The tremor that occurs only when the limb is maintained in a certain position is called postural tremor, most commonly when the upper limb is flat and extended. The tremor is often suppressed during active movement, intensified during emotional stress, and disappears at complete rest and sleep. Postural tremor is one of the symptoms of Parkinson’s disease. The following are some of the tests for Parkinson’s disease: 1. Laboratory tests 1. decreased serum renin activity and tyrosine content; decreased NE and 5-HT content in the substantia nigra and striatum, and 50% lower glutamic acid decarboxylase (GAD) activity compared to controls. 2, GABA in CSF decreased, and the content of HVA, a metabolite of DA and 5-HT in CSF, was significantly reduced. 3, Biochemical assay The content of growth inhibitor in CSF was decreased by radioimmunoassay. Urinary DA and its metabolites 3-methoxytyramine, 5-HT and epinephrine, NE were also reduced. The CT and MRI images show that Parkinson’s disease is a degenerative disease of the central nervous system, and the pathological changes are mainly in the substantia nigra, striatum, pallidum, caudate nucleus and cerebral cortex. The T2-weighted image often shows multiple high-signal spots in the basal ganglia and white matter of the brain. (1) Functional images through dopamine receptors (DAR): Dopamine receptors are widely distributed in the dopaminergic pathways in the central nervous system, mainly in the substantia nigra and striatum. SPECT is used to diagnose early Parkinson’s disease by injecting radionuclides, currently 123I-IBZM, 131I-IBZM, specific D2 receptor markers, intravenously into the body to reflect the number and function of DAR receptors by the ratio of radioactivity in the basal ganglia region to frontal, occipital or cerebellar radioactivity. If patients are treated early with dopa preparations, the DAR (D2) is upregulated in the brain contralateral to the onset of the disease. In patients with mid- to late-stage Parkinson’s disease on long-term dopa preparations, the basal ganglia/occipital lobe and basal ganglia/frontal lobe ratios in the brain are reduced. SPECT functional imaging can only detect the number of DAR receptors and cannot help to confirm the diagnosis of primary Parkinson’s disease, but can distinguish certain secondary Parkinson’s disease, and can also be used as an indicator of the evolution of Parkinson’s disease and the effect of drug therapy. (2) Dopamine transporter protein (DAT) functional imaging: How DAT transports dopamine (DA) is not clear, DAT is mainly distributed in the basal ganglia and thalamus, followed by the frontal lobe, DAT content is positively correlated with the severity of Parkinson’s disease, and the decrease of DAT in the basal ganglia is significant in patients with early Parkinson’s disease. SPECT was performed using 11C-WIN35428, 123Ibeta;-CIT, and the basal ganglia/cerebellar activity ratio as well as the thalamus/cerebellar activity ratio, reflecting the amount of DAT in different regions of the center, were measured after intravenous injection into the body. In patients with early stage Parkinson’s disease, the number of DAT in the basal ganglia region is significantly reduced. 3. PET functional imaging Positron emission tomography (PET) for the diagnosis of Parkinson’s disease, which works basically similar to SPECT in principle and method, currently relies mainly on brain glucose metabolism imaging, generally using 18F deoxyglucose (18FDG). This is because the local glucose metabolic rate in the striatum is moderately reduced in early Parkinson’s disease patients and further reduced in late stages. There are many receptor imaging agents with PET, and PET neurotransmitter function imaging agents are mainly used with nuclei such as 18F-dopa-PET (18FD-PET), and the basic principle is the same as SPECT. PET can be used for early diagnosis of Parkinson’s disease, and can be used for early diagnosis in people at high risk of Parkinson’s disease, and is an objective indicator of the severity of the disease.