From the Guidelines
The diagnostic workup for Parkinson's disease (PD) primarily involves a thorough clinical evaluation, as there is no definitive diagnostic test, and should include a detailed neurological examination, medical history, and neuroimaging with MRI to exclude other conditions that might mimic Parkinson's. A neurologist should perform a detailed neurological examination looking for cardinal features: resting tremor, bradykinesia, rigidity, and postural instability 1. Medical history should focus on symptom progression, family history, and medication use. Neuroimaging with MRI is recommended to exclude other conditions that might mimic Parkinson's, though it typically appears normal in Parkinson's patients. DaTscan (dopamine transporter scan) can help confirm dopaminergic deficiency. A levodopa challenge test may be performed, where significant symptom improvement after administering carbidopa-levodopa supports the diagnosis. Some key points to consider in the diagnostic workup include:
- Laboratory tests including CBC, metabolic panel, thyroid function, vitamin B12, and ceruloplasmin levels help rule out other causes 1
- Sleep studies may be ordered if REM sleep behavior disorder is suspected, as this can precede motor symptoms
- Neuropsychological testing can assess cognitive function, as cognitive changes often accompany Parkinson's
- The diagnosis remains primarily clinical, based on the presence of motor symptoms and response to dopaminergic therapy, with testing mainly serving to exclude alternative diagnoses 1. It's also important to consider other Parkinsonian syndromes, such as progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and corticobasal degeneration (CBD), which can present with similar symptoms but have distinct clinical features and prognoses 1.
From the Research
Diagnostic Workup for Parkinson's Disease (PD)
The diagnostic workup for Parkinson's disease (PD) involves several key components, including:
- History and examination to identify prodromal features, characteristic movement difficulty, and psychological or cognitive problems 2
- Identification of motor symptoms such as bradykinesia, tremor, and rigidity 2, 3, 4
- Assessment of nonmotor symptoms, which can be just as bothersome as motor symptoms 3
Diagnostic Criteria
Diagnosis of PD is based on the presence of:
- Bradykinesia plus tremor or rigidity 3
- At least two of three major clinical features: resting tremor, bradykinesia, and rigidity 4
- Minor signs such as cognitive slowing, speech abnormalities, depression, dysautonomia, and sleep disturbances may also be present 4
Diagnostic Tools
- Dopamine transporter single-photon emission computed tomography can improve the accuracy of diagnosis when the presence of parkinsonism is uncertain 2
- Deep brain stimulation (DBS) can be used to treat advanced disease in whom medical treatment fails to provide adequate symptom control 5
Importance of Early Recognition and Diagnosis
Early recognition and diagnosis of PD are crucial, as patients may demonstrate prodromal nonmotor symptoms 5-20 years prior to diagnosis 3 A practical approach to diagnosis and initial treatment can have a lasting impact on the patient experience 6