Parkinson's Disease (PD)

Exam Cram

• Parkinson's disease (simplified) is caused by hypo-dopamine, resulting in reduction of movements

• Presentation: TRAP- tremor (resting, unilateral), rigidity, akinesia (bradykinesia), postural instability; constipation

• Management: dopamne agonists (L dopa)

• Parkinsonism is caused my dopamine blockers (antipsychotics) and presents with a bilateral tremor

outline

Background

• Parkinson's is thought to have to be caused by low levels of dopamine due to its response to dopamine agonists and the parkinsonism features caused by dopamine antagonists

• Particularly low levels of dopamine in the substantia nigra

Assessment

History

• Elderly pt with subacute - chronic onset 

• Slowing of movements: walking, writing, speech

• Falls, constipation, poor memory

Examination (TRAP)

• Tremor

  • Unilateral resting (Parkinson's)

  • Bilateral resting (Parkinsonism)

• Rigidity: cogwheel rigidity when moving wrists slowly

• Bradykinesia (akinesia for acronymn)

• Postural hypotension

Investigations

• BP: orthstatic hypotension

• CT-H normal

• DaT Scan: dopamine labelled functional MRI: observe low levels of dopamine in substantia nigra

Diagnosis

Diagnostic criteria: clinical (symptoms + DaT Scan)

Differentials

• Parkinson's: unilateral resting tremor, rigidity, bradykinesia, postural instability and constipation

• Parkinsonism: caused by dopamine antagonists (commonly antipsychotics) presents with a bilateral tremor

• Parkinson plus syndromes present with a poor response to dopamine agonistis and

  • • Progressive supranuclear palsy: impairment of eye movements horizontally or vertically

    • Multi-system atrophy: large postural drop

• Lewy Body Dementia is hypothesised to be part of a similar disease process (low dopamine). It presents with primarily dementia and can develop motor symptoms, Parkinson's is vice versa. 

Management

Chronic

1. L-DOPA or pramipexole

2. Addition of entacapone

3. Rivastigmine

4. Apomorphine

5. End of Life Care 

Management Notes

• L-dopa and pramipexole are dopamine agonists. 

• Pramipexole side effects:

  • • Hypersomnolence

    • Risk taking behaviour- gambling

• Entacapone reduces the breakdown of L-DOPA, prolonging its action, by inhibiting COMT.

• Quetiapine and clozapine are licensed for psychosis [1]

• Benzodiazepines used > haloperidol for agitation

Parkinsonism

Parkinsonism is the presentation of hypo-dopamine state. 

Causes:

• Idiopathic Parkinsons Disease (above)

• Medication Induced Parkinsonism

• Vascular Parkinsonism

• Parkinson Plus Syndromes

Medication Induced Parkinsonism

• Caused by antipsychotics long term use in schizophrenia

• Bilateral tremor (Parkinson's Disease is unilateral tremor)

• Management: stop the offending drug 

Parkinson Plus Syndrome

Features

• Acute and aggressive onset

• Poor response to dopamine agonists

• Typically normal dopamine DAT scans of substantia nigra

• Poor life expectancy

Progressive Supranuclear Palsy (PSP)

• Examination: unable to move eyes superiorly

Multi System Atrophy (MSA)

• Autonomic system disproportinely affected

• Investigation: lying- standing BP to show postural hypotension (noting Parkinsons can cause this too)

• Other features of Parkinson plus- aggressive onset, poor response to levodopa

Corticobasal syndrome (CBS) 

• Cognition is typically a core feature

Lewy Body Dementia

• An overlap with Parkinsons and sometimes considered a Parkinsons Pus Syndrome

• Dementia with hallucinations is typical and hard to treat

Resources and References

1. https://www.sciencedirect.com/science/article/abs/pii/S1353802020301437

Page written in 2024.