Differing Demographics of Vascular Parkinsonism and Idiopathic Parkinson’s Disease

1. Differing Demographics of Vascular Parkinsonism and Idiopathic Parkinson’s Disease Karthik Sarma MD Resident PGY4 Shreyansh Shah MD and William Ondo MD Dept of Neurology 14th April, 2011 63rd AAN Annual Meeting, Hawaii, 2011.

2. Disclosures • Anand K Sarma, MD • Shreyansh D Shah, MD • William G Ondo, MD No disclosures No disclosures W. Ondo: Grant Support: Ipsen, Acadia, Bayer, Takeda, Allergan, PSG, HSG, IMPAX Speaking / Consulting fees: GSK, Allergan, Novartis, Ipsen, TEVA, UCB Pharma, Merz, Lundbeck

3. Vascular Parkinsonism • Critchley introduced the term in 1929 • Initially used to describe clinical presentations consisting of… • rigidity • short-stepping gait • fixed facies • pyramidal, pseudobulbar signs and cerebellar signs • dementia and urinary incontinence • Variously referred to as Lower Body Parkinsonism, Arteriosclerotic Pseudo-Parkinsonism, etc.

4. Features of VP • Clinical • Typically older age of onset • Shorter duration of symptoms at presentation • Symmetric gait difficulties • No rest tremor • Imaging • Typically chronic small vessel ischemic changes • Pathology • Absence of Lewy body pathology

5. Imaging Source: BCM imaging database

6. Diagnosing VP • No consensus diagnostic criteria available • Diagnostic problem in the community especially when non-neurologists and non-movement disorders experts involved in making the diagnosis of Parkinsonian symptoms • Several criteria proposed including: • Vascular Rating Scale by Winikates and Jankovic • Loeb and Gandolfo’s modification of Hachinski score • Zijlmans et al criteria for VP

7. Epidemiology of idiopathic PD • Age of the patient considered as one of the most important risk factors for development of PD AGE α RISK of PD • Studies have revealed that both Incidence and Prevalence increase with age

8. Prevalence studies

9. Incidence of PD Age- and sex-specific average annual incidence rates (per 100,000 person-years) of parkinsonism and its types: Olmsted County, MN, 1976–1990* Incidence and distribution of parkinsonism in Olmsted County, Minnesota, 1976-1990. Bower JH, Maraganore DM, McDonnell SK, Rocca WA. Neurology. 1999 Apr 12;52(6):1214-20.

10. Question… Does the misdiagnosis of VP as PD increase the age of onset of PD in epidemiologic studies?

11. Hypothesis VP misdiagnosed as PD would cause the average age at symptom onset of PD to increase, altering the age related distribution of PD and hence the epidemiology of PD. The incidence of PD in the population follows a bell shaped (normal) distribution about a median age of 60 years.

12. Study Methods • Queried the PDCMDC database for the last 100 consecutive active patients with a diagnosis of VP and PD each. • Collected demographic information including age at symptom onset, risk factors, clinical and radiological features. • Examined entire database for diagnoses ratio. • Calculated how VP would alter epidemiology of PD if labeled as PD.

13. Results • No. of VP charts examined: 108 • Diagnosis changed after initial assignment: 10 • Total No. of VP considered for analysis: 98 • The difference of the mean age at symptom onset between VP with and without overt stroke was not significantly different, p = 0.34

14. Results continued *- using Mann Whitney U test

15. Early Clinical Features: Comparison * Chi Square test

16. Prominent Clinical Features at Presentation % Patients Clinical features

17. Risk Factors: Comparison * Chi Square test

18. Risk Factors: Comparison * Chi Square test

19. Risk Factors % Patients Vascular Risk Factors

20. Imaging Characteristics % Patients

21. Age wise distribution of Onset of Symptoms % Patients Age Groups in years Age Groups in years

22. Caveats of extrapolating the results to predict age of onset for “PD”… • Sample of 200 patients may not be a representative sample of the database • Patient sample and database may not be representative of the population • Obvious recruitment bias at a Parkinson’s Disease center • Relative occurrence of VP and PD in the population are not similar to database

23. But if we did extrapolate… Does VP misdiagnosed as PD increase the average age at onset of PD?

24. Mean Age at Onset for PD would increase from: 57.81 to 59.36 [ 73.59 * 805 / 7742 ] + [ 57.81 * 6937 / 7742 ] = 59.36 Proportional weighting based on relative occurrence

25. Value of study • Provides a possible explanation for variability in epidemiology trials of age of onset for PD and more commonly, falsely elevated ages • Encouraged future studies such as the ongoing sorting of our entire database • Demands a population based incidence study differentiating VP and PD • Importance of differentiating the two in the community given disparate pathophysiology, progression, response to treatment, prognosis and importantly, person making the diagnosis.

26. Acknowledgements I would like to thank my friend and colleague, Yogeshwar V Kalkonde for his valuable input and help.

27. Questions? View of Waikiki sunset from my room. Karthik Sarma; 9th April, 2011. Thank you!