Parkinson's Disease

Question 1

Definition

Answer 1

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

o Bradykinesia
o Rigidity
o Resting tremor
o Postural instability

Question 2

Pathophysiology

Answer 2

o Degeneration of dopaminergic neurones projecting from the substantia nigra to the striatum

o Patients are only symptomatic after the loss of > 70% of dopaminergic neurones

Question 3

Aetiology

Answer 3

• Sporadic/Idiopathic Parkinson’s Disease
o Most COMMON
o Aetiology UNKNOWN
o May be related to environmental toxins and oxidative stress

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

• There are some familial forms of Parkinson’s disease

Question 4

Epidemiology

Answer 4

• Very COMMON
• Prevalence: 1-2% of > 60 yrs
• Mean age of onset: 57 yrs

Question 5

Presenting symptoms

Answer 5

• 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 6

Signs on physical examination (tremor)

Answer 6

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

Question 7

Signs on physical examination (rigidity)

Answer 7

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

Question 8

Signs on physical examination (gait)

Answer 8

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

Question 9

Signs on physical examination (postural instability)

Answer 9

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

Question 10

Signs on physical examination (other features)

Answer 10

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

Question 11

Signs on physical examination (psychiatric)

Answer 11

o Depression

o Cognitive problems and dementia (in later stages)

Question 12

Investigations

Answer 12

• CLINICAL diagnosis

• Levodopa Trial
o Timed walking and clinical assessment after administration of levodopa

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

• CT or MRI Brain
o To exclude other causes of gait decline (e.g. hydrocephalus)

• Dopamine Transporter Scintigraphy
o Reduction in striatum and putamen