MOVEMENT DISORDERS
Parkinsonism
The essential
feature is bradykinesia defined as slowness of initiation of movement and
progressive reduction in speed and amplitude of repetitive movement. Muscular
rigidity is also present and is lead-pipe or cogwheel in nature, equal in
flexion and extension.
In addition a
rest tremor is characteristic of Parkinson's disease, and postural instability
an early feature of Steele-Richardson-Olszewski disease and a later feature of
other forms of parkinsonism.
Common causes of
parkinsonism are Parkinson's disease, drug-induced parkinsonism, and less
commonly, striatonigral degeneration and SteeleRichardson-Olszewski disease.
Chorea may be
defined as the continuous or semi-continuous random flow of muscle activity
from one muscle group to another, and from one part of the body to another. The
movements produced may appear fragmented and jerky or normal in their nature.
They may be fast or slow.
Common causes of
chorea are anti-psychotic drug therapy (tardive dyskinesia) and levodopa use in
Parkinson's disease. Less common causes of chorea are Huntington's disease,
anticardiolipin antibody syndrome, Sydenham's chorea, oestrogen therapy.
Dystonia
describes a type of involuntary movement as well as a disorder characterised by
a dystonic movements. Dystonia can be defined as sustained muscle contraction
causing twisting and abnormal postures or repetitive movements.
Common causes or
dystonia syndromes are antipsychotic drug induced dystonia, focal intracerebral
lesions such as infarction, idiopathic dystonia, and dystonia associated with
parkinsonism or its treatment. Wilson's disease is an uncommon but important
cause.
Idiopathic
dystonia is characterised by generalised dystonia in childhood and by focal
dystonia (blepharospasm, torticollis, writer's cramp, facial grimacing) in
adulthood.
Tremor is defined
as a rhythmical oscillation of a body part.
There are three
main types of tremor.
1 Rest tremor, as in Parkinson's disease
2 Postural tremor, as occurs in anxiety
(or any cause of an increase in adrenaline) or as in essential tremor
(familial)
3 Intention tremor as in disorders
affecting the cerebellum.
These are wild
flinging movements of the limbs, usually occurring as hemiballism due to a
contralateral stroke in or near the subthalamic nucleus.
Myoclonus is a
sudden brief shock-like involuntary movement.
Myoclonus is most
commonly physiological, such as in hiccups and on falling to sleep (hypnic
jerks). Myoclonus is also a feature of epilepsy, degenerative brain disorders,
particularly Creutzfeldt-Jakob disease and subacute sclerosing panencephalitis
and metabolic and viral encephalopathies.
Tics are abrupt, jerky,
repetitive movements of discrete muscle groups which last about 100
milliseconds. They are most commonly seen in the head and neck.
Tics are most
commonly seen in young schoolboys and are transient. Persistent tics are part
of a chronic tic disorder, and when vocal tics also occur this is know as
Gilles de la Tourette's syndrome.
Akathisia
describes a mental and motor restlessness causing marching on the spot and
repetitive pacing amongst other activities.
The most common
cause is antipsychotic drug therapy. It also occurs in parkinsonism.