Since there is no definite diagnostic test to confirm the diagnosis of Parkinson’s disease, only proper history taking and examination of the patient for specific signs and symptoms can lead to diagnosis. The typical features of tremor, rigidity, bradykinesia (slowness of movement) and loss of postural reflex which is present in Parkinson’s disease is also a feature of certain other diseases, so tests may need to be done to rule out these other disorders. New tests are constantly being developed for quicker and more conclusive diagnosis of Parkinson’s disease but currently, final diagnosis is widely based on that of the practitioner’s findings and discretion.
Symptoms for Diagnosing Parkinson’s Disease
- Diagnosis is made more difficult in the early stages of Parkinson’s disease since there may not be any of the typical symptoms initially and only a few non-specific symptoms may be present such as tiredness, depression, or mental slowness, which may be mistaken for normal signs of aging.
- Symptoms of Parkinson’s disease usually start on one side of the body but gradually affect both sides.
- Parkinson’s disease is a disease of old age, rarely starts before the age of 50 and is more common after the age of 65. However, early onset of Parkinson’s disease before the age of 40 years is possible.
- Of the three major signs – tremor, rigidity and bradykinesis – at least two need to be present to confirm the diagnosis of Parkinson’s disease.
- One of the earliest symptoms is tremor present at rest, starting in the upper limb and gradually involving the legs, mouth and tongue. It is a coarse tremor with a “pill rolling” action of thumb over fingers commonly referred to as the Parkinson’s tremor.
- The rigidity, or increased muscular tone, causes an increase in resistance to the passive stretching of muscles, which may be continuous and is called ‘lead pipe’ rigidity or may be interrupted by tremors and is then called ‘cogwheel’ rigidity.
- Bradykinesia, or slowness of initiation or repeating of movements, develops gradually and results in slowness of gait. Difficulty with fine rapid movements, especially of the fingers, results in problem in performing tasks such as shaving, fastening buttons or writing.
- Expressionless face, drooling, soft indistinct speech, and short shuffling steps are all features that may develop in Parkinson’s disease.
- Dementia may be a late feature of the disease, often associated with depression and psychosis.
Other diseases with similar symptoms like Parkinson’s disease
- Alzheimer’s disease – this is also a disease of old age and diagnosis may be further complicated since Alzheimer’s and Parkinson’s disease may co-exist.
- Diffuse vascular disease.
- Lewy body disease – here dementia is an early symptom.
- Essential tremor – tremor is more of the head, worsening on motion and less on rest
- Wilson’s disease
- Multiple system atrophy
- Drugs such as certain antipsychotics and antiepileptics.
Final Diagnosis of Parkinson’s Disease
- Diagnosis of Parkinson’s disease is based mainly on the history, symptoms, and neurological examination of the patient.
- Blood tests, EEG, CT scan or MRI of brain show no definite abnormality in patients with Parkinson’s disease but may be done to rule out other diseases.
- Levodopa challenge test – patients with Parkinson’s disease show dramatic and significant improvement on starting treatment with levodopa, thus differentiating them from other neurological diseases.