Clinical features suggestive of diagnoses other than PD: The features listed below include but are not restricted to the exclusion criteria and red flags from the MDS diagnostic criteria for PD, simplified and explained for practical application.*
| CLINICAL FEATURES8 | RATIONALE AGAINST DIAGNOSIS OF PD |
|---|---|
| Absence of response to levodopa trial at target dosage (>600 mg/d)4,8 | Patients with PD demonstrate clear subjective and objective improvement in motor symptoms with dopaminergic therapy |
| Early bilateral symmetric parkinsonism Lack of progression of motor symptoms or absence of common nonmotor symptoms (eg, constipation, orthostasis, hyposmia) of PD after 5 y | In PD, motor features are usually unilateral in onset and then progress in distribution and severity over time |
| Early recurrent (>1/y) falls because of impaired balance within 3 y of onset Rapid progression of gait impairment to substantial postural imbalance requiring use of a walker by 3 y and a wheelchair by 5 y (“wheelchair sign”)28 | Falls are common in older adults and often have multiple causes. The falls implicated here are those owing to postural instability. Early unexplained falls or quickly progressing mobility challenges may reflect PSP or MSA |
| Severe autonomic failure (eg, unexplained orthostatic hypotension, urinary retention or incontinence) in the first 5 y of disease | More likely reflects conditions such as MSA |
| Downward vertical gaze palsy or slowing of downward vertical saccades | More likely reflects PSP |
| Parkinsonism with history of stroke | Consider vascular parkinsonism unless classic PD signs present |
| Findings restricted to the lower limbs for more than 3 y | PD involves the upper and lower limbs. Vascular parkinsonism may be limited to the lower limbs |
| Parkinsonism while taking a dopamine receptor blocker (eg, typical antipsychotics, metoclopramide) or a dopamine-depleting agent | Depending on dose and time course, this may reflect drug-induced parkinsonism |
| Early cognitive impairment and visual hallucinations, either spontaneous or with low-dose levodopa treatment* | More suggestive of DLB |
| History of repeated head injury | Although PD is still possible, chronic traumatic encephalopathy should be considered |
| Symptoms of behavioural variant frontal temporal dementia symptoms (marked apathy, disinhibition, personality changes) or primary progressive aphasia (early impairment of speech affecting comprehension or fluency) within first 5 y | Suggests alternative pathological process such as tauopathy |
Unexpected neurologic findings, such as the following:
| These features are not typical for PD and should prompt workup for other neurologic conditions |
DLB—dementia with Lewy bodies, MDS—International Parkinsonism and Movement Disorder Society, MSA—multiple system atrophy, PD—Parkinson disease, PSP—progressive supranuclear palsy.
↵* DLB is an entity related to PD, with related pathophysiology. New diagnostic criteria no longer list dementia within first 5 y except for frontotemporal dementia as an exclusion criterion or red flag.3,8 The distinction between DLB and PD warrants a more nuanced discussion, as the treatment approach to each is different. Family physicians should be alert to the fact that early cognitive dysfunction with visual hallucinations suggests DLB.