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Parkinson's Disease: Sensitivity and Specificity

Introduction: Specifically, idiopathic Parkinson's. The differential diagnosis would include Essential Tremor, Parkinson's-Plus syndromes (Multi-System Atrophy, Progressive Supranuclear Palsy, Dementia with Lewy Bodies), and secondary Parkinson's (toxic such as MPTP, traumatic such as dementia pugilistica).

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Tags: Neurologic Tag this Diagnosis.

Prevalence

Population / CalculatorPrevalence Comments / Study / Link
Age > 60 1%
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The sensitivity and specificity of findings for Parkinson's Disease are listed below. See the left navigation bar to change the display.

Sensitive Findings

Finding SensitivitySpecificity Comments, Study
Can Ride a Bicycle Edit 96%52%

i.e. patient can still ride a bicycle

versus Parkinson's-Plus

Study: The Lancet 377(9760):125 (2011). http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(11)60018-4/fulltext

Levodopa Responsiveness Edit 94%30%

>94% of true PD patients will respond to levodopa in general (see the other entry for a specific study, albeit with lower responsiveness). However, many other disorders, e.g. MSA and DLB, have good initial responsiveness (my 30% was ballparking based on separate series with different diseases).

Study: Arch Neurol. 1999 Jan;56(1):33-9. PMID: 9923759

Rigidity Edit Sensitivity = 89%

specificity not assessed but believed to be poor

Study: Arch Neurol. 1999 Jan;56(1):33-9. PMID: 9923759

Poorly Diagnostic Findings

Finding SensitivitySpecificity Comments, Study
Levodopa Challenge Edit 71%81%

250/50 mg of L-dopa-carbidopa for an improvement of 30% on UPDRS score. At 24 month follow-up, they were re-tested with 1 g for 1 month when required. At this point, clinical criteria of the U.K. Parkinson's Disease Society Brain Bank were applied and definitive clinical diagnosis of PD was made.

Study: Mov Disord. 2002 Jul;17(4):795-8. PMID: 12210878

Cardinal Features Edit 69%75%

>=2 of tremor, rigidity, and bradykinesia. Confirmed by autopsy.

Study: Arch Neurol. 1999 Jan;56(1):33-9. PMID: 9923759

Resting Tremor Edit 69%66%

i.e. 34% of MSA patients have resting tremor.

Study: Arch Neurol. 1999 Jan;56(1):33-9. PMID: 9923759

Asymmetric Onset Edit 72%58%

i.e. 42% of movement disorders that are not PD begin asymmetrically

Study: Arch Neurol. 1999 Jan;56(1):33-9. PMID: 9923759

Bradykinesia Edit Sensitivity = 77%

specificity not assessed

Study: Arch Neurol. 1999 Jan;56(1):33-9. PMID: 9923759

Postural Instability Edit Sensitivity = 37%

within first 5 years of presentation. Specificity not assessed, however early postural instability is usually diagnostic of PSP.

Study: Arch Neurol. 1999 Jan;56(1):33-9. PMID: 9923759