Here is a detailed overview of involuntary movements in pediatrics:
Involuntary Movements in Pediatrics
Involuntary movements in children fall under the broad category of movement disorders — abnormal, uncontrolled movements that occur without the child's intention. They are classified based on their character, rhythm, and the neural pathway involved.
1. CHOREA
Definition: Rapid, irregular, non-repetitive, unpredictable jerky movements that flow from one body part to another — described as "dance-like."
Characteristics:
- Involuntary, random, brief
- Involves face, limbs, trunk
- Child cannot suppress them voluntarily
- Worsens with stress, improves with sleep
Causes in children:
| Cause | Notes |
|---|
| Sydenham's chorea | Post-streptococcal (rheumatic fever) — most common acquired chorea in children |
| Cerebral palsy (double athetosis) | Due to perinatal hypoxia or kernicterus |
| Kernicterus | Bilirubin toxicity to basal ganglia |
| Huntington disease | Juvenile onset — rare |
| SLE, antiphospholipid syndrome | Autoimmune |
| Drug-induced | Antipsychotics, anticonvulsants |
2. ATHETOSIS
Definition: Slow, writhing, sinuous, worm-like continuous movements — mainly involving distal limbs (fingers, hands, feet).
Characteristics:
- Slower than chorea
- Flowing, twisting quality
- Often combined with chorea → Choreoathetosis
- Severely affects fine motor tasks
Common cause in children:
- Double athetosis — most frequent congenital extrapyramidal disorder; caused by:
- Perinatal hypoxic-ischemic encephalopathy
- Kernicterus (Rh incompatibility, hyperbilirubinemia)
Clinical note: In double athetosis, choreoathetosis may not appear at birth — it manifests months to years later. In mild cases, it may be mistaken for simple restlessness or "fidgets." In severe cases, every voluntary movement triggers violent involuntary spasms.
3. DYSTONIA
Definition: Sustained or intermittent muscle contractions causing abnormal, often repetitive twisting postures or movements.
Characteristics:
- Can affect one body part (focal) or whole body (generalized)
- Movements are patterned and predictable — unlike chorea
- Often triggered or worsened by voluntary movement (action dystonia)
- May cause fixed abnormal posture
Types in children:
| Type | Example |
|---|
| Primary/Idiopathic | Dystonia musculorum deformans (DYT1 gene) |
| Secondary | CP, Wilson disease, metabolic disorders |
| Drug-induced | Acute dystonic reaction (metoclopramide, antipsychotics) |
4. TREMOR
Definition: Rhythmic, oscillatory, involuntary movement of a body part — the most common involuntary movement.
Types:
| Type | When It Occurs | Common Cause in Children |
|---|
| Resting tremor | At rest, diminishes with movement | Rare in children; Wilson disease |
| Action/postural tremor | During maintained posture | Essential tremor, physiological tremor |
| Intention tremor | Worsens on approaching a target | Cerebellar disease |
5. MYOCLONUS
Definition: Sudden, brief, shock-like involuntary muscle jerks — either flexion or extension.
Characteristics:
- Very brief (milliseconds)
- Can be single muscle or widespread
- May be rhythmic or arrhythmic
- Can be physiological (hypnic jerks when falling asleep) or pathological
Causes in children:
- Epileptic myoclonus — juvenile myoclonic epilepsy, infantile spasms
- Progressive myoclonic epilepsies — Lafora disease, Unverricht-Lundborg
- Metabolic — uraemia, hypoxia
- Post-hypoxic — Lance-Adams syndrome
6. TICS
Definition: Sudden, rapid, recurrent, non-rhythmic, stereotyped movements or vocalizations that the child can partially suppress (but with inner urge/tension).
Characteristics:
- Child feels a premonitory urge before the tic
- Can be suppressed briefly, but tension builds
- Worsens with stress, fatigue
- Disappears during sleep
Types:
| Type | Example |
|---|
| Simple motor tics | Eye blinking, head jerking, shoulder shrugging |
| Complex motor tics | Jumping, touching, obscene gestures (copropraxia) |
| Simple vocal tics | Sniffing, throat clearing, grunting |
| Complex vocal tics | Repeating words, coprolalia (rare) |
Most important condition:
- Tourette syndrome — multiple motor tics + at least one vocal tic, lasting >1 year, onset before 18 years
7. FASCICULATIONS
Definition: Spontaneous, irregular, visible twitching of small groups of muscle fibers (motor units) — not causing joint movement.
Significance in children:
- Sign of lower motor neuron (LMN) disease
- Seen in spinal muscular atrophy (SMA), poliomyelitis
- Not normally visible at rest in healthy children
Quick Comparison Table
| Movement | Speed | Rhythm | Pattern | Suppressible? |
|---|
| Chorea | Fast | Arrhythmic | Random, flowing | No |
| Athetosis | Slow | Arrhythmic | Writhing, distal | No |
| Dystonia | Variable | Sustained | Twisting, patterned | No |
| Tremor | Variable | Rhythmic | Oscillatory | No |
| Myoclonus | Very fast | Variable | Shock-like jerks | No |
| Tics | Fast | Semi-rhythmic | Stereotyped | Partially yes |
| Fasciculations | Fast | Irregular | Isolated muscle twitch | No |
Key Pediatric Points
- Double athetosis (choreoathetosis from perinatal injury) is the most common congenital extrapyramidal disorder
- Children with severe choreoathetosis are often wrongly assumed to have intellectual disability — cognitive function may be intact
- Early hypotonia → delayed motor milestones is the typical early presentation of extrapyramidal CP
- Tonic neck reflexes persist beyond their normal disappearance time in these children
- Sydenham's chorea is the most common acquired chorea in children (post-streptococcal)
- Tourette syndrome is the most important tic disorder in pediatrics
— Adams and Victor's Principles of Neurology, 12th ed. | Harriet Lane Handbook, 23rd ed.