rhythmic. Then you look for a cause, which may be a drug, a genetic or metabolic condition, a structural lesion, or a functional disorder.
  • Treatment depends on the type. Examples are dopaminergic therapy for Parkinson disease, botulinum toxin for focal dystonia, VMAT2 inhibitors for chorea and tardive dyskinesia, and deep brain stimulation for selected patients.
The library has dedicated "Movement Disorders" chapters in Bradley and Daroff's Neurology in Clinical Practice. I'll use those for whichever topic you pick.
Asking for Preferences

Which topic do you want in detail?

"Movement disorder" covers a lot of ground, so here is a map of the topic. Then I'll ask which part you want in depth.
Topic breakdown
  1. Classification: hypokinetic (parkinsonism) versus hyperkinetic disorders
  2. Parkinson disease and atypical parkinsonism (MSA, PSP, CBD, Lewy body disease)
  3. Tremor (essential, parkinsonian, dystonic, cerebellar, functional)
  4. Dystonia (focal, generalized, drug-induced)
  5. Chorea, Huntington disease, and other choreas (Sydenham, drug-induced)
  6. Tics and Tourette syndrome
  7. Myoclonus, ataxia, and restless legs syndrome
  8. Drug-induced movement disorders (tardive dyskinesia, akathisia, neuroleptic malignant syndrome)
  9. Wilson disease and other metabolic or genetic causes
  10. Treatment (levodopa, DBS, botulinum toxin, VMAT2 inhibitors)
Brief overview
Movement disorders are neurological syndromes with too much or too little movement that are not caused by weakness or spasticity. They mostly arise from dysfunction of the basal ganglia and their cortical, thalamic and cerebellar circuits.
  • Hypokinetic disorders show bradykinesia and rigidity, as in parkinsonism. Parkinson disease is the commonest cause, from loss of dopaminergic neurons in the substantia nigra pars compacta.
  • Hyperkinetic disorders show excess involuntary movement. These include tremor, dystonia, chorea, tics, myoclonus and stereotypies.
  • Diagnosis is mostly clinical. You identify the phenomenology first: what the movement looks like, whether it is at rest or on action, and whether it is rhythmic. Then you look for a cause, which may be a drug, a genetic or metabolic condition, a structural lesion, or a functional disorder.
  • Treatment depends on the type. Examples are dopaminergic therapy for Parkinson disease, botulinum toxin for focal dystonia, VMAT2 inhibitors for chorea and tardive dyskinesia, and deep brain stimulation for selected patients.
The library has dedicated "Movement Disorders" chapters in Bradley and Daroff's Neurology in Clinical Practice. I'll use those for whichever topic you pick.
Finding Sources
Finding Sources
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"movement disorders"[MeSH Terms] AND "classification"

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movement disorders classification basal ganglia hyperkinetic hypokinetic

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Movement disorders: classification and approach

You didn't pick a subtopic, so this covers the framework that underlies all of them. Tell me which disorder you want next and I'll go deeper on it.

Core idea

Movement disorders are neurological syndromes of too much or too little movement. They are not caused by weakness or spasticity. They mainly reflect dysfunction of the basal ganglia and their loops with the cortex, thalamus and cerebellum.

1. Two broad groups

Hypokinetic (parkinsonian):
  • Features are akinesia, bradykinesia and rigidity. Rest tremor and postural instability are also common.
  • Parkinson disease is the commonest cause.
  • Other causes are atypical parkinsonism (MSA, PSP, CBD, dementia with Lewy bodies), drug-induced parkinsonism, vascular parkinsonism and normal pressure hydrocephalus.
Hyperkinetic:
  • These are involuntary movements without weakness.
  • The Goldman-Cecil abstract notes that hyperkinetic disorders are "easy to distinguish clinically from the parkinsonian hypokinetic disorders" (Goldman-Cecil Medicine, Table 379-1).
  • Harrison's cautions that the split is "somewhat arbitrary". Parkinson disease often has tremor, and severe dystonia can look like slowness or restricted movement (Harrison's Principles of Internal Medicine 22E, ch. 447).

2. Hyperkinetic phenomenology (Harrison's Table 447-1)

TypeDefinition
TremorRhythmic oscillation of a body part from intermittent muscle contractions
DystoniaInvoluntary, patterned, sustained or repeated contractions, often twisting with abnormal posture
AthetosisSlow, distal, writhing movements of the arms and hands (dystonia with more mobility)
ChoreaRapid, semi-purposeful, dance-like, nonpatterned movements. Large-amplitude proximal chorea is called ballism.
MyoclonusSudden, brief (<100 ms), jerk-like, arrhythmic twitches
TicBrief, repeated, stereotyped contractions that can often be suppressed briefly
Ataxia, gait disorders and stereotypies are classified alongside these in some texts (Kaplan & Sadock's Comprehensive Textbook of Psychiatry, Comparative Nosology).

3. Practical approach

  1. Name the phenomenology first. Ask the following:
    • Is there too little movement (parkinsonism) or too much?
    • Is it rhythmic (tremor) or non-rhythmic?
    • Is it sustained and patterned (dystonia) or flowing and random (chorea)?
    • Is it brief and jerky (myoclonus) or suppressible with a premonitory urge (tic)?
  2. Characterise tremor along two axes. Axis 1 is the clinical picture (rest, postural, kinetic or intention; distribution; associated signs). Axis 2 is the etiology (genetic, secondary or idiopathic). Harrison's gives these contrasts:
    • Essential tremor is postural or action tremor.
    • Parkinson disease has a predominant rest tremor.
    • Cerebellar disease causes kinetic or intention tremor with hypotonia and past-pointing.
    • Physiologic tremor is fine and high-frequency (10 to 12 Hz).
  3. Look for a cause.
    • Drugs: antipsychotics, metoclopramide, valproate, lithium, SSRIs, anticonvulsants and others.
    • Metabolic or toxic: Wilson disease, thyroid disease, hepatic encephalopathy.
    • Genetic: Huntington disease and the dystonias.
    • Structural, vascular, infectious or autoimmune: stroke, anti-NMDAR encephalitis, paraneoplastic syndromes.
    • Functional.
  4. Check for red flags. These suggest an atypical or secondary cause:
    • Early falls
    • Poor levodopa response
    • Early autonomic failure
    • Rapid progression
    • Onset in youth
    • Abrupt onset
  5. Investigate selectively. Options include ceruloplasmin for young-onset cases, MRI, DaT-SPECT for unclear parkinsonism, genetic testing, and autoimmune or paraneoplastic panels.

4. Treatment, by target

  • Parkinson disease: levodopa, dopamine agonists, MAO-B or COMT inhibitors, and DBS in selected patients.
  • Essential tremor: propranolol or primidone, then DBS or focused ultrasound.
  • Focal dystonia: botulinum toxin. Anticholinergics and DBS are used for generalized disease.
  • Chorea and tardive dyskinesia: VMAT2 inhibitors (tetrabenazine, valbenazine, deutetrabenazine).
  • Tics: behavioural therapy (CBIT), then alpha-agonists or antipsychotics.
I wrote the treatment list from my own knowledge, not from a library passage.

Recent literature check

Recent systematic reviews do not contradict the framework above. Two of them refine it:
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Which would you like next: Parkinson disease and atypical parkinsonism, tremor, dystonia, chorea and Huntington disease, tics, or drug-induced movement disorders?
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