DISORDERS OF MOVEMENT
• These can take the form of negative symptoms like weakness, and
bradykinesia or positive symptoms such as tremor, dystonia, chorea,
athetosis, hemiballismus, tics and myoclonus.
INVOLUNTORY MOVEMENTS
• Abnormal movements usually imply a disorder in the basal ganglia.
Tremor
• It is a rhythmic oscillating movement of a limb or part of a limb, or of the
head.
• It is divided into rest tremor and action tremor.
• Action tremor is further subdivided into:
1. Postural tremor
2. Intention tremor
3. Flapping tremor (astrixis)
Action tremor
Causes of action tremor include:
1- Exaggerated physiological tremor
2- Essential tremor
3-Parkinson's disease (rest tremor more usual)
4-Wilson's disease
5-Cerebellar hemisphere disease
• A physiological tremor (frequency between 8 and 12 Hz) can be
identified in the limbs of normal subjects; exaggeration of this
physiological tremor occurs in:
1. Anxiety
2. Fatigue
3. Thyrotoxicosis
4. Pheochromacytoma
5. Hypoglycaemia
6. Alcohol withdrawal
7. Drugs like
o
β-agonists (e.g. salbutamol)
o
Theophylline
o
Caffeine
o
Sodium valproate
o
Tricyclics
o
Amphetamines
Essential tremor is slower than a physiological action tremor and may become
quite disabling.
The condition is often familial.
Characteristic of essential tremor
is that alcohol suppresses it, sometimes to the extent that the patient becomes
addicted.
Centrally acting β-adrenoceptor antagonists (β-blockers) such as propranolol are
often effective in treatment. Other second choice drugs are primidone and
gabapentine.
Intention tremor is the characteristic oscillation at the end of a movement which
occurs in cerebellar disease.
Flapping tremor is seen in
o
Renal failure
o
Liver failure
o
Hypercapnia
o
Drug toxicity (e.g. phenytoin)
o
Acute focal parietal or thalamic lesions
Chorea
• Non-rhythmic, sudden and semipurposeful involuntary movements
resembling nonpathological “fidgetiness”.