• Suspect Parkinson's disease if the person has any of the following characteristic features (which, early in the disease, are usually unilateral, but become bilateral as the disease progresses):
• Bradykinesia (slowness of movement) or hypokinesia (poverty of movement) — for example:
• Reduced facial expression, arm swing, or blinking.
• Difficulty with fine movements such as buttoning clothes and opening jars, or small, cramped handwriting.
• Slow, shuffling gait, or difficulty turning in bed.
• Stiffness or rigidity, which may be:
• Lead-pipe rigidity, which describes the constant resistance felt when a limb is passively flexed in the presence of increased tone without tremor, or
• Cogwheel rigidity, which describes the regular intermittent relaxation of tension felt when a limb is passively flexed in the presence of tremor and increased tone.
• Rest tremor, which:
• Improves on moving.
• May appear at the thumb and index finger ('pill-rolling'), the wrist, or the leg.
• Is absent in up to 30% of people at disease onset.
• Parkinson's disease may be confused with other causes of tremor and parkinsonism — see Differential diagnosis.
• If the person is taking a drug known to cause parkinsonism (that is: an antipsychotic; the anti-emetics, metoclopramide and prochlorperazine; or, less commonly, an antidepressant, amiodarone, cinnarizine, lithium, sodium valproate, or a cholinesterase inhibitor), see Differentiating Parkinson's disease from drug-induced parkinsonism.

In depth

• Suspect drug-induced parkinsonism if symptoms appear whilst the person is taking a drug known to induce parkinsonism. In the case of antipsychotics, symptoms usually appear within 10 weeks of starting the drug.
• Other features of drug-induced parkinsonism include:
• Motor symptoms that are rapid in onset and bilateral (as opposed to starting slowly and being unilateral, as in early Parkinson's disease).
• Absence of rigidity.
• Absence of rest tremor, or the presence of an action tremor (postural and kinetic).
• In people taking an antipsychotic, the presence of akathisia (restlessness of arms and legs) and dystonia (abnormal movements and postures caused by involuntary spasms).
• However, it is often not possible to distinguish drug-induced parkinsonian from Parkinson's disease on the basis of signs and symptoms.
• Many clinical features of drug-induced parkinsonism are similar to those of Parkinson's disease, including akinesia and bradykinesia, masked face, reduced blinking, postural instability, flexed posture, reduced arm-swing when walking, and a shuffling gait with hurrying small steps (festinating).
• If drug-induced parkinsonism is suspected, reduce or stop the drug (if possible) and refer to a specialist.
• Do not delay referral to assess the response.

In depth

• If a diagnosis of essential tremor is not clear, refer to a specialist.
• Tremor in Parkinson's disease:
• Is usually unilateral or asymmetrical early in the course of the disease, becoming bilateral as the disease progresses.
• Usually occurs at rest and improves on moving, with mental concentration, and during sleep. However, an action tremor is occasionally present.
• Usually affects the distal part of a limb, typically at the thumb and index finger ('pill-rolling') or the wrist.
• It can also involve the lips, chin, jaw, and legs, but rarely involves the head, neck, or voice.
• Essential tremor:
• Is not usually associated with bradykinesia or postural instability.
• Is usually bilateral and symmetrical.
• Is an action tremor. There is no tremor at rest.
• May worsen with stress, excitement, caffeine, or sleep deprivation.
• Involves the head, neck, or voice as well as the limbs.
• Often improves with alcohol and beta-blockers.

In depth

• Refer people with suspected Parkinson's disease quickly, and untreated, to a specialist (with expertise in the differential diagnosis of this condition) for diagnosis.
• The National Institute for Health and Clinical Excellence (NICE) states that people with suspected mild Parkinson's disease should be seen within 6 weeks, but new referrals in later disease with more complex problems require an appointment within 2 weeks.
• If Parkinson's disease is suspected, but the person is taking a drug known to induce parkinsonism (that is: an antipsychotic; the anti-emetics metoclopramide or prochlorperazine; or, less commonly, an antidepressant, amiodarone, cinnarizine, lithium, sodium valproate, or a cholinesterase inhibitor):
• Reduce or stop the drug if appropriate.
• Do not delay referral to assess the response.

In depth