Parkinson's Disease: Symptoms, Diagnosis and Treatment

Parkinson's disease (PD) is a chronic, progressive neurodegenerative disorder — the second most common after Alzheimer's disease — affecting approximately 8–10 million people worldwide. It results from the gradual death of dopamine-producing neurons in a region of the midbrain called the substantia nigra, which is part of the basal ganglia, the brain's motor control system.

Parkinson's disease typically begins between the ages of 50 and 79 and advances slowly over years to decades. Although there is currently no cure, treatment can substantially control symptoms and maintain quality of life for many years.

How Parkinson's Disease Develops

The basal ganglia regulate the initiation, execution, and smoothness of voluntary movement. They rely on dopamine as their principal neurotransmitter. In Parkinson's disease, dopamine neurons in the substantia nigra progressively degenerate. As dopamine levels fall — by the time motor symptoms appear, approximately 60–80% of these neurons have already been lost — the basal ganglia lose their ability to coordinate smooth, controlled movement.

At the cellular level, a key pathological feature is the accumulation of misfolded alpha-synuclein protein into clumps called Lewy bodies within neurons. These aggregates spread through the nervous system, causing dysfunction and neuronal death. Growing evidence suggests Parkinson's disease begins in the enteric nervous system (gut) and olfactory bulb years before motor symptoms appear.

Symptoms

Parkinson's disease produces both motor (movement-related) and non-motor symptoms.

The Four Cardinal Motor Features

1. Resting tremor — the most recognisable symptom. A rhythmic, "pill-rolling" tremor of the hand or fingers at 4–6 Hz, present at rest and suppressed by voluntary movement. Begins unilaterally; may spread to the other side. Also affects the jaw and legs.
2. Rigidity — increased resistance to passive movement throughout the range of motion ("cogwheel" rigidity when tremor is superimposed). Causes stiffness, aching muscles, and reduced arm swing when walking. Contributes to the characteristic stooped posture.
3. Bradykinesia — slowness of movement, with progressive loss of amplitude and speed (hypokinesia). Manifests as: slow shuffling gait with short steps; micrographia (progressively smaller handwriting); reduced facial expression (hypomimia — the "masked face"); difficulty with fine tasks (buttoning, typing, using utensils); soft, monotone voice (hypophonia).
4. Postural instability — difficulty maintaining upright balance; impaired righting reflexes. The main cause of falls. Typically a later feature (not required for diagnosis). Festinating gait (involuntary acceleration of steps to prevent falling) and freezing of gait (sudden inability to move the feet, as though stuck to the floor) are related phenomena.

Parkinson's disease is typically asymmetric — symptoms begin on one side and remain more pronounced on that side throughout.

Non-Motor Symptoms

Non-motor symptoms are equally important and often appear years before motor symptoms:

Autonomic dysfunction:

• Orthostatic hypotension (dizziness on standing) — often made worse by medication
• Constipation — severe and persistent; one of the earliest symptoms
• Urinary urgency and frequency
• Excessive sweating or drooling (sialorrhoea)

Neuropsychiatric:

• Depression — affects approximately 40% of patients; often precedes motor symptoms
• Anxiety — common and distressing
• Dementia — affects approximately 30% of patients, typically later in the disease; related to cortical Lewy body spread (see Lewy body dementia)
• Psychosis — visual hallucinations and delusions, often medication-related; a leading cause of hospitalisation
• Impulse control disorders — compulsive gambling, hypersexuality, binge eating; associated with dopamine agonist therapy

Sleep disorders:

• REM sleep behaviour disorder (RBD) — acting out dreams with vigorous movements during sleep; often precedes Parkinson's by years and is a strong predictor
• Insomnia and excessive daytime sleepiness
• Restless legs syndrome

Other non-motor features:

• Anosmia (loss of smell) — often the earliest symptom, years before diagnosis
• Pain — neuropathic, musculoskeletal, or akathisia-related
• Cognitive slowing and executive dysfunction (in absence of full dementia)
• Seborrhoea (greasy skin)

Diagnosis

Parkinson's disease is a clinical diagnosis — there is no blood test or imaging study that can definitively confirm it. Diagnosis rests on the presence of bradykinesia plus at least one of resting tremor, rigidity, or postural instability, combined with a clear response to levodopa.

Clinical Assessment

The neurologist assesses:

• Finger-tapping and hand opening/closing speed (bradykinesia)
• Tone — cogwheel rigidity on passive wrist rotation
• Resting tremor (tremor that diminishes on movement)
• Gait — reduced arm swing, shuffling, festination, freezing
• Postural stability — "pull test" (tapping the patient's shoulders from behind)

Features that suggest an alternative diagnosis (atypical parkinsonism): early falls, early dementia, rapid progression, symmetrical onset, no tremor, poor levodopa response.

Investigations

• Brain MRI: cannot diagnose Parkinson's, but is used to exclude other causes of parkinsonism (stroke, normal pressure hydrocephalus, brain tumours). MRI may show characteristic changes in atypical parkinsonism syndromes.
• DAT scan (DaTSCAN): a SPECT imaging study that measures dopamine transporter density in the striatum. A reduced, asymmetric uptake pattern confirms presynaptic dopaminergic degeneration, distinguishing true Parkinsonism (PD, multiple system atrophy, PSP) from essential tremor or drug-induced parkinsonism.
• Levodopa trial: a dramatic, sustained response to levodopa strongly supports the diagnosis of Parkinson's disease rather than an atypical Parkinsonian syndrome.

Treatment

There is currently no disease-modifying treatment that slows neurodegeneration. Treatment is aimed at controlling symptoms.

Dopaminergic Therapy

Levodopa (combined with carbidopa or benserazide) — the most effective and best-tolerated treatment. Levodopa crosses the blood-brain barrier and is converted to dopamine. Carbidopa/benserazide prevent peripheral conversion to dopamine (reducing nausea, vomiting, and hypotension). Provides dramatic early relief of motor symptoms in >85% of patients.

Long-term complications of levodopa therapy (typically after 5–10 years):

• Motor fluctuations — "wearing off" of medication before next dose; "on-off" phenomena with unpredictable swings between good and poor control
• Dyskinesias — involuntary, writhing movements (chorea), typically at peak dose; related to pulsatile dopamine stimulation from shorter drug half-life

Dopamine agonists (pramipexole, ropinirole, rotigotine patch) — stimulate dopamine receptors directly; less effective than levodopa but cause fewer motor complications; preferred initial therapy in younger patients to delay levodopa introduction. Risk of impulse control disorders requires monitoring.

MAO-B inhibitors (rasagiline, selegiline) — prevent dopamine breakdown; modest symptomatic benefit; used as initial monotherapy in early disease or as adjuncts.

COMT inhibitors (entacapone, opicapone) — extend levodopa duration by inhibiting its peripheral breakdown; reduce wearing-off.

Amantadine — reduces dyskinesias; useful in later disease.

Deep Brain Stimulation (DBS)

Deep brain stimulation is the main surgical treatment for Parkinson's disease. It is appropriate when medication is no longer providing adequate control — typically with significant motor fluctuations, dyskinesias, or tremor unresponsive to medication — in patients with good cognition and no dementia.

The procedure: Under local or general anaesthesia, stereotactically guided electrodes are implanted into the subthalamic nucleus (STN) or globus pallidus internus (GPi). The electrodes are connected via subcutaneous leads to a pulse generator (IPG) implanted in the chest. Continuous high-frequency electrical stimulation modulates abnormal circuit activity.

Outcomes:

• Reduces tremor, rigidity and bradykinesia dramatically — often by 50–70%
• Reduces dyskinesias and "off" time
• Allows levodopa dose reduction, further reducing dyskinesias
• Does not help postural instability, cognitive symptoms, or speech
• Effects are adjustable via programming; the device can be turned off; it is reversible in principle

Physiotherapy and Occupational Therapy

• Physiotherapy targeting gait training, balance, flexibility and cardiorespiratory fitness — the LSVT BIG programme uses high-amplitude movements to counteract bradykinesia/hypokinesia
• Occupational therapy for daily living adaptations, fall prevention, handwriting aids
• LSVT LOUD speech therapy for hypophonia
• Tai chi and dance therapy with evidence for improving balance

Managing Non-Motor Symptoms

• Depression: SSRIs, SNRIs, or antidepressants not worsening parkinsonism
• Psychosis: clozapine or pimavanserin (dopamine receptor antagonists safe in PD); quetiapine
• Constipation: high fibre, hydration, macrogol, lubiprostone
• Orthostatic hypotension: fludrocortisone, midodrine, droxidopa
• Insomnia and RBD: melatonin, clonazepam for RBD; address sleep hygiene

Parkinson's Disease Care in China

China's neurology and neurosurgery centres offer:

• Comprehensive movement disorder evaluation: specialist neurologist assessment, DaTSCAN imaging, DAT-SPECT, and MRI at leading centres
• High-volume DBS surgery: China's leading centres perform hundreds of DBS procedures annually with outcomes comparable to the top European and North American centres; experienced neurosurgeons using Medtronic, Abbott, and Chinese-manufactured DBS systems
• Advanced DBS programming: specialist programming and adjustment services post-implantation
• Levodopa dosing optimisation and infusion: continuous subcutaneous apomorphine and levodopa-carbidopa intestinal gel (LCIG/Duodopa) available at specialist centres
• Multidisciplinary PD rehabilitation: specialist physiotherapy, speech therapy, and neuropsychological support
• Cost: care in China is generally less expensive than UK private treatment, but the hospital prices each case individually — ask us for the written quote before you commit.

Contact a ChinaMedicalTour care navigator to arrange a Parkinson's disease assessment, DBS evaluation, or second opinion on treatment.

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Medical content based on MSD Manuals, authored by Hector A. Gonzalez-Usigli MD (HE UMAE Centro Médico Nacional de Occidente). Evidence reviewed 2025.

Frequently Asked Questions

Can overseas neurological patients have their MRI or EEG scans evaluated remotely?

Yes. Foreign neuroimaging scans, EEG recordings, and specialist consult notes can be submitted through pre-consultation coordination for detailed evaluation by Chinese cognitive neurology and movement disorder teams.

What multidisciplinary care is offered for chronic neurological conditions in China?

Tertiary neurology departments provide structured clinical assessments, cognitive battery testing, advanced biomarker diagnostics, individualized pharmacological management, and specialized neurorehabilitation planning.

How are medications and ongoing neurological care managed after returning home?

The treating medical team issues a comprehensive bilingual medical summary and prescription guidance to facilitate safe care continuity with the patient's domestic neurologist.