Examination and clinical correlation of olfactory system disorders by an objective method Sniffin' Sticks odor test in Parkinson's disease

Abstract

Objectives: This study is aimed to investigate the frequency of olfactory dysfunction in Parkinson’s Disease (PD) and its relationship with motor/non-motor symptoms and treatment in comparison to isolated olfactory dysfunction patients and healthy controls.

Methods: This study includes 40 PD patients, 37 anosmia patients and 42 healthy controls. PD patients are evaluated with PD evaluation form including; sociodemographic features, disease history, Unified Parkinson’s Disease Rating Scale (UPDRS) score, and Hoehn and Yahr (H-Y) score. All patients were evaluated with cranial CT and MRI. Olfactory function was evaluated with Sniffin' Sticks Test (SST). A p value < 0.05 was considered to be statistically significant. 

Results::The mean age and median disease duration of PD patients were 62.2 ± 11.9 and 4.5 years, respectively. Fifteen of them had comorbid diseases. Median UPDRS score was 19.5 (4-60) and 67.5% of subjects were H-Y Stage-1. Most frequent non-motor symptom was constipation (67.5%). Olfactory dysfunction was found in 75% of PD patients by SST. No difference was observed between PD patients with or without olfactory dysfunction regarding non-motor symptoms and dementia (p > 0.05). Patients with isolated olfactory dysfunction were significntly younger than both patients with PD and the healthy controls (p <0.001). Non-motor symptoms were not significantly different between isolated olfactory dysfunction group and healthy subjects (p > 0.05). 

Conclusions: Most of the patients with PD had olfactory dysfunction, which was found not to be correlated with disease duration and stage based on the results of an objective test, namely Sniffin-Sticks odor test.This result might support the role of non-dopaminergic pathways in the etiopathogenesis of olfactory dysfunctions in PD. In clinical practice, data from further studies is required to comment on an ideal screening or diagnostic test in the olfactory system evaluation of early stage PD patients that would be repeatable and objective. 

Keywords

• Parkinson’s disease
• olfactory dysfunction
• Sniffin' Sticks test
• anosmia

References

1. 1. Tolosa E, Wenning G, Poewe W. The diagnosis of Parkinson's disease. Lancet Neurol 2006;5:75-86.
2. 2. Ubeda-Banon I, Saiz-Sanchez D, de la Rosa-Prieto C, Martinez-Marcos A. α-synuclein in the olfactory system in Parkinson's disease: role of neural connections on spreading pathology. Brain Struct Funct 2014;219:1513-26.
3. 3. Chaudhuri KR, Schapira AHV. Non-motor symptoms of Parkinson's disease: dopaminergic pathophysiology and treatment. Lancet Neurol 2009;8:464-74.
4. 4. Wu L, Mu N, Yang F, Zang J, Zheng JP. A study of the non-motor symptoms in early Parkinson's disease with olfactory deficits. Eur Rev Med Pharmacol Sci 2016;20:3857-62.
5. 5. Morley JF, Duda JE. Neuropsychological correlates of olfactory dysfunction in Parkinson's disease. J Neurol Sci 2011;310:228-30.
6. 6. Muzerengi S, Contrafatto D, Chaudhuri KR. Non-motor symptoms: identification and management. Parkinsonism Relat Disord 2007;13 Suppl 3:S450-6.
7. 7. Berendse HW, Roos DS, Raijmakers P, Doty RL. Motor and non-motor correlates of olfactory dysfunction in Parkinson's disease. J Neurol Sci 2011;310:21-4.
8. 8. Doty RL. Olfaction in Parkinson's disease. Parkinsonism Relat Disord 2007;13 Suppl 3:S225-8.

9. 9. Rossi M, Perez-Lloret S, Millar Vernetti P, Drucaroff L, Costanzo E, Ballesteros D, et al. Olfactory dysfunction evaluation is not affected by comorbid depression in Parkinson's disease. Mov Disord 2015;30:1275-9.
10. 10. Doty RL. Olfaction in Parkinson's disease and related disorders. Neurobiol Dis 2012;46:527-52.
11. 11. Lee EY, Eslinger PJ, Du G, Kong L, Lewis MM, Huang X. Olfactory-related cortical atrophy is associated with olfactory dysfunction in Parkinson's disease. Mov Disord 2014;29:1205-8.
12. 12. Folstein MF, Folstein SE, McHugh PR. "Mini-mental state". A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975;12:189-98.
13. 13. Hummel T, Sekinger B, Wolf SR, Pauli E, Kobal G. 'Sniffin' Sticks': olfactory performance assessed by the combined testing of odor identification, odor discrimination and olfactory threshold. Chem Senses 1997;22:39-52.
14. 14. Hoyles K, Sharma JC. Olfactory loss as a supporting feature in the diagnosis of Parkinson's disease: a pragmatic approach. J Neurol 2013;260:2951-8.
15. 15. Hahner A, Maboshe W, Baptista RB, Storch A, Reichmann H, Hummel T. Selective hyposmia in Parkinson's disease? J Neurol 2013;260:3158-60.
16. 16. Moccia M, Picillo M, Erro R, Vitale C, Amboni M, Palladino R, et al. How does smoking affect olfaction in Parkinson's disease? J Neurol Sci 2014;340:215-7.
17. 17. Witt M, Bormann K, Gudziol V, Pehlke K, Barth K, Minovi A, et al. Biopsies of olfactory epithelium in patients with Parkinson's disease. Mov Disord 2009;24:906-14.
18. 18. Ozelius LJ, Senthil G, Saunders-Pullman R, Ohmann E, Deligtisch A, Tagliati M, et al. LRRK2 G2019S as a cause of Parkinson's disease in Ashkenazi Jews. N Engl J Med 2006;354:424-5.