Do non-motor symptoms in Parkinson's disease differ from essential tremor before initial diagnosis? A clinical and...

Non-motor symptoms (NMS) in Parkinson's disease (PD) are common, increase the patients' disability and have a significantly negative impact on their quality of life. Essential tremor (ET) is also affected by non-motor symptoms and often enters into the differential diagnosis with PD. Brain scintigraphy with [(123)I]β-CIT SPECT is a technique used to facilitate differential diagnosis between PD and ET.

We evaluated both motor impairment (MDS-UPDRS-III) and non-motor symptoms (NMSQuest) in patients who underwent a [(123)I]β-CIT SPECT examination for diagnostic purposes. Both the clinical and the scintigraphic data obtained from the selected PD (n = 31) and ET (n = 22) patients were compared.

We did not detect a significant difference in the total number of NMS reported by either PD (10.4 ± 4.9) or ET patients (8.41 ± 3.3). PD patients reported more drooling (29%), hyposmia (32.2%), hallucinations (19.3%), difficulty in concentrating (51.6%), orthostatic dizziness (67.7%), falling (19.3%), vivid dreams (32.2%), REM sleep behavior disorder (58%), and diplopia (22.5%) compared with ET patients. PD patients who complained of drooling, orthostatic dizziness, and diplopia had greater denervation of the caudata than did the PD patients who did not report the same symptoms. The differences observed were not associated with differences in age, sex, UPDRS-III score, and the presence/absence of tremor.

The declaration of non-motor symptoms is influenced by subjective factors that are widely suggestible. When analyzed early and before receiving a definitive diagnosis, PD patients complain of specific symptoms that seem to depend on different pathogenetic mechanisms.