Parkinson's disease is named after Dr. James Parkinson, a British Physician, who wrote a famous description of the disease called "Essay on the Shaking Palsy" in 1847.

PD is a progressive degenerative condition of the brain which preferentially affects a specific group of nerves in an area of the brain called the "substantial nigra pars compacta". This area of the brain is responsible for producing a brain chemical called dopamine which is critical in control of movement. When this brain chemical is deficient, the signs of PD are present including tremor, rigidity of the limbs and body, slowness or lack of movement (bradykinesia) and walking difficulties characterized by a flexed posture and short shuffling steps (petit pas gait). People with this disease may develop episodes of sudden inability to continue or initiate a movement, as well as reduction in the usual animated facial movements, blinking frequency and normal arm swing while walking. Their writing may become small and difficult to read (micrographia). The voice may become soft and quiet (hypophonia). Symptoms often begin on one side of the body and later spread.

PD is usually a progressive disorder and gradually worsens over time. It is frequently associated with depression which can occur at any time during the course of the disease. Later in the disease, up to 30% of patients may develop dementia. Some patients also complain of difficulty with peeing, waxy build upon the skin (seborrhea), and a deep achy sensation in the limbs.

The exact cause of PD is not known. A somewhat similar disease pattern can be produced due to the toxic effects of certain drugs on the substantia nigra raising this as a possible mechanism. Infectious causes and a possible genetic pre-disposition have also been proposed as contributing causes.

PD occurs most commonly in the elderly (>60 yr.) but can be seen in younger adults and very rarely in juveniles. 15% of cases tend to run in families. Recent research suggests that this may be due to an abnormal gene on chromosome 6.

Yes. PD is one of a group of degenerative conditions that may present in a similar fashion including progressive supranuclear palsy (PSP), striatonigral degeneration (SND), and multi-systems atrophy. In addition, several medications, especially the anti psychotic type can produce a PD-like picture.

The diagnosis of PD is usually made based on the patient's history and physical examination. Additional testing to rule out other causes of Parkinson's syndromes can be helpful including CT scanning of the head and positron emission tomography (PET) in atypical cases.

Although there is no cure for PD at the moment, there are several therapies available that are quite effective in controlling the symptoms and that improve function for quite an extended period of time. Exercise and mental activity are important in maintaining function and flexibility and in  reducing side effects such as depression.

Most patients begin treatment when their symptoms begin to interfere with their work or daily life activities. A variety of medications are useful. These are primarily aimed at replacing or mimicking the activity of dopamine in the brain. The initial choice of medication depends on the patient's overall medical condition and age with the general goal to use the minimum dose of anti-parkinsonian medication necessary to control symptoms.

The main groups of medications for treating PD including Carbi-dopa/Levo-Dopa combination drugs (e.g. Sinemet), dopamine agonists (e.g. bromocriptine, pergolide, ropinirole, pramipexole), catachol-O-methyltransferase (COMPT) inhibitors (e.g. Entacapone), Amantadine and anticholinergics (e.g. Trihexyphenidyl Hydrochloride, Benztropine).

The dopamine agonists are often the initial choice for therapy since there is some evidence that using these agents alone may delay or reduce later complications of PD. Levo-dopa/Carbi-dopa combinations are often more powerful drugs for the treatment of slowness and stiffness and may be the first choice if the patient has medical problems or impaired cognition. Anticholinergic medications are primarily effective for the tremor, but tend to have problematic side effects including blurred vision, dry mouth, confusion and memory difficulties that limit their usefulness, especially in older patients.

You should discuss with your physician what drugs would be most appropriate and what the overall strategy for treatment is.

Surgical therapy is usually considered in patients whose symptoms are no longer controlled with medical therapy. The type of surgical therapy depends upon the primary symptom. Thalamotomy (placement of lesions in the thalamus) has been used in the treatment of tremor, but has mostly given way to deep brain stimulation due to the high incidence of complications such as speech problems.

Pallidotomy, placing lesions in the internal segment of the globus pallidus (GPi) can improve tremor, rigidity and slowness of movement. When done on both sides of the brain however, it can lead to complications of softness of speech (hypophonia) which make it less useful when the disease is prominent on both sides.

Deep brain stimulation involves placing an electrode within the GPi or subthalamic nucleus (STN) and connecting to a stimulator under the skin. This can be effective for both tremor and the stiffness and slowness of PD and can be performed on both sides of the brain.

Brain cell transplantation remains an experimental therapy of uncertain usefulness.

Surgical treatment of PD requires evaluation at a centre and with a surgeon who is familiar with the treatment. In British Columbia, this is only taking place at Vancouver General Hospital at the moment.

Dr. R. O'Brien

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