Parkinson’s disease is the second most common neurodegenerative disease in neurology after Alzheimer’s disease, and its clinical diagnostic criteria are the British Brain Bank criteria published in 1997. However, with the continuous development of research in the last two decades, the old criteria are no longer adapted to clinical and research needs. Recently, the International Movement Disorder Society (MDS) published a revised version of the latest diagnostic criteria. Compared to the British Brain Bank criteria, the role of non-motor symptoms in diagnosis has been increased and the certainty of diagnosis has been categorized (confirmed PD and probable PD). Core Criteria The primary core criterion for diagnosis is definite Parkinson’s disease, defined as the presence of motor slowing and the presence of at least one of the two cardinal signs of resting tremor or tonus. A clinical diagnosis of Parkinson’s disease (PD) requires: 1. no absolute exclusion criteria 2. at least two supportive criteria, and 3. no red flags A diagnosis of probable PD requires: 1. no absolute exclusion criteria; 2. if red flags are present, they need to be counterbalanced by supportive criteria: if 1 red flag is present, at least 1 supportive criterion is needed; 2. if 1 red flag is present, it must be offset by at least 1 supportive criterion; and 3. at least 1 supportive criterion is needed. If 1 warning sign is present, at least 1 supporting criterion is required If 2 warning signs are present, at least 2 supporting criteria must be required Note: More than 2 warning signs are not allowed under this classification. Interpretation of the Terms Supportive Criteria 1. A clear and significant effective response to dopaminergic drug therapy. The patient’s functioning returns to normal or near normal levels during the initial treatment period. In the absence of a clear record, a significant response to initial therapy can be categorized as either: ? Significant improvement of symptoms when the drug dose is increased and significant worsening of symptoms when it is decreased; minor changes are excluded. These changes are documented either objectively (more than 30% improvement in UPDRS-III score after treatment) or subjectively (clear confirmation of the presence of a significant change from a reliable patient or caregiver); ? Clear and significant “on/off” phase fluctuations; must include predictable end-of-dose phenomena to some extent. 2. the presence of levodopa-induced anisotropy. 3. a single limb resting tremor documented on clinical physical examination (previous or current examination). 4. Loss of sense of smell or cardiac desensitization by cardiac MIBG scintigraphy. The presence of any of the following excludes the diagnosis of PD: 1. Definite cerebellar abnormalities such as cerebellar gait, limb ataxia, or cerebellar oculomotor abnormalities (sustained gaze-induced nystagmus, giant square-wave sharp jumps, hyperrhythmic sweeps). 2. 2. Downward vertical supranuclear gaze paralysis, or selective slowing of downward vertical sweeps. 3. A diagnosis of probable behavioral variant frontotemporal lobe dementia or primary progressive aphasia within the first 5 years of onset (according to consensus criteria published in 2011). 4. Manifestations of Parkinson’s syndrome that remain confined to the lower extremities for more than 3 years after onset. 5, Treatment with dopamine receptor blockers or dopamine depleting agents (e.g., antipsychotics such as dromolyn/chlorpromazine) at doses and time courses consistent with drug-induced Parkinson’s syndrome. 6, Lack of observable therapeutic response to high-dose levodopa therapy despite at least moderate severity. 7. Definite cortical sensory loss (e.g., impairment of skin writing and solid discrimination in the presence of intact primary sensory organs), definite motor loss of limb perception, or progressive aphasia. 8. Normal functional neuroimaging of the presynaptic dopaminergic system. 9. Clearly documented other conditions that can lead to Parkinson’s syndrome or are suspected to be related to the patient’s symptoms, or based on the overall diagnostic evaluation, the professional evaluator feels that it may be another syndrome rather than PD. Warning signs (Red Flags) 1. Rapidly progressing gait disturbance within 5 years of onset and requiring regular use of a wheelchair. 2. 2. Complete lack of progression of motor signs or symptoms for 5 or more years after onset; unless such stabilization is treatment-related. 3. Early onset of bulbar dysfunction: severe dysphonia or dysarthria (speech that is difficult to understand most of the time) or severe dysphagia (need to eat softer foods, or nasogastric tube, gastrostomy feeding) that occurs within 5 years of onset. 4. Inspiratory respiratory dysfunction: daytime or nighttime inspiratory stridor or frequent inspiratory sighs. 5. Severe autonomic dysfunction within 5 years of onset, including: ? Postural hypotension – a drop in systolic blood pressure of at least 30 mmHg or a drop in diastolic blood pressure of at least 15 mmHg within 3 minutes of rising from a standing position and the patient is not dehydrated, on other medications, or with a medical condition that might explain the autonomic dysfunction; ? Severe urinary retention or incontinence within 5 years of onset (excluding prolonged or minor stress incontinence in women) that is not simply functional incontinence. In male patients, urinary retention is not due to prostate disease and must be associated with erectile dysfunction. 6. Repeated (>1 fall/year) within 3 years of onset due to balance impairment. 7. Disproportionate neck pronation (dystonia) or contractures of the arms and legs within 10 years of disease onset. 8. Even after 5 years of disease duration, none of the common non-motor symptoms, including sleep disorders (hypersomnia with sleep retention disorder, excessive daytime sleepiness, REM sleep behavior disorder), autonomic dysfunction (constipation, daytime urgency to urinate, symptomatic postural hypotension), hyperosmia, psychiatric disorders (depression, anxiety, or hallucinations), or other causes of unexplained conkers. 9. cone-bundle sign not explained by other causes, defined as cone-bundle limb weakness or clearly pathologically active reflexes (including mild reflex asymmetry as well as isolated metatarsophalangeal responses). 10. bilaterally symmetrical parkinsonian syndrome. The patient or caregiver reports bilateral onset without any lateral dominance and no significant laterality is observed on objective physical examination. APPLICATION OF CRITERIA 1. Is the patient diagnosed with Parkinson’s syndrome according to the MDS criteria? If the answer is no, neither probable PD nor clinically diagnosed PD can be diagnosed; if the answer is yes, proceed to the next step of the evaluation: 2. Are there any absolute exclusion criteria? If the answer is yes, neither probable PD nor clinically confirmed PD can be diagnosed; if the answer is no, proceed to the next step of the assessment: 3. Assessment of the presence of warning signs and supportive criteria by: recording the number of warning signs; recording the number of supportive criteria; are there at least 2 supportive criteria and no warning signs? If the answer is yes, the patient meets the criteria for a clinical diagnosis of PD; if the answer is no, proceed to the next step in the assessment: more than 2 warning signs? If the answer is yes, a diagnosis of probable PD cannot be made; if the answer is no, proceed to the next step in the assessment: Is the number of warning signs equal to or less than the number of supportive criteria? If the answer is yes, the patient meets the diagnostic criteria for probable PD.