Friendly Print preview

...   PATIENT INFORMATION ... DRUGS

ABOUT PARKINSON'S

JAMES PARKINSON (1755-1824)
James Parkinson, renowned for first describing the shaking palsy in 1817, was a GP who was a prodigious writer, scientist and political activist.

He published almost a dozen political pamphlets in the post-French Revolution period, when Britain was in political chaos. Writing under his own name and pseudonym "Old Hubert", he called for radical changes to the social system.

His activities led to his being hauled before the Privy Council to give evidence about a plot to assassinate King George III - but he sensibly refused to testify until he was certain he would not be made to incriminate himself. Parkinson also contributed extensively to medical journals and wrote several books on medical subjects and palaeontology. However, his fame sprang from his major opus, "An Essay on the Shaking Palsy", in which he vividly described the disease and its different stages and gave it the Latin name of "paralysis agitans".

Although he appeared to have substantial first-hand knowledge of the disease, his most important work was, in fact, based on six cases. He gleaned his information from patient history and clinical findings deduced form observation, rather than actual examination of his patients. Indeed, three of the six cases were noticed casually in the street.

Parkinson's wish was that a remedy would be found so that progress of the disease, known by his name, would be halted.

PREDISPOSING FACTORS
Establishing the cause
Despite an enormous amount of work, the cause of Parkinson's disease has eluded researchers. The search is more than academic; specific treatment directed at a known cause might slow or even prevent the disease. Several factors are clear:

• The only unequivocal risk factor in PD is increasing age.
• There is little difference between racial groups or socio-economic status, although, interestingly, smokers seem less likely to develop the condition. Despite media speculation, in the case of Muhammed Ali, head trauma is not linked to with classical PD.

Inherited?
The disease is not normally inherited. The rate of dizygous and monozygous twins is identical. Although familial PD occurs, the disease in such families is severe and of early onset. No biological marker for the condition has been found, although a 1997 report suggests that an abnormality on chromosome 4 is linked to one cluster of familial PD.

Infective?
Most GPs would be aware of the incidence of PD in survivors of encephalitis lethargica. There are still few survivors from this consequence of the 1910-1920 influenza pandemic. Their disease was slow in onset and showed little progression. No new outbreaks have been reported. However, there have been reports of parkinsonism as a consequence of HIV related disease.

MPTP: One intriguing chemical cause of parkinsonism has been discovered: 1-methyl-4-phenyl-1,2,3,6-tetrahydropyidine (M.P.T.P). This occasional contaminant of certain designer drugs can produce irreversible full blown parkinsonism within a few days. The drug is toxic to the substantia nigra, does not produce Lewy Bodies and has similarities to several pesticides in common use. Selegiline, a drug which has been studied for its role in slowing the progression of PD, seems to protect against the toxic affects of MPTP.

Toxic?
The discovery of MPTP has given weight to research efforts into an environmental cause of PD. A naturally occurring environmental toxin or toxins, structurally similar to MPTP, may gain access to the nervous system in some individuals and cause the disease.

Numerous case control studies have indicated that PD is associated with rural residence, farming, well water drinking and herbicide/pesticide exposure. Furthermore, families have been identified in which age of onset in parent and child correspond to a past common environmental trigger. The similarity of numerous pesticides with MPTP is intriguing. Parkinsonism in manganese exposed workers has been reported all over the world.

Insufficient neuro protection?
There has been speculation that anti-oxidant vitamins could protect against PD. Two case control studies suggested that tocopherol may decrease the risk of developing PD.

PARKINSON'S DISEASE :_ PRIMARY CLINICAL FEATURES

There have been few well conducted studies of the presentation of early PD in general practice. With no biological marker existing , diagnosis remains clinical.

Risk Factors for Parkinson's Disease

• Increasing age
• Rural residence
• Exposure to pesticides

Non specific early features
The earliest manifestations of PD are subtle and gradual. Patients complain of tiredness, lethargy, mild depression or restlessness. Many will have non specific limb pain, aching muscles and vague paeasthesias.

Resting tremor
Found in about 75% of patients at presentation, tremor is the commonest early symptom. In early stages it rarely interferes with movements. To the patient it feels "like a motor running all the time". It is most frequently confused with essential tremor.

Early features of Parkinson's Disease

• tiredness
• lethargy
• mild depression
• restlessness
• tremor at rest
• non specific limb pain

Bradykinesia
Is slowness in initiating movement. This includes:

• large voluntary movements (standing up or hurrying)
• fine movements (difficulty fastening buttons or cutting food; writing may become smaller and more cramped)
• involuntary movements (slow blinking, reduced arm swinging and loss of facial expression)
• automatic movements (constipation, unstable bladder, dysphagia)

Rigidity
Rigidity produces the perplexing muscle pains described by many sufferers. Muscle tone increases producing cramps, stiffness and aches in arm or leg muscles.

Postural instability
The gait and balance is affected. Patients may feel unsteady, possibly limp, and may begin to stoop. Falls are so frequent in the elderly PD patient that anyone with a fractured neck or femur should be examined for PD.

The four major manifestations of PD

• tremor
• bradykinesia
• rigidity
• postural instability

SECONDARY CLINICAL FEATURES

Postural hypotension
Postural hypotension in PD is thought to result mainly from automatic dysfunction. It is potentiated by most anti parkinsonian drugs.

Restless legs
This primary sleep disorder is so common in PD patients that it should always raise suspicion of the condition. It consists of uncomfortable sensations in the legs and an overwhelming desire to stretch or walk.

Speech problems
Speech difficulty may be an early problem. Bradykinesia of the speech mechanism makes the voice quiet, monotonous and often slow despite patients feeling that they are speaking normally. They find it hard to shout and have difficulty using the phone. Paradoxically some patients may have rapid (festinating) speech. Stuttering is also common.

A 63 year old university professor with a history of previous anxiety became rapidly disabled by inability to raise his voice and express himself when lecturing. His anxiety over the symptom made it worse. He responded very well to intermittent doses of Madopar Q,, and was able to return to work with his confidence restored.

Other "soft" symptoms

Problems with body functions are frequent. Anosmia (loss of sense of smell) is remarkably common. Sufferers sometimes have dysphagia and take a long time to eat their meals, Impotence is not unusual.

I wasn't able to cope with even things like getting family meals without great difficulty - I was just flopping about the place. The other things that I thought were relatively minor things, and related to the menopause, were incontinence, bowel problems, constipation and bleeding. It was when my left leg started to behave strangely that I was diagnosed. (Sarah, age 46)

Produced for: Parkinson’s Association of WA Inc, 320 Rokeby Road, SUBIACO WA 6008