Parkinson’s disease (PD) Diagnosis
The diagnosis of Parkinson’s disease is mainly based on clinical examination; doctors diagnose it by observing symptoms and movement problems rather than using a single laboratory test.
The most important symptom required is bradykinesia, which means movements become slow, movements become smaller or weaker over time, speed decreases during repeated movement.
Doctors usually check bradykinesia using tests such as finger tapping, foot tapping, and turning the hands repeatedly (pronation–supination movement)
In addition to bradykinesia, the patient must also have at least one of these symptoms of rest tremor, and rigidity. These symptoms together help confirm a parkinsonian syndrome.
Around 30% of people who truly had Parkinson’s disease did not show tremor in the beginning. So, absence of shaking does not rule out Parkinson’s disease.
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Diagnosis is not easy in PD
Diagnosing Parkinson’s Disease is not always easy because some other neurological disorders look very similar. Therefore, doctors should reassess or re-check the diagnosis regularly, especially if unusual symptoms appear later.
The most common conditions mistaken for Parkinson’s disease are called atypical parkinsonian syndromes, mainly:
These disorders can initially look like Parkinson’s disease because they also cause slow movement, stiffness, and balance problems. However, compared with Parkinson’s disease, MSA and PSP usually progress faster, become more severe earlier and respond poorly to dopamine-based medicines like levodopa
In younger patients with parkinsonism, doctors must think about additional causes, such as inherited (genetic/monogenic) forms of parkinsonism, or treatable causes such as Wilson’s Disease.
Wilson’s disease is important because it is potentially reversible if diagnosed early. It occurs due to abnormal copper accumulation in the body and can produce Parkinson-like symptoms.
If postural tremor is the main symptom, doctors must consider other disorders besides Parkinson’s disease, especially essential Tremor and dystonic tremor.
Essential Tremor usually causes shaking during action or posture holding, rather than the classic resting tremor of Parkinson’s disease.
“Dystonic tremor” is tremor associated with abnormal muscle contractions or unusual postures (dystonia).
Dopamine-transporter single-photon emission computed tomography (DAT-SPECT scan)
This scan checks dopamine activity in the brain. DAT-SPECT can help doctors distinguish Parkinson’s disease (where dopamine pathways are damaged) from tremor disorders like essential tremor (where dopamine pathways are usually normal).
However, this scan is not very reliable for distinguishing Parkinson’s disease from other degenerative parkinsonian disorders like Multiple System Atrophy (MSA), and Progressive Supranuclear Palsy (PSP), because all of these conditions can show reduced dopamine function.
Structural magnetic resonance imaging (MRI)
MRI used to look at brain anatomy and structure.
MRI is useful when doctors suspect Multiple System Atrophy, and Progressive Supranuclear Palsy. These diseases may show shrinkage (atrophy) in specific brain regions. MRI can also help interpret dopamine scans because old strokes, brain injuries, and other lesions may interfere with scan interpretation and mimic abnormal dopamine findings.
Parkinson’s Treatment
Pharmacological treatment of Parkinson’s disease
Currently there is no medicine that can stop, reverse, or permanently slow Parkinson’s disease progression. Most current treatments are symptomatic; they help control symptoms but do not cure the disease
Parkinson’s disease symptoms mainly occur because of low dopamine levels in the brain. Therefore, treatment focuses on replacing dopamine, increasing dopamine activity and preventing dopamine breakdown. This is called dopaminergic replacement or modulation.
Levodopa, dopamine agonists and MAO-B inhibitors (Monoamine oxidase B inhibitors) are used as initial therapy.
Anticholinergics were previously used more often for tremor. However, they are now used less because they can cause confusion, memory problems, hallucinations and worsening cognition especially in older adults.
Doctors have become more cautious about using dopamine agonists because these medicines can sometimes cause serious behavioral and psychological problems called impulse-control disorders (ICDs). Dopamine agonists are medicines that imitate dopamine activity in the brain. They help improve Parkinson’s movement symptoms.
Impulse-control disorders (ICDs)
ICDs are conditions where people have difficulty controlling urges or behaviors. Examples are pathological gambling, hypersexuality, compulsive shopping, compulsive eating etc. These behaviors can become excessive and harmful.
ICDs occur in around 14% of Parkinson’s patients overall, and 2–3 times more common in people taking dopamine agonists. More recent studies suggest that after 5 years of dopamine agonist treatment, ICDs may occur in over 40% of patients. Risk increases with higher drug doses, and longer treatment duration.
Dopamine agonists stimulate brain reward pathways involved in pleasure, motivation and reward-seeking behavior. This can sometimes lead to compulsive actions.
Stopping dopamine agonists suddenly may cause anxiety, depression, fatigue, irritability, and drug craving. This is sometimes called dopamine agonist withdrawal syndrome. Therefore, doctors usually reduce the medicine gradually.
Patients and families should be informed about ICD symptoms early so behavioral changes can be recognized quickly.
Adjunctive therapies in Parkinson’s disease
Adjunctive therapies are commonly used in Parkinson’s disease to manage motor complications that develop during long-term levodopa treatment. One of the most frequent complications is “wearing-off,” in which the therapeutic effect of levodopa decreases before the next dose is due, leading to the return of motor symptoms such as tremor, rigidity, and bradykinesia.
Patients may also experience delayed-on periods, where levodopa takes longer to produce its effect, or sudden and unpredictable “off” episodes. Another major complication is levodopa-induced dyskinesia, characterized by involuntary choreiform or dystonic movements that usually occur when levodopa reaches peak effectiveness. To reduce off-time and improve on-time, medications such as dopamine agonists, MAO-B inhibitors, and COMT inhibitors are often added to levodopa therapy. However, although these agents improve motor control, they may also increase dyskinesia. Amantadine is considered the primary oral medication used to manage dyskinesia in Parkinson’s disease.
Two newer adjunctive therapies have recently been approved for managing motor fluctuations in Parkinson’s disease. One of these is Opicapone, a once-daily COMT inhibitor that significantly reduces “off-time” compared with placebo and has been shown to be as effective as Entacapone.
Another recently approved drug is Safinamide, which acts both as an MAO-B inhibitor and a glutamate release inhibitor. Safinamide improves “on-time,” meaning the period during which patients experience better motor control, compared with placebo treatment. Although it was also expected to reduce dyskinesia, this anti-dyskinetic benefit was mainly observed only in patients who already had more severe dyskinesia at baseline.
Advanced therapies for Parkinson’s disease
When patients with Parkinson’s disease continue to experience significant off-time or dyskinesia despite optimized oral medications, advanced therapies are considered. One such therapy is Apomorphine, a powerful dopamine agonist administered through continuous subcutaneous infusion. This treatment is considered one of the least invasive and simplest advanced therapeutic options for Parkinson’s disease. Clinical studies and long-term experience have shown that apomorphine effectively improves motor fluctuations. In particular, the TOLEDO study, a recent double-blind clinical trial, demonstrated that apomorphine significantly reduced off-time and increased on-time compared with placebo, resulting in better and more sustained motor symptom control.
Parkinson’s disease patients with severe motor fluctuations or tremor that do not respond adequately to medication may benefit from advanced therapies such as Deep Brain Stimulation (DBS). DBS involves surgically implanting electrodes into specific brain regions, most commonly the subthalamic nucleus, to regulate abnormal brain activity and improve motor symptoms. This therapy is generally recommended for patients who do not have major balance, gait, speech, or neuropsychiatric problems. DBS has been shown to improve motor function, reduce off-time, and enhance quality of life, even in patients with an average disease duration of about seven years. Long-term studies demonstrate that the benefits on motor symptoms, daily activities, and motor fluctuations can persist for up to 10 years after surgery, although symptoms related to posture, balance, and gait may continue to worsen over time. Another advanced treatment option is levodopa–carbidopa intestinal gel infusion, which delivers medication directly into the intestine through a jejunostomy tube. This method provides more continuous levodopa delivery and has been shown to reduce off-time more effectively than oral levodopa therapy. It is usually offered in specialized centers when other advanced therapies are unsuitable, ineffective, or contraindicated. Decisions regarding advanced therapies depend on factors such as symptom severity, patient suitability, cognitive status, and overall treatment goals.
Non-motor symptoms in Parkinson’s disease
In addition to motor symptoms, patients with Parkinson’s disease commonly experience non-motor symptoms such as depression, constipation, and REM sleep behaviour disorder. These symptoms are increasingly recognized as important features of the disease and may appear many years before the clinical diagnosis of Parkinson’s disease. Patients may also experience non-motor fluctuations, in which symptoms vary according to medication effects and “wearing-off” periods. Some of these fluctuations can improve when dopaminergic therapies are optimized to provide more stable symptom control. However, many non-motor symptoms arise from non-dopaminergic pathways or from brain regions outside the substantia nigra, meaning they may not respond fully to dopamine-based treatments. Therefore, management of non-motor symptoms often requires additional targeted therapies and supportive care approaches.
Non-pharmacological management
Exercise is increasingly recognized as an important component in the management of Parkinson’s disease. A recent randomized controlled trial involving 130 patients with early Parkinson’s disease demonstrated that six months of home-based aerobic exercise significantly improved motor symptoms during the off-state compared with control participants. Although these findings are promising, the long-term benefits of exercise still require further investigation.
In addition, referrals to specialist physiotherapy, speech and language therapy, and occupational therapy are advised for patients experiencing problems related to gait and falls, communication or swallowing difficulties, and challenges in activities of daily living, respectively. Palliative care services are also becoming increasingly important, particularly during advanced and end-of-life stages of Parkinson’s disease, although they may provide valuable support and care planning at any stage of the disease.
Inpatient management of Parkinson’s disease
Patients with Parkinson’s disease are frequently admitted to hospitals for conditions unrelated to Parkinson’s disease; however, the complexity of the disorder often results in poorer clinical outcomes if specialized care is not provided. Many hospitals use alert systems to notify Parkinson’s disease specialist teams when a patient is admitted so that proactive consultations and management can be initiated. A critical aspect of hospital care is ensuring that medications are administered on time and at the correct dosage, as sudden reduction, delay, or withdrawal of these medications may lead to severe complications, including parkinsonism hyperpyrexia syndrome, a potentially life-threatening condition characterized by severe rigidity, fever, and autonomic instability. Dopamine-blocking medications should also be avoided because they can significantly worsen Parkinsonian symptoms. If patients are unable to take oral medications, equivalent doses should ideally be administered through a nasogastric tube. When enteral administration is not possible or contraindicated, cautious use of the Rotigotine transdermal patch may help maintain dopaminergic therapy and symptom control.
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