Parkinson's Disease & other movement disorders

These are caused by dysfunction of the basal ganglia, a collection of primitive nuclei at the base of the brain, clearly important in motor control but increasingly recognised as additionally regulating thinking, behaviour & mood. One of the major basal ganglia neurotransmitters, dopamine, is either deficient or dysregulated in these conditions.

1. Idiopathic Parkinson’s Disease

This is a degenerative disease of the central nervous system due to the premature death of a small collection of cells in the brainstem. It is common and affects 1% of people over 60.

The cause is unknown though there is a genetic influence and possibly, an environmental toxin may be contributory. Secondary causes include some drugs, head injury and encephalitis. There are a variety of Parkinson-plus syndromes which respond less well to treatment.

Symptoms include general malaise and tiredness, stooped posture, slow walking and scruffy spidery handwriting. The face appears blank, there is infrequent blinking and a soft slightly monotonous voice. The limbs are restless and stiff, there may be numbness, tingling & pain and a shake of one or other hand or foot at rest. There are problems with bowels, waterworks and sexual function. Thinking is slow and mood frequently depressed.

The diagnosis is made clinically without the need to resort to extensive testing.

Treatment is with drugs and other interventions including physiotherapy, occupational therapy, speech & language therapy and the use of a Parkinson's Disease nurse specialist. These therapies give very good control of symptoms but there is no cure. Drug side effects, with progressive shortening of the duration of effect, makes drug management difficult in the middle and late stages of disease. Confusion and hallucinations, often visual, may suggest the presence of an underlying associated dementing illness.

2. Essential Tremor

This is often confused with tremor-dominant Parkinson's disease. However the tremor here is largely limited to the hands and sometimes the head. There is often a family history and a prominent positive response to alcohol. Although progressive, this tremor is hardly ever disabling and there are a number of good drug treatments available.

3. Huntington's Disease

This disease only runs in families. There is a characteristic combination of jerky movements (chorea), dementia, change in personality and depression. It is incurable and symptomatic drug treatments are unsatisfactory. Genetic testing is now available both diagnostic and predictive.

4. Restless Legs syndrome (RLS)

This common condition, it possibly affects 10% of the population, was first described in 1672 and remains both desperately under-diagnosed and frequently mis-diagnosed. RLS, and an associated condition referred to as periodic leg movements during sleep (PLMS) are caused by dopamine dysregulation and altered handling of iron in the central nervous system. Most cases are primary and often inherited, there may be a loose association with obsessive-compulsive disorder (OCD) and attention deficit hyperactivity disorder (ADHD), and secondary causes include peripheral neuropathy, iron deficiency and kidney disease.

Symptoms are diurnal, tending to come on at rest in the evening and particularly in bed when trying to sleep. The arms can be affected and symptoms by day can occur, but less commonly. Complaints include unpleasant/uncomfortable aching, pulling/drawing, creeping/crawling & tingling/numbness, with an irresistible urge to move the legs, with clear improvement on movement. There is associated sleep disturbance and excessive daytime somnolence with significant reduction in life quality. Treatment in the past was with benzodiazepines (valium-like drugs) and opioids, though now these have largely been replaced by non-ergot dopamine agonists.