Is Clinical Diagnosis of Parkinson’s disease (IPD) Enough?
Still, some clinicians argue that their clinical diagnosis is sufficient. However, two considerations are worth noting.
First, Walker and colleagues (J Neurol Neurosurg Psychiatry. 2007;78:1176-1181) demonstrated that the specificity of clinical diagnosis was considerably lower than that of DaTSCAN. Sensitivity of clinical diagnosis and DaTSCAN were similar at about 85%; however, specificity of DaTSCAN was 86% and that of clinical examination was only 50%. One example of a clinically deceptive situation is psychogenic or pharmacological tremor, which can be confused with IPD, leading to unnecessary treatment.
Second, the other parkinsonian syndromes, such as Lewy Body Dementia, can initially look clinically indistinguishable from IPD. DaTSCAN gives much more of a differentiation.
Using quantitative analysis can greatly enhance the diagnostic potential of DaTSCAN.
A Superior Way to Differentiate
Classically, IPD can present with asymmetry in the loss of dopamine reuptake sites, manifested by DaTSCAN tracer binding. In this case, the binding is much lower on the left and there is a classic posterior to anterior gradient. In contrast, in the case of MSA, there is symmetrical binding. Note that a posterior to anterior gradient is still present. A superior way to differentiate IPD from the other parkinsonian syndromes is by a combination of DaTSCAN with perfusion SPECT or fluorodeoxyglucose PET.
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