Movement disorders are neurological syndromes where there may be excess of movement or a paucity of movement that is not connected to weakness, paralysis of spasticity of the muscles. Movement disorders commonly affect the speed, fluency or smoothness, quality, and ease of movement.
The pathology more often than not lies in the brain especially in an area of the brain called the basal ganglia. This region is part of the grey matter that lies deep within the brain or cerebrum.
The defects may also lie in the base of the brain or cerebellum. This leads to difficulty in walking, locomotion or maintenance of posture and normal body balance.
Although genetics is the commonly implicated cause of abnormal movements there are other causes such as stress, drugs and so forth. (1-5)
Stress, anxiety and emotional disturbances
These may lead to abnormalities of movements like tremors. Tremors are rhythmic movements of hands, feet, head or voice.
They may be triggered by emotional components as well as stress. Older individuals commonly manifest essential tremors. Although the condition is not fatal, it may cause severe debility.
Drugs as cause of movement disorders
Dyskinesias signify a range of abnormal movements that may include:
- hypokinesia (less movements)
- bradykinesia (slowing of movements)
- akinesia (absence of movements)
- chorea (rapid jerky movements)
- athetosis (slow writing movements)
- tics (rapid repeated twitches)
These may be caused due to intake of certain drugs. Antipsychotic medications taken for psychiatric conditions like Schizophrenia or anti-nausea agents like Metoclopramide may lead to these movement disorders.
Chronic diseases and movement disorders
Chronic disease like an over active thyroid gland can lead to abnormal movements like tremors.
Alcohol consumption may lead to ataxia – an abnormal movement or gait. There are problems with coordination and balance.
There are many different types. Commonly the cerebellum is affected in this condition.
Iron deficiency is thought to be responsible for Restless leg syndrome although the exact cause of the condition is unknown.
Excess nicotine, alcohol and caffeine has also been implicated.
Restless legs syndrome affects nearly 20% of women during pregnancy and disappears after delivery. Those with renal failure may also develop symptoms.
Some evidence exists that the use of antidepressants, lithium (mood stabilizer), and blood pressure lowering drugs like calcium channel blockers may aggravate the condition.
Excess copper in the body
Copper excess in the body leads to Wilson’s disease characterized by abnormal movements, psychiatric and liver disease manifestations.
There may be tremors, lack of coordination and abnormal movements. It affects 1 in 30,000 to 1 in 40,000 individuals.
It affects all races but there is an increased incidence among European Jews, Italians, Sicilians, and Japanese.
There may be a defect in the way the body handles excess copper leading to its deposition in the liver and brain. Usually the cause is genetic with the problem lying in the 13th chromosome.
Parkinson’s disease is a neurodegenerative condition. There is a reduction of cells in the basal ganglia that produce a chemical messenger of the brain called Dopamine.
It has mainly genetics as a cause. There are other causes such as exposure to heavy metals, such as prolonged exposure to copper and manganese or exposure to pesticides and exposure to antipsychotic drugs like phenothiazines, prochlorperazine, thioridazine, chlorpromazine, haloperidol and anti-vomiting agent metoclopramide.
Genetic causes of movement disorders
Huntington’s disease is primarily caused by genetic defects that are inherited. The defect lies in the 4th chromosome and is transmitted to the offspring almost certainly (autosomal dominant trait).
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)