Parkinson Disease
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Direct answer
Parkinson disease is a neurodegenerative disorder defined clinically by bradykinesia plus either rest tremor or rigidity, with a clear sustained levodopa response supporting the diagnosis; the Movement Disorder Society 2015 criteria formalise this with supportive features and red flags. Levodopa remains the most effective symptomatic therapy, and deep brain stimulation of the subthalamic nucleus or globus pallidus serves selected patients with motor complications. The atypical parkinsonisms declare themselves by what Parkinson disease is not: early falls, gaze palsy, early autonomic failure and levodopa non-response.
What you must remember
- MDS 2015 criteria: bradykinesia is mandatory, accompanied by rest tremor or rigidity; supportive features include clear levodopa response, levodopa-induced dyskinesia, olfactory loss and cardiac sympathetic denervation on MIBG scintigraphy.
- Red flags: early falls within the first year, rapid progression, supranuclear gaze palsy, cerebellar or upper motor neuron signs, symmetrical onset, early dysautonomia and no levodopa benefit at adequate dose.
- Therapy initiation: levodopa for symptom control — the most effective drug, and early use does not hasten degeneration; dopamine agonists for younger patients with impulse-control counselling; monoamine oxidase-B inhibitors for mild or adjunctive benefit.
- Motor complications: wearing-off responds to shortened intervals, entacapone or rasagiline; dyskinesia to amantadine; refractory fluctuations to device therapies — apomorphine, jejunal levodopa infusion or deep brain stimulation, with access varying across India.
- Non-motor management: REM sleep behaviour disorder (clonazepam or melatonin), constipation, orthostatic hypotension, depression, dementia with rivastigmine, and psychosis by reducing antiparkinsonian drugs then quetiapine or clozapine with monitoring.
- Atypical and secondary parkinsonism: progressive supranuclear palsy (early falls, vertical gaze palsy), multiple system atrophy (early autonomic or cerebellar signs, poor levodopa response), corticobasal degeneration (apraxia, alien limb), vascular parkinsonism (lower-body gait) and drug-induced disease from dopamine blockers.
- Genetics and rehabilitation: LRRK2 is the commonest autosomal dominant cause, GBA variants raise risk and PRKN mutations produce young-onset disease with excellent levodopa response, while physiotherapy, speech therapy, exercise and fall prevention run throughout within a multidisciplinary clinic.
Common confusion
Essential tremor is bilateral, postural and action tremor with a family history and no bradykinesia, whereas Parkinson tremor is at rest and unilateral at onset. Drug-induced parkinsonism is symmetrical, often tremor-poor, emerges within weeks of a dopamine antagonist and resolves slowly — a neuroleptic or antiemetic history is a mandatory question. Early falls with vertical gaze restriction mean progressive supranuclear palsy, and urinary plus postural failure within a year of motor onset shifts the label to multiple system atrophy. Vascular parkinsonism disables gait while sparing the upper body and responds poorly to levodopa.
Exam-focused takeaway
Two words carry the diagnosis — bradykinesia mandatory — and two phrases carry management: levodopa most effective, deep brain stimulation for refractory fluctuations. Examiners test the red-flag list more than the criteria list, so anchor early falls, gaze palsy, autonomic failure and non-response. The Indian twist is a hidden antiemetic or antipsychotic prescription, whose recognition changes the answer.
Frequently asked questions
What is mandatory for a diagnosis of Parkinson disease?
Bradykinesia, plus either rest tremor or rigidity, with supportive features such as clear levodopa response.
Does starting levodopa early worsen the disease?
No; it is the most effective symptomatic drug and trials show no acceleration of degeneration, though dyskinesia risk rises with duration and dose.
How are motor fluctuations managed?
Shorten inter-dose intervals, add catechol-O-methyltransferase or monoamine oxidase-B inhibitors, use amantadine for dyskinesia, consider infusion or stimulation for refractory cases.
Which antipsychotic is preferred for psychosis in Parkinson disease?
Quetiapine is used in practice and clozapine has trial support with haematological monitoring; classic dopamine blockers are avoided.
What suggests a diagnosis other than Parkinson disease?
Early falls, vertical gaze palsy, cerebellar or pyramidal signs, early severe autonomic failure, symmetric onset and absent levodopa benefit.