parkinson's disease

Question 1

definition

Answer 1

*** triad of parkisonism: tremor (pill-rolling), rigidity/increased tone, bardykinesia/hypokinesia

Idiopathic Parkinson’s disease (PD) is a neurodegenerative disorder. The cardinal features include resting tremor, rigidity, bradykinesia, and postural instability. Patients may demonstrate a combination of these motor symptoms, as well as other non-motor symptoms.

(Neurodegenerative disease of the dopaminergic neurones of the substantia nigra)

Question 2

symptoms

Answer 2

Insidious onset.
Tremor at rest, usually noticed in hands.
Stiffness and slowness of movements.
Difficulty initiating movements (e.g. getting out of chair, rolling in bed). Frequent falls.
Smaller hand writing (micrographia).
Insomnia, mental slowness (bradyphenia).

Question 3

signs

Answer 3

Tremor: Classically pill rolling rest tremor in the hands of about 4–6 Hz frequency. Decreased on action or flexed posture. Usually asymmetrical.

Rigidity: Lead pipe rigidity of muscle tone, with superimposed tremor (cogwheel rigidity). Rigidity can be enhanced by distraction (asking the patient to keep raising and lowering the other arm).

Gait: Stooped, simian, shuffling, small-stepped gait with reduced arm swing. Freezing (difficulty in initiation of walking).

Postural instability: Falls easily with little pressure from the back (propulsion) or the front (retropulsion).

Other features: Frontalis overactivation (furrowing of the brow), expressionless face (hypomimia), soft monotonous voice (hypophonia), impaired olfaction on formal testing.

There may be mild impairment of up-gaze and tendency to drool (sialorrhoea). Involuntary movements in one part of the face associated with voluntary movement in another part of the face (synkinesis).

Psychiatric: Depression is very common. Cognitive problems and dementia may occur in late disease.

Question 4

pathogenesis

Answer 4

Degeneration of midbrain dopaminergic neurones projecting from the substantia nigra to the striatum (caudate nucleus and putamen). Surviving neurones often contain eosinophilic cytoplasmic inclusions (Lewy bodies). Patients only symptomatic after >70% neuronal loss. Nigrostriatal dopaminergic deficiency causes abnormalities of plasticity in the basal ganglia and cerebral cortex.

Question 5

investigations

Answer 5

diagnosis is clinical!!

possible 1st investigation:
levodopa trial

others:
DaT scan (parkinson's does not really show much abnormality on MRI/CT, but can do MRI later if needed)

Question 6

what is an illegal drug that is associated with parkinsonism

Answer 6

MPTP in heroin use can cause parkinsonism symptoms (‘chemically’ destroys neurons in substantia nigra and produces the same disease pattern)

Question 7

what is a prescribed drug class that is associated with parkinsonism

Answer 7

Anti-neuroleptics (to treat schizophrenia) such as chlorpromazine and haloperidol can produce parkinsonian features by their dopamine depleting/blocking action centrally.

Risperidone and trifluoperazine are antipsychotic drugs which are well known to cause parkinsonian side-effects.

SSRIs also can cause parkinsonism (e.g. sertraline, citalopram)

Question 8

other differentials

Answer 8

• PSP (progressive supranuclear palsy):
  Axial dystonia in extension with supranuclear opthalmoplegia are the characteristic signs that define this condition in addition to the parkinsonian features.
• Cortical-basal ganglionic degeneration:
  may be mistaken for Parkinson’s disease, but intellectual decline, aphasia, apraxia and sensory neglect predominate and give the diagnosis.
• Diffuse Lewy body disease: parkinsonism is joined with a conspicuous dementia with evidence of widespread neurologic involvement.
• Shy-Drager syndrome is a Parkinson + syndrome associated with autonomic neuropathy.

Question 9

side effect of levodopa

Answer 9

levodopa/drug-induced dyskinesia is common in patients receiving treatment for parkinson’s