Parkinson's

Question 1

Definition

Answer 1

neurodegenerative disease of the dopaminergic neurones of the substantia nigra, characterised by:

• Bradykinesia
• Rigidity
• Resting tremor
• Postural instability

Pathophysiology

• Degeneration of dopaminergic neurones projecting from the substantia nigra to the striatum
• Patients are only symptomatic after the loss of > 70% of dopaminergic neurones

Question 2

Aetiology

Answer 2

Sporadic/Idiopathic Parkinson’s Disease

• Most COMMON
• Aetiology UNKNOWN
• May be related to environmental toxins and oxidative stress

Secondary Parkinson’s Disease

• Neuroleptic therapy (e.g. for schizophrenia)
• Vascular insults (e.g. in the basal ganglia)
• MPTP toxin from illicit drug contamination
• Post-encephalitis
• Repeated head injury

There are some familial forms of Parkinson’s disease

Question 3

Epidemiology

Answer 3

Very COMMON

Prevalence: 1-2% of > 60 yrs

Mean age of onset: 57 yrs

Question 4

Symptoms

Answer 4

• INSIDIOUS onset
• Resting tremor (mainly in hands)
• Stiffness and slowness of movements
• Difficulty initiating movements
• Frequent falls
• Smaller hand writing (micrographia)
• Insomnia
• Mental slowness (bradyphenia)

Question 5

Signs

Answer 5

Tremor

• Pill rolling rest tremor
• 4-6 Hz
• Decreased on action
• Usually asymmetrical

Rigidity

• Lead pipe rigidity of muscle tone
• Superimposed tremor can cause cogwheel rigidity
• Rigidity can be enhanced by distraction

Gait

• Stooped
• Shuffling
• Small-stepped gait
• Reduced arm swing
• Difficulty initiating walking

Postural Instability

• Falls easily with little pressure from the back or the front

Other features

• Frontalis overactivation (leads to furrowing of the brow)
• Hypomimic face
• Soft monotonous voice
• Impaired olfaction
• Tendency to drool
• Mild impairment of up-gaze

Psychiatric

• Depression
• Cognitive problems and dementia (in later stages)

Question 6

Investigations

Answer 6

CLINICAL diagnosis

Levodopa Trial

• Timed walking and clinical assessment after administration of levodopa

Bloods

• Serum caeruloplasmin - rule out Wilson’s disease as a cause of Parkinson’s disease

CT or MRI Brain

• To exclude other causes of gait decline (e.g. hydrocephalus)

Dopamine Transporter Scintigraphy

• Reduction in striatum and putamen