Features of Parkinson’s Disease

The classic triad of PD is made up of tremor, rigidity and bradykinesia. However, there are other features [3].

Motor functions:

Tremor

Tremor is the most apparent and well-known symptom. Classically affecting the thumb it is often termed a ‘pill-rolling tremor’. The tremor is maximal when the limb is at rest and disappears during voluntary movement and sleep. It is typically unilateral at onset.

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Approximately 30% of PD sufferers do not have tremor at disease onset

Rigidity

Rigidity is due to increased muscle tone, which combined with a resting tremor produces ‘cogwheel rigidity’ – when the limb is passively moved. Rigidity may be associated with joint pain.

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Joint pain secondary to limb rigidity is a common feature of PD.

Bradykinesia

Bradykinesia – slowness of movement – is the third characteristic of the classical triad of clinical features of PD.

In the later stages of the disease, the combination of rigidity, tremor and bradykinesia leads to postural instability with impaired balance and falls.

Other motor features

There are many other characteristic motor features of PD including:

• Decreased arm swing
• A forward-flexed posture
• The use of small steps when walking
• Speech and swallowing disturbances
• A mask-like face expression
• Small handwriting

Neuropsychiatric disturbances

Less recognised by many lay people and clinicians are the neuropsychiatric disturbances that PD causes, which include cognitive deficits, and mood problems [4]. Table 1 provides an indication of the prevalence of these:

Table 1 Prevalence of neuropsychiatric disturbances

The commonest cognitive problems are deficits in executive function causing inattention and defective planning and problem solving. These deficits progress with time – often developing into dementia.

The prevalence of dementia is increased 6-fold in patients with PD. It is seen in 30% of patients with advanced PD.

In addition to cognitive and motor symptoms, PD can impair other body functions. Sleep problems are a core feature of the disease manifesting as daytime somnolence, or nocturnal insomnia.

Autonomic disturbances

Autonomic disturbances may result in:

• Orthostatic hypotension
• Oily skin
• Excessive sweating
• Constipation
• Urinary incontinence

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The classic triad of PD is made up of tremor, rigidity and bradykinesia. However, neuropsychiatric and autonomic abnormalities may cause even greater problems.