From the Guidelines
A Parkinson's disease workup should begin with a thorough clinical evaluation focusing on cardinal motor symptoms: resting tremor, bradykinesia, rigidity, and postural instability, as initial imaging is crucial in the evaluation of Parkinsonian syndromes, according to the American College of Radiology Appropriateness Criteria 1.
Clinical Evaluation
The clinical presentation of Parkinson's disease (PD) is characterized by resting tremor, bradykinesia, and rigidity, related to progressive degeneration of the dopaminergic neurons in the substantia nigra projecting to the striatum 1. A thorough clinical evaluation is essential to diagnose PD and differentiate it from other Parkinsonian syndromes, such as progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and corticobasal degeneration (CBD).
Diagnostic Approach
Diagnosis is primarily clinical, but laboratory tests, including complete blood count, comprehensive metabolic panel, thyroid function tests, and vitamin B12 levels, should be performed to rule out other conditions 1. Neuroimaging with MRI is recommended to exclude structural lesions, though it typically appears normal in Parkinson's. DaTscan (dopamine transporter imaging) can help differentiate Parkinson's from essential tremor or drug-induced parkinsonism.
Additional Testing
Levodopa challenge testing, administering 250mg carbidopa/levodopa and observing for symptom improvement, supports diagnosis if positive. Genetic testing may be considered for early-onset cases or strong family history, focusing on mutations in genes like SNCA, LRRK2, and Parkin. Neuropsychological testing helps assess cognitive function, as cognitive impairment often accompanies Parkinson's.
Importance of Accurate Diagnosis
Correctly diagnosing a Parkinsonian syndrome on clinical features alone can be quite challenging, and imaging remains an essential diagnostic tool in the evaluation of a patient presenting with Parkinsonian symptoms 1. This comprehensive approach enables accurate diagnosis and appropriate treatment planning, recognizing that Parkinson's remains a clinical diagnosis with supportive testing rather than definitive laboratory markers.
From the Research
Parkinson's Disease Workup
- Parkinson's disease is a neurological disorder characterized by movement problems such as rigidity, slowness, and tremor 2
- Diagnosis of Parkinson's disease is based on history and examination, including prodromal features, characteristic movement difficulty, and psychological or cognitive problems 2
- Dopamine transporter single-photon emission computed tomography can improve the accuracy of diagnosis when the presence of parkinsonism is uncertain 2
Treatment Options
- Treatment is symptomatic, focused on improvement in motor and nonmotor signs and symptoms 2
- Dopamine-based therapies, such as levodopa, typically help initial motor symptoms 2, 3
- Nonmotor symptoms require nondopaminergic approaches, such as selective serotonin reuptake inhibitors for psychiatric symptoms and cholinesterase inhibitors for cognition 2
- Rehabilitative therapy and exercise complement pharmacologic treatments 2
Comparison of Treatment Options
- A study comparing dopamine agonists and monoamine oxidase type-B inhibitors found that dopamine agonists were effective as treatment for Parkinson's disease, both when given as monotherapy and in combination with levodopa 4
- Selegiline and rasagiline were also found to be effective for treating Parkinson's disease, and selegiline was the best option in combination with levodopa among all the drugs investigated 4
- Another study found that levodopa-sparing therapy, such as dopamine agonists or monoamine oxidase type B inhibitors, was not as effective as levodopa in improving patient-rated mobility scores 5
Advanced Treatments
- Advanced treatments, such as therapy with levodopa-carbidopa enteral suspension or deep brain stimulation, can help individuals with medication-resistant tremor, worsening symptoms when the medication wears off, and dyskinesias 2, 3
- Palliative care is also an important part of Parkinson's disease management 2