There is no specific test for Parkinson’s disease, making it sometimes a difficult condition to diagnose, especially early on. Parkinsonism - the group of signs and symptoms of Parkinson’s disease - may have other causes, such as dementia with Lewy bodies, progressive supranuclear palsy, as well as some antipsychotic medication, toxins, head injuries, and some types of stroke.
A GP (general practitioner, primary care physician), usually the first health care professional people see, will base diagnosis on the signs and symptoms, the patient’s medical history, as well as the results of a clinical examination.
Initially, when symptoms are mild during the early stages of Parkinson’s disease, a GP will find it hard to definitively diagnose the condition. If Parkinson’s is suspected, the GP will probably refer the patient to a specialist (neurologist).
It is vital that the doctor has experience with all the possible disorders than can masquerade as Parkinson’s disease.
As part of their medical history, the physician will need to know about any drugs the patient is/was taking, and also whether any close family members have/had Parkinson’s disease.
A neurological examination usually evaluates the patient’s walking, coordination, and some simple hand tasks. The doctor may also check the patient’s sense of smell. He/she may also prescribe a medication for Parkinson’s disease - if it helps symptoms, it may help find out whether the individual has the disease.
The following tests may be ordered:
- Blood test - usually to rule out any other condition, such as abnormal thyroid hormone levels or liver damage.
- MRI or CT scan - to check for signs of a stroke or brain tumor. If there is/was no stroke or brain tumor, most MRI or CT scans of people with Parkinson’s disease will appear normal.
- PET (positron emission tomography) scan - this imaging test may sometimes detect low levels of dopamine in the brain. As PET scans are expensive and not present in all hospitals, this option may sometimes not be available. PET is a highly specialized imaging technique which uses radioactive substances to create 3-dimensional colored images of those substances functioning in the body. Information about the body’s chemistry can be gained with a PET scan, which is not the case with other imaging techniques.
- Two of the four main symptoms must be present - for a neurologist to consider a Parkinson’s disease diagnosis, the patient must have two of the four main symptoms. They must be present over a specific period. The four main symptoms are:
- Tremor or shaking
- Bradykinesia - slowness of movement
- Rigidity (stiffness) of the arms, legs or trunk
- Postural instability - balance problems and possible falls
- Look at a detailed medical history of the patient
- Carry out a physical exam
- Check medications currently being taken, and those taken in the past
- Carry out a detailed neurological exam, during which the patient performs tasks to assess agility of legs and arms, muscle tone, gait, and balance.
- Usually, results of an exam are entered into a table, called United Parkinson’s Disease Rating Scale (UPDRS). UPDRS was created to comprehensively assess and document the examination of a patient with Parkinson’s disease, and be able to compare data entered with future follow up examinations, or to communicate data with other neurologists.
- Observe the patient’s response to Parkinson’s disease medications (drugs that stimulate Dopamine production or imitate it). An example of a Parkinson’s drug is levodopa.
- Two of the four main Parkinson’s symptoms have been present for some time
- Symptoms started on just one side of the body
- Tremor (shaking) is more evident at rest
- A Parkinson’s drug (e.g. levodopa) produces a strong, positive response
The doctor may have to observe the patient for some time before symptoms are deemed to be consistently present. Clinical practice guidelines, which were introduced in the United Kingdom in 2006, state that diagnosis and follow-up of Parkinson’s disease should be carried out by a specialist - usually a neurologist or geriatrician with an interest in movement disorders. A neurologist is a doctor who is specialized in the diagnosis and treatment of disorders of the nervous system. A geriatrician is a doctor who is specialized in the care of older and aging adults.