What is Parkinson Disease (PD)?
- Parkinson disease (PD) is caused by a disruption
of dopaminergic neurotransmission in the basal ganglia and development of eosinophilic inclusions (Lewy bodies) in the residual neurons. - Genetic predisposition: May present; up to 15% of patients have a first- or second-degree relative with Parkinson disease.
- No clear environmental links to the disease identified.
Epidemiology
- In US
- Parkinson disease is the second most common progressive neurodegenerative disorder after Alzheimer disease.
- Parkinson affects about 1% of the population older than age 60 years
- 4% to 5% of those older than 85 years
- 4% to 5% of those older than 85 years
- In Australia
- Prevalence: 120–150 per 100 000
- Lifetime risk is 1 in 40
- Mean age of onset: Between 58 and 62 years.
Clinical Features
The hallmark clinical features of Parkinson disease (usually asymmetric onset) include
- Tremor
- Presenting symptom in up to 70% of patients.
- Asymmetric rest tremor is virtually pathognomonic of Parkinson disease.
- Differential Diagnosis: essential tremor
- Usually symmetric
- Exacerbated by action
- Rigidity: Cog wheeling quality during passive movement of the limb
- Bradykinesia:
- Refers to the slowness of movements
- Usually begins in an asymmetric fashion
- Described by the patient as “weakness” of an extremity
- Strength testing: Normal
- Difficulty with fine finger tasks
- Micrographia
- Paucity of facial expression (masked face)
- Lack of blinking
- Excessive salivation (late stages)
- Swallowing problems
- Soft, slow monotonous speech
Other clinical features associated with Parkinson disease include
- General presentations:
- Tiredness
- Lethargy
- Restlessness
- Trouble getting out of chair or car and turning over in bed
- Gait disorder
- Start hesitation
- Festination
- No arm swing on one or both sides
- Slow and narrow based gait
- Short steps (petit pas)
- Slow turning circle (‘turn by numbers’)
- ‘Freezing’ when approaching an obstacle
- Poor balance
- Posture
- Progressive forward flexion of trunk (stooped)
- Flexion of elbow at affected side
- Autonomic symptoms
- Constipation: common
- Postural hypotension: may be induced by treatment
- Neuropsychiatric
- Depression (early stages)
- Anxiety
- Sleep disorder
- Progressive dementia in 30–40% usually after 10 years.
- Hallucinations
- Reduced sense of smell: One of the first symptoms
- Think of PD in an older person presenting with falls
Diagnosis
- Based on the history and examination (it is a clinical diagnosis)
- There is no laboratory test for PD
- Differential diagnosis include hypothyroidism and depression
- Drug-induced Parkinsonism:
- Common drugs: phenothiazines, butyrophenones and reserpine.
- Tremor is uncommon
- Rigidity and bradykinesia may be severe.
Management
- Pharmacotherapy
- Surgical treatment
- Treatment of Non-motor Symptoms