Long-term follow-up study of SWEDD patients with mild parkinsonian signs
1Neurology, Agano City Hospital, Agano, Niigata, Japan.
Background:
Whether scan without evidence of dopaminergic deficit (SWEDD) can be a reliable indication of a clinical entity of Parkinson's disease (PD) is controversial.
Objective:
To evaluate the proportion of SWEDD patients with mild parkinsonian signs who are classifiable as idiopathic PD.
Methods:
32 SWEDD patients with unilateral or asymmetric finger tremor with a rest component and unilateral rigidity (Unified Parkinson's Disease Rating Scale (UPDRS)-III scores of 3-5) were enrolled. They underwent longitudinal examination by UPDRS-III, Mini-Mental State Examination (MMSE), smell test and 123I-FP-CIT SPECT (DaTSCAN) at baseline (first DaTSCAN) and at follow-up (second DaTSCAN) after 27-83 months. Age-matched controls (n=112) also underwent MMSE and smell test.
Results:
At follow-up, 21 of 32 SWEDD patients (65.6%) showed significantly reduced specific binding ratios below the normal range, that is, positive DaTSCAN, sometimes with increased asymmetry index (n=11). Among these 21 patients, the mean (SD) UPDRS-III score at follow-up was significantly higher than that at baseline (5.5 (2.2) vs 4.0 (0.5)) (p=0.003). The mean (SD) MMSE scores in SWEDD patients (n=32) at baseline and follow-up were not significantly different compared with those in controls. Olfactory function both in SWEDD patients with positive and negative DaTSCAN was significantly impaired versus controls (p<0.001), although no significant difference was recognised between patients with positive (n=21) and negative (n=11) second DaTSCAN.
Conclusion:
The majority of SWEDD patients with mild rest tremor and rigidity could be classified as having idiopathic PD in this longitudinal and long-term follow-up study.
