Abnormal Movements
Abnormal movements are involuntary, excessive, reduced, or poorly coordinated movements resulting from dysfunction of:
- Basal ganglia
- Cerebellum
- Motor cortex
- Brainstem
- Peripheral nerves
- Neuromuscular junction
- Functional circuits
1️⃣ Classification of Abnormal Movements
|
Movement Type |
Speed |
Rhythm |
Typical Lesion |
|
Tremor |
Rhythmic |
Regular |
Cerebellum/BG |
|
Chorea |
Rapid |
Irregular |
Basal ganglia |
|
Athetosis |
Slow writhing |
Irregular |
Basal ganglia |
|
Ballism |
Violent flinging |
Irregular |
Subthalamic nucleus |
|
Myoclonus |
Sudden jerk |
Brief |
Cortex/brainstem |
|
Dystonia |
Sustained |
Twisting |
Basal ganglia |
|
Tics |
Sudden repetitive |
Stereotyped |
Basal ganglia |
|
Parkinsonism |
Slow |
— |
Substantia nigra |
|
Cerebellar |
Incoordination |
— |
Cerebellum |
2️⃣ Tremor
A. Resting Tremor
- Present at rest
- Improves with action
- 4–6 Hz
- “Pill-rolling”
- Seen in Parkinson’s disease
B. Postural Tremor
- Present when arms outstretched
- Seen in:
- Essential tremor
- Thyrotoxicosis
- Anxiety
- Drug-induced (salbutamol, lithium)
C. Intention Tremor
- Worse near target
- Cerebellar lesion
- Seen in Multiple sclerosis
D. Wing-Beating Tremor
- Proximal large amplitude
- Seen in Wilson’s disease
If tremor improves with alcohol → Essential tremor
3️⃣ Chorea
Features
- Rapid, jerky, irregular
- “Fidgety”
- Milkmaid grip
- Darting tongue
Causes
- Huntington’s disease
- Sydenham chorea
- SLE
- Pregnancy (chorea gravidarum)
- OCP
- Hyperthyroidism
4️⃣ Athetosis
- Slow, writhing
- Often with cerebral palsy
- Basal ganglia damage
5️⃣ Ballism
- Violent flinging
- Usually unilateral → hemiballismus
- Cause: lesion of Subthalamic nucleus
- Often vascular
6️⃣ Dystonia
Cervical dystonia
Writer’s cramp
Tardive dystonia
4
Features
- Sustained twisting posture
- Sensory trick (geste antagoniste)
Causes
- Primary
- Drug-induced (antipsychotics)
- Wilson disease
- Parkinsonism
7️⃣ Myoclonus
- Sudden shock-like jerk
- Causes:
- Epilepsy
- Metabolic (uraemia, hypoxia)
- Creutzfeldt-Jakob disease
- Post-hypoxic
8️⃣ Tics
- Suppressible
- Premonitory urge
- Motor ± vocal
- Associated ADHD/OCD
9️⃣ Parkinsonism
Parkinson’s disease
Multiple system atrophy
Progressive supranuclear palsy
4
Cardinal Features
- Bradykinesia (essential)
- Rigidity
- Rest tremor
- Postural instability
Red Flags
- Early falls → Progressive supranuclear palsy
- Early autonomic failure → Multiple system atrophy
- Asymmetry → Parkinson’s
🔟 Cerebellar Ataxia
Spinocerebellar ataxia
Friedreich’s ataxia
Signs
- Wide-based gait
- Dysdiadochokinesia
- Nystagmus
- Intention tremor
1️⃣1️⃣ Functional (Psychogenic) Movement Disorder
Clues
- Inconsistent
- Distractible
- Variable frequency
- Hoover’s sign positive