Neurology - Dyskinesias Flashcards
Dyskinesia
= Abnormal involuntary movement
Caused by extrapyramidal or cerebellar lesions
Tremor
= Regular, rhythmic oscillation
NB Asterexis is not the same, it is rhythmic myoclonus
Types of tremor
“RAPID”
- Resting (e.g. PD)
- Action/ Postural
- Intention (e.g. cerebellar)
- Dystonic
What are the features of resting tremor?
4-6Hz pill rolling
Abolished on voluntary movement/ action
Increases with distraction - e.g. counting backwards
Cause - PD (basal ganglia abnormalities manifest at rest)
Features of an action/ postural tremor
6-12Hz
Absent at rest
Worse with outstretched hands or movement
Equally bad at all stages of movement
What are the causes of an action/ postural tremor?
“BEATS”
- Benign essential tremor
- Endocrine - thyrotoxicosis, decr. glucose, phaeo
- Alcohol withdrawel
- Toxins - beta agonists, theophyline, valproate
- Sympathetic - physiological tremor may be enhanced e.g. anxiety
Features of an intention tremor
Irregular, large amplitude
Worse at the end of movement - e.g. past pointing
Cause - cerebellar damage
Important features of benign essential tremor
Autosomal dominant Occurs with action and worse with anxiety, emotion etc Arms, neck and voice Doesn't occur during sleep Better with alcohol
What is myoclonus?
= Sudden involuntary jerks
Causes of myoclonus
Epilepsy (i.e. juvenile myoclonic epilepsy, infantile spasms)
Neurodegenerative diseases
CJD - important one to remember!
Chorea
= Irregular random movements that have a flowing/ purposeful quality
Any part of the body can be affected
Causes of chorea
Hereditary (e.g. Huntington's) Post infectious (Sydenhams chorea is associated with rheumatic fever) Polycythaemia rubra vera SLE Wilson's disease
What are tics?
Type of dyskinesia
= Rapid, compulsive, repetitive stereotyped movement s
Also referred to as “habit spasms”
Associated with involuntary utterances in Tourette’s syndrome
Hemiballismus
= Violent, jerky movements typically restricted to one side of the body
Caused by damage to the contralateral sub thalamic nucleus (often elderly diabetics)
Resolves spontaneously
Athetosis
= Slow, within movements often seen with congenital brain damage in cerebral palsy
What is the difference between physiological and pathological tremor?
Physiological tremor - appears when maintaining a fixed posture, fine character
Pathological tremor - occurs at rest or movement (action), slow rate and course character
How should a tremor be examined?
Observe the tremor at rest (e.g. PD)
Observe on maintaining posture (e.g. physiological or postural)
Observe on movement and at the end of movement - finger nose pointing (e.g. cerebellar)
What is dystonia?
= Prolonged muscle contracture causing unusual joint posture or repetitive movements
How are dystonia’s classified?
By distribution:
- Generalised
- Focal - limited to one area of the body
By aetiology:
- Primary - often genetic involvement
- Secondary - e.g. drugs, metabolic disorders etc
Idiopathic generalised dystonia
Autosomal dominant
Childhood onset
Begins in one leg then spreads to that side of the body over 5-10 years
Idiopathic focal dystonia
Most common form of dystonia Affects one part of the body Worsened by stress Types: - Spasmodic torticolis (cervical dystonia) - Writers cramp - Oromandibular dystonia
Negative features of extrapyramidal disease
Hypokinetic features of extrapyramidal disease
- ) Bradykinesia - loss or slowness of voluntary movement
- ) Postural disturbance - flexion of limbs and trunk is associated with a failure to make quick postural “righting” adjustments to correct balance
Positive features of extrapyramidal disease
Hyperkinetic features of extrapyramidal disease
- ) Abnormal involuntary movements - “Dyskinesia”
- ) Rigidity
What is the definition of rigidity?
Velocity independent increase in tone
Affects flexor and extensor muscle groups equally
Also called “Lead pipe rigidity” - indicates extrapyramidal disease
Cog wheel rigidity
Tremor superimposed on rigidity
Tardive dyskinesia
= Delayed onset (“tardive”) following chronic exposure to Da agonists (e.g. antipsychotics, anti-emetics, L-DOPA)
Da receptors become super-sensitive
How is tardive dyskinesia treated?
1) Using new atypical antipsychotics
2) Early recognition and drug withdrawal
Wilson’s disease
(Hepatolenticular degeneration)
Autosomal recessive disorder - build up of copper in the lentiform nucleus (= globus pallidus + putamen)
What is the underlying biochemical defect in Wilson’s disease?
Deficiency of alpha 2 globulin - Ceruloplasmin - normally binds 98% of plasma copper and transfers to a copper enzyme
Increase in loosely bound copper/ albumin and organ deposition (esp liver and brain)
Acute form of Wilson’s disease
There are 2 clinical forms of Wilson's disease Acute: 1) Bradykinesia 2) Behavioural change 3) Involuntary movements 4) Liver involvement common
HIGH mortality rate if untreated (death in approx 2 years)
Chronic form of Wilson’s disease
Proximal “wing beating” tremor
Dysarthria, dystonia, and rigidity
Psychosis and behavioural disorders
Liver involvement is less severe
How are neurotransmitter substances altered in extrapyramidal disease?
Dopamine - inhibitory
ACh - excitatory
Extrapyramidal disease involves imbalance of these 2 neurotransmitters:
- Dopamine deficiency or ACh excess - akinetic rigid syndrome
- Dopamine excess or ACh deficiency - involuntary movements (i.e. dyskinesia)
