This article covers types of dyskinesia and their causes, with later focus on:
Dyskinesias are defined as abnormal involuntary movements. They include:
Athetosis is characterised by slow, writhing movements, most commonly seen in the fingers and hands. It should be differentiated from pseudoathetosis, the 'piano-playing' movement of fingers, present in patients with deficits in proprioception. This phenomenon is elicited by asking the patient to hold their hands out in front of them with closed eyes.
Chorea is characterised by rapid, jerky, 'dancelike' movements, most commonly in the limbs and head. Movements may appear semi-purposeful, and are not repetitive, but move fluidly to different parts of the body.
These two dyskinesias often occur together as choreoathetosis. Causes include:
Hemiballismus affects one side of the body, most commonly the arm. It is a sudden flinging movement that can often be problematic as objects may be unintentionally thrown, or the arm might hit other people/objects in the vicinity. Most commonly caused by subthalamic stroke.
Dystonias are spasmodic movements that may occur during intentional movement, either rhythmically (giving a repetitive appearance), or persistently (resulting in typical fixed postures). Focal dystonias may be responsive to treatment with botox. They may be :
These focal dystonias are usually acquired. In contrast, generalized dystonias are normally hereditary. Some can be treated with carbidopa.
Rapid, sometimes repetitive, jerks of a muscle or group of muscles. Hiccoughs are a benign example, and people often experience myoclonus as they are falling asleep. Pathological manifestations include:
Tics are rapid, repetitive, stereotyped movements. Patients may describe feeling an urge to do the tic, similar to an urge to sneeze, that can sometimes be supressed for short periods of time. However the urge usually becomes irresistable after several minutes, and the patient may feel momentary relief during and after performing the tic.
Simple tics include excessive blinking, grimacing, A quarter of children develop tics at one point in their development that usually resolve within a year.
Complex tics may be caused by Gilles de la Tourette syndrome. This may also include vocal tics, such as involuntary swearing.
Neuroleptics (antipsychotics) can induce tardive dyskinesia. This is characterised by movements of the mouth such as chewing, lip-smacking and protrusion of the tongue. Extrapyramidal movements are also common side effects. These include rigidity, pill-rolling tremor, and bradykinesia (slowing of movement). Extrapyramidal movements induced by medication tend to be symmetrical, in contrast with Parkinson's disease where onset of tremor and rigidity is usually asymmetrical.
Parkinson's medications such as levodopa can induce choreatic and athetoid movements. They may also induce myoclonus, as can antihistamines and tricyclic antidepressants.
This is an autosomal dominant, neurodegenerative disease affecting the basal ganglia. Onset is insidious, and usually between the ages of 35 and 50.
Signs and symptoms
The early signs and symptoms, which may persist for 10 years before onset of chorea, include:
Core features are:
Dysarthria, dysphagia, myoclonus and tics are also common. Later in the disease chorea may be superseded by dystonia and parkinsonism.
No known treatments are effective in slowing or stopping disease progress. Instead treatment is symptomatic:
Genetic counselling is strongly recommended, as is the early arrangement of an advance directive.
Most patients die within 13-15 years of disease onset.
Though Parkinson's disease is the main form of parkinsonism, some other rarer diseases can also manifest with some or all of the triad of rigidity, tremor and bradykinesia:
Multiple system atrophy (MSA)
Extrapyramidal symptoms in this disease is mostly unresponsive to treatment. The tremor is generally not 'pill-rolling' as in parkinson's disease, and postural instability is often a core feature. Aside from extrapyramidal symptoms, this is characterised by changes in:
1. THE AUTONOMIC SYSTEM. When this feature predominates, MSA is sometimes called Shy-Drager syndrome.
2. THE CEREBELLUM
Progressive supranuclear palsy (PSP)
This is characterised by:
It is unresponsive to therapy, and as suggested by the name, characterisd by progressive neurodegeneration.
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