Parkinson's Disease

Parkinson's disease is the most common type of Parkinsonian Syndrome, which is characterised by bradykinesia, plus one of rigidity, tremor or postural instability. With this disease, there's a loss of dopaminergic neurons in the substantia nigra.

The motor symptoms seen here are called the Parkinsonian Triad, which includes:

• Bradykinesia - Actions slow and decrease in amplitude with repetition, e.g. parkinsonian gait, blink rate, micrographia, hypomimia

• Resting tremor - often ‘pill-rolling’ of thumb over fingers

• Rigidity

Parkinsonian gait - Shuffling, forward tilt, stooped posture with reduced arm swing and asymmetric tremor. There is also festination (tendency to pick up speed).

The non-motor symptoms seen includes:

• Autonomic dysfunction – constipation, postural hypotension, sweating, impotence, nausea, sexual dysfunction

  • If these autonomic symptoms are very prominent, it points more towards Multiple System Atrophy instead (Parkinson-plus syndrome)

• REMS disorder

• Loss of smell

• Cognitive impairment – affects most in the end

• Psychiatric features – depression, anxiety, hallucinations

Parkinson’s tremor vs Benign Essential tremor

Parkinson’s tremor:

• Asymmetrical

• Present at rest

• Goes with intention

• Other PD features

• No change with alcohol

Benign Essential Tremor:

• Symmetrical

• Not present at rest

• Postural - Worse with intention

• No other PD features

• Improves with alcohol

Investigations

• DAT scan

N.B. A DAT scan looks at the function of dopamine transporters in the brain. A radioactive tracer tags the dopamine cells in the brain and the camera detects the location and density of these cells. In PD, there's be less density.

Management

Most patients experience on and off periods with the medication, which become more common as the drug decreases in efficacy over time. This is important to taken into account so you know when is best to start pharmacological management i.e. may be better to start late (e.g. when 70+) or when PD seriously interferes with life.

Levodopa is the best drug that can be given, but it becomes less effective over time, therefore is often kept for when other options are no longer effective. The main SE with this drug is Dyskinesia, which occurs when the dose is too high; includes dystonia, chorea, athetosis (writhing movements).

Other drug options - DA, COMT-I, MAOB-I, NMDA R Antagonists

As the disease progesses, patients tend to experience:

• End-of-dose effects – Motor activity declines as the previous dose wears off

• On-off phenomena – Random fluctuations in drug effect

Parkinson-plus Syndromes

• Progressive Supranuclear Palsy (PSP) – Parkinsonism and Vertical gaze palsy, rigidity of trunk > limbs; symmetrical onset, bulbar symptoms, little tremor

• Multiple System Atrophy – Degeneration of neurones of multiple systems in brain, affecting basal ganglia – Parkinsonism and early autonomic dysfunction (postural hypotension, constipation, sexual dysfunction)

• Lewy-Body Dementia – Cognitive impairment and visual hallucinations before Parkinsonism

• Corticobasal Degeneration – Parkinsonism and spontaneous activity or akinetic rigidity of a limb