Objective: Analyze the result of the SPECT-TRODAT image exam in patients with ET and to evaluate the predictive value of a possible evolution to the patient to PD (Parkinson’s disease).

Background: Essential Tremor (ET) is the most common movement disorder in the general population and its diagnosis is based solely on clinical criteria: postural tremor, action tremor and Froment’s sign. Its main differential diagnosis is Idiopathic Parkinson’s disease (PD) However, in about 20% of ET cases there may be an overlap with signs that are more prevalent in PD, such as rest tremor making the diagnosis more difficult. The SPECT using the TRODAT-99mTc radiotracer, which has a high affinity for the dopamine transporter, can help to differentiate these two diseases, since in PD the exam is usually altered and in ET is normal.

Method: 36 patients with ET were assessed with neurological exam, Archimede’s spiral and  MDS-UPDRS III scale  in two visits with four years interval. SPECT exams were performed in all subjects after the first visit.

Results: After the second visit, 30 patients continued to be classified as ET. However, six patients developed parkinsonism associated with the ET features (ET-PD). ET-PD subjects were older than ET (76.85±8.75 vs. 58.71±17.91 years, p = 0.021), and had also an older age of tremor onset (55.66±14.37 vs. 38.1±18.23 years, p = 0.033). Presence of family history of tremor and Archimede’s spiral were not statistically significant. ET-PD group scored higher in MDS-UPDRS III (20.83±7.65 vs. 8.96±5.34 , p < 0.001), especially in regards with bradykinesia (11 vs. 2 points, p=0.0004), and none of them developed rest tremor. The SPECT was altered in 83.3% of ET-PD patients versus 33% of ET (p = 0.034 ) and 50% of ET-PD had the exam unilaterally altered corresponding to the most affected body side, in comparison with just 6% of ET group (p = 0.024).

Conclusion: Some patients with ET can develop PD. Clinical features, older age of tremor onset and a higher UPDRS score could be related to the evolution to PD in ET patients. Changes in neuroimage suggested that SPECT-TRODAT could be used to predict evolution to PD.

References: 1.Gerasimou, G. et all., (2012). SPECT study with I-123-Ioflupane (DaTSCAN) in patients with essential tremor. Is there any correlation with Parkinson’s disease? Annals of Nuclear Medicine, 26(4), 337–344. 2.Lee, M. S. et all., (1999). 123I-IPT brain SPECT study in essential tremor and Parkinson’s disease. Neurology, 52(7), 1422–1422. 3.Louis, E. D. (2014). Essential tremor: From bedside to bench and back to bedside. Current Opinion in Neurology, 27(4), 461–467. 4.Pagano, G., Ferrara, N., Brooks, D. J., & Pavese, N. (2016). Age at onset and Parkinson disease phenotype. Neurology, 86(15), 1400–1407.

« Back to MDS Virtual Congress 2021

MDS Abstracts - https://www.mdsabstracts.org/abstract/evolution-of-parkinsons-disease-in-patients-with-essential-tremor-clinical-and-neuroimaging-aspects/